WorldWideScience

Sample records for white light generation

  1. White Light Generation in Human Saliva

    Science.gov (United States)

    Santhosh, C.; Dharmadhikari, A. K.; Dharmadhikari, J. A.; Alti, K.; Mathur, D.

    2011-07-01

    Interaction of intense, femto-second pulses of infrared light (800 nm) with water generates white light supercontinuum due to nonlinear optical effects. This supercontinuum was found to be suppressed by the addition of alpha amylase, a major protein in the human saliva. We have studied the suppression of supper continuum by human saliva, collected from healthy subjects with and without smoking habits. Suppression of the blue-sided components was observed significantly in non-smokers saliva than chain smokers.

  2. Generation of three wide frequency bands within a single white-light cavity

    Science.gov (United States)

    Othman, Anas; Yevick, David; Al-Amri, M.

    2018-04-01

    We theoretically investigate the double-Λ scheme inside a Fabry-Pérot cavity employing a weak probe beam and two strong driving fields together with an incoherent pumping mechanism. By generating analytical expressions for the susceptibility and applying the white-light cavity conditions, we devise a procedure that reaches the white-light condition at a smaller gas density than the values typically cited in similar previous studies. Further, when the intensities of the two driving fields are equal, a single giant white band is obtained, while for unequal driving fields three white bands can be present in the cavity. Two additional techniques are then advanced for generating three white bands and a method is described for displacing the center frequency of the bands. Finally, some potential applications are suggested.

  3. Simulation of white light generation and near light bullets using a novel numerical technique

    Science.gov (United States)

    Zia, Haider

    2018-01-01

    An accurate and efficient simulation has been devised, employing a new numerical technique to simulate the derivative generalised non-linear Schrödinger equation in all three spatial dimensions and time. The simulation models all pertinent effects such as self-steepening and plasma for the non-linear propagation of ultrafast optical radiation in bulk material. Simulation results are compared to published experimental spectral data of an example ytterbium aluminum garnet system at 3.1 μm radiation and fits to within a factor of 5. The simulation shows that there is a stability point near the end of the 2 mm crystal where a quasi-light bullet (spatial temporal soliton) is present. Within this region, the pulse is collimated at a reduced diameter (factor of ∼2) and there exists a near temporal soliton at the spatial center. The temporal intensity within this stable region is compressed by a factor of ∼4 compared to the input. This study shows that the simulation highlights new physical phenomena based on the interplay of various linear, non-linear and plasma effects that go beyond the experiment and is thus integral to achieving accurate designs of white light generation systems for optical applications. An adaptive error reduction algorithm tailor made for this simulation will also be presented in appendix.

  4. Photoluminescence from a Tb-doped photonic crystal microcavity for white light generation

    International Nuclear Information System (INIS)

    Li Yigang; Almeida, Rui M

    2010-01-01

    Terbium-doped one-dimensional triple microcavities have been prepared by sol-gel processing. The photoluminescence (PL) of Tb 3+ ions outside a microcavity structure, when excited by blue laser light at 488 nm, consisted of three distinct peaks at 542, 587 and 619 nm. When embedded in the microcavities, the three Tb 3+ PL peaks were enhanced, balanced and broadened by the photonic crystal structure and combined into a continuous broad band. An analysis in the CIE colour space showed that white light can be obtained by mixing the modified Tb 3+ PL with the blue exciting light, while this is impossible with the original PL profile. This novel technique may improve white light generation by enhancing and modifying the spontaneous emission of current phosphors. It may also lead to the development of new rare-earth phosphor materials based on 4f-4f transitions, able to generate white light more efficiently, via simpler and cheaper alternatives to the current phosphor compositions. A novel configuration to combine this kind of structure with a white light-emitting-diode (LED) is also proposed.

  5. Tandem white organic light-emitting diodes adopting a C60:rubrene charge generation layer

    International Nuclear Information System (INIS)

    Bi Wen-Tao; Wu Xiao-Ming; Hua Yu-Lin; Sun Jin-E; Xiao Zhi-Hui; Wang Li; Yin Shou-Gen

    2014-01-01

    Organic bulk heterojunction fullerence (C 60 ) doped 5, 6, 11, 12-tetraphenylnaphthacene (rubrene) as the high quality charge generation layer (CGL) with high transparency and superior charge generating capability for tandem organic light emitting diodes (OLEDs) is developed. This CGL shows excellent optical transparency about 90%, which can reduce the optical interference effect formed in tandem OLEDs. There is a stable white light emission including 468 nm and 500 nm peaks from the blue emitting layer and 620 nm peak from the red emitting layer in tandem white OLEDs. A high efficiency of about 17.4 cd/A and CIE coordinates of (0.40, 0.35) at 100 cd/m 2 and (0.36, 0.34) at 1000 cd/m 2 have been demonstrated by employing the developed CGL, respectively. (condensed matter: electronic structure, electrical, magnetic, and optical properties)

  6. White Light Generation and Anisotropic Damage in Gold Films near Percolation Threshold

    DEFF Research Database (Denmark)

    Novikov, Sergey M.; Frydendahl, Christian; Beermann, Jonas

    2017-01-01

    in vanishingly small gaps between gold islands in thin films near the electrically determined percolation threshold. Optical explorations using two-photon luminescence (TPL) and near-field microscopies reveals supercubic TPL power dependencies with white-light spectra, establishing unequivocally...... that the strongest TPL signals are generated close to the percolation threshold films, and occurrence of extremely confined (similar to 30 nm) and strongly enhanced (similar to 100 times) fields at the illumination wavelength. For linearly polarized and sufficiently powerful light, we observe pronounced optical...

  7. White light generation tuned by dual hybridization of nanocrystals and conjugated polymers

    International Nuclear Information System (INIS)

    Demir, Hilmi Volkan; Nizamoglu, Sedat; Ozel, Tuncay; Mutlugun, Evren; Huyal, Ilkem Ozge; Sari, Emre; Holder, Elisabeth; Tian Nan

    2007-01-01

    Dual hybridization of highly fluorescent conjugated polymers and highly luminescent nanocrystals (NCs) is developed and demonstrated in multiple combinations for controlled white light generation with high color rendering index (CRI) (> 80) for the first time. The generated white light is tuned using layer-by-layer assembly of CdSe/ZnS core-shell NCs closely packed on polyfluorene, hybridized on near-UV emitting nitride-based light emitting diodes (LEDs). The design, synthesis, growth, fabrication and characterization of these hybrid inorganic-organic white LEDs are presented. The following experimental realizations are reported: (i) layer-by-layer hybridization of yellow NCs (λ PL =580 nm) and blue polyfluorene (λ PL =439 nm) with tristimulus coordinates of (x, y)=(0.31, 0.27), correlated color temperature of T c =6962 K and CRI of R a =53.4; (ii) layer-by-layer assembly of yellow and green NCs (λ PL =580 and 540 nm) and blue polyfluorene (λ PL =439 nm) with (x, y)=(0.23, 0.30), T c =14395 K and R a =65.7; and (iii) layer-by-layer deposition of yellow, green and red NCs (λ PL =580, 540 and 620 nm) and blue polyfluorene (λ PL =439 nm) with (x, y)=(0.38, 0.39), T c =4052 K and R a = 83.0. The CRI is demonstrated to be well controlled and significantly improved by increasing multi-chromaticity of the NC and polymer emitters

  8. White light generation tuned by dual hybridization of nanocrystals and conjugated polymers

    Energy Technology Data Exchange (ETDEWEB)

    Demir, Hilmi Volkan [Devices and Sensors Group and Nanotechnology Research Center, Bilkent University, Ankara 06800 (Turkey); Nizamoglu, Sedat [Devices and Sensors Group and Nanotechnology Research Center, Bilkent University, Ankara 06800 (Turkey); Ozel, Tuncay [Devices and Sensors Group and Nanotechnology Research Center, Bilkent University, Ankara 06800 (Turkey); Mutlugun, Evren [Devices and Sensors Group and Nanotechnology Research Center, Bilkent University, Ankara 06800 (Turkey); Huyal, Ilkem Ozge [Devices and Sensors Group and Nanotechnology Research Center, Bilkent University, Ankara 06800 (Turkey); Sari, Emre [Devices and Sensors Group and Nanotechnology Research Center, Bilkent University, Ankara 06800 (Turkey); Holder, Elisabeth [Functional Polymers Group and Institute of Polymer Technology, University of Wuppertal, Gaussstrasse 20, D-42097 Wuppertal (Germany); Tian Nan [Functional Polymers Group and Institute of Polymer Technology, University of Wuppertal, Gaussstrasse 20, D-42097 Wuppertal (Germany)

    2007-10-15

    Dual hybridization of highly fluorescent conjugated polymers and highly luminescent nanocrystals (NCs) is developed and demonstrated in multiple combinations for controlled white light generation with high color rendering index (CRI) (> 80) for the first time. The generated white light is tuned using layer-by-layer assembly of CdSe/ZnS core-shell NCs closely packed on polyfluorene, hybridized on near-UV emitting nitride-based light emitting diodes (LEDs). The design, synthesis, growth, fabrication and characterization of these hybrid inorganic-organic white LEDs are presented. The following experimental realizations are reported: (i) layer-by-layer hybridization of yellow NCs ({lambda}{sub PL}=580 nm) and blue polyfluorene ({lambda}{sub PL}=439 nm) with tristimulus coordinates of (x, y)=(0.31, 0.27), correlated color temperature of T{sub c}=6962 K and CRI of R{sub a}=53.4; (ii) layer-by-layer assembly of yellow and green NCs ({lambda}{sub PL}=580 and 540 nm) and blue polyfluorene ({lambda}{sub PL}=439 nm) with (x, y)=(0.23, 0.30), T{sub c}=14395 K and R{sub a}=65.7; and (iii) layer-by-layer deposition of yellow, green and red NCs ({lambda}{sub PL}=580, 540 and 620 nm) and blue polyfluorene ({lambda}{sub PL}=439 nm) with (x, y)=(0.38, 0.39), T{sub c}=4052 K and R{sub a}= 83.0. The CRI is demonstrated to be well controlled and significantly improved by increasing multi-chromaticity of the NC and polymer emitters.

  9. White light emission and second harmonic generation from secondary group participation (SGP) in a coordination network.

    Science.gov (United States)

    He, Jun; Zeller, Matthias; Hunter, Allen D; Xu, Zhengtao

    2012-01-25

    We describe a white emitting coordination network solid that can be conveniently applied as a thin film onto a commercial UV-LED lamp for practical white lighting applications. The solid state material was discovered in an exercise of exploring molecular building blocks equipped with secondary groups for fine-tuning the structures and properties of coordination nets. Specifically, CH(3)SCH(2)CH(2)S- and (S)-CH(3)(OH)CHCH(2)S- (2-hydroxylpropyl) were each attached as secondary groups to the 2,5- positions of 1,4-benzenedicarboxylic acid (bdc), and the resultant molecules (L1 and L2, respectively) were crystallized with Pb(II) into the topologically similar 3D nets of PbL1 and PbL2, both consisting of interlinked Pb-carboxyl chains. While the CH(3)S- groups in PbL1 are not bonded to the Pb(II) centers, the hydroxy groups in PbL2 participate in coordinating to Pb(II) and thus modify the bonding features around the Pb(II), but only to a slight and subtle degree (e.g., Pb-O distances 2.941-3.116 Å). Interestingly, the subtle change in structure significantly impacts the properties, i.e., while the photoluminescence of PbL1 is yellowish green, PbL2 features bright white emission. Also, the homochiral side group in PbL2 imparts significant second harmonic generation, in spite of its seemingly weak association with the main framework (the NLO-phore). In a broad perspective, this work showcases the idea of secondary group participation (SGP) in the construction of coordination networks, an idea that parallels that of hemilabile ligands in organometallics and points to an effective strategy in developing advanced functions in solid state framework materials. © 2011 American Chemical Society

  10. Donor doping process and white light generation in CaMoO4 powders with multivalence Pr codoping

    International Nuclear Information System (INIS)

    Zhu Fang; Xiao Zhisong; Zhang Feng; Yan Lu; Huang Anping

    2011-01-01

    Both trivalent praseodymium (Pr 3+ ) and quadrivalent praseodymium (Pr 4+ ) were doped in molybdate powders. Visible emission from matrix was enhanced by multivalent Pr codoping. It was proposed that Pr 3+ ions was donor and supplied quasi-free electron when Pr 3+ took place the Pr 4+ sites. The result showed that multivalence codoping would be an effective way to enhance emission of CaMoO 4 . White light can be generated from Ca 0.98 Pr 0.02 MoO 4 powder via combination of broadband emissions originated from CaMoO 4 matrix and radiative transition of Pr 3+ . It showed warm white light with T c of 3450 K that implies promising application in white light emitting diodes (LEDs).

  11. White emitting CdS quantum dot nanoluminophores hybridized on near-ultraviolet LEDs for high-quality white light generation and tuning

    International Nuclear Information System (INIS)

    Nizamoglu, Sedat; Mutlugun, Evren; Akyuz, Ozgun; Perkgoz, Nihan Kosku; Demir, Hilmi Volkan; Liebscher, Lydia; Sapra, Sameer; Gaponik, Nikolai; Eychmueller, Alexander

    2008-01-01

    To generate white light using semiconductor nanocrystal (NC) quantum dots integrated on light emitting diodes (LEDs), multiple hybrid device parameters (emission wavelengths of the NCs and the excitation platform, order of the NCs with different sizes, amount of the different types of NCs, etc) need to be carefully designed and properly implemented. In this study, we introduce and demonstrate white LEDs based on simple device hybridization using only a single type of white emitting CdS quantum dot nanoluminophores on near-ultraviolet LEDs. Here we present their design, synthesis-growth, fabrication and characterization. With these hybrid devices, we achieve high color rendering index (>70), despite using only a single NC type. Furthermore, we conveniently tune their photometric properties including the chromaticity coordinates, correlated color temperature, and color rendering index with the number of hybridized nanoluminophores in a controlled manner

  12. Phosphors for near UV-Emitting LED's for Efficacious Generation of White Light

    Energy Technology Data Exchange (ETDEWEB)

    McKittrick, Joanna [Univ. of California, San Diego, CA (United States)

    2013-09-30

    1) We studied phosphors for near-UV (nUV) LED application as an alternative to blue LEDs currently being used in SSL systems. We have shown that nUV light sources could be very efficient at high current and will have significantly less binning at both the chip and phosphor levels. We identified phosphor blends that could yield 4100K lamps with a CRI of approximately 80 and LPWnUV,opt equal to 179 for the best performing phosphor blend. Considering the fact that the lamps were not optimized for light coupling, the results are quite impressive. The main bottleneck is an optimum blue phosphor with a peak near 440 nm with a full width half maximum of about 25 nm and a quantum efficiency of >95%. Unfortunately, that may be a very difficult task when we want to excite a phosphor at ~400 nm with a very small margin for Stokes shift. Another way is to have all the phosphors in the blend having the excitation peak at 400 nm or slightly shorter wavelength. This could lead to a white light source with no body color and optimum efficacy due to no self-absorption effects by phosphors in the blend. This is even harder than finding an ideal blue phosphor, but not necessarily impossible. 2) With the phosphor blends identified, light sources using nUV LEDs at high current could be designed with comparable efficacy to those using blue LEDs. It will allow us to design light sources with multiple wattages using the same chips and phosphor blends simply by varying the input current. In the case of blue LEDs, this is not currently possible because varying the current will lower the efficacy at high current and alter the color point. With improvement of phosphor blends, control over CRI could improve. Less binning at the chip level and also at the phosphor blend level could reduce the cost of SSL light sources. 3) This study provided a deeper understanding of phosphor characteristics needed for LEDs in general and nUV LEDs in particular. Two students received Ph.D. degrees and three

  13. White light generation from Dy3+-doped yttrium aluminium gallium mixed garnet nano-powders

    International Nuclear Information System (INIS)

    Praveena, R.; Balasubrahmanyam, K.; Jyothi, L.; Venkataiah, G.; Basavapoornima, Ch.; Jayasankar, C.K.

    2016-01-01

    Yttrium aluminium gallium garnet (here after referred as YAGG), Y 3 Al 5−y Ga y O 12 (where y=1.0, 2.5 and 4.0), nano-powders doped with 1.0 mol% of dysprosium (Dy 3+ ) ions were synthesised by the citrate sol–gel method. The structure, phase evolution, morphology and luminescence properties of these nano-crytalline powders were characterized by means of XRD, FTIR, Raman, electron microscopy and UV–vis spectroscopy. From the XRD results, the crystallite sizes were found to be in the range of 18–26 nm. Excitation spectra of YAGG nano-powders showed that the samples can be efficiently excited by near UV and blue LEDs. Upon excitation at 448 nm, the emission spectra of all these samples showed two bands centred at 485 (blue) and 585 nm (yellow) which corresponds to the 4 F 9/2 → 6 H 15/2 and 4 F 9/2 → 6 H 13/2 transitions of Dy 3+ ion, respectively. Intensity of blue emission was found to be stronger than the yellow emission in all the three samples. Integrated yellow to blue (Y/B) emission intensity was found to be increased with increasing the Ga content in the present YAGG host. Therefore, concentration (0.1, 1.0, 2.0 and 4.0 mol%) of Dy 3+ ions was varied in the Ga rich (Y 3 Ga 4 AlO 12 ) nano-powder. The chromaticity co-ordinates of all the prepared nano-powders were located in the white light region and also found to be dependent on Dy 3+ ion concentration and excitation wavelength. The decay curves for 4 F 9/2 level of Dy 3+ ion exhibited non-exponential nature in all the studied samples and the lifetime values remained constant (~1.0 ms) with increasing the Ga content, but were found to decrease with increasing the Dy 3+ ion concentration. The results indicated that 2.0 mol% of Dy 3+ -doped Y 3 Ga 4 AlO 12 nano-powder under 352 nm excitation is suitable for the white light emitting device applications.

  14. Energy transfer and colour tunability in UV light induced Tm3+/Tb3+/Eu3+: ZnB glasses generating white light emission.

    Science.gov (United States)

    Naresh, V; Gupta, Kiran; Parthasaradhi Reddy, C; Ham, Byoung S

    2017-03-15

    A promising energy transfer (Tm 3+ →Tb 3+ →Eu 3+ ) approach is brought forward to generate white light emission under ultraviolet (UV) light excitation for solid state lightening. Tm 3+ /Tb 3+ /Eu 3+ ions are combinedly doped in zinc borate glass system in view of understanding energy transfer process resulting in white light emission. Zinc borate (host) glass displayed optical and luminescence properties due to formation of Zn(II) x -[O(-II)] y centres in the ZnB glass matrix. At 360nm (UV) excitation, triply doped Tm 3+ /Tb 3+ /Eu 3+ : ZnB glasses simultaneously shown their characteristic emission bands in blue (454nm: 1 D 2 → 3 F 4 ), green (547nm: 5 D 4 → 7 F 5 ) and red (616nm: 5 D 0 → 7 F 2 ) regions. In triple ions doped glasses, energy transfer dynamics is discussed in terms of Forster-Dexter theory, excitation & emission profiles, lifetime curves and from partial energy level diagram of three ions. The role of Tb 3+ in ET from Tm 3+ →Eu 3+ was discussed using branch model. From emission decay analysis, energy transfer probability (P) and efficiency (η) were evaluated. Colour tunability from blue to white on varying (Tb 3+ , Eu 3+ ) content is demonstrated from Commission Internationale de L'Eclairage (CIE) chromaticity coordinates. Based on chromaticity coordinates, other colour related parameters like correlated colour temperature (CCT) and colour purity are also computed for the studied glass samples. An appropriate blending of such combination of rare earth ions could show better suitability as potential candidates in achieving multi-colour and warm/cold white light emission for white LEDs application in the field of solid state lightening. Copyright © 2016 Elsevier B.V. All rights reserved.

  15. Two stacked tandem white organic light-emitting diodes employing WO3 as a charge generation layer

    Science.gov (United States)

    Bin, Jong-Kwan; Lee, Na Yeon; Lee, SeungJae; Seo, Bomin; Yang, JoongHwan; Kim, Jinook; Yoon, Soo Young; Kang, InByeong

    2016-09-01

    Recently, many studies have been conducted to improve the electroluminescence (EL) performance of organic lightemitting diodes (OLEDs) by using appropriate organic or inorganic materials as charge generation layer (CGL) for their application such as full color displays, backlight units, and general lighting source. In a stacked tandem white organic light-emitting diodes (WOLEDs), a few emitting units are electrically interconnected by a CGL, which plays the role of generating charge carriers, and then facilitate the injection of it into adjacent emitting units. In the present study, twostacked WOLEDs were fabricated by using tungsten oxide (WO3) as inorganic charge generation layer and 1,4,5,8,9,11- hexaazatriphenylene hexacarbonitrile (HAT-CN) as organic charge generation layer (P-CGL). Organic P-CGL materials were used due to their ease of use in OLED fabrication as compared to their inorganic counterparts. To obtain high efficiency, we demonstrate two-stacked tandem WOLEDs as follows: ITO/HIL/HTL/HTL'/B-EML/ETL/N-CGL/P-CGL (WO3 or HAT-CN)/HTL″/YG-EML/ETL/LiF/Al. The tandem devices with blue- and yellow-green emitting layers were sensitive to the thickness of an adjacent layer, hole transporting layer for the YG emitting layer. The WOLEDs containing the WO3 as charge generation layer reach a higher power efficiency of 19.1 lm/W and the current efficiency of 51.2 cd/A with the white color coordinate of (0.316, 0.318) than the power efficiency of 13.9 lm/W, and the current efficiency of 43.7 cd/A for organic CGL, HAT-CN at 10 mA/cm2, respectively. This performance with inserting WO3 as CGL exhibited the highest performance with excellent CIE color coordinates in the two-stacked tandem OLEDs.

  16. White light generation using CdSe/ZnS core-shell nanocrystals hybridized with InGaN/GaN light emitting diodes

    International Nuclear Information System (INIS)

    Nizamoglu, S; Ozel, T; Sari, E; Demir, H V

    2007-01-01

    We introduce white light generation using CdSe/ZnS core-shell nanocrystals of single, dual, triple and quadruple combinations hybridized with InGaN/GaN LEDs. Such hybridization of different nanocrystal combinations provides the ability to conveniently adjust white light parameters including the tristimulus coordinates (x,y), correlated colour temperature (T c ) and colour rending index (R a ). We present the design, growth, fabrication and characterization of our white hybrid nanocrystal-LEDs that incorporate combinations of (1) yellow nanocrystals (λ PL = 580 nm) on a blue LED (λ EL = 440 nm) with (x,y) = (0.37,0.25), T c = 2692 K and R a 14.69; (2) cyan and red nanocrystals (λ PL = 500 and 620 nm) on a blue LED (λ EL = 440 nm) with (x,y) = (0.37,0.28), T c = 3246 K and R a = 19.65; (3) green, yellow and red nanocrystals (λ PL = 540, 580 and 620 nm) on a blue LED (λ EL = 452 nm) with (x,y) = (0.30,0.28), T c = 7521 K and R a = 40.95; and (4) cyan, green, yellow and red nanocrystals (λ PL = 500, 540, 580 and 620 nm) on a blue LED (λ EL = 452 nm) with (x,y) = (0.24,0.33), T c = 11 171 K and R a 71.07. These hybrid white light sources hold promise for future lighting and display applications with their highly adjustable properties

  17. White-light-emitting supramolecular gels.

    Science.gov (United States)

    Praveen, Vakayil K; Ranjith, Choorikkat; Armaroli, Nicola

    2014-01-07

    Let there be light, let it be white: Recent developments in the use of chromophore-based gels as scaffolds for the assembly of white-light-emitting soft materials have been significant. The main advantage of this approach lies in the facile accommodation of selected luminescent components within the gel. Excitation-energy-transfer processes between these components ultimately generate the desired light output. Copyright © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  18. Concept of white light in stage lighting

    Science.gov (United States)

    Rinaldi, Mauricio R.

    2002-06-01

    In perceiving objects, generally we see them in a white light situation. But, actually, there is not an absolute white, in such a manner that the different light sources have a determined kind of white, what it is known as color temperature. Even the white light may be of different kinds (different color temperature), the individual mind tends to perceive it as the same kind of white, that is to say, there is in our mind a psychological function by which we operate an integration in the perception in order to do the object perceptually invariable. On the other hand, it is a common practice in stage lighting to use color light sources. It is a well known phenomenon that a color of light produces a change in the object color perception. However, when we go to theater, we see the objects as having their real color, even if the lighting is not white. In this paper the concept of white light in stage lighting is presented, showing its possibilities of aesthetical expression.

  19. Experimental and theoretical studies in non-linear optical applications. Fiber oscillatiors, regenerative amplifiers, simulations on white-light generation

    Energy Technology Data Exchange (ETDEWEB)

    Zia, Haider

    2015-12-15

    Compact and stable ultrafast laser sources for electron diffraction experiments are the first step in accomplishing the dream experiment of producing a molecular movie. This thesis work focuses on developing new robust laser sources to enable arbitrary scaling in laser repetition rate, pulse energy, duration and stability as needed to provide sufficient integrated detected electrons for high quality diffraction patterns that can be inverted to real space movies. In chapter 2, the construction of a novel stable and high power stretched pulse fiber oscillator outputting 300 mW at 31 MHz and compressible pulses to below 90 fs will be described. Chapter 3 describes the construction of a solid-state regenerative amplifier that was developed to achieve pulse energies above 1mJ with 0.40 mJ already achieved at 1 kHz. Novel simulation techniques were explored that aided the construction of the amplifier. Chapter 4 derives a new, fast and powerful numerical theory that is implemented for generalized non-linear Schrodinger equations in all spatial dimensions and time. This new method can model complicated terms in these equations that outperforms other numerical methods with respect to minimizing numerical error and increased speed. These advantages are due to this method's Fourier nature. A simulation tool was created, employing this numerical technique to simulate white-light generation in bulk media. The simulation matches extremely well with published experimental data, and is superior to the original simulation method used to match the experiment. The use of this tool enables accurate calculations of continuum or white light generation as needed for different experimental protocols and serves as the primary input to generate wide bandwidth coherent light.This work has solved the problem of predictably designing continuum generation within targeted wavelength ranges. This information is needed as part of an overall scheme in laser source development to coherently

  20. Experimental and theoretical studies in non-linear optical applications. Fiber oscillatiors, regenerative amplifiers, simulations on white-light generation

    International Nuclear Information System (INIS)

    Zia, Haider

    2015-12-01

    Compact and stable ultrafast laser sources for electron diffraction experiments are the first step in accomplishing the dream experiment of producing a molecular movie. This thesis work focuses on developing new robust laser sources to enable arbitrary scaling in laser repetition rate, pulse energy, duration and stability as needed to provide sufficient integrated detected electrons for high quality diffraction patterns that can be inverted to real space movies. In chapter 2, the construction of a novel stable and high power stretched pulse fiber oscillator outputting 300 mW at 31 MHz and compressible pulses to below 90 fs will be described. Chapter 3 describes the construction of a solid-state regenerative amplifier that was developed to achieve pulse energies above 1mJ with 0.40 mJ already achieved at 1 kHz. Novel simulation techniques were explored that aided the construction of the amplifier. Chapter 4 derives a new, fast and powerful numerical theory that is implemented for generalized non-linear Schrodinger equations in all spatial dimensions and time. This new method can model complicated terms in these equations that outperforms other numerical methods with respect to minimizing numerical error and increased speed. These advantages are due to this method's Fourier nature. A simulation tool was created, employing this numerical technique to simulate white-light generation in bulk media. The simulation matches extremely well with published experimental data, and is superior to the original simulation method used to match the experiment. The use of this tool enables accurate calculations of continuum or white light generation as needed for different experimental protocols and serves as the primary input to generate wide bandwidth coherent light.This work has solved the problem of predictably designing continuum generation within targeted wavelength ranges. This information is needed as part of an overall scheme in laser source development to coherently

  1. Generation of White Light from Dysprosium-Doped Strontium Aluminate Phosphor by a Solid-State Reaction Method

    Science.gov (United States)

    Sahu, Ishwar Prasad; Bisen, D. P.; Brahme, N.; Tamrakar, Raunak Kumar

    2016-04-01

    A single-host lattice, white light-emitting SrAl2O4:Dy3+ phosphor was synthesized by a solid-state reaction method. The crystal structure of prepared SrAl2O4:Dy3+ phosphor was in a monoclinic phase with space group P21. The chemical composition of the sintered SrAl2O4:Dy3+ phosphor was confirmed by the energy dispersive x-ray spectroscopy technique. Under ultra-violet excitation, the characteristic emissions of Dy3+ are peaking at 475 nm, 573 nm and 660 nm, originating from the transitions of 4F9/2 → 6H15/2, 4F9/2 →&!nbsp; 6H13/2 and 4F9/2 → 6H11/2 in the 4f9 configuration of Dy3+ ions. Commission International de I'Eclairage color coordinates of SrAl2O4:Dy3+ are suitable for white light-emitting phosphor. In order to investigate the suitability of the samples as white color light sources for industrial uses, correlated color temperature (CCT) and color rendering index (CRI) values were calculated. Values of CCT and CRI were found well within the defined acceptable range. Mechanoluminescence (ML) intensity of SrAl2O4:Dy3+ phosphor increased linearly with increasing impact velocity of the moving piston. Thus, the present investigation indicates piezo-electricity was responsible for producing ML in sintered SrAl2O4:Dy3+ phosphor. Decay rates of the exponential decaying period of the ML curves do not change significantly with impact velocity. The photoluminescence and ML results suggest that the synthesized SrAl2O4:Dy3+ phosphor was useful for the white light-emitting diodes and stress sensor respectively.

  2. Recent developments in white light emitting diodes

    Science.gov (United States)

    Lohe, P. P.; Nandanwar, D. V.; Belsare, P. D.; Moharil, S. V.

    2018-05-01

    In the recent years solid state lighting based on LEDs has revolutionized lighting technology. LEDs have many advantages over the conventional lighting based on fluorescent and incandescent lamps such as mercury free, high conversion efficiency of electrical energy into light, long lifetime reliability and ability to use with many types of devices. LEDs have emerged as a new potentially revolutionary technology that could save up to half of energy used for lighting applications. White LEDs would be the most important light source in the future, so much so that this aspect had been highlighted by the Nobel committee during the award of 2014 Nobel Prize for Physics. Recent advancement in the fabrication of GaN chip capable of emitting in blue and near UV region paved way for fabrication of white LED lamps. Mainly there are two approaches used for preparing white emitting solid state lamp. In the first approach blue light (λ=450 nm) emitted from the InGaN LED chip is partially absorbed by the YAG:Ce3+ phosphor coated on it and re-emitted as yellow fluorescence. A white light can be generated by the combination of blue + yellow emission bands. These lamps are already available. But they are suffering from major drawback that their Colour Rendering Index (CRI) is low. In the second approach, white LEDs are made by coating near ultraviolet emitting (360 to 410nm) LED with a mixture of high efficiency red, green and blue emitting phosphors, analogous to the fluorescent lamp. This method yields lamps with better color rendition. Addition of a yellow emitting phosphor improves CRI further. However conversion efficiency is compromised to some extent. Further the cost of near UV emitting chip is very high compared to blue emitting chips. Thus cost and light output wise, near UV chips are much inferior to blue chips. Recently some rare earth activated oxynitrides, silicates, fluorides have emerged as an important family of luminescent materials for white LED application

  3. Dy3+-doped nano-glass ceramics comprising NaAlSiO4 and NaY9Si6O26 nanocrystals for white light generation

    International Nuclear Information System (INIS)

    Bagga, Ruchika; Achanta, Venu Gopal; Goel, Ashutosh; Ferreira, José M.F.; Singh, Narinder Pal; Singh, Davinder Paul; Falconieri, Mauro; Sharma, Gopi

    2013-01-01

    Highlights: ► Environment safe glass ceramics were fabricated via heat treatment. ► Optical and structural properties were studied before and after heat treatment. ► White light generation with single RE 3+ ion-doping was observed under UV excitation. ► Emission color temperature was between fluorescent tube and daylight values. - Abstract: The radiative emission properties of the Dy 3+ ions in oxyfluoride glasses and glass ceramics have been investigated for the generation of white light. The X-ray diffraction pattern of the glass ceramics reveals the presence of NaAlSiO 4 nanocrystals along with secondary phase of NaY 9 Si 6 O 26 in the glass matrix after a suitable thermal treatment of the pristine glasses. Intense white light emission has been observed when the samples are excited with 350 nm light. Yellow to blue emission intensity ratios and chromaticity color coordinates have been determined from the visible luminescence spectra. All color coordinates are found to lie in the white region of the chromaticity color diagram proposing the suitability of the present studied materials for color display devices.

  4. Long-term stable stacked CsPbBr3 quantum dot films for highly efficient white light generation in LEDs.

    Science.gov (United States)

    Song, Young Hyun; Yoo, Jin Sun; Kang, Bong Kyun; Choi, Seung Hee; Ji, Eun Kyung; Jung, Hyun Suk; Yoon, Dae Ho

    2016-12-01

    We report highly efficient ethyl cellulose with CsPbBr 3 perovskite QD films for white light generation in LED application. Ethyl cellulose with CsPbBr 3 quantum dots is applied with Sr 2 Si 5 N 8  : Eu 2+ red phosphor on an InGaN blue chip, achieving a highly efficient luminous efficacy of 67.93 lm W -1 under 20 mA current.

  5. Studying Light Color using White LED Lighting

    Science.gov (United States)

    Yamagishi, Misako; Yamaba, Kazuo; Nagata, Manori; Kubo, Chiho; Nokura, Kunihiro

    Recently, white Light Emitting Diodes (LEDs) are receiving attention worldwide as new lighting devices. This study examined effects of a lighting application on performance using white LEDs. The light color—the correlated color temperature (CCT) —was assessed. It affected to psychological states and physiological conditions. Three CCT conditions were respectively set for the experiment: 2500 K, 5000 K, and 8200 K. In all, 20 younger subjects (20-30 years old), 15 middle-aged to elderly subjects (45-60 years old) and 12 elderly subjects (over 65 years-old) participated. They were presented a Numerical Verification (NV) task for performance measurement. The psychological states on performance were evaluated using the lighting assessment questionnaire. The physiological conditions were recorded using an electrocardiograph. Results show that the effects of CCT differ among age groups. Especially, the performance of younger subjects might differ from CCT conditions; elderly subjects are affected by CCT condition because of their visual acuity or response to contrast of objects.

  6. Light Converting Inorganic Phosphors for White Light-Emitting Diodes

    Directory of Open Access Journals (Sweden)

    Chiao-Wen Yeh

    2010-03-01

    Full Text Available White light-emitting diodes (WLEDs have matched the emission efficiency of florescent lights and will rapidly spread as light source for homes and offices in the next 5 to 10 years. WLEDs provide a light element having a semiconductor light emitting layer (blue or near-ultraviolet (nUV LEDs and photoluminescence phosphors. These solid-state LED lamps, rather than organic light emitting diode (OLED or polymer light-emitting diode (PLED, have a number of advantages over conventional incandescent bulbs and halogen lamps, such as high efficiency to convert electrical energy into light, reliability and long operating lifetime. To meet with the further requirement of high color rendering index, warm light with low color temperature, high thermal stability and higher energy efficiency for WLEDs, new phosphors that can absorb excitation energy from blue or nUV LEDs and generate visible emissions efficiently are desired. The criteria of choosing the best phosphors, for blue (450-480 nm and nUV (380-400 nm LEDs, strongly depends on the absorption and emission of the phosphors. Moreover, the balance of light between the emission from blue-nUV LEDs and the emissions from phosphors (such as yellow from Y3Al5O12:Ce3+ is important to obtain white light with proper color rendering index and color temperature. Here, we will review the status of phosphors for LEDs and prospect the future development.

  7. Light Converting Inorganic Phosphors for White Light-Emitting Diodes

    Science.gov (United States)

    Chen, Lei; Lin, Chun-Che; Yeh, Chiao-Wen; Liu, Ru-Shi

    2010-01-01

    White light-emitting diodes (WLEDs) have matched the emission efficiency of florescent lights and will rapidly spread as light source for homes and offices in the next 5 to 10 years. WLEDs provide a light element having a semiconductor light emitting layer (blue or near-ultraviolet (nUV) LEDs) and photoluminescence phosphors. These solid-state LED lamps, rather than organic light emitting diode (OLED) or polymer light-emitting diode (PLED), have a number of advantages over conventional incandescent bulbs and halogen lamps, such as high efficiency to convert electrical energy into light, reliability and long operating lifetime. To meet with the further requirement of high color rendering index, warm light with low color temperature, high thermal stability and higher energy efficiency for WLEDs, new phosphors that can absorb excitation energy from blue or nUV LEDs and generate visible emissions efficiently are desired. The criteria of choosing the best phosphors, for blue (450−480 nm) and nUV (380−400 nm) LEDs, strongly depends on the absorption and emission of the phosphors. Moreover, the balance of light between the emission from blue-nUV LEDs and the emissions from phosphors (such as yellow from Y3Al5O12:Ce3+) is important to obtain white light with proper color rendering index and color temperature. Here, we will review the status of phosphors for LEDs and prospect the future development.

  8. Light Sterile Neutrinos: A White Paper

    DEFF Research Database (Denmark)

    Abazajian, K. N.; Acero, M. A.; Agarwalla, S. K.

    2012-01-01

    This white paper addresses the hypothesis of light sterile neutrinos based on recent anomalies observed in neutrino experiments and the latest astrophysical data.......This white paper addresses the hypothesis of light sterile neutrinos based on recent anomalies observed in neutrino experiments and the latest astrophysical data....

  9. Light Converting Inorganic Phosphors for White Light-Emitting Diodes

    OpenAIRE

    Chen, Lei; Lin, Chun-Che; Yeh, Chiao-Wen; Liu, Ru-Shi

    2010-01-01

    White light-emitting diodes (WLEDs) have matched the emission efficiency of florescent lights and will rapidly spread as light source for homes and offices in the next 5 to 10 years. WLEDs provide a light element having a semiconductor light emitting layer (blue or near-ultraviolet (nUV) LEDs) and photoluminescence phosphors. These solid-state LED lamps, rather than organic light emitting diode (OLED) or polymer light-emitting diode (PLED), have a number of advantages over conventional incand...

  10. White organic light emitting diodes

    Energy Technology Data Exchange (ETDEWEB)

    Rosenow, Thomas Conrad

    2011-03-22

    Three approaches were taken in order to achieve reproducible and highly efficient white OLEDs with excellent colour quality. The first approach is based on the triplet harvesting concept. Otherwise unused triplet excitons are transferred from a fluorescent to a phosphorescent emitter with a smaller triplet energy. Because a blue emitter allowing for triplet transfer to a phosphorescent green emitter was not available, a model system for a three-colour white OLED was developed and investigated. This model device consists of the fluorescent blue emitter 4P-NPD and the phosphorescent emitters Ir(dhfpy){sub 2}acac and Ir(MDQ){sub 2}acac emitting in the yellow and red region, respectively. Here, it was shown that both phosphorescent emitters are excited by triplet diffusion and not by direct charge carrier recombination. The second approach is based on a hybrid white OLED with a single emission layer. This layer is a combination of a fluorescent blue and two phosphorescent emitters in a common matrix material. Because of the above mentioned lack of a blue emitter, which allows for triplet transfer to a green phosphorescent emitter, the concentrations of all emitters were chosen in a way that exciton transfer between the emitters was suppressed. The result is a non-radiative recombination of triplet excitons on the fluorescent blue emitter and an accordingly low quantum efficiency. However, a remarkable colour stability against varying brightness was achieved with this OLED. The most successful approach is based on a stacked OLED. Here, the concept of triplet harvesting is limited to triplet transfer between a fluorescent blue and a phosphorescent red emitter. The resulting spectral gap is filled by a full phosphorescent unit comprising the emission of a green and a yellow emitter, which is stacked on top of the triplet harvesting OLED. By individually optimising both units, it was possible to reach lighting relevant luminous efficacies up to {eta}{sub {nu}}=33 lm/W at

  11. Light Beam Generation

    DEFF Research Database (Denmark)

    2007-01-01

    The invention relates to a method and a system for synthesizing a set of controllable light beams by provision of a system for synthesizing a set of light beams, comprising a spatially modulated light source for generation of electromagnetic radiation with a set of replicas of a predetermined......(x-xs, y-ys), a Fourier transforming lens for Fourier transforming the electromagnetic radiation, a first spatial light modulator for phase shifting the Fourier transformed electromagnetic radiation with the phase -F(u, v) of S*, S* is the complex conjugate of the Fourier transformed symbol s, a Fourier...... transforming lens for Inverse Fourier transforming the spatially modulated radiation, whereby a set of light beams are formed propagating through the inverse Fourier plane (x', y') at desired positions (x's, y's), and a controller for controlling the position of a replica of the symbol, s, for movement...

  12. White Light Photorefractive Phase Zone Plates

    International Nuclear Information System (INIS)

    Yuan-Mei, Gao; Si-Min, Liu

    2008-01-01

    Incoherent white light from an incandescent source is employed to fabricate volume phase zone plates in LiNbO 3 : Fe, for the first time to our knowledge, which can guide and modulate the input white light or laser light. The diffractive efficiency of the white light volume phase zone plates fabricated can reach as high as 12%. In addition, we test the volume phase zone plates by a probe beam and find that the volume phase zone plate is present in the direction perpendicular to the c-axis and absent in the direction parallel to the c-axis. This directly proves the existence of photovoltaic photorefractive anisotropy of white light

  13. Laser induced white lighting of tungsten filament

    Science.gov (United States)

    Strek, W.; Tomala, R.; Lukaszewicz, M.

    2018-04-01

    The sustained bright white light emission of thin tungsten filament was induced under irradiation with focused beam of CW infrared laser diode. The broadband emission centered at 600 nm has demonstrated the threshold behavior on excitation power. Its intensity increased non-linearly with excitation power. The emission occurred only from the spot of focused beam of excitation laser diode. The white lighting was accompanied by efficient photocurrent flow and photoelectron emission which both increased non-linearly with laser irradiation power.

  14. White LED visible light communication technology research

    Science.gov (United States)

    Yang, Chao

    2017-03-01

    Visible light communication is a new type of wireless optical communication technology. White LED to the success of development, the LED lighting technology is facing a new revolution. Because the LED has high sensitivity, modulation, the advantages of good performance, large transmission power, can make it in light transmission light signal at the same time. Use white LED light-emitting characteristics, on the modulation signals to the visible light transmission, can constitute a LED visible light communication system. We built a small visible optical communication system. The system composition and structure has certain value in the field of practical application, and we also research the key technology of transmitters and receivers, the key problem has been resolved. By studying on the optical and LED the characteristics of a high speed modulation driving circuit and a high sensitive receiving circuit was designed. And information transmission through the single chip microcomputer test, a preliminary verification has realized the data transmission function.

  15. The Whiteness of Things and Light Scattering

    Science.gov (United States)

    Gratton, L. M.; Lopez-Arias, T.; Calza, G.; Oss, S.

    2009-01-01

    We discuss some simple experiments dealing with intriguing properties of light and its interaction with matter. In particular, we show how to emphasize that light reflection, refraction and scattering can provide a proper, physical description of human perception of the "colour" white. These experiments can be used in the classroom with an enquiry…

  16. White light coronagraph in OSO-7

    International Nuclear Information System (INIS)

    Koomen, M.J.; Detwiler, C.R.; Brueckner, G.E.; Cooper, H.W.; Tousey, R.

    1975-01-01

    A small, externally occulted Lyot-type coronagraph, designated for use in the seventh unmanned Orbiting Solar Observatory (OSO-7), is described. Optical configuration, suppression of stray light, SEC vidicon detector, and data system are discussed, as well as integration of the instrument into the spacecraft and operation in orbit. Orbital operation produced daily images of the white light corona, from 2.8 to 10 solar radii, at least once per day for 2 3/4 yr. The first records of white light coronal transient events were obtained, and the corona was shown to be constantly changing

  17. Tunable white light generation from Ce{sup 3+}-Tb{sup 3+}-Mn{sup 2+} doped metaphosphate glass for LED and solar cell applications

    Energy Technology Data Exchange (ETDEWEB)

    Ghosh, Debarati; Biswas, K.; Balaji, S. [CSIR-Network of Institute for Solar Energy (NISE) (India); Glass Division, Glass Science and Technology Section, CSIR-Central Glass and Ceramic Research Institute, 196, Raja S.C. Mullick Road, Kolkata 700032 (India); Annapurna, K., E-mail: annapurnak@cgcri.res.in [CSIR-Network of Institute for Solar Energy (NISE) (India); Glass Division, Glass Science and Technology Section, CSIR-Central Glass and Ceramic Research Institute, 196, Raja S.C. Mullick Road, Kolkata 700032 (India)

    2017-03-15

    Alkali free Ba-Al metaphosphate glasses doped with Ce, Tb and Mn are prepared and their concentration is tuned to achieve white light emission for production of LEDs and luminescent concentrator for Si-PV applications. The occurrence of a redox reaction among dopant ions (Ce{sup 4+}, Tb{sup 3+}→Ce{sup 3+}, Tb{sup 4+}) is observed from the absorption spectra while there is no change in oxidation state of Mn{sup 2+} ions. This is confirmed from ESR studies. Emission spectra indicated effective downshifting of radiation from near visible to green and red region of the spectrum. On tuning the concentration of Tb{sup 3+} and Mn{sup 2+}, bright white light emission (CIE coordinates: x=3.32, y=3.33) corresponding to CCT of 5900 K is obtained. This white light produced has been further tuned to different hues by varying the excitation wavelength of this triply doped glass.

  18. Polymer OLED White Light Development Program

    Energy Technology Data Exchange (ETDEWEB)

    Homer Antoniadis; Vi-En Choong; Stelios Choulis; Brian Cumpston; Rahul Gupta; Mathew Mathai; Michael Moyer; Franky So

    2005-12-19

    OSRAM Opto Semiconductors (OSRAM) successfully completed development, fabrication and characterization of the large area, polymer based white light OLED prototype at their OLED Research and Development (R&D) facility in San Jose, CA. The program, funded by the Department of Energy (DOE), consisted of three key objectives: (1) Develop new polymer materials and device architectures--in order to improve the performance of organic light emitters. (2) Develop processing techniques--in order to demonstrate and enable the manufacturing of large area, white light and color tunable, solid state light sources. (3) Develop new electronics and driving schemes for organic light sources, including color-tunable light sources. The key performance goals are listed. A world record efficiency of 25 lm/W was established for the solution processed white organic device from the significant improvements made during the project. However, the challenges to transfer this technology from an R&D level to a large tile format such as, the robustness of the device and the coating uniformity of large area panels, remain. In this regard, the purity and the blend nature of the materials are two factors that need to be addressed in future work. During the first year, OSRAM's Materials and Device group (M&D) worked closely with the major polymer material suppliers to develop the polymer emissive technology. M&D was successful in demonstrating a 7-8 lm/W white light source which was based on fluorescent materials. However, it became apparent that the major gains in efficiency could only be made if phosphorescent materials were utilized. Thus, in order to improve the performance of the resulting devices, the focus of the project shifted towards development of solution-processable phosphorescent light emitting diodes (PHOLEDs) and device architectures. The result is a higher efficiency than the outlined project milestone.

  19. White light signal simulator microcontroller design | Haghighi ...

    African Journals Online (AJOL)

    In this research, first through experimental studies, the recorded signals associated with the light white from human retina cells were digitized, then the digital data were calculated and the resulted mathematical equation was programmed on a microcontroller, and by designing a circuit, the output voltage over time similar to ...

  20. White light generation from YAG/YAM:Ce{sup 3+}, Pr{sup 3+}, Cr{sup 3+} nanophosphors mixed with a blue dye under 340 nm excitation

    Energy Technology Data Exchange (ETDEWEB)

    Oliva, J. [Centro de Investigaciones en Optica, A.P. 1-948, León, Gto 37150, México (Mexico); De la Rosa, E., E-mail: elder@cio.mx [Centro de Investigaciones en Optica, A.P. 1-948, León, Gto 37150, México (Mexico); Diaz-Torres, L.A [Centro de Investigaciones en Optica, A.P. 1-948, León, Gto 37150, México (Mexico); Torres, A. [Universidad Autónoma de Nuevo León, A.P. 126-F, Monterrey, NL 66450, México (Mexico); Salas, P. [Centro de Física Aplicada y Tecnología Avanzada, Universidad Nacional Autónoma de México, A.P. 1-1010, Juriquilla, Qro. 76000, México (Mexico); Meza, O. [Benemérita Universidad Autónoma de Puebla, 4 Sur 104 Centro Historico, 72000 Puebla, México (Mexico)

    2014-10-15

    The structural and luminescent properties of Y{sub 3}Al{sub 5}O{sub 12}/Y{sub 4}Al{sub 2}O{sub 9}:Ce{sup 3+}(0.1%)–Pr{sup 3+}(0.1%) –Cr{sup 3+} (trace impurities) nanophosphors synthesized by a simple hydrothermal method were studied. The crystalline phase was composed of Yttrium Aluminum Garnet (YAG) and Yttrium Aluminum Monoclinic (YAM) depending on the ammonia concentration and annealing temperature. Ammonia increased the stabilization of YAG from 55 wt% to 63 wt% in the samples annealed at 900 °C, and an increment of 83% of the overall emission under 460 nm excitation was observed. Quenching of the emitted signal after annealing at 1100 °C was observed in spite of single YAG crystalline phase stabilization, due to the formation of Ce{sup 4+}, Pr{sup 4+}, and color centers. In addition to the green–yellow emission from Ce{sup 3+}, all samples present a broad red emission band produced by the relaxations from the broad band {sup 4}T{sub 2} toward the {sup 4}A{sub 2} energy level of Cr{sup 3+} impurities, under 340 nm excitation. By taking advantage of this broad green–yellow–red emission and using a blue dye, white light with CIE coordinates of (0.30, 0.36) under 340 nm excitation was produced. - Highlights: • YAG/YAM:Ce{sup 3+}, Pr{sup 3+}, Cr{sup 3+} nanophosphors were synthesized with a hydrothermal method. • Ammonia introduced during the synthesis increased the emission of nanophosphors. • White light was obtained by combining the emissions of a blue dye and nanophosphors. • The CIE coordinates for this white light are (0.30, 0.36)

  1. Efficient and stable laser-driven white lighting

    Directory of Open Access Journals (Sweden)

    Kristin A. Denault

    2013-07-01

    Full Text Available Laser-based white lighting offers a viable option as an efficient and color-stable high-power solid-state white light source. We show that white light generation is possible using blue or near-UV laser diodes in combination with yellow-emitting cerium-substituted yttrium aluminum garnet (YAG:Ce or a mixture of red-, green-, and blue-emitting phosphors. A variety of correlated color temperatures (CCT are achieved, ranging from cool white light with a CCT of 4400 K using a blue laser diode to a warm white light with a CCT of 2700 K using a near-UV laser diode, with respective color rendering indices of 57 and 95. The luminous flux of these devices are measured to be 252 lm and 53 lm with luminous efficacies of 76 lm/W and 19 lm/W, respectively. An estimation of the maximum efficacy of a device comprising a blue laser diode in combination with YAG:Ce is calculated and the results are used to optimize the device.

  2. Next Generation Light Robotics

    DEFF Research Database (Denmark)

    Glückstad, Jesper

    Light Robotics is a new field of research where ingredients from photonics, nanotechnology and biotechnology are put together in new ways to realize light-driven robotics at the smallest scales to solve major challenges primarily within the nanobio-domain but not limited hereto. Exploring the full...... potential of this new ‘drone-like’ light-printed, light-driven, light-actuated micro- and nano-robotics in challenging geometries requires a versatile and real-time reconfigurable light addressing that can dynamically track a plurality of tiny tools in 3D to ensure real-time continuous light...

  3. Warm white light generation from single phase Sr3Y(PO4)3:Dy3+, Eu3+ phosphors with near ultraviolet excitation

    International Nuclear Information System (INIS)

    Huang, B.Y.; Feng, B.L.; Luo, L.; Han, C.L.; He, Y.T.; Qiu, Z.R.

    2016-01-01

    Highlights: • Novel single phase phosphors were synthesized in an ambient air atmosphere. • A direct band gap about 4.5 eV of the host is calculated for the first time. • It is suitable for near UV chip excitation. • It emits warm white light with better CIE and lower CCT over previous reports. • The thermal quenching is similar to that of YAG:0.06Ce 3+ commercial phosphor. - Abstract: Novel Sr 3 Y(PO 4 ) 3 :Dy 3+ , Eu 3+ (SYP:Dy 3+ , Eu 3+ ) phosphors were synthesized by a standard solid-state reaction under an ambient air atmosphere and their structural and optical properties were investigated. XRD and diffuse reflectance spectra (DRS) were used to explore structural properties. The former showed that single phase phosphors were obtained and that the rare earth ions entered into the cubic host by substituting the smaller Y 3+ ions and thereby enlarging the unit cell. The DRS indicated that the host has a direct bandgap of 4.5 eV. Under 393 nm excitation, a strong and stable warm white light emission with high color purity was achieved in SY 0.92 P:0.06Dy 3+ , 0.04Eu 3+ . The energy transfer from Dy 3+ to Eu 3+ ions was investigated and the related mechanism was discussed based on the optical spectra and emission decay curves. The thermal quenching of emission is similar to that of YAG:0.06Ce 3+ . The results show the single phase phosphor is potential in warm white LED.

  4. White light emission from engineered silicon carbide

    DEFF Research Database (Denmark)

    Ou, Haiyan

    Silicon carbide (SiC) is a wide indirect bandgap semiconductor. The light emission efficiency is low in nature. But this material has very unique physical properties like good thermal conductivity, high break down field etc in addition to its abundance. Therefore it is interesting to engineer its...... light emission property so that to take fully potential applications of this material. In this talk, two methods, i.e. doping SiC heavily by donor-acceptor pairs and making SiC porous are introduced to make light emission from SiC. By co-doping SiC with nitrogen and boron heavily, strong yellow emission...... is demonstrated. After optimizing the passivation conditions, strong blue-green emission from porous SiC is demonstrated as well. When combining the yellow emission from co-doped SiC and blue-green from porous SiC, a high color rendering index white light source is achieved....

  5. Recent advances in light outcoupling from white organic light-emitting diodes

    Science.gov (United States)

    Gather, Malte C.; Reineke, Sebastian

    2015-01-01

    Organic light-emitting diodes (OLEDs) have been successfully introduced to the smartphone display market and have geared up to become contenders for applications in general illumination where they promise to combine efficient generation of white light with excellent color quality, glare-free illumination, and highly attractive designs. Device efficiency is the key requirement for such white OLEDs, not only from a sustainability perspective, but also because at the high brightness required for general illumination, losses lead to heating and may, thus, cause rapid device degradation. The efficiency of white OLEDs increased tremendously over the past two decades, and internal charge-to-photon conversion can now be achieved at ˜100% yield. However, the extraction of photons remains rather inefficient (typically physics of outcoupling in white OLEDs and review recent progress toward making light extraction more efficient. We describe how structures that scatter, refract, or diffract light can be attached to the outside of white OLEDs (external outcoupling) or can be integrated close to the active layers of the device (internal outcoupling). Moreover, the prospects of using top-emitting metal-metal microcavity designs for white OLEDs and of tuning the average orientation of the emissive molecules within the OLED are discussed.

  6. Cold and warm white light generation using Zn(PO{sub 3}){sub 2} glasses activated by Ce{sup 3+}, Dy{sup 3+} and Mn{sup 2+}

    Energy Technology Data Exchange (ETDEWEB)

    Caldino, U., E-mail: cald@xanum.uam.mx [Departamento de Fisica, Universidad Autonoma Metropolitana-Iztapalapa, P.O. Box 55-534, 09340 Mexico, D.F. (Mexico); Alvarez, E. [Departamento de Fisica, Universidad de Sonora (UNISON), Boulevard Luis Encinas y Rosales s/n, Hermosillo, Sonora 83000 (Mexico); Speghini, A.; Bettinelli, M. [Dipartimento di Biotecnologie, Universita di Verona, and INSTM, UdR Verona, Strada Le Grazie 15, I-37314 Verona (Italy)

    2012-08-15

    The photoluminescence of zinc metaphosphate glasses activated by Dy{sup 3+}, Ce{sup 3+}/Dy{sup 3+} and Ce{sup 3+}/Dy{sup 3+}/Mn{sup 2+} ions was investigated. Non-radiative energy transfers from Ce{sup 3+} to Dy{sup 3+} and Ce{sup 3+} to Mn{sup 2+} are observed upon 280 nm excitation. The non-radiative nature of these transfers is inferred from the increase in the decay rate of the Ce{sup 3+} emission when the glass is co-doped with Dy{sup 3+} or Dy{sup 3+}/Mn{sup 2+}. It is demonstrated that zinc metaphosphate glasses can generate cold or warm white light emission when they are doped with Ce{sup 3+}/Dy{sup 3+} or Ce{sup 3+}/Dy{sup 3+}/Mn{sup 2+} and pumped at 280 nm (peak emission wavelength of AlGaN-based LEDs). The CIE1931 chromaticity coordinates and color temperature were (0.34, 0.35) and 5250 K for the cold light, and (0.47, 0.43) and 2700 K for the warm light. - Highlights: Black-Right-Pointing-Pointer Non-radiative energy transfer from Ce{sup 3+} to Dy{sup 3+} and Mn{sup 2+} takes place in Zn(PO{sub 3}){sub 2} glasses doped with Ce{sup 3+}/Dy{sup 3+}/Mn{sup 2+}. Black-Right-Pointing-Pointer Zn(PO{sub 3}){sub 2} glasses doped with Ce{sup 3+}/Dy{sup 3+} can generate 5250 K cold white light emission. Black-Right-Pointing-Pointer Zn(PO{sub 3}){sub 2} glasses doped with Ce{sup 3+}/Dy{sup 3+}/Mn{sup 2+} can generate 2700 K warm yellowish orange light emission.

  7. High efficient white organic light emitting diodes

    Energy Technology Data Exchange (ETDEWEB)

    Seidel, Stefan; Krause, Ralf [Department of Materials Science VI, University of Erlangen-Nuremberg (Germany); Siemens AG, CT MM 1, Erlangen (Germany); Kozlowski, Fryderyk; Schmid, Guenter; Hunze, Arvid [Siemens AG, CT MM 1, Erlangen (Germany); Winnacker, Albrecht [Department of Materials Science VI, University of Erlangen-Nuremberg (Germany)

    2007-07-01

    Due to the rapid progress in the last years the performance of organic light emitting diodes (OLEDs) has reached a level where general lighting presents a most interesting application target. We demonstrate, how the color coordinates of the emission spectrum can be adjusted using a combinatorial evaporation tool to lie on the desired black body curve representing cold and warm white, respectively. The evaluation includes phosphorescent and fluorescent dye approaches to optimize lifetime and efficiency, simultaneously. Detailed results are presented with respect to variation of layer thicknesses and dopant concentrations of each layer within the OLED stack. The most promising approach contains phosphorescent red and green dyes combined with a fluorescent blue one as blue phosphorescent dopants are not yet stable enough to achieve long lifetimes.

  8. Limits of computational white-light holography

    International Nuclear Information System (INIS)

    Mader, Sebastian; Kozacki, Tomasz; Tompkin, Wayne

    2013-01-01

    Recently, computational holograms are being used in applications, where previously conventional holograms were applied. Compared to conventional holography, computational holography is based on imaging of virtual objects instead of real objects, which renders them somewhat more flexibility. Here, computational holograms are calculated based on the superposition of point sources, which are placed at the mesh vertices of arbitrary 3D models. The computed holograms have full parallax and exhibit a problem in viewing that we have called g hosting , which is linked to the viewing of computational holograms based on 3D models close to the image plane. Experimental white-light reconstruction of these holograms showed significant blurring, which is explained here based on simulations of the lateral as well as the axial resolution of a point image with respect to the source spectrum and image distance. In accordance with these simulations, an upper limit of the distance to the image plane is determined, which ensures high quality imaging.

  9. Environmentally Benign Technology for Efficient Warm-White Light Emission

    Science.gov (United States)

    Shen, Pin-Chun; Lin, Ming-Shiun; Lin, Ching-Fuh

    2014-06-01

    Nowadays efficient down conversion for white light emission is mainly based on rare-earth doped phosphors or cadmium-containing quantum dots. Although they exhibit high luminescence efficiency, the rare-earth mining and cadmium pollution have so far led to extremely high environmental cost, which conflicts the original purpose of pursuing efficient lighting. Here, we explore a new strategy to achieve efficient luminescence conversion based on polymer-decorated nanoparticles. The ZnO and Mn2+ doped ZnS nanoparticles are encapsulated by poly(9,9-di-n- hexylfluorenyl-2,7-diyl). The resultant core-shell nanocomposites then encompass three UV-to-visible luminescence conversion routes for photon emissions at blue, green, and orange colors, respectively. As a result, the color temperature is widely tunable (2100 K ~ 6000 K), so candle light or pure white light can be generated. The quantum yield up to 91% could also be achieved. Such rare-earth-element free nanocomposites give the bright perspectives for energy-saving, healthy, and environmentally benign lighting.

  10. Next generation light water reactors

    International Nuclear Information System (INIS)

    Omoto, Akira

    1992-01-01

    In the countries where the new order of nuclear reactors has ceased, the development of the light water reactors of new type has been discussed, aiming at the revival of nuclear power. Also in Japan, since it is expected that light water reactors continue to be the main power reactor for long period, the technology of light water reactors of next generation has been discussed. For the development of nuclear power, extremely long lead time is required. The light water reactors of next generation now in consideration will continue to be operated till the middle of the next century, therefore, they must take in advance sufficiently the needs of the age. The improvement of the way men and the facilities should be, the simple design, the flexibility to the trend of fuel cycle and so on are required for the light water reactors of next generation. The trend of the development of next generation light water reactors is discussed. The construction of an ABWR was started in September, 1991, as No. 6 plant in Kashiwazaki Kariwa Power Station. (K.I.)

  11. Light extraction efficiency enhancement for fluorescent SiC based white light-emitting diodes

    DEFF Research Database (Denmark)

    Ou, Haiyan; Ou, Yiyu; Argyraki, Aikaterini

    Fluorescent SiC based white light-emitting diodes(LEDs) light source, as an innovative energy-efficient light source, would even have longer lifetime, better light quality and eliminated blue-tone effect, compared to the current phosphor based white LED light source. In this paper, the yellow...

  12. Three-peak standard white organic light-emitting devices for solid-state lighting

    Science.gov (United States)

    Guo, Kunping; Wei, Bin

    2014-12-01

    Standard white organic light-emitting device (OLED) lighting provides a warm and comfortable atmosphere and shows mild effect on melatonin suppression. A high-efficiency red OLED employing phosphorescent dopant has been investigated. The device generates saturated red emission with Commission Internationale de l'Eclairage (CIE) coordinates of (0.66, 0.34), characterized by a low driving voltage of 3.5 V and high external quantum efficiency of 20.1% at 130 cd m-2. In addition, we have demonstrated a two-peak cold white OLED by combining with a pure blue emitter with the electroluminescent emission of 464 nm, 6, 12-bis{[N-(3,4-dimethylpheyl)-N-(2,4,5-trimethylphenyl)]} chrysene (BmPAC). It was found that the man-made lighting device capable of yielding a relatively stable color emission within the luminance range of 1000-5000 cd m-2. And the chromaticity coordinates, varying from (0.25, 0.21) to (0.23, 0.21). Furthermore, an ultrathin layer of green-light-emitting tris (2-phenylpyridinato)iridium(Ⅲ) Ir(ppy)3 in the host material was introduced to the emissive region for compensating light. By appropriately controlling the layer thickness, the white light OLED achieved good performance of 1280 cd m-2 at 5.0 V and 5150 cd m-2 at 7.0 V, respectively. The CIE coordinates of the emitted light are quite stable at current densities from 759 cd m-2 to 5150 cd m-2, ranging from (0.34, 0.37) to (0.33, 0.33).

  13. Determination of illuminants representing typical white light emitting diodes sources

    DEFF Research Database (Denmark)

    Jost, S.; Ngo, M.; Ferrero, A.

    2017-01-01

    is to develop LED-based illuminants that describe typical white LED products based on their Spectral Power Distributions (SPDs). Some of these new illuminants will be recommended in the update of the CIE publication 15 on colorimetry with the other typical illuminants, and among them, some could be used......Solid-state lighting (SSL) products are already in use by consumers and are rapidly gaining the lighting market. Especially, white Light Emitting Diode (LED) sources are replacing banned incandescent lamps and other lighting technologies in most general lighting applications. The aim of this work...... to complement the CIE standard illuminant A for calibration use in photometry....

  14. Tuning the colour of white polymer light emitting diodes

    NARCIS (Netherlands)

    Kok, M.M. de; Sarfert, W.; Paetzold, R.

    2010-01-01

    Colour tuning of white polymer light emitting diode (LED) light sources can be attained by various methods at various stages in the production process of the lamps and/or by the design of the active material incorporated in the LEDs. In this contribution we will describe the methods and discuss the

  15. White organic light-emitting diodes with fluorescent tube efficiency.

    Science.gov (United States)

    Reineke, Sebastian; Lindner, Frank; Schwartz, Gregor; Seidler, Nico; Walzer, Karsten; Lüssem, Björn; Leo, Karl

    2009-05-14

    The development of white organic light-emitting diodes (OLEDs) holds great promise for the production of highly efficient large-area light sources. High internal quantum efficiencies for the conversion of electrical energy to light have been realized. Nevertheless, the overall device power efficiencies are still considerably below the 60-70 lumens per watt of fluorescent tubes, which is the current benchmark for novel light sources. Although some reports about highly power-efficient white OLEDs exist, details about structure and the measurement conditions of these structures have not been fully disclosed: the highest power efficiency reported in the scientific literature is 44 lm W(-1) (ref. 7). Here we report an improved OLED structure which reaches fluorescent tube efficiency. By combining a carefully chosen emitter layer with high-refractive-index substrates, and using a periodic outcoupling structure, we achieve a device power efficiency of 90 lm W(-1) at 1,000 candelas per square metre. This efficiency has the potential to be raised to 124 lm W(-1) if the light outcoupling can be further improved. Besides approaching internal quantum efficiency values of one, we have also focused on reducing energetic and ohmic losses that occur during electron-photon conversion. We anticipate that our results will be a starting point for further research, leading to white OLEDs having efficiencies beyond 100 lm W(-1). This could make white-light OLEDs, with their soft area light and high colour-rendering qualities, the light sources of choice for the future.

  16. 30 years of squeezed light generation

    DEFF Research Database (Denmark)

    Andersen, Ulrik Lund; Gehring, Tobias; Marquardt, Christoph

    2016-01-01

    Squeezed light generation has come of age. Significant advances on squeezed light generation have been made over the last 30 years—from the initial, conceptual experiment in 1985 till today’s top-tuned, application-oriented setups. Here we review the main experimental platforms for generating...... quadrature squeezed light that have been investigated in the last 30 years....

  17. Warm white LEDs lighting over Ra=95 and its applications

    Science.gov (United States)

    Kobashi, Katsuya; Taguchi, Tsunemasa

    2007-02-01

    We have for the first time developed warm white LEDs lighting using a combination of near ultraviolet LED and three-band (red, green and blue) white phosphors. This LED has the average color-rendering index Ra=96. Moreover, special color-rendering index R9 (red) and R15 (face color of Japanese) are estimated to be 95 and 97, respectively. We will describe the results of evaluation on the medical lighting applications such as operation, treatment and endoscope experiments, application to the LED fashions and application to the Japanese antique art (ink painting) lighting.

  18. Newly patented process enables low-cost solution for increasing white light spectrum of LEDs

    Science.gov (United States)

    Spanard, Jan-Marie

    2017-10-01

    A newly patented process for completing the spectral light array emitted by LED bulbs provides a low-cost method for producing better human centered lighting (HCL). This process uses non-luminescent colorant filters, filling out the jagged LED spectral emission into a full, white light array. While LED bulbs have the distinct economic advantages of using less energy, producing less heat and lasting years longer than traditional incandescent bulbs, the persistent metameric failure of LED bulbs has resulted in slower, and sometimes reluctant, adoption of LED lighting by the residential, retail and architectural markets. Adding missing wavelengths to LED generated bulbs via colorant filters increases the aesthetic appeal of the light by decreasing current levels of metameric failure, reducing the `flatness', `harshness', and `dullness' of LED generated light reported by consumers. LED phosphor-converted light can be successfully tuned to "whiter" white light with selective color filtering using permanent, durable transparent pigments. These transparent pigments are selectively applied in combination with existing manufacturing technologies and utilized as a final color-tuning step in bulb design. The quantity of emitted light chosen for color filtering can be adjusted from 1% to 100% of emitted light, creating a custom balance of light quantity with light quality. This invention recognizes that "better light" is frequently chosen over "more light" in the consumer marketplace.

  19. High-efficiency white organic light-emitting diodes using thermally activated delayed fluorescence

    International Nuclear Information System (INIS)

    Nishide, Jun-ichi; Hiraga, Yasuhide; Nakanotani, Hajime; Adachi, Chihaya

    2014-01-01

    White organic light-emitting diodes (WOLEDs) have attracted much attention recently, aimed for next-generation lighting sources because of their high potential to realize high electroluminescence efficiency, flexibility, and low-cost manufacture. Here, we demonstrate high-efficiency WOLED using red, green, and blue thermally activated delayed fluorescence materials as emissive dopants to generate white electroluminescence. The WOLED has a maximum external quantum efficiency of over 17% with Commission Internationale de l'Eclairage coordinates of (0.30, 0.38).

  20. Blue and white light emission from zinc oxide nanoforests

    Directory of Open Access Journals (Sweden)

    Nafisa Noor

    2015-12-01

    Full Text Available Blue and white light emission is observed when high voltage stress is applied using micrometer-separated tungsten probes across a nanoforest formed of ZnO nanorods. The optical spectrum of the emitted light consistently shows three fine peaks with very high amplitude in the 465–485 nm (blue range, corresponding to atomic transitions of zinc. Additional peaks with smaller amplitudes in the 330–650 nm range and broad spectrum white light is observed depending on the excitation conditions. The spatial and spectral distribution of the emitted light, with pink–orange regions identifying percolation paths in some cases and high intensity blue and white light with center to edge variations in others, indicate that multiple mechanisms lead to light emission. Under certain conditions, the tungsten probe tips used to make electrical contact with the ZnO structures melt during the excitation, indicating that the local temperature can exceed 3422 °C, which is the melting temperature of tungsten. The distinct and narrow peaks in the optical spectra and the abrupt increase in current at high electric fields suggest that a plasma is formed by application of the electrical bias, giving rise to light emission via atomic transitions in gaseous zinc and oxygen. The broad spectrum, white light emission is possibly due to the free electron transitions in the plasma and blackbody radiation from molten silicon. The white light may also arise from the recombination through multiple defect levels in ZnO or due to the optical excitation from solid ZnO. The electrical measurements performed at different ambient pressures result in light emission with distinguishable differences in the emission properties and I–V curves, which also indicate that the dielectric breakdown of ZnO, sublimation, and plasma formation processes are the underlying mechanisms.

  1. Warm-White-Light-Emitting Diode Based on a Dye-Loaded Metal-Organic Framework for Fast White-Light Communication.

    Science.gov (United States)

    Wang, Zhiye; Wang, Zi; Lin, Bangjiang; Hu, XueFu; Wei, YunFeng; Zhang, Cankun; An, Bing; Wang, Cheng; Lin, Wenbin

    2017-10-11

    A dye@metal-organic framework (MOF) hybrid was used as a fluorophore in a white-light-emitting diode (WLED) for fast visible-light communication (VLC). The white light was generated from a combination of blue emission of the 9,10-dibenzoate anthracene (DBA) linkers and yellow emission of the encapsulated Rhodamine B molecules. The MOF structure not only prevents dye molecules from aggregation-induced quenching but also efficiently transfers energy to the dye for dual emission. This light-emitting material shows emission lifetimes of 1.8 and 5.3 ns for the blue and yellow components, respectively, which are significantly shorter than the 200 ns lifetime of Y 3 Al 5 O 12 :Ce 3+ in commercial WLEDs. The MOF-WLED device exhibited a modulating frequency of 3.6 MHz for VLC, six times that of commercial WLEDs.

  2. Tunable white light source for medical applications

    Science.gov (United States)

    Blaszczak, Urszula J.; Gryko, Lukasz; Zajac, Andrzej

    2017-08-01

    Development of light-emitting diodes has brought new possibilities in many applications, especially in terms of flexible adjustment of light spectra. This feature is very useful in construction of many devices, for example for medical diagnosis and treatment. It was proved, that in some cases LEDs can easily replace lasers during therapy of cancer without reduction of efficiency of this process. On the other hand during diagnosis process LED-based constructions can provide unique ability to adjust the color temperature of the output light while maintaining high color rendering. It allows for optimum surface contrast and enhanced tissue differentiation at the operator site. In the paper we describe the construction of the tunable LED-based source designed for application in endoscopy. It was optimized from the point of view of the color rendition for 5 different correlated color temperatures (illuminant A, D55, D65, 3500K and 4500K) with the restriction of very high (>90) values of general and specific color rendering indexes (according to Ra method). The source is composed of 13 light-emitting diodes from visible region mounted on the common radiator and controlled by dedicated system. Spectra of the components are mixed and the spectra of output light is analyzed. On the basis of obtained spectra colorimetric parameters are calculated and compared with the results of theoretical analysis.

  3. Color-stable and efficient tandem white organic light-emitting devices using a LiF n-doping layer and a MoO{sub x} p-doping layer as charge generating unit

    Energy Technology Data Exchange (ETDEWEB)

    Chen, Yu; Wu, Qingyang; Zhang, Zhensong; Yue, Shouzhen; Guo, Runda; Wang, Peng; Wu, Mingzhu; Gou, Changhua; Zhao, Yi, E-mail: yizhao@jlu.edu.cn; Liu, Shiyong

    2013-10-31

    We have demonstrated color-stable and efficient tandem organic light-emitting devices (OLEDs) using 4,7-diphenyl-1,10-phenanthroline (Bphen):LiF/4,4′,4″-tris(N-3-methylphenyl-N-phenyl-amino)triphenylamine (m-MTDATA):molybdenum oxide (MoO{sub x}) as charge generating unit (CGU), which has the advantages of air stability and ease of fabrication; the working mechanism of Bphen:LiF/m-MTDATA:MoO{sub x} is also discussed through analysis of the electrical and spectral emission properties of tandem devices with different CGUs. The performance of tandem white OLED, comprising blue and yellow phosphorescent EL units, can be improved by optimizing the thickness of Bphen:LiF layer. The device comprised of 30 nm Bphen:LiF layer has a maximum current efficiency of 38.7 cd/A and it can still maintain 24.6 cd/A at the luminance of 10,370 cd/m{sup 2}. Moreover, the Commission Internationale de L'Eclairage (CIE) coordinates of the device are rather stable and the variation is only (± 0.003, ± 0.007) over a wide range of luminance (100–13,000 cd/m{sup 2}). - Highlights: • LiF n-doping layer and MoO{sub x} p-doping layer were used as charge generating units. • The device performance was improved by optimizing the thickness of n-doping layer. • High luminance and efficiency were both achieved at a very low current density. • The device showed rather stable spectra over a wide range of luminance.

  4. Solution processed, white emitting tandem organic light-emitting diodes with inverted device architecture.

    Science.gov (United States)

    Höfle, Stefan; Schienle, Alexander; Bernhard, Christoph; Bruns, Michael; Lemmer, Uli; Colsmann, Alexander

    2014-08-13

    Fully solution processed monochromatic and white-light emitting tandem or multi-photon polymer OLEDs with an inverted device architecture have been realized by employing WO3 /PEDOT:PSS/ZnO/PEI charge carrier generation layers. The luminance of the sub-OLEDs adds up in the stacked device indicating multi-photon emission. The white OLEDs exhibit a CRI of 75. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  5. Color design model of high color rendering index white-light LED module.

    Science.gov (United States)

    Ying, Shang-Ping; Fu, Han-Kuei; Hsieh, Hsin-Hsin; Hsieh, Kun-Yang

    2017-05-10

    The traditional white-light light-emitting diode (LED) is packaged with a single chip and a single phosphor but has a poor color rendering index (CRI). The next-generation package comprises two chips and a single phosphor, has a high CRI, and retains high luminous efficacy. This study employs two chips and two phosphors to improve the diode's color tunability with various proportions of two phosphors and various densities of phosphor in the silicone used. A color design model is established for color fine-tuning of the white-light LED module. The maximum difference between the measured and color-design-model simulated CIE 1931 color coordinates is approximately 0.0063 around a correlated color temperature (CCT) of 2500 K. This study provides a rapid method to obtain the color fine-tuning of a white-light LED module with a high CRI and luminous efficacy.

  6. Colour tuning in white hybrid inorganic/organic light-emitting diodes

    International Nuclear Information System (INIS)

    Bruckbauer, Jochen; Brasser, Catherine; Edwards, Paul R; Martin, Robert W; Findlay, Neil J; Skabara, Peter J; Wallis, David J

    2016-01-01

    White hybrid inorganic/organic light-emitting diodes (LEDs) were fabricated by combining a novel organic colour converter with a blue inorganic LED. An organic small molecule was specifically synthesised to act as down-converter. The characteristics of the white colour were controlled by changing the concentration of the organic molecule based on the BODIPY unit, which was embedded in a transparent matrix, and volume of the molecule and encapsulant mixture. The concentration has a critical effect on the conversion efficiency, i.e. how much of the absorbed blue light is converted into yellow light. With increasing concentration the conversion efficiency decreases. This quenching effect is due to aggregation of the organic molecule at higher concentrations. Increasing the deposited amount of the converter does not increase the yellow emission despite more blue light being absorbed. Degradation of the organic converter was also observed during a period of 15 months from LED fabrication. Angular-dependent measurements revealed slight deviation from a Lambertian profile for the blue and yellow emission peaks leading to a small change in ‘whiteness’ with emission angle. Warm white and cool white light with correlated colour temperatures of 2770 K and 7680 K, respectively, were achieved using different concentrations of the converter molecule. Although further work is needed to improve the lifetime and poor colour rendering, these hybrid LEDs show promising results as an alternative approach for generating white LEDs compared with phosphor-based white LEDs. (paper)

  7. White-Light Emission from Layered Halide Perovskites.

    Science.gov (United States)

    Smith, Matthew D; Karunadasa, Hemamala I

    2018-03-20

    With nearly 20% of global electricity consumed by lighting, more efficient illumination sources can enable massive energy savings. However, effectively creating the high-quality white light required for indoor illumination remains a challenge. To accurately represent color, the illumination source must provide photons with all the energies visible to our eye. Such a broad emission is difficult to achieve from a single material. In commercial white-light sources, one or more light-emitting diodes, coated by one or more phosphors, yield a combined emission that appears white. However, combining emitters leads to changes in the emission color over time due to the unequal degradation rates of the emitters and efficiency losses due to overlapping absorption and emission energies of the different components. A single material that emits broadband white light (a continuous emission spanning 400-700 nm) would obviate these problems. In 2014, we described broadband white-light emission upon near-UV excitation from three new layered perovskites. To date, nine white-light-emitting perovskites have been reported by us and others, making this a burgeoning field of study. This Account outlines our work on understanding how a bulk material, with no obvious emissive sites, can emit every color of the visible spectrum. Although the initial discoveries were fortuitous, our understanding of the emission mechanism and identification of structural parameters that correlate with the broad emission have now positioned us to design white-light emitters. Layered hybrid halide perovskites feature anionic layers of corner-sharing metal-halide octahedra partitioned by organic cations. The narrow, room-temperature photoluminescence of lead-halide perovskites has been studied for several decades, and attributed to the radiative recombination of free excitons (excited electron-hole pairs). We proposed that the broad white emission we observed primarily stems from exciton self-trapping. Here, the

  8. Non-doped-type white organic light-emitting diodes for lighting purpose

    Energy Technology Data Exchange (ETDEWEB)

    Zhu Jianzhuo [Key Laboratory of Excited State Processes, Changchun Institute of Optics, Fine Mechanics and Physics, Chinese Academy of Sciences, Changchun 130033 (China); Graduate School of Chinese Academy of Sciences, Beijing 100039 (China); Li Wenlian, E-mail: wllioel@yahoo.com.c [Key Laboratory of Excited State Processes, Changchun Institute of Optics, Fine Mechanics and Physics, Chinese Academy of Sciences, Changchun 130033 (China); Chu Bei, E-mail: beichu@163.co [Key Laboratory of Excited State Processes, Changchun Institute of Optics, Fine Mechanics and Physics, Chinese Academy of Sciences, Changchun 130033 (China); Yan Fei; Yang Dongfang; Liu Huihui; Wang Junbo [Key Laboratory of Excited State Processes, Changchun Institute of Optics, Fine Mechanics and Physics, Chinese Academy of Sciences, Changchun 130033 (China); Graduate School of Chinese Academy of Sciences, Beijing 100039 (China)

    2010-05-15

    We demonstrate a non-doped white organic light-emitting diode (WOLED) in which the blue-, green- and red-emissions are generated from 4,4'-bis(2,2'-diphenylvinyl)-1,1'-biphenyl, tris(8-hydroxyquinoline)aluminum (Alq) and 4-(dicyanomethylene)-2-t-butyl-6-(1,1,7,7-tetramethyl-julolidyl 9-enyl)-4H-pyran (DCJTB), which is used as an ultrathin layer. The DCJTB ultrathin layer plays the chromaticity tuning role in optimizing the white spectral band by modulating the location of the DCJTB ultrathin layer in the green emissive Alq layer. The optimized WOLED gives the Commission Internationale de l'Eclairage-1931 xy coordinates of (0.319, 0.335), a color rendering index of 91.2 at 10 V, a maximum brightness of 21010 cd/m{sup 2} at 12 V and a maximum current efficiency of 5.17 cd/A at 6.6 V. The electroluminescence mechanism of the white device is also discussed.

  9. Efficient light harvesting from flexible perovskite solar cells under indoor white light-emitting diode illumination

    NARCIS (Netherlands)

    Lucarelli, G.; Di Giacomo, F.; Zardetto, V.; Creatore, M.; Brown, T.M.

    2017-01-01

    This is the first report of an investigation on flexible perovskite solar cells for artificial light harvesting by using a white light-emitting diode (LED) lamp as a light source at 200 and 400 lx, values typically found in indoor environments. Flexible cells were developed using either

  10. Imaging camera system of OYGBR-phosphor-based white LED lighting

    Science.gov (United States)

    Kobashi, Katsuya; Taguchi, Tsunemasa

    2005-03-01

    The near-ultraviolet (nUV) white LED approach is analogous to three-color fluorescent lamp technology, which is based on the conversion of nUV radiation to visible light via the photoluminescence process in phosphor materials. The nUV light is not included in the white light generation from nUV-based white LED devices. This technology can thus provide a higher quality of white light than the blue and YAG method. A typical device demonstrates white luminescence with Tc=3,700 K, Ra > 93, K > 40 lm/W and chromaticity (x, y) = (0.39, 0.39), respectively. The orange, yellow, green and blue OYGB) or orange, yellow, red, green and blue (OYRGB) device shows a luminescence spectrum broader than of an RGB white LED and a better color rendering index. Such superior luminous characteristics could be useful for the application of several kinds of endoscope. We have shown the excellent pictures of digestive organs in a stomach of a dog due to the strong green component and high Ra.

  11. Supporting Information Blue and White light electroluminescence in ...

    Indian Academy of Sciences (India)

    Administrator

    Blue and White light electroluminescence in a multilayer OLED using a new Aluminium complex. Pabitra K. Nayak a. , Neeraj Agarwal a. , Farman Ali a. , Meghan P. Patankar b. , K. L.. Narasimhan b. *, N. Periasamy a. *. 1. Department of Chemical Sciences,. 2. Department of Condensed Matter Physics and. Materials ...

  12. Improved light extraction from white organic light-emitting devices using a binary random phase array

    Energy Technology Data Exchange (ETDEWEB)

    Inada, Yasuhisa, E-mail: inada.yasuhisa@jp.panasonic.com; Nishiwaki, Seiji; Hirasawa, Taku; Nakamura, Yoshitaka; Hashiya, Akira; Wakabayashi, Shin-ichi; Suzuki, Masa-aki [R and D Division, Panasonic Corporation, 1006 Kadoma, Kadoma City, Osaka 571-8501 (Japan); Matsuzaki, Jumpei [Device Development Center, Eco Solutions Company, Panasonic Corporation, 1048 Kadoma, Osaka 571-8686 Japan (Japan)

    2014-02-10

    We have developed a binary random phase array (BRPA) to improve the light extraction performance of white organic light-emitting devices (WOLEDs). We demonstrated that the scattering of incoming light can be controlled by employing diffraction optics to modify the structural parameters of the BRPA. Applying a BRPA to the substrate of the WOLED leads to enhanced extraction efficiency and suppression of angle-dependent color changes. Our systematic study clarifies the effect of scattering on the light extraction of WOLEDs.

  13. Improved light extraction from white organic light-emitting devices using a binary random phase array

    International Nuclear Information System (INIS)

    Inada, Yasuhisa; Nishiwaki, Seiji; Hirasawa, Taku; Nakamura, Yoshitaka; Hashiya, Akira; Wakabayashi, Shin-ichi; Suzuki, Masa-aki; Matsuzaki, Jumpei

    2014-01-01

    We have developed a binary random phase array (BRPA) to improve the light extraction performance of white organic light-emitting devices (WOLEDs). We demonstrated that the scattering of incoming light can be controlled by employing diffraction optics to modify the structural parameters of the BRPA. Applying a BRPA to the substrate of the WOLED leads to enhanced extraction efficiency and suppression of angle-dependent color changes. Our systematic study clarifies the effect of scattering on the light extraction of WOLEDs

  14. White OLED devices and processes for lighting applications

    Science.gov (United States)

    Ide, Nobuhiro; Tsuji, Hiroya; Ito, Norihiro; Matsuhisa, Yuko; Houzumi, Shingo; Nishimori, Taisuke

    2010-05-01

    In these days, the basic performances of white OLEDs are dramatically improved and application of OLEDs to "Lighting" is expected to be true in the near future. We have developed various technologies for OLED lighting with the aid of the Japanese governmental project, "High-efficiency lighting based on the organic light-emitting mechanism." In this project, a white OLED with high efficiency (37 lm/W) and high quality emission characteristics (CRI of 95 with a small variation of chromaticity in different directions and chromaticity just on the black-body radiation curve) applicable to "Lighting" was realized by a two-unit structure with a fluorescent deep blue emissive unit and a phosphorescent green and red emissive unit. Half-decay lifetime of this white OLED at 1,000 cd/m2 was over 40,000 h. A heat radiative, thin encapsulation structure (less than 1 mm) realized a very stable emission at high luminance of over 3,000 cd/m2. A new deposition source with a hot-wall and a rate controllable valve was developed. Thickness uniformity within +/- 3% at high deposition rate of over 8 nm/s, high material utilization of over 70 %, and repeatable deposition rate controllability were confirmed.

  15. White polymer light-emitting diode based on polymer blending

    International Nuclear Information System (INIS)

    Lee, Yong Kyun; Kwon, Soon Kab; Kim, Jun Young; Park, Tae Jin; Song, Dae Ho; Kwon, Jang Hyuk; Choo, Dong Jun; Jang, Jin; Jin, Jae Kyu; You, Hong

    2006-01-01

    A series of white polymer light emitting devices have been fabricated by using a polymer blending system of polyfluorene-based blue and MEH-PPV red polymers. A device structure of ITO/PEDOT:PSS/polymer/LiF/Al was employed. The white polymer device exhibited a current efficiency of 4.33 cd/A (4,816 cd/m 2 , Q.E. = 1.9 %) and a maximum luminance of 21,430 cd/m 2 at 9.2 V. The CIE coordinates were (0.35, 0.37) at 5 V and (0.29, 0.30) at 9 V.

  16. Synthesis and Electroluminescent Property of New Orange Iridium Compounds for Flexible White Organic Light Emitting Diodes.

    Science.gov (United States)

    Lee, Ho Won; Jeong, Hyunjin; Kim, Young Kwan; Ha, Yunkyoung

    2015-10-01

    Recently, white organic light-emitting diodes (OLEDs) have aroused considerable attention because they have the potential of next-generation flexible displays and white illuminated applications. White OLED applications are particularly heading to the industry but they have still many problems both materials and manufacturing. Therefore, we proposed that the new iridium compounds of orange emitters could be demonstrated and also applied to flexible white OLEDs for verification of potential. First, we demonstrated the chemical properties of new orange iridium compounds. Secondly, conventional two kinds of white phosphorescent OLEDs were fabricated by following devices; indium-tin oxide coated glass substrate/4,4'-bis[N-(napthyl)-N-phenylamino]biphenyl/N,N'-dicarbazolyl-3,5-benzene doped with blue and new iridium compounds for orange emitting 8 wt%/1,3,5-tris[N-phenylbenzimidazole-2-yl]benzene/lithium quinolate/aluminum. In addition, we fabricated white OLEDs using these emitters to verify the potential on flexible substrate. Therefore, this work could be proposed that white light applications can be applied and could be extended to additional research on flexible applications.

  17. Human Adolescent Phase Response Curves to Bright White Light.

    Science.gov (United States)

    Crowley, Stephanie J; Eastman, Charmane I

    2017-08-01

    Older adolescents are particularly vulnerable to circadian misalignment and sleep restriction, primarily due to early school start times. Light can shift the circadian system and could help attenuate circadian misalignment; however, a phase response curve (PRC) to determine the optimal time for receiving light and avoiding light is not available for adolescents. We constructed light PRCs for late pubertal to postpubertal adolescents aged 14 to 17 years. Participants completed 2 counterbalanced 5-day laboratory sessions after 8 or 9 days of scheduled sleep at home. Each session included phase assessments to measure the dim light melatonin onset (DLMO) before and after 3 days of free-running through an ultradian light-dark (wake-sleep) cycle (2 h dim [~20 lux] light, 2 h dark). In one session, intermittent bright white light (~5000 lux; four 20-min exposures) was alternated with 10 min of dim room light once per day for 3 consecutive days. The time of light varied among participants to cover the 24-h day. For each individual, the phase shift to bright light was corrected for the free-run derived from the other laboratory session with no bright light. One PRC showed phase shifts in response to light start time relative to the DLMO and another relative to home sleep. Phase delay shifts occurred around the hours corresponding to home bedtime. Phase advances occurred during the hours surrounding wake time and later in the afternoon. The transition from delays to advances occurred at the midpoint of home sleep. The adolescent PRCs presented here provide a valuable tool to time bright light in adolescents.

  18. Warm white light generation from single phase Sr{sub 3}Y(PO{sub 4}){sub 3}:Dy{sup 3+}, Eu{sup 3+} phosphors with near ultraviolet excitation

    Energy Technology Data Exchange (ETDEWEB)

    Huang, B.Y. [School of Physics & Optoelectronic Engineering, Guangdong University of Technology, Guangzhou 510006 (China); Feng, B.L. [State Key Laboratory of Optoelectronic Materials and Technologies, School of Physics, Sun Yat-sen University, Guangzhou 510275 (China); Luo, L., E-mail: luoli@gdut.edu.cn [School of Physics & Optoelectronic Engineering, Guangdong University of Technology, Guangzhou 510006 (China); Han, C.L. [School of Physics & Optoelectronic Engineering, Guangdong University of Technology, Guangzhou 510006 (China); He, Y.T.; Qiu, Z.R. [State Key Laboratory of Optoelectronic Materials and Technologies, School of Physics, Sun Yat-sen University, Guangzhou 510275 (China)

    2016-10-15

    Highlights: • Novel single phase phosphors were synthesized in an ambient air atmosphere. • A direct band gap about 4.5 eV of the host is calculated for the first time. • It is suitable for near UV chip excitation. • It emits warm white light with better CIE and lower CCT over previous reports. • The thermal quenching is similar to that of YAG:0.06Ce{sup 3+} commercial phosphor. - Abstract: Novel Sr{sub 3}Y(PO{sub 4}){sub 3}:Dy{sup 3+}, Eu{sup 3+} (SYP:Dy{sup 3+}, Eu{sup 3+}) phosphors were synthesized by a standard solid-state reaction under an ambient air atmosphere and their structural and optical properties were investigated. XRD and diffuse reflectance spectra (DRS) were used to explore structural properties. The former showed that single phase phosphors were obtained and that the rare earth ions entered into the cubic host by substituting the smaller Y{sup 3+} ions and thereby enlarging the unit cell. The DRS indicated that the host has a direct bandgap of 4.5 eV. Under 393 nm excitation, a strong and stable warm white light emission with high color purity was achieved in SY{sub 0.92}P:0.06Dy{sup 3+}, 0.04Eu{sup 3+}. The energy transfer from Dy{sup 3+} to Eu{sup 3+} ions was investigated and the related mechanism was discussed based on the optical spectra and emission decay curves. The thermal quenching of emission is similar to that of YAG:0.06Ce{sup 3+}. The results show the single phase phosphor is potential in warm white LED.

  19. Formulating CdSe quantum dots for white light-emitting diodes with high color rendering index

    International Nuclear Information System (INIS)

    Li, Fei; Li, Wan-Nan; Fu, Shao-Yun; Xiao, Hong-Mei

    2015-01-01

    Generation of white light using CdSe quantum dots (QDs) alone presents exciting possibilities for solid state lighting technology. In this work, Cd(Ac) 2 ·2H 2 O and Na 2 SeSO 3 are used as precursors to synthesize CdSe-QDs with an average diameter ranging from 2.77 to 4.65 nm at the low temperature from 60 to 180 °C. Smaller CdSe-QDs with an average diameter of 2.29 nm are got by an oxidation etching process using H 2 O 2 as oxidant. The structural and optical properties of these QDs are investigated and proper formulation of CdSe QDs with various sizes is carefully designed to achieve white light with a high color rendering index (CRI). It is observed for the first time that the as-prepared white light-emitting diodes from single CdSe-QDs show the Commission Inernationale del’Eclairage coordinate (CIE) of (0.30,0.34) very close to that (0.33,0.33) of pure white light and a high CRI of 84. Owing to these advantages, the as-prepared white light-emitting diodes from a single compound are promising for lighting applications. - Highlights: • CdSe-quantum dots (QDs) with a continuously changing size from 2.31 to 4.74 nm are prepared. • The obtained CdSe-QDs emit lights with tunable colors in the whole visible range. • The obtained mixture sample generates white light with a high color rendering index of 84. • The sample yields white light with the CIE coordinate (0.30, 0.34) very close to that of pure white light

  20. Intrinsic white-light emission from layered hybrid perovskites.

    Science.gov (United States)

    Dohner, Emma R; Jaffe, Adam; Bradshaw, Liam R; Karunadasa, Hemamala I

    2014-09-24

    We report on the second family of layered perovskite white-light emitters with improved photoluminescence quantum efficiencies (PLQEs). Upon near-ultraviolet excitation, two new Pb-Cl and Pb-Br perovskites emit broadband "cold" and "warm" white light, respectively, with high color rendition. Emission from large, single crystals indicates an origin from the bulk material and not surface defect sites. The Pb-Br perovskite has a PLQE of 9%, which is undiminished after 3 months of continuous irradiation. Our mechanistic studies indicate that the emission has contributions from strong electron-phonon coupling in a deformable lattice and from a distribution of intrinsic trap states. These hybrids provide a tunable platform for combining the facile processability of organic materials with the structural definition of crystalline, inorganic solids.

  1. Signal-to-noise limitations in white light holography.

    Science.gov (United States)

    Ribak, E; Roddier, C; Roddier, F; Breckinridge, J B

    1988-03-15

    A simple derivation is given for the signal-to-noise ratio (SNR) in images reconstructed from incoherent holograms. Dependence is shown to be on the hologram SNR, object complexity, and the number of pixels in the detector. Reconstruction of involved objects becomes possible with high dynamic range detectors such as charge coupled devices. We have produced such white light holograms by means of a rotational shear interferometer combined with a chromatic corrector. A digital inverse transform recreated the object.

  2. Signal-to-noise limitations in white light holography

    Science.gov (United States)

    Ribak, Erez; Breckinridge, James B.; Roddier, Claude; Roddier, Francois

    1988-01-01

    A simple derivation is given for the SNR in images reconstructed from incoherent holograms. Dependence is shown to be on the hologram SNR, object complexity, and the number of pixels in the detector. Reconstruction of involved objects becomes possible with high-dynamic-range detectors such as CCDs. White-light holograms have been produced by means of a rotational shear interferometer combined with a chromatic corrector. A digital inverse transform recreated the object.

  3. Effects of doping parameters on the CIE value of flexible white organic light emitting diodes

    Energy Technology Data Exchange (ETDEWEB)

    Juang Fuhshyang; Lin Mingyein; Yang Chanyi [Institute of Electro-Optical and Materials Science, National Huwei University of Science and Technology, Huwei, Yunlin (Taiwan); Tsai Yusheng [Department of Electro-Optics Engineering, National Huwei University of Science and Technology, Huwei, Yunlin (Taiwan); Lin, David [Windell Corporation, 1F, No. 9, Kung-Yen 7 Road, Industrial Zone, Taichung (Taiwan); Wang Wentunn; Shen Chaiyuan [Electronics Research and Service Organization, Industrial Technology Research Institute, 195 Chung Hsing Rd., Sec. 4 Chu Tung, Hsin Chu (Taiwan)

    2004-09-01

    Red dopants were doped in different emitters, blue and green, respectively, to fabricate white organic light emitting diodes on flexible substrates. The competitive emission between blue and red emitters with various doped-zones was studied. When the DCJT doped zone was located far away from the hole-injection layer, both the blue and red color can be emitted. An appropriate red-dopant position in the device enhanced the green emission from 8-hydroxyquinoline aluminum (Alq3) which was combined with the red and blue emission to generate a white light. Finally, a white emission with the CIE value, (0.30, 0.32), independent of the applied voltage, was obtained with the optimum doped width and location. (copyright 2004 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)

  4. An organic white light-emitting dye: very small molecular architecture displays panchromatic emission.

    Science.gov (United States)

    Nandhikonda, Premchendar; Heagy, Michael D

    2010-11-14

    The synthesis and photophysical characterization of a new white-light fluorophore is described. The optimization of excitation wavelengths allows the naphthalimide (NI) dyes to display blue, green or white light emission depending on the excitation wavelength.

  5. Development of Key Technologies for White Lighting Based on Light-Emitting Diodes (LEDs)

    Energy Technology Data Exchange (ETDEWEB)

    Werner Goetz; Bill Imler; James Kim; Junko Kobayashi; Andrew Kim; Mike Krames; Rick Mann; Gerd Mueller-Mach; Anneli Munkholm; Jonathan Wierer

    2004-03-31

    This program was organized to focus on materials development issues critical to the acceleration of solid-state lighting, and was split into three major thrust areas: (1) study of dislocation density reduction for GaN grown on sapphire using 'cantilever epitaxy', and the impact of dislocation density on the performance of state-of-the-art high-power LEDs; (2) the evaluation of in situ techniques for monitoring gas phase chemistry and the properties of GaN-based layers during metal-organic vapor phase epitaxy (MOCVD), and (3) feasibility for using semiconductor nanoparticles ('quantum dots') for the down-conversion of blue or ultraviolet light to generate white light. The program included a partnership between Lumileds Lighting (epitaxy and device fabrication for high power LEDs) and Sandia National Laboratories (cantilever epitaxy, gas phase chemistry, and quantum dot synthesis). Key findings included: (1) cantilever epitaxy can provide dislocation density reduction comparable to that of more complicated approaches, but all in one epitaxial growth step; however, further improvements are required to realize significant gains in LED performance at high drive currents, (2) in situ tools can provide detailed knowledge about gas phase chemistry, and can be used to monitor and control epitaxial layer composition and temperature to provide improved yields (e.g., a fivefold increase in color targeting is demonstrated for 540nm LEDs), and (3) quantum efficiency for quantum dots is improved and maintained up to 70% in epoxy thin films, but further work is necessary to increase densification (absorption) and robustness before practical application to LEDs.

  6. Cold white light generation through the simultaneous emission from Ce{sup 3+}, Dy{sup 3+} and Mn{sup 2+} in 90Al{sub 2}O{sub 3}{center_dot}2CeCl{sub 3}{center_dot}3DyCl{sub 3}{center_dot}5MnCl{sub 2} thin film

    Energy Technology Data Exchange (ETDEWEB)

    Gonzalez, W. [Departamento de Fisica, Universidad Autonoma Metropolitana-Iztapalapa, P.O. Box 55-534, Mexico, D.F. 09340 (Mexico); Alvarez, E. [Departamento de Fisica, Universidad de Sonora (UNISON), Boulevard Luis Encinas y Rosales s/n, Hermosillo, Sonora 83000 (Mexico); Martinez-Martinez, R.; Yescas-Mendoza, E. [Instituto de Fisica y Matematicas, Universidad Tecnologica de la Mixteca, Carretera a Acatlima Km. 2.5, Huajuapan de Leon, Oaxaca 69000 (Mexico); Camarillo, I. [Departamento de Fisica, Universidad Autonoma Metropolitana-Iztapalapa, P.O. Box 55-534, Mexico, D.F. 09340 (Mexico); Caldino, U., E-mail: cald@xanum.uam.mx [Departamento de Fisica, Universidad Autonoma Metropolitana-Iztapalapa, P.O. Box 55-534, Mexico, D.F. 09340 (Mexico)

    2012-08-15

    The photoluminescence of a CeCl{sub 3}, DyCl{sub 3} and MnCl{sub 2} doped aluminum oxide film deposited by ultrasonic spray pyrolysis was characterized by excitation, emission and decay time spectroscopy. A nonradiative energy transfer from Ce{sup 3+} to Dy{sup 3+} and Mn{sup 2+} is observed upon UV excitation at 278 nm (peak emission wavelength of AlGaN-based LEDs). Such energy transfer leads to a simultaneous emission of these ions in the blue, green, yellow and red regions, resulting in white light emission with CIE1931 chromaticity coordinates, x=0.34 and y=0.23, which correspond to cold white light with a color temperature of 4900 K. - Highlights: Black-Right-Pointing-Pointer 90Al{sub 2}O{sub 3}{center_dot}2CeCl{sub 3}{center_dot}3DyCl{sub 3}{center_dot}5MnCl{sub 2} thin film (AOCDM) could be prepared by spray pyrolysis. Black-Right-Pointing-Pointer Non-radiative energy transfer from Ce{sup 3+} to Dy{sup 3+} and Mn{sup 2+} takes place in AOCDM. Black-Right-Pointing-Pointer AOCDM (pumped with 278 nm-UV light) can generate 4900 K cold white light.

  7. White light Sagnac interferometer—a common (path) tale of light

    Science.gov (United States)

    Schwartz, Eyal

    2017-11-01

    White or polychromatic light sources are vastly abundant in nature and lie in our most basic understanding of the theory of light, beginning from stars like our Sun and extending to every common household light bulb or street lamp. In this paper, I present concepts of white light interferometery using a common-path Sagnac interferometer, manifested in a straightforward laboratory experiment. I further show the use of this as a Fourier transform spectrometer while presenting a basic overview of the theoretical concepts and spectrum of different light sources obtained experimentally. This work, both experimentally and analytically, is suitable for upper-level undergraduate physics or engineering courses where electromagnetic theory and optics are discussed. The experiment and theory presents important deep concepts and aspects in modern optics and physics that every science student should acquire.

  8. White light Sagnac interferometer—a common (path) tale of light

    International Nuclear Information System (INIS)

    Schwartz, Eyal

    2017-01-01

    White or polychromatic light sources are vastly abundant in nature and lie in our most basic understanding of the theory of light, beginning from stars like our Sun and extending to every common household light bulb or street lamp. In this paper, I present concepts of white light interferometery using a common-path Sagnac interferometer, manifested in a straightforward laboratory experiment. I further show the use of this as a Fourier transform spectrometer while presenting a basic overview of the theoretical concepts and spectrum of different light sources obtained experimentally. This work, both experimentally and analytically, is suitable for upper-level undergraduate physics or engineering courses where electromagnetic theory and optics are discussed. The experiment and theory presents important deep concepts and aspects in modern optics and physics that every science student should acquire. (paper)

  9. The High-Temperature Synthesis of the Nanoscaled White-Light Phosphors Applied in the White-Light LEDs

    Directory of Open Access Journals (Sweden)

    Hao-Ying Lu

    2015-01-01

    Full Text Available The white-light phosphors consisting of Dy3+ doped YPO4 and Dy3+ doped YP1-XVXO4 were prepared by the chemical coprecipitation method. After the 1200°C thermal treatment in the air atmosphere, the white-light phosphors with particle sizes around 90 nm can be obtained. In order to reduce the average particle size of phosphors, the alkaline washing method was applied to the original synthesis process, which reduces the particle sizes to 65 nm. From the PLE spectra, four absorption peaks locating at 325, 352, 366, and 390 nm can be observed in the YPO4-based phosphors. These peaks appear due to the following electron transitions: 6H15/2→4K15/2, 6H15/2→4M15/2+6P7/2, 6H15/2→4I11/2, and 6H15/2→4M19/2. Besides, the emission peaks of wavelengths 484 nm and 576 nm can be observed in the PL spectra. In order to obtain the white-light phosphors, the vanadium ions were applied to substitute the phosphorus ions to compose the YP1-XVXO4 phosphors. From the PL spectra, the strongest PL intensity can be obtained with 30% vanadium ions. As the concentration of vanadium ions increases to 40%, the phosphors with the CIE coordinates locating at the white-light area can be obtained.

  10. First demonstration of 'white-light' laser cooling of a stored ion beam

    International Nuclear Information System (INIS)

    Atutov, S.N.; Biancalana, V.; Calabrese, R.; Clauser, T.; Grimm, R.; Guidi, V.; Lamanna, G.; Lauer, I.; Lenisa, P.; Luger, V.; Mariotti, E.; Moi, L.; Schramm, U.; Stagno, V.; Stoessel, M.; Tecchio, L.; Variale, V.

    1998-01-01

    'White-light' cooling of an ion beam confined in a storage ring has been demonstrated at Test Storage Ring in Heidelberg. Measurements aimed at comparing 'white-light' with single-mode laser cooling show that 'white-light' cooling gives lower temperatures at higher ion densities both in a coasting and in a bunched beam

  11. Performance of new generation pole light

    International Nuclear Information System (INIS)

    Foo, K C; Karunanithi, S; Thio, G

    2013-01-01

    This paper describes the design and implementation of a standalone photovoltaic power supply which caters for garden lighting scheme. New Generation Pole Light (NGPL) consists of three parts which are light dependent resistor (LDR) and pyroelectric infrared (PIR) sensors, microcontroller and light emitting diode (LED) and finally, solar charging system. During the night, LED is switched on with two operating modes which are ultra-bright lighting for a predetermine period (when human presence is detected) and dim lighting. Meanwhile, LED is switched off at day time and solar charging system will recover the capacity of discharged battery. NGPL provides portable, sustainable, environmental friendly and requires minimal maintenance for outdoor lighting scheme for both urban and rural areas.

  12. Mercury in canned tuna: white versus light and temporal variation

    International Nuclear Information System (INIS)

    Burger, Joanna; Gochfeld, Michael

    2004-01-01

    There are abundant data and advisories for mercury levels in wild fish, but far fewer for commercial fish that compose a large majority of the fish most people eat. Until recently, relatively little attention has been devoted to examining mercury in canned tuna, despite its great importance in human diets. There is substantial media coverage of the benefits and risk from fish consumption, but few peer-reviewed data on canned tuna, the most commonly consumed fish in the United States. In this paper, we examine the levels of total mercury in canned tuna obtained from a New Jersey grocery store from 1998 to 2003, looking for temporal consistency within this data set and particularly for comparison with the Food and Drug Administration's 1991 study. We analyzed 168 cans individually for total mercury. All values are reported as parts per million (=μg/g) on a wet weight basis. In a subset of samples analyzed for total and inorganic mercury, the inorganic mercury was below detection levels; hence at least 89% of the mercury can be considered methylmercury. We found that white-style tuna had significantly more total mercury (mean 0.407 ppm) than light-style tuna (mean 0.118 ppm), presumably reflecting that 'white' tuna is albacore, a species relatively larger than the skipjack tuna, which is commonly available as 'light' or 'chunk light'. The maximum mercury in a can was 0.997 ppm, but 25% of white tuna samples exceeded 0.5 ppm. Data suggest a slight increase in levels since 1991, and mercury levels were significantly higher in 2001 than in other years. The mean level of mercury in white tuna (mean 0.407 ppm) was significantly higher than the mean value of 0.17 ppm currently used by the U.S. Food and Drug Administration (FDA) in its risk assessment and public information. There were no significant differences in mercury levels in tuna packed in oil compared to water. Draining contents had no effect on mercury levels, and the fluid, both oil and water, contained little

  13. Efficient white organic light emission by single emitting layer

    Energy Technology Data Exchange (ETDEWEB)

    Ko, Young Wook; Chung, Choong-Heui; Lee, Jin Ho; Kim, Yong-Hae; Sohn, Choong-Yong; Kim, Bong-Chul; Hwang, Chi-Sun; Song, Yoon-Ho; Lim, Jongtae; Ahn, Young-Joo; Kang, Gi-Wook; Lee, Namheon; Lee, Changhee

    2003-02-24

    Stable organic white light-emitting diodes are successfully fabricated by a single organic white emitting layer, which is Bis (2-methyl-8-quinolinato) (triphenylsiloxy) aluminum (III) (SAlq) doped red fluorescent dye of 4-(dicyanomethylene)-2-tert-butyl-6(1,1,7,7-tetramethyljulolidyl-9-enyl)- 4H-pyran (DCJTB). The incomplete energy transfer from blue-emitting SAlq to red-emitting DCJTB enables to obtain a stable white balanced light-emission by the DCJTB doping concentration of 0.5%. A device with the structure of ITO/TPD (50 nm)/SAlq:DCJTB (30 nm, 0.5%)/Alq{sub 3} (20 nm)/LiF (0.5 nm)/Al (110 nm) shows maximum luminance of 20 400 cd/m{sup 2} at 810 mA/cm{sup 2}, external quantum efficiency of 2% at 200 cd/m{sup 2} ({approx}3 mA/cm{sup 2}), power efficiency of 2.3 lm/W at 67 cd/m{sup 2} ({approx}1 mA/cm{sup 2}), and a Commission Internationale de l'Eclairage chromaticity coordinates of (0.34, 0.39) at 1.8 mA/cm{sup 2} to (0.31, 0.38) at 36 mA/cm{sup 2}.

  14. Laser Based Phosphor Converted Solid State White Light Emitters

    Science.gov (United States)

    Cantore, Michael

    Artificial lighting and as a consequence the ability to be productive when the sun does not shine may be a profound achievement in society that is largely taken for granted. As concerns arise due to our dependence on energy sources with finite lifespan or environmentally negative effects, efforts to reduce energy consumption and create clean renewable alternatives has become highly valued. In the scope of artificial lighting, the use of incandescent lamps has shifted to more efficient light sources. Fluorescent lighting made the first big gains in efficiency over incandescent lamps with peak efficiency for mature designs reaching luminous efficacy of approximately 90 lm/W; more than three times as efficient as an incandescent lamp. Lamps based on light emitting diodes (LEDs) which can produce light at even greater efficiency, color quality and without the potential for hazardous chemical release from lamp failure. There is a significant challenge with LED based light sources. Their peak efficiency occurs at low current densities and then droops as the current density increases. Laser diodes (LDs) do not suffer from decreasing efficiency due to increased current. An alternative solid state light source using LDs has potential to make further gains in efficiency as well as allow novel illuminant designs which may be impractical or even impossible even with LED or other conventional sources. While similar to LEDS, the use of LDs does present new challenges largely due to the increased optical power density which must be accommodated in optics and phosphor materials. Single crystal YAG:Ce has been shown to be capable of enduring this more extreme operating environment while retaining the optical and fluorescing qualities desired for use as a wavelength converter in phosphor converted LD based white emitting systems. The incorporation of this single crystal phosphor in a system with a commercial laser diode with peak wall plug efficiency of 31% resulted in emission of

  15. White organic light-emitting diodes from three emitter layers

    Energy Technology Data Exchange (ETDEWEB)

    Kim, M.S. [Department of Advanced Materials Science and Engineering, SungKyunKwan University, Suwon, Gyonggi-Do, 440-746 (Korea, Republic of); Lim, J.T. [Department of Advanced Materials Science and Engineering, SungKyunKwan University, Suwon, Gyonggi-Do, 440-746 (Korea, Republic of); Jeong, C.H. [Department of Advanced Materials Science and Engineering, SungKyunKwan University, Suwon, Gyonggi-Do, 440-746 (Korea, Republic of); Lee, J.H. [Department of Advanced Materials Science and Engineering, SungKyunKwan University, Suwon, Gyonggi-Do, 440-746 (Korea, Republic of); Yeom, G.Y. [Department of Advanced Materials Science and Engineering, SungKyunKwan University, Suwon, Gyonggi-Do, 440-746 (Korea, Republic of)]. E-mail: gyyeom@skku.edu

    2006-11-23

    Three-wavelength white organic light-emitting diodes (WOLEDs) were fabricated using two doped layers, which were obtained by separating the recombination zones into three emitter layers. A sky blue emission originated from the 4,4'-bis(2,2'-diphenylethen-1-yl)biphenyl (DPVBi) layer. A green emission originated from a tris(8-quinolinolato)aluminum (III) (Alq{sub 3}) host doped with a green fluorescent 10-(2-benzothiazolyl)-1,1,7,7-tetramethyl-2,3,6,7-tetrahydro-1H,5H,11H-[1] benz opyrano [6,7,8-ij]-quinolizin-11-one (C545T) dye. An orange emission was obtained from the N,N'-bis(1-naphthyl)-N,N'-diphenyl-1,1'-biphenyl-4,4'-diamine (NPB) host doped with a red fluorescent dye, 4-(dicyanomethylene)-2-tert-butyl-6-(1,1,7,7-tetramethyljulolidyl-9-enyl)-4 H-pyran (DCJTB). A white light resulted from the partial excitations of these three emitter layers by controlling the layer thickness and concentration of the fluorescent dyes in each emissive layer simultaneously. The electroluminescent spectrum of the device was not sensitive to the driving voltage of the device. The white light device showed a maximum luminance of approximately 53,000 cd/m{sup 2}. The external quantum and power efficiency at a luminance of approximately 100 cd/m{sup 2} were 2.62% and 3.04 lm/W, respectively.

  16. Testing the stationarity of white dwarf light-curves

    International Nuclear Information System (INIS)

    Molnar, L; Kollath, Z; Plachy, E; Paparo, M

    2009-01-01

    Long period white dwarfs show changes in their frequency spectra from one observing season to another, i.e. their light-curves cannot be considered as stationary multiperiodic variations on long timescales. However, due to the complex frequency spectra of these stars and the narrow frequency spacing, it is still unknown, what the shortest time scale is, where real physical modulation exists. We present tests on artificial data, resembling the observations, using time-frequency distributions (TFDs), Fourier-analysis and the analytical signal method.

  17. Capturing triplet emission in white organic light emitting devices

    Energy Technology Data Exchange (ETDEWEB)

    Singh, Jai [Faculty of EHSE, School of Engineering and IT, B-purple-12, Charles Darwin University, Darwin, NT 0909 (Australia)

    2011-08-15

    The state-of-the art in the white organic light emitting devices (WOLEDs) is reviewed for further developments with a view to enhance the capture of triplet emission. In particular, applying the new exciton-spin-orbit-photon interaction operator as a perturbation, rates of spontaneous emission are calculated in a few phosphorescent materials and compared with experimental results. For iridium based phosphorescent materials the rates agree quite well with the experimental results. (Copyright copyright 2011 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

  18. Spectral confocal reflection microscopy using a white light source

    Science.gov (United States)

    Booth, M.; Juškaitis, R.; Wilson, T.

    2008-08-01

    We present a reflection confocal microscope incorporating a white light supercontinuum source and spectral detection. The microscope provides images resolved spatially in three-dimensions, in addition to spectral resolution covering the wavelength range 450-650nm. Images and reflection spectra of artificial and natural specimens are presented, showing features that are not normally revealed in conventional microscopes or confocal microscopes using discrete line lasers. The specimens include thin film structures on semiconductor chips, iridescent structures in Papilio blumei butterfly scales, nacre from abalone shells and opal gemstones. Quantitative size and refractive index measurements of transparent beads are derived from spectral interference bands.

  19. Improvements of phosphorescent white OLEDs performance for lighting application.

    Science.gov (United States)

    Lee, Jonghee; Chu, Hye Yong; Lee, Jeong-Ik; Song, Ki-Im; Lee, Su Jin

    2008-10-01

    We developed white OLED device with high power efficiency, in which blue and orange phosphorescent emitters were used. By introduction of multi-functional interlayer which has partial doping of orange dopant inside EBL, we report WOLEDs with peak external efficiencies up to (14.1% EQE, 31.3 Im/W) without light out-coupling technique. At 1000 cd/m2, the performance achieved was 11.9% EQE, 18.7 Im/W with CIE = (0.39, 0.44). We also found that WOLED performances are related with doping ratio of the orange dopant that was inserted inside EBL.

  20. Efficient white organic light-emitting diodes based on an orange iridium phosphorescent complex

    International Nuclear Information System (INIS)

    Chen Ping; Zhao Li; Duan Yu; Zhao Yi; Xie Wenfa; Xie Guohua; Liu Shiyong; Zhang Liying; Li Bin

    2011-01-01

    Stable and efficient white light emission is obtained by mixing blue fluorescence and orange phosphorescence. The introduction of double exciton blocking layers brings about well confinement of both charge-carriers and excitons in the emission layer. By systematically adjusting blue fluorescent and orange phosphorescent emission layers thickness, carriers in emission zone are balanced, and electrically generated excitons can be efficiently utilized. One white device with power efficiency of 14.4 lm/W at 100 cd/m 2 has excellently stable spectra. The improvement of performance is attributed to efficient utilization of the excitons and more balance of charge-carriers in emission layer. - Highlights: → Stable and efficient white light emission is obtained by mixing blue fluorescence and orange phosphorescence. → White device has power efficiency of 14.4 and 10.1 lm/W obtained at 100 and 1000 cd/m 2 , respectively. → White device has excellently stable spectra over a wide range of luminance. → Singlet and triplet excitons are sufficiently utilized by fluorescent and phosphorescent materials.

  1. Steering and filtering white light with resonant waveguide gratings

    Science.gov (United States)

    Quaranta, Giorgio; Basset, Guillaume; Martin, Olivier J. F.; Gallinet, Benjamin

    2017-08-01

    A novel thin-film single-layer structure based on resonant waveguide gratings (RWGs) allows to engineer selective color filtering and steering of white light. The unit cell of the structure consists of two adjacent finite-length and cross-talking RWGs, where the former acts as in-coupler and the latter acts as out-coupler. The structure is made by only one nano-imprint lithography replication and one thin film layer deposition, making it fully compatible with up-scalable fabrication processes. We characterize a fabricated optical security element designed to work with the flash and the camera of a smartphone in off-axis light steering configuration, where the pattern is revealed only by placing the smartphone in the proper position. Widespread applications are foreseen in a variety of fields, such as multifocal or monochromatic lenses, solar cells, biosensors, security devices and seethrough optical combiners for near-eye displays.

  2. Molecular-scale simulation of electroluminescence in a multilayer white organic light-emitting diode

    DEFF Research Database (Denmark)

    Mesta, Murat; Carvelli, Marco; de Vries, Rein J

    2013-01-01

    we show that it is feasible to carry out Monte Carlo simulations including all of these molecular-scale processes for a hybrid multilayer organic light-emitting diode combining red and green phosphorescent layers with a blue fluorescent layer. The simulated current density and emission profile......In multilayer white organic light-emitting diodes the electronic processes in the various layers--injection and motion of charges as well as generation, diffusion and radiative decay of excitons--should be concerted such that efficient, stable and colour-balanced electroluminescence can occur. Here...

  3. Monolithic Inorganic ZnO/GaN Semiconductors Heterojunction White Light-Emitting Diodes.

    Science.gov (United States)

    Jeong, Seonghoon; Oh, Seung Kyu; Ryou, Jae-Hyun; Ahn, Kwang-Soon; Song, Keun Man; Kim, Hyunsoo

    2018-01-31

    Monolithic light-emitting diodes (LEDs) that can generate white color at the one-chip level without the wavelength conversion through packaged phosphors or chip integration for photon recycling are of particular importance to produce compact, cost-competitive, and smart lighting sources. In this study, monolithic white LEDs were developed based on ZnO/GaN semiconductor heterojunctions. The electroluminescence (EL) wavelength of the ZnO/GaN heterojunction could be tuned by a post-thermal annealing process, causing the generation of an interfacial Ga 2 O 3 layer. Ultraviolet, violet-bluish, and greenish-yellow broad bands were observed from n-ZnO/p-GaN without an interfacial layer, whereas a strong greenish-yellow band emission was the only one observed from that with an interfacial layer. By controlled integration of ZnO/GaN heterojunctions with different postannealing conditions, monolithic white LED was demonstrated with color coordinates in the range (0.3534, 0.3710)-(0.4197, 0.4080) and color temperatures of 4778-3349 K in the Commission Internationale de l'Eclairage 1931 chromaticity diagram. Furthermore, the monolithic white LED produced approximately 2.1 times higher optical output power than a conventional ZnO/GaN heterojunction due to the carrier confinement effect at the Ga 2 O 3 /n-ZnO interface.

  4. Efficient white organic light emitting devices with dual emitting layers

    International Nuclear Information System (INIS)

    Wu Yaoshan; Hwang Shiaowen; Chen Hsianhung; Lee Mengting; Shen Wenjian; Chen, C.H.

    2005-01-01

    In this paper, a new white organic light-emitting device (OLED) with the structure of indium tin oxide / CF x / 1,4-bis[N-(1-naphthyl)-N'-phenylamino]-biphenyl (NPB) (30 nm)/NPB: 2,8-di(t-butyl)-5,11-di[4-(t-butyl)phenyl]-6,12-diphenylnaphthacene (20 nm; 1.6 %) / 2-methyl-9,10-di(2-naphthyl) anthracene: p-bis(p-N,N-di-phenyl-aminostyryl)benzene (40 nm, 3%) / aluminum tris(8-hydroxyquinoline) (20 nm) / LiF (1 nm) / Al (200 nm) has been investigated. The device showed white emission with a high-luminous yield of 9.75 cd/A at 20 mA/cm 2 , but its Commission Internationale de l'Eclairage chromaticity coordinates appeared to change from (0.34, 0.42) at 6 mA/cm2 to (0.27, 0.37) at 200 mA/cm 2 due to the shift of recombination zone. The change of color with drive current was suppressed by introduction of an electron-blocking layer of NPB along with a hole-blocking layer of aluminum (III) bis(2-methyl-8-quinolinato)4-phenylphenolato to the white OLED which successfully confined the recombination site and achieved a luminous yield of 9.9 cd/A at 20 mA/cm 2

  5. Efficient white organic light emitting devices with dual emitting layers

    Energy Technology Data Exchange (ETDEWEB)

    Wu Yaoshan [Department of Applied Chemistry, National Chiao Tung University, Hsinchu, Taiwan, 30050 (China); Hwang Shiaowen [Display Institute, Microelectronics and Information Systems Research Center, National Chiao Tung University, Hsinchu, Taiwan, 30050 (China)]. E-mail: jesse@faculty.nctu.edu.tw; Chen Hsianhung [Department of Applied Chemistry, National Chiao Tung University, Hsinchu, Taiwan, 30050 (China); Lee Mengting [Department of Applied Chemistry, National Chiao Tung University, Hsinchu, Taiwan, 30050 (China); Shen Wenjian [Department of Applied Chemistry, National Chiao Tung University, Hsinchu, Taiwan, 30050 (China); Chen, C.H. [Display Institute, Microelectronics and Information Systems Research Center, National Chiao Tung University, Hsinchu, Taiwan, 30050 (China)

    2005-09-22

    In this paper, a new white organic light-emitting device (OLED) with the structure of indium tin oxide / CF {sub x} / 1,4-bis[N-(1-naphthyl)-N'-phenylamino]-biphenyl (NPB) (30 nm)/NPB: 2,8-di(t-butyl)-5,11-di[4-(t-butyl)phenyl]-6,12-diphenylnaphthacene (20 nm; 1.6 %) / 2-methyl-9,10-di(2-naphthyl) anthracene: p-bis(p-N,N-di-phenyl-aminostyryl)benzene (40 nm, 3%) / aluminum tris(8-hydroxyquinoline) (20 nm) / LiF (1 nm) / Al (200 nm) has been investigated. The device showed white emission with a high-luminous yield of 9.75 cd/A at 20 mA/cm{sup 2}, but its Commission Internationale de l'Eclairage chromaticity coordinates appeared to change from (0.34, 0.42) at 6 mA/cm2 to (0.27, 0.37) at 200 mA/cm{sup 2} due to the shift of recombination zone. The change of color with drive current was suppressed by introduction of an electron-blocking layer of NPB along with a hole-blocking layer of aluminum (III) bis(2-methyl-8-quinolinato)4-phenylphenolato to the white OLED which successfully confined the recombination site and achieved a luminous yield of 9.9 cd/A at 20 mA/cm{sup 2}.

  6. A white organic light emitting diode with improved stability

    International Nuclear Information System (INIS)

    Zhang Zhilin; Jiang Xueyin; Zhu Wenqing; Zhang Buxin; Xu Shaohong

    2001-01-01

    A white organic light emitting diode (OLED) has been constructed by employing a new blue material and a red dye directly doped in the blue emitting layer. For comparison, another white cell with a blocking layer has also been made. The configurations of the devices are ITO/CuPc/NPB/JBEM(P):DCJT/Alq/MgAg (device 1) and ITO/CuPc/NPB/TPBi:DCJT/Alq/MgAg (device 2) where copper phthalocyanine (CuPc) is the buffer layer, N,N'-bis-(1-naphthyl)-N,N'-diphenyl-1.1'bipheny1-4-4'-diamine (NPB) is the hole transporting layer, 9,10-bis(3'5'-diaryl)phenyl anthracene doped with perylene (JBEM(P)) is the new blue emitting material, N,arylbenzimidazoles (TPBi) is the hole blocking layer, tris(8-quinolinolato)aluminium complex (Alq) is the electron transporting layer, and DCJT is a red dye. A stable and current independent white OLED has been obtained in device 1, which has a maximum luminance of 14 850 cd m -2 , an efficiency of 2.88 Lm W -1 , Commission Internationale de l'Eclairage coordinates of x=0.32, y=0.38 between 4-200 mA cm -2 , and a half lifetime of 2860 h at the starting luminance of 100 cd m -2 . Device 1 has a stability more than 50 times better than that of device 2. (author)

  7. 4-Gbit/s visible light communication link based on 16-QAM OFDM transmission over remote phosphor-film converted white light by using blue laser diode

    KAUST Repository

    Duran Retamal, Jose Ramon

    2015-12-21

    Visible Light Communication (VLC) as a new technology for ultrahigh-speed communication is still limited when using slow modulation light-emitting diode (LED). Alternatively, we present a 4-Gbit/s VLC system using coherent blue-laser diode (LD) via 16-quadrature amplitude modulation orthogonal frequency division multiplexing. By changing the composition and the optical-configuration of a remote phosphor-film the generated white light is tuned from cool day to neutral, and the bit error rate is optimized from 1.9 × 10-2 to 2.8 × 10-5 in a blue filter-free link due to enhanced blue light transmission in forward direction. Briefly, blue-LD is an alternative to LED for generating white light and boosting the data rate of VLC. © 2015 Optical Society of America.

  8. 4-Gbit/s visible light communication link based on 16-QAM OFDM transmission over remote phosphor-film converted white light by using blue laser diode

    KAUST Repository

    Duran Retamal, Jose Ramon; Oubei, Hassan M.; Janjua, Bilal; Chi, Yu-Chieh; Wang, Huai-Yung; Tsai, Cheng-Ting; Ng, Tien Khee; Hsieh, Dan-Hua; Kuo, Hao-Chung; Alouini, Mohamed-Slim; He, Jr-Hau; Lin, Gong-Ru; Ooi, Boon S.

    2015-01-01

    Visible Light Communication (VLC) as a new technology for ultrahigh-speed communication is still limited when using slow modulation light-emitting diode (LED). Alternatively, we present a 4-Gbit/s VLC system using coherent blue-laser diode (LD) via 16-quadrature amplitude modulation orthogonal frequency division multiplexing. By changing the composition and the optical-configuration of a remote phosphor-film the generated white light is tuned from cool day to neutral, and the bit error rate is optimized from 1.9 × 10-2 to 2.8 × 10-5 in a blue filter-free link due to enhanced blue light transmission in forward direction. Briefly, blue-LD is an alternative to LED for generating white light and boosting the data rate of VLC. © 2015 Optical Society of America.

  9. Tuning the white light spectrum of light emitting diode lamps to reduce attraction of nocturnal arthropods.

    Science.gov (United States)

    Longcore, Travis; Aldern, Hannah L; Eggers, John F; Flores, Steve; Franco, Lesly; Hirshfield-Yamanishi, Eric; Petrinec, Laina N; Yan, Wilson A; Barroso, André M

    2015-05-05

    Artificial lighting allows humans to be active at night, but has many unintended consequences, including interference with ecological processes, disruption of circadian rhythms and increased exposure to insect vectors of diseases. Although ultraviolet and blue light are usually most attractive to arthropods, degree of attraction varies among orders. With a focus on future indoor lighting applications, we manipulated the spectrum of white lamps to investigate the influence of spectral composition on number of arthropods attracted. We compared numbers of arthropods captured at three customizable light-emitting diode (LED) lamps (3510, 2704 and 2728 K), two commercial LED lamps (2700 K), two commercial compact fluorescent lamps (CFLs; 2700 K) and a control. We configured the three custom LEDs to minimize invertebrate attraction based on published attraction curves for honeybees and moths. Lamps were placed with pan traps at an urban and two rural study sites in Los Angeles, California. For all invertebrate orders combined, our custom LED configurations were less attractive than the commercial LED lamps or CFLs of similar colour temperatures. Thus, adjusting spectral composition of white light to minimize attracting nocturnal arthropods is feasible; not all lights with the same colour temperature are equally attractive to arthropods. © 2015 The Author(s) Published by the Royal Society. All rights reserved.

  10. High-flux focusable color-tunable and efficient white-light-emitting diode light engine for stage lighting

    DEFF Research Database (Denmark)

    Chakrabarti, Maumita; Pedersen, Henrik Chresten; Petersen, Paul Michael

    2016-01-01

    colors through a microlens array(MA) at the gate of ∅50 mm. Hence, it produces homogeneous color-mixed tunable white light from 3000 to6000 K that can be adjustable from flood to spot position providing 10% translational loss, whereas the correspondingloss from the halogen–Fresnel spotlight is 37...

  11. Transforming White Light into Rainbows: Segmentation Strategies for Successful School Tax Elections

    Science.gov (United States)

    Senden, J. Bradford; Lifto, Don E.

    2009-01-01

    In the late 1600s, British physicist Sir Isaac Newton first demonstrated refraction and dispersion in a triangular prism. He discovered that a prism could decompose white light into a spectrum. Hold a prism up to the light at the correct angle and white light magically splits into vivid colors of the rainbow! So what do prisms and rainbows have to…

  12. Investigations of white light emitting europium doped zinc oxide nanoparticles

    International Nuclear Information System (INIS)

    Ashtaputre, S S; Nojima, A; Marathe, S K; Matsumura, D; Ohta, T; Tiwari, R; Dey, G K; Kulkarni, S K

    2008-01-01

    Europium doped zinc oxide nanoparticles have been synthesized using a chemical route. The amount of doped europium was varied which shows the changes in the photoluminescence (PL) intensity. The post synthesis annealing effect on the properties of ZnO nanoparticles has also been investigated. In general, PL is broad and a white light is emitted which originates from ZnO and the intra-4f transitions of Eu 3+ ions. The x-ray diffraction patterns do not show any Eu-related peaks for as-synthesized ZnO nanoparticles as well as for annealed samples. X-ray absorption spectroscopy reveals that europium ions are present on the surface of the core of ZnO and inside the shell of zinc hydroxide [Zn(OH 2 )] after annealing

  13. A simple white noise analysis of neuronal light responses.

    Science.gov (United States)

    Chichilnisky, E J

    2001-05-01

    A white noise technique is presented for estimating the response properties of spiking visual system neurons. The technique is simple, robust, efficient and well suited to simultaneous recordings from multiple neurons. It provides a complete and easily interpretable model of light responses even for neurons that display a common form of response nonlinearity that precludes classical linear systems analysis. A theoretical justification of the technique is presented that relies only on elementary linear algebra and statistics. Implementation is described with examples. The technique and the underlying model of neural responses are validated using recordings from retinal ganglion cells, and in principle are applicable to other neurons. Advantages and disadvantages of the technique relative to classical approaches are discussed.

  14. Radio and white-light observations of coronal transients

    Science.gov (United States)

    Dulk, G. A.

    1980-01-01

    Optical, radio and X-ray evidence of violent mass motions in the corona has existed for some years but only recently have the form, nature, frequency and implication of the transients become obvious. In this paper the observed properties of coronal transients are reviewed, with concentration on the white-light and radio manifestations. The classification according to speeds seems to be meaningful, with the slow transients having thermal emissions at radio wavelengths and the fast ones nonthermal. The possible mechanisms involved in the radio bursts are then discussed and estimates of various forms of energy are reviewed. It appears that the magnetic energy transported from the sun by the transient exceeds that of any other form, and that magnetic forces dominate in the dynamics of the motions. The conversion of magnetic energy into mechanical energy, by expansion of the field, provides a possible driving force for the coronal and interplanetary shock waves.

  15. Radio and white-light observations of coronal transients

    International Nuclear Information System (INIS)

    Dulk, G.A.

    1980-01-01

    Optical, radio and X-ray evidence of violent mass motions in the corona has existed for some years but only recently have the form, nature, frequency and implication of the transients become obvious. The author reviews the observed properties of coronal transients, concentrating on the white-light and radio manifestations. The classification according to speeds seems to be meaningful, with the slow transients having thermal emissions at radio wavelengths and the fast ones non-thermal. The possible mechanisms involved in the radio bursts are discussed and the estimates of various forms of energy are reviewed. It appears that the magnetic energy transported from the Sun by the transient exceeds that of any other form, and that magnetic forces dominate in the dynamics of the motions. The conversion of magnetic energy into mechanical energy, by expansion of the fields, provides a possible driving force for the coronal and interplanetary shock waves. (Auth.)

  16. Topology of White Stars in Relativistic Fragmentation of Light Nuclei

    CERN Document Server

    Andreeva, N P; Vokal, S; Vokalova, A; Gaitinov, A Sh; Gerassimov, S G; Goncharova, L A; Dronov, V A; Zarubin, P I; Zarubina, I G; Kovalenko, A D; Kravchakova, A; Larionova, V G; Levitskaja, O V; Lepehin, F G; Malakhov, A I; Moiseenko, A A; Orlova, G I; Peresadko, N G; Polukhina, N G; Rukojatkin, P A; Rusakova, V V; Salmanova, N A; Sarkisian, V R; Simonov, B B; Stan, E; Stanoeva, R; Chernyavsky, M M; Haidue, M; Kharlamov, S P; Tsakov, I; Shchedrina, T V

    2004-01-01

    In the present paper, experimental observation of the multifragmentation processes of light relativistic nuclei carried out by means of emulsions are reviewed. Events of the type of "white stars" in which the dissociation of relativistic nuclei is not accompanied by the production of mesons and the target-nucleus fragments are considered. A distinctive feature of the charge topology in the dissociation of the Ne, Mg, Si and S nuclei is an almost total suppression of the binary splitting of nuclei to fragments with charges higher than 2. The growth of the nuclear fragmentation degree is revealed in an increase in the multiplicity of singly and doubly charged fragments with decreasing charge of the main non-excited part of the fragmenting nucleus. The processes of dissociation of stable Li, Be, B, C, N, and O isotopes to charged fragments were used to study special features of the formation of systems consisting of the lightest nuclei - alpha, d and t. Clustering of the 3He nucleus can be detected in "white sta...

  17. White light quality of phosphor converted light-emitting diodes: A phosphor materials perspective of view

    International Nuclear Information System (INIS)

    Sommer, Christian; Hartmann, Paul; Pachler, Peter; Hoschopf, Hans; Wenzl, Franz P.

    2012-01-01

    Highlights: ► We discuss the impact of the optical properties of a phosphor for colour temperature constancy in solid state lighting. ► Quantitative evaluation of permissible variations of the optical properties for batch-to-batch reproducibility. ► Quantitative evaluation of permissible variations of the optical properties upon temperature increase. ► Quantitative evaluation of permissible variations of the optical properties upon materials degradation. - Abstract: For a systematic approach to improve the white light quality of phosphor converted LEDs and to fulfil the demands for colour temperature reproducibility and constancy, it is imperative to understand how variations of the extinction coefficient and the quantum efficiency of the phosphor particles as well as variations of the excitation wavelength of the blue LED die affect the correlated colour temperature of the white LED source. Based on optical ray tracing of a phosphor converted white LED package we deduce permissible values for the variation of a given extinction coefficient and a given quantum efficiency of a phosphor material in order to maintain acceptable colour variations. These quantitative valuations of the required constancy of the optical properties of the phosphors will in particular provide some benchmarks for the synthesis of improved phosphor materials aiming at solid state lighting applications.

  18. Noise analysis of a white-light supercontinuum light source for multiple wavelength confocal laser scanning fluorescence microscopy

    Energy Technology Data Exchange (ETDEWEB)

    McConnell, Gail [Centre for Biophotonics, Strathclyde Institute for Biomedical Sciences, University of Strathclyde, 27 Taylor Street, Glasgow, G4 0NR (United Kingdom)

    2005-08-07

    Intensity correlations of a Ti : sapphire, Kr/Ar and a white-light supercontinuum were performed to quantify the typical signal amplitude fluctuations and hence ascertain the comparative output stability of the white-light supercontinuum source for confocal laser scanning microscopy (CLSM). Intensity correlations across a two-pixel sample (n = 1000) of up to 98%, 95% and 94% were measured for the Ti : sapphire, Kr/Ar and white-light supercontinuum source, respectively. The white-light supercontinuum noise level is therefore acceptable for CLSM, with the added advantage of wider wavelength flexibility over traditional CLSM excitation sources. The relatively low-noise white-light supercontinuum was then used to perform multiple wavelength sequential CLSM of guinea pig detrusor to confirm the reliability of the system and to demonstrate system flexibility.

  19. Gigabit-per-second white light-based visible light communication using near-ultraviolet laser diode and red-, green-, and blue-emitting phosphors

    KAUST Repository

    Lee, Changmin; Shen, Chao; Cozzan, Clayton; Farrell, Robert M.; Speck, James S.; Nakamura, Shuji; Ooi, Boon S.; DenBaars, Steven P.

    2017-01-01

    Data communication based on white light generated using a near-ultraviolet (NUV) laser diode (LD) pumping red-, green-, and blue-emitting (RGB) phosphors was demonstrated for the first time. A III-nitride laser diode (LD) on a semipolar (2021

  20. Polaron self-localization in white-light emitting hybrid perovskites

    KAUST Repository

    Cortecchia, Daniele

    2017-02-03

    Two-dimensional (2D) perovskites with the general formula APbX are attracting increasing interest as solution processable, white-light emissive materials. Recent studies have shown that their broadband emission is related to the formation of intra-gap colour centres. Here, we provide an in-depth description of the charge localization sites underlying the generation of such radiative centres and their corresponding decay dynamics, highlighting the formation of small polarons trapped within their lattice distortion field. Using a combination of spectroscopic techniques and first-principles calculations to study the white-light emitting 2D perovskites (EDBE)PbCl and (EDBE)PbBr, we infer the formation of Pb , Pb, and X (where X = Cl or Br) species confined within the inorganic perovskite framework. Due to strong Coulombic interactions, these species retain their original excitonic character and form self-trapped polaron-excitons acting as radiative colour centres. These findings are expected to be relevant for a broad class of white-light emitting perovskites with large polaron relaxation energy.

  1. Handheld White Light Interferometer for Measuring Defect Depth in Windows

    Science.gov (United States)

    Youngquist, Robert; Simmons, Stephen; Cox, Robert

    2010-01-01

    Accurate quantification of defects (scratches and impacts) is vital to the certification of flight hardware and other critical components. The amount of damage to a particular component contributes to the performance, reliability, and safety of a system, which ultimately affects the success or failure of a mission or test. The launch-commit criteria on a Space Shuttle Orbiter window are governed by the depth of the defects that are identified by a visual inspection. This measurement of a defect is not easy to obtain given the environment, size of the defect, and location of the window(s). The determination of depth has typically been performed by taking a mold impression and measuring the impression with an optical profiling instrument. Another method of obtaining an estimate of the depth is by using a refocus microscope. To use a refocus microscope, the surface of the glass and bottom of the defect are, in turn, brought into focus by the operator. The amount of movement between the two points corresponds to the depth of the defect. The refocus microscope requires a skilled operator and has been proven to be unreliable when used on Orbiter windows. White light interferometry was chosen as a candidate to replace the refocus microscope. The White Light Interferometer (WLI) was developed to replace the refocus microscope as the instrument used for measuring the depth of defects in Orbiter windows. The WLI consists of a broadband illumination source, interferometer, detector, motion control, displacement sensor, mechanical housing, and support electronics. The illumination source for the WLI is typically a visible light emitting diode (LED) or a near-infrared superluminescent diode (SLD) with power levels of less than a milliwatt. The interferometer is a Michelson configuration consisting of a 1-in. (2.5-cm) cube beam splitter, a 0.5-in. (1.3-cm) optical window as a movable leg (used to closely match the return intensity of the fixed leg from the window), and a

  2. Ultrabroad linewidth orange-emitting nanowires LED for high CRI laser-based white lighting and gigahertz communications

    KAUST Repository

    Janjua, Bilal; Ng, Tien Khee; Zhao, Chao; Oubei, Hassan M.; Shen, Chao; Prabaswara, Aditya; Alias, Mohd Sharizal; Alhamoud, Abdullah Ali; Alatawi, Abdullah Awaad; Albadri, Abdulrahman M.; Alyamani, Ahmed Y.; El-Desouki, Munir M.; Ooi, Boon S.

    2016-01-01

    intensity- and bandwidth-tunable for high color-quality remained unexplored. In this paper, we present for the first time, the proof-of-concept of the generation of high-quality white light using an InGaN-based orange nanowires (NWs) LED grown on silicon

  3. Wideband perfect coherent absorber based on white-light cavity

    Science.gov (United States)

    Kotlicki, Omer; Scheuer, Jacob

    2015-03-01

    Coherent Perfect Absorbers (CPAs) are optical cavities which can be described as time-reversed lasers where light waves that enter the cavity, coherently interfere and react with the intra-cavity losses to yield perfect absorption. In contrast to lasers, which benefit from high coherency and narrow spectral linewidths, for absorbers these properties are often undesirable as absorption at a single frequency is highly susceptible to spectral noise and inappropriate for most practical applications. Recently, a new class of cavities, characterized by a spectrally wide resonance has been proposed. Such resonators, often referred to as White Light Cavities (WLCs), include an intra-cavity superluminal phase element, designed to provide a phase response with a slope that is opposite in sign and equal in magnitude to that of light propagation through the empty cavity. Consequently, the resonance phase condition in WLCs is satisfied over a band of frequencies providing a spectrally wide resonance. WLCs have drawn much attention due to their attractiveness for various applications such as ultra-sensitive sensors and optical buffering components. Nevertheless, WLCs exhibit inherent losses that are often undesirable. Here we introduce a simple wideband CPA device that is based on the WLC concept along with a complete analytical analysis. We present analytical and FDTD simulations of a practical, highly compact (12µm), Silicon based WLC-CPA that exhibits a flat and wide absorption profile (40nm) and demonstrate its usefulness as an optical pulse terminator (>35db isolation) and an all optical modulator that span the entire C-Band and exhibit high immunity to spectral noise.

  4. Use of a supercontinuum white light in evaluating the spectral sensitivity of the pupil light reflex

    Science.gov (United States)

    Chin, Catherine; Leick, Lasse; Podoleanu, Adrian; Lall, Gurprit S.

    2018-03-01

    We assessed the spectral sensitivity of the pupillary light reflex in mice using a high power super continuum white light (SCWL) source in a dual wavelength configuration. This novel approach was compared to data collected from a more traditional setup using a Xenon arc lamp fitted with monochromatic interference filters. Irradiance response curves were constructed using both systems, with the added benefit of a two-wavelength, equivocal power, output using the SCWL. The variables applied to the light source were intensity, wavelength and stimulus duration through which the physiological output measured was the minimum pupil size attained under such conditions. We show that by implementing the SCWL as our novel stimulus we were able to dramatically increase the physiological usefulness of our pupillometry system.

  5. White LEDs and modules in chip-on-board technology for general lighting

    Science.gov (United States)

    Hartmann, Paul; Wenzl, Franz P.; Sommer, Christian; Pachler, Peter; Hoschopf, Hans; Schweighart, Marko; Hartmann, Martin; Kuna, Ladislav; Jakopic, Georg; Leising, Guenther; Tasch, Stefan

    2006-08-01

    At present, light-emitting diode (LED) modules in various shapes are developed and designed for the general lighting, advertisement, emergency lighting, design and architectural markets. To compete with and to surpass the performance of traditional lighting systems, enhancement of Lumen output and the white light quality as well as the thermal management and the luminary integration are key factors for success. Regarding these issues, white LEDs based on the chip-on-board (COB) technology show pronounced advantages. State-of-the-art LEDs exploiting this technology are now ready to enter the general lighting segments. We introduce and discuss the specific properties of the Tridonic COB technology dedicated for general lighting. This technology, in combination with a comprehensive set of tools to improve and to enhance the Lumen output and the white light quality, including optical simulation, is the scaffolding for the application of white LEDs in emerging areas, for which an outlook will be given.

  6. White- and blue-light-emitting dysprosium(III) and terbium(III)-doped gadolinium titanate phosphors.

    Science.gov (United States)

    Antić, Ž; Kuzman, S; Đorđević, V; Dramićanin, M D; Thundat, T

    2017-06-01

    Here we report the synthesis and structural, morphological, and photoluminescence analysis of white- and blue-light-emitting Dy 3 + - and Tm 3 + -doped Gd 2 Ti 2 O 7 nanophosphors. Single-phase cubic Gd 2 Ti 2 O 7 nanopowders consist of compact, dense aggregates of nanoparticles with an average size of ~25 nm for Dy 3 + -doped and ~50 nm for Tm 3 + -doped samples. The photoluminescence results indicated that ultraviolet (UV) light excitation of the Dy 3 + -doped sample resulted in direct generation of white light, while a dominant yellow emission was obtained under blue-light excitation. Intense blue light was obtained for Tm 3 + -doped Gd 2 Ti 2 O 7 under UV excitation suggesting that this material could be used as a blue phosphor. Copyright © 2016 John Wiley & Sons, Ltd.

  7. Diffraction of white-light supercontinuum by femtosecond laser-induced transient grating in carbon bisulfide

    International Nuclear Information System (INIS)

    Li, Huang; Yan-Qiang, Yang; Ying-Hui, Wang; Zhi-Ren, Zheng; Wen-Hui, Su

    2010-01-01

    Experiments on fs laser-induced transient grating (LITG) in carbon bisulfide (CS 2 ) are carried out to explore the chirp characteristics of a white-light supercontinuum (SC) generated by a 800-nm, 160-fs laser pulse in a 4-mm thick Al 2 O 3 crystal. Two orders of diffraction signals of SC by fs LITG in CS 2 are observed, demonstrating that both the third-order process and the fifth-order process are present simultaneously. The experimental results also imply that the formation of an fs transient refractive-index grating in CS 2 is mainly due to the electronic polarization process. (classical areas of phenomenology)

  8. Exposing broiler eggs to green, red and white light during incubation.

    Science.gov (United States)

    Archer, G S

    2017-07-01

    Previous work has shown that exposing broiler eggs to white light during incubation can improve hatchability and post-hatch animal welfare. It was hypothesized that due to how different wavelengths of light can affect avian physiology differently, and how pigmented eggshells filter light that different monochromatic wavelengths would have differential effects on hatchability and post-hatch animal welfare indicators. To determine, we incubated chicken eggs (n=6912) under either no light (dark), green light, red light or white light; the light level was 250 lux. White and red light were observed to increase hatch of fertile (P0.05). Fear response of during isolation and tonic immobility was reduced (P0.05) from dark incubated broilers. All light incubated broilers had lower (Phatchery efficiency and post-hatch animal welfare at the same time.

  9. Second Harmonic Generation of Unpolarized Light

    Science.gov (United States)

    Ding, Changqin; Ulcickas, James R. W.; Deng, Fengyuan; Simpson, Garth J.

    2017-11-01

    A Mueller tensor mathematical framework was applied for predicting and interpreting the second harmonic generation (SHG) produced with an unpolarized fundamental beam. In deep tissue imaging through SHG and multiphoton fluorescence, partial or complete depolarization of the incident light complicates polarization analysis. The proposed framework has the distinct advantage of seamlessly merging the purely polarized theory based on the Jones or Cartesian susceptibility tensors with a more general Mueller tensor framework capable of handling partial depolarized fundamental and/or SHG produced. The predictions of the model are in excellent agreement with experimental measurements of z -cut quartz and mouse tail tendon obtained with polarized and depolarized incident light. The polarization-dependent SHG produced with unpolarized fundamental allowed determination of collagen fiber orientation in agreement with orthogonal methods based on image analysis. This method has the distinct advantage of being immune to birefringence or depolarization of the fundamental beam for structural analysis of tissues.

  10. Structured white light scanning of rabbit Achilles tendon.

    Science.gov (United States)

    Hayes, Alex; Easton, Katrina; Devanaboyina, Pavan Teja; Wu, Jian-Ping; Kirk, Thomas Brett; Lloyd, David

    2016-11-07

    The cross-sectional area (CSA) of a material is used to calculate stress under load. The mechanical behaviour of soft tissue is of clinical interest in the management of injury; however, measuring CSA of soft tissue is challenging as samples are geometrically irregular and may deform during measurement. This study presents a simple method, using structured light scanning (SLS), to acquire a 3D model of rabbit Achilles tendon in vitro for measuring CSA of a tendon. The Artec Spider™ 3D scanner uses structured light and stereophotogrammetry technologies to acquire shape data and reconstruct a 3D model of an object. In this study, the 3D scanner was integrated with a custom mechanical rig, permitting 360-degree acquisition of the morphology of six New Zealand White rabbit Achilles tendons. The reconstructed 3D model was then used to measure CSA of the tendon. SLS, together with callipers and micro-CT, was used to measure CSA of objects with a regular or complex shape, such as a drill flute and human cervical vertebra, for validating the accuracy and repeatability of the technique. CSA of six tendons was measured with a coefficient of variation of less than 2%. The mean CSA was 9.9±1.0mm 2 , comparable with those reported by other researchers. Scanning of phantoms demonstrated similar results to μCT. The technique developed in this study offers a simple and accurate method for effectively measuring CSA of soft tissue such as tendons. This allows for localised calculation of stress along the length, assisting in the understanding of the function, injury mechanisms and rehabilitation of tissue. Copyright © 2016 Elsevier Ltd. All rights reserved.

  11. Generating Selected Color using RGB, Auxiliary Lights, and Simplex Search

    Directory of Open Access Journals (Sweden)

    Kim HyungTae

    2015-01-01

    Full Text Available A mixed light source generates various colors, with the potential to adjust intensities of multiple LEDs, which makes it possible to generate arbitrary colors. Currently, PCs and OSs provide color selection windows that can obtain the RGB or HSL color coordinates of a user’s selection. Mixed light sources are usually composed of LEDs in the primary colors, with LEDs in auxiliary colors such as white and yellow used in a few cases. When using auxiliary color LEDs, the number of LED inputs, the dimming levels, is larger than the number of elements in the color coordinate, which causes an under-determined problem. This study proposed how to determine the dimming levels of LEDs based on the selected color. Commercial LEDs have di_erent optical power values and impure color coordinates, even if they are RGB. Hence, the characteristics of the LEDs were described using a linear model derived from the tri-stimulus values (an XYZ color coordinate model and dimming levels. Color mixing models were derived for the arbitrary number of auxiliary color LEDs. The under-determined problem was solved using a simplex search method without an inverse matrix operation. The proposed method can be applied to a machine vision system and an RGBW light mixer for semiconductor inspection. The dimming levels, obtained using the proposed method were better than derived using other methods.

  12. WHITE-LIGHT FLARES ON CLOSE BINARIES OBSERVED WITH KEPLER

    International Nuclear Information System (INIS)

    Gao, Qing; Xin, Yu; Liu, Ji-Feng; Zhang, Xiao-Bin; Gao, Shuang

    2016-01-01

    Based on Kepler data, we present the results of a search for white light flares on 1049 close binaries. We identify 234 flare binaries, of which 6818 flares are detected. We compare the flare-binary fraction in different binary morphologies (“detachedness”). The result shows that the fractions in over-contact and ellipsoidal binaries are approximately 10%–20% lower than those in detached and semi-detached systems. We calculate the binary flare activity level (AL) of all the flare binaries, and discuss its variations along the orbital period ( P orb ) and rotation period ( P rot , calculated for only detached binaries). We find that the AL increases with decreasing P orb or P rot , up to the critical values at P orb ∼ 3 days or P rot ∼ 1.5 days, and thereafter the AL starts decreasing no matter how fast the stars rotate. We examine the flaring rate as a function of orbital phase in two eclipsing binaries on which a large number of flares are detected. It appears that there is no correlation between flaring rate and orbital phase in these two binaries. In contrast, when we examine the function with 203 flares on 20 non-eclipse ellipsoidal binaries, bimodal distribution of amplitude-weighted flare numbers shows up at orbital phases 0.25 and 0.75. Such variation could be larger than what is expected from the cross section modification.

  13. Performance evaluation of a vibration desensitized scanning white light interferometer

    International Nuclear Information System (INIS)

    Troutman, J; Evans, C J; Ganguly, V; Schmitz, T L

    2014-01-01

    Surface metrology instruments normally require thermal, seismic and acoustic isolation. Shop-floor metrology solutions offer reduced cost and process time. If they operate on the same principles as laboratory devices, an inherent sensitivity to vibration remains. This paper describes a methodology for evaluating ‘environmental tolerance’ and applying it to characterize a recently introduced ‘environmentally tolerant’ scanning white light interferometer (SWLI). Previously published measurements of replicated nickel reference standards on the new instrument and on a stylus profilometer showed good correlation. Surface topography repeatabilities (per ISO 25178-604:2013) were insignificantly different when evaluated on the SWLI instrument in a metrology laboratory and in a manufacturing area. Measurements of reference standards under forced vibration of the entire instrument show maximum ripple error and data dropout in regions of structural resonance. Measurements were performed with large forced horizontal and vertical sample oscillation beneath the objective, exhibiting maximum ripple error near odd integer multiples of half the instrument detector frequency. Error due to data dropout was also investigated. (paper)

  14. Toward a fourth-generation light source

    International Nuclear Information System (INIS)

    Moncton, D. E.

    1999-01-01

    Historically, x-ray research has been propelled by the existence of urgent and compelling scientific questions and the push of powerful and exquisite source technology. These two factors have gone hand in hand since Rontgen discovered x-rays. Here we review the progress being made with existing third-generation synchrotron-radiation light sources and the prospects for a fourth-generation light source with dramatically improved laser-like beam characteristics. The central technology for high-brilliance x-ray beams is the x-ray undulator, a series of alternating-pole magnets situated above and below the particle beam. When the particle beam is oscillated by the alternating magnetic fields, a set of. interacting and interfering wave fronts is produced, which leads to an x-ray beam with extraordinary properties. Third-generation sources of light in the hard x-ray range have been constructed at three principal facilities: the European Synchrotrons Radiation Facility (ESRF) in France; the Super Photon Ring 8-GeV (or Spring-8) in Japan; and the Advanced Photon Source (APS) in the US. Undulator technology is also used on a number of low-energy machines for radiation in the ultraviolet and soft x-ray regimes. At the APS, these devices exceed all of our original expectations for beam brilliance, tunability, spectral range, and operational flexibility. Shown in Fig. 1 are the tuning curves of the first few harmonics, showing x-ray production from a few kV to better than 40 keV. High-brilliance radiation extends to over 100 keV

  15. Human phase response curve to a 1 h pulse of bright white light

    Science.gov (United States)

    St Hilaire, Melissa A; Gooley, Joshua J; Khalsa, Sat Bir S; Kronauer, Richard E; Czeisler, Charles A; Lockley, Steven W

    2012-01-01

    The phase resetting response of the human circadian pacemaker to light depends on the timing of exposure and is described by a phase response curve (PRC). The current study aimed to construct a PRC for a 1 h exposure to bright white light (∼8000 lux) and to compare this PRC to a dim background light PRC. These data were also compared to a previously completed 6.7 h bright white light PRC and a dim background light PRC constructed under similar conditions. Participants were randomized for exposure to 1 h of either bright white light (n= 18) or dim background light (n= 18) scheduled at 1 of 18 circadian phases. Participants completed constant routine (CR) procedures in dim light (light exposure to assess circadian phase. Phase shifts were calculated as the difference in timing of dim light melatonin onset (DLMO) during pre- and post-stimulus CRs. Exposure to 1 h of bright white light induced a Type 1 PRC with a fitted peak-to-trough amplitude of 2.20 h. No discernible PRC was observed in the dim background light PRC. The fitted peak-to-trough amplitude of the 1 h bright light PRC was ∼40% of that for the 6.7 h PRC despite representing only 15% of the light exposure duration, consistent with previous studies showing a non-linear duration–response function for the effects of light on circadian resetting. PMID:22547633

  16. Synthesis, X-ray Structure, Optical, and Electrochemical Properties of a White-Light-Emitting Molecule

    Directory of Open Access Journals (Sweden)

    Jiun-Wei Hu

    2016-01-01

    Full Text Available A new white-light-emitting molecule (1 was synthesized and characterized by NMR spectroscopy, high resolution mass spectrometry, and single-crystal X-ray diffraction. Compound 1 crystallizes in the orthorhombic space group Pnma, with a = 12.6814(6, b = 7.0824(4, c = 17.4628(9 Å, α = 90°, β = 90°, γ = 90°. In the crystal, molecules are linked by weak intermolecular C-H···O hydrogen bonds, forming an infinite chain along [100], generating a C(10 motif. Compound 1 possesses an intramolecular six-membered-ring hydrogen bond, from which excited-state intramolecular proton transfer (ESIPT takes place from the phenolic proton to the carbonyl oxygen, resulting in a tautomer that is in equilibrium with the normal species, exhibiting a dual emission that covers almost all of the visible spectrum and consequently generates white light. It exhibits one irreversible one-electron oxidation and two irreversible one-electron reductions in dichloromethane at modest potentials. Furthermore, the geometric structures, frontier molecular orbitals (MOs, and the potential energy curves (PECs for 1 in the ground and the first singlet excited state were fully rationalized by density functional theory (DFT and time-dependent DFT calculations. The results demonstrate that the forward and backward ESIPT may happen on a similar timescale, enabling the excited-state equilibrium to be established.

  17. The ALS [Advanced Light Source]: A third generation light source

    International Nuclear Information System (INIS)

    Robinson, A.L.; Schlachter, A.S.

    1989-09-01

    The Advanced Light Source, a third-generation national synchrotron-radiation facility now under construction at the Lawrence Berkeley Laboratory, is scheduled to begin serving qualified users across a broad spectrum of research areas in April 1993. Based on a low- emittance electron storage ring optimized to operate at 1.5 GeV, the ALS will have 11 long straight sections available for insertion devices (undulators and wigglers). Undulators will generate high- brightness soft x-ray and ultraviolet (XUV) radiation; wigglers will extend the spectrum generated into the hard x-ray region, but at a lower brightness. Up to 48 bending-magnet ports will also be available. Engineering design has begun on a complement of three undulators with periods of 8.0, 5.0, and 3.9 cm that between them will cover the photon-energy range from 5.4 eV to 2.5 keV when the first, third, and fifth harmonics are used, as well as a wiggler with a critical energy of 3.1 keV. Undulator beam lines will be based on high-resolution spherical-grating monochromators. A Call for Proposals has been issued for those who wish to participate in the design, development, commissioning, and operation of the initial complement of ALS experimental facilities (insertion devices, beam lines, and experimental stations) as members of a participating research team. The deadline for receipt of proposals was August 15, 1989. Proposals are expected to reflect the Letters of Interest received from potential PRTs during the previous year. 6 refs., 4 figs., 5 tabs

  18. Green light drives leaf photosynthesis more efficiently than red light in strong white light: revisiting the enigmatic question of why leaves are green.

    Science.gov (United States)

    Terashima, Ichiro; Fujita, Takashi; Inoue, Takeshi; Chow, Wah Soon; Oguchi, Riichi

    2009-04-01

    The literature and our present examinations indicate that the intra-leaf light absorption profile is in most cases steeper than the photosynthetic capacity profile. In strong white light, therefore, the quantum yield of photosynthesis would be lower in the upper chloroplasts, located near the illuminated surface, than that in the lower chloroplasts. Because green light can penetrate further into the leaf than red or blue light, in strong white light, any additional green light absorbed by the lower chloroplasts would increase leaf photosynthesis to a greater extent than would additional red or blue light. Based on the assessment of effects of the additional monochromatic light on leaf photosynthesis, we developed the differential quantum yield method that quantifies efficiency of any monochromatic light in white light. Application of this method to sunflower leaves clearly showed that, in moderate to strong white light, green light drove photosynthesis more effectively than red light. The green leaf should have a considerable volume of chloroplasts to accommodate the inefficient carboxylation enzyme, Rubisco, and deliver appropriate light to all the chloroplasts. By using chlorophylls that absorb green light weakly, modifying mesophyll structure and adjusting the Rubisco/chlorophyll ratio, the leaf appears to satisfy two somewhat conflicting requirements: to increase the absorptance of photosynthetically active radiation, and to drive photosynthesis efficiently in all the chloroplasts. We also discuss some serious problems that are caused by neglecting these intra-leaf profiles when estimating whole leaf electron transport rates and assessing photoinhibition by fluorescence techniques.

  19. Highly efficient white top-emitting organic light-emitting diodes with forward directed light emission

    Energy Technology Data Exchange (ETDEWEB)

    Freitag, Patricia; Reineke, Sebastian; Furno, Mauro; Luessem, Bjoern; Leo, Karl [Institut fuer Angewandte Photophysik, TU Dresden (Germany)

    2010-07-01

    The demand for highly efficient and energy saving illumination has increased considerably during the last decades. Organic light emitting diodes (OLEDs) are promising candidates for future lighting technologies. They offer high efficiency along with excellent color quality, allowing substantially lower power consumption than traditional illuminants. Recently, especially top-emitting devices have attracted high interest due to their compatibility with opaque substrates like metal sheets. In this contribution, we demonstrate top-emitting OLEDs with white emission spectra employing a multilayer hybrid cavity structure with two highly efficient phosphorescent emitter materials for orange-red (Ir(MDQ)2(acac)) and green (Ir(ppy)3) emission as well as the stable fluorescent blue emitter TBPe. To improve the OLED performance and modify the color quality, two different electron blocking layers and anode material combinations are tested. Compared to Lambertian emission, our devices show considerably enhanced forward emission, which is preferred for most lighting applications. Besides broadband emission and angle independent emission maxima, power efficiencies of 13.3 lm/W at 3 V and external quantum efficiencies of 5.3% are achieved. The emission shows excellent CIE coordinates of (0.420,0.407) at approx. 1000 cd/m{sup 2} and color rendering indices up to 77.

  20. Studies of redox active silicalite-2 and the development of stable white-light phosphors

    Science.gov (United States)

    Lita, Adrian

    Mn-silicalite-2 was synthesized at high pH using the molecular cluster, Mn12O12(O2CCH3)16 as a Mn Source. No precipitation of manganese hydroxide was observed with this cluster even with the use of tetrabutylammonium hydroxide as a templating agent. This synthetic approach resulted in the incorporation of up to 2.5 mol % Mn into the silicalite-2 with direct substitution into the framework verified by a linear relationship between unit cell volume and loading. The Mn is reduced to Mn(II) during hydrothermal synthesis and incorporated into the silicalite-2 framework during calcination at 500°C. Further calcination at 750°C does not affect the crystallinity but oxidizes essentially all of the Mn(II) to Mn(III). Cr(IV) substituted silicalite-2 was generated by reduction of Cr(VI)-silicalite-2 lattice sites at in a CO atmosphere. The reduction process, Reduction at high pressures was found to give almost complete conversion of the Cr(VI) sites to Cr(IV). As generated, the Cr(IV) sites do not reoxidize to Cr(VI) under ambient conditions or in the presence of oxidants under reaction conditions. We report the development of new class solid-state white-light phosphors based on stable nanoparticle-silica glass composites. These materials are made from the incorporating of CdSe nanoparticles into a silica Sol-gel solution. Once it gelled and aged the materials are calcined at 500°C under oxygen. The solid that results are robust with a bright white luminescence (20%) under UV excitation that gives virtually pure white light with coordinates of (0.34, 0.36) on the CIE 1931 chromaticity diagram and, more importantly, the emission envelope coincides nearly identically with the scotopic eye response function. The white-light phosphors have a scotopic/phtopic ratio of 2.56, indicating that these phosphors will be perceived as a particularly efficient illumination source in a dark environment thereby being more energy efficient. The emission comes from a distribution of

  1. White light emission from Tm3+/Dy3+ co-doped oxyfluoride germanate glasses under UV light excitation

    International Nuclear Information System (INIS)

    Lakshminarayana, G.; Yang Hucheng; Qiu Jianrong

    2009-01-01

    In this paper, we report on the absorption and photoluminescence properties of Tm 3+ /Dy 3+ ions co-doped oxyfluoride germanate glasses for white light emission. The X-ray diffraction (XRD) and differential thermal analysis (DTA) profiles of the host glass have been carried out to confirm its structure and thermal stability. From the measured absorption spectra, Judd-Ofelt (J-O) intensity parameters (Ω 2 , Ω 4 and Ω 6 ) have been evaluated for Tm 3+ and Dy 3+ ions. A combination of blue, yellow and red emissions has emerged in these glasses, which allows the observation of bright white light when the glasses are excited by the ultraviolet light. The white light luminescence colour could be changed by varying the excitation wavelength. Also, various colours of luminescence, including white light, can be easily tuned by adjusting the concentrations of Tm 3+ or Dy 3+ ions in the co-doped glasses. Concentration quenching effect was also investigated and possible energy transfer mechanism from Dy 3+ →Tm 3+ ions was explained which is also confirmed by the decay lifetime measurements. - Graphical Abstract: A combination of blue, yellow and red emissions has emerged from Tm 3+ /Dy 3+ co-doped glasses, which allows the observation of bright white light and makes them as excellent candidates applicable in the solid-state multi-colour three-dimensional display.

  2. CdSe white quantum dots-based white light-emitting diodes with high color rendering index

    Science.gov (United States)

    Su, Yu-Sheng; Hsiao, Chih-Chun; Chung, Shu-Ru

    2016-09-01

    A white light emission CdSe quantum dots (QDs) can be prepared by chemical route under 180°C. An organic oleic acid (OA) is used to react with CdO to form Cd-OA complex. Hexadecylamine (HDA) and 1-Octadecene (ODE) were used as co-surfactants. By controlling the reaction time, a white light emission CdSe QDs can be obtained after reacts for 3 to 10 min. The luminescence spectra compose two obvious emission peaks and entire visible light ranges from 400 to 650 nm. Based on TEM measurement result, spherical morphologies with particle size 2.39+/-0.27 nm can be obtained. The quantum yields (QYs) of white CdSe QD are between 20 and 60 %, which depends on reaction time. A white CdSe QDs were mixed with UV cured gel (OPAS-226) with weight ratios 50.0 wt. %, and putted the mixture into reflective cup (3020, 13 mil) as convert type. The white LEDs have controllable CIE coordinates and correlated color temperature (CCT). The luminous efficacy of the device is less than 3 lm/W, but the color rendering index (CRI) for all devices are higher than 80. Since the luminous efficacy of hybrid devices has a direct dependence on the external QY of the UV-LED as well, the luminous efficacy can be improved by well dispersion of CdSe QDs in UV gel matrix and using optimized LED chips. Therefore, in this study, we provide a new and simple method to prepare high QY of white CdSe QDs and its have a potential to applicate in solid-state lighting.

  3. White-light Detection for Nanoparticle Sizing with the TSI Ultrafine Condensation Particle Counter

    International Nuclear Information System (INIS)

    Dick, William D.; McMurry, Peter H.; Weber, Rodney J.; Quant, Frederick R.

    2000-01-01

    Several of the most common methods for measuring nanoparticle size distributions employ the ultrafine condensation particle counter (UCPC) for detection purposes. Among these methods, the pulse height analysis (PHA) technique, in which the optical response of the UCPC detector is related to initial particle diameter in the 3-10 nm range, prevails in applications where fast sampling is required or for which concentrations of nanoparticles are frequently very low. With the PHA technique, white light is required for particle illumination in order to obtain a monotonic relationship between initial particle diameter and optical response (pulse height). However, the popular, commercially available TSI Model 3025A UCPC employs a laser for particle detection. Here, we report on a novel white-light detection system developed for the 3025A UCPC that involves minimal alteration to the instrument and preserves normal counting operation. Performance is illustrated with pulse height spectra produced by differential mobility analyzer (DMA) - generated calibration aerosols in the 3-50 nm range

  4. Suction generation in white-spotted bamboo sharks Chiloscyllium plagiosum.

    Science.gov (United States)

    Wilga, Cheryl D; Sanford, Christopher P

    2008-10-01

    After the divergence of chondrichthyans and teleostomes, the structure of the feeding apparatus also diverged leading to alterations in the suction mechanism. In this study we investigated the mechanism for suction generation during feeding in white-spotted bamboo sharks, Chiloscyllium plagiosum and compared it with that in teleosts. The internal movement of cranial elements and pressure in the buccal, hyoid and pharyngeal cavities that are directly responsible for suction generation was quantified using sonomicrometry and pressure transducers. Backward stepwise multiple linear regressions were used to explore the relationship between expansion and pressure, accounting for 60-96% of the variation in pressure among capture events. The progression of anterior to posterior expansion in the buccal, hyoid and pharyngeal cavities is accompanied by the sequential onset of subambient pressure in these cavities as prey is drawn into the mouth. Gape opening triggers the onset of subambient pressure in the oropharyngeal cavities. Peak gape area coincides with peak subambient buccal pressure. Increased velocity of hyoid area expansion is primarily responsible for generating peak subambient pressure in the buccal and hyoid regions. Pharyngeal expansion appears to function as a sink to receive water influx from the mouth, much like that of compensatory suction in bidirectional aquatic feeders. Interestingly, C. plagiosum generates large suction pressures while paradoxically compressing the buccal cavity laterally, delaying the time to peak pressure. This represents a fundamental difference from the mechanism used to generate suction in teleost fishes. Interestingly, pressure in the three cavities peaks in the posterior to anterior direction. The complex shape changes that the buccal cavity undergoes indicate that, as in teleosts, unsteady flow predominates during suction feeding. Several kinematic variables function together, with great variation over long gape cycles to

  5. Phase shifting white light interferometry using colour CCD for optical metrology and bio-imaging applications

    Science.gov (United States)

    Upputuri, Paul Kumar; Pramanik, Manojit

    2018-02-01

    Phase shifting white light interferometry (PSWLI) has been widely used for optical metrology applications because of their precision, reliability, and versatility. White light interferometry using monochrome CCD makes the measurement process slow for metrology applications. WLI integrated with Red-Green-Blue (RGB) CCD camera is finding imaging applications in the fields optical metrology and bio-imaging. Wavelength dependent refractive index profiles of biological samples were computed from colour white light interferograms. In recent years, whole-filed refractive index profiles of red blood cells (RBCs), onion skin, fish cornea, etc. were measured from RGB interferograms. In this paper, we discuss the bio-imaging applications of colour CCD based white light interferometry. The approach makes the measurement faster, easier, cost-effective, and even dynamic by using single fringe analysis methods, for industrial applications.

  6. A stable Alq3@MOF composite for white-light emission.

    Science.gov (United States)

    Xie, Wei; He, Wen-Wen; Du, Dong-Ying; Li, Shun-Li; Qin, Jun-Sheng; Su, Zhong-Min; Sun, Chun-Yi; Lan, Ya-Qian

    2016-02-25

    A stable mesoporous blue-emitting MOF NENU-521 was successfully constructed. NENU-521 can serve as a host for encapsulating Alq3 to obtain tunable and efficient white-light emission. The Alq3@NENU-521 composite possesses excellent stability and can be used as a promising white phosphor in WLEDs.

  7. Hydrothermal synthesis and white light emission of cubic ZrO2:Eu3+ nanocrystals

    International Nuclear Information System (INIS)

    Meetei, Sanoujam Dhiren; Singh, Shougaijam Dorendrajit

    2014-01-01

    Highlights: • White light emitting cubic ZrO 2 :Eu 3+ nanocrystal is synthesized by hydrothermal technique. • Eu 3+ is used to stabilize crystalline phase and to get red counterpart of the white light. • Defect emission and Eu 3+ emission combined to give white light. • The white light emitted from this nanocrystal resembles vertical daylight of the Sun. • Lifetime corresponding to red counterpart of the sample is far longer than conventional white light emitters. -- Abstract: Production of white light has been a promising area of luminescence studies. In this work, white light emitting nanocrystals of cubic zirconia doped with Eu 3+ are synthesized by hydrothermal technique. The dopant Eu 3+ is used to stabilize crystalline phase to cubic and at the same time to get red counterpart of the white light. The synthesis procedure is simple and precursor required no further annealing for crystallization. X-ray diffraction patterns show the crystalline phase of ZrO 2 :Eu 3+ to be cubic and it is confirmed by Fourier Transform Infrared spectroscopy. From transmission electron microscopy images, size of the crystals is found to be ∼5 nm. Photoluminescence emission spectrum of the sample, on monitoring excitation at O 2− –Eu 3+ charge transfer state shows broad peak due to O 2− of the zirconia and that of Eu 3+ emission. Commission Internationale de l’éclairage co-ordinate of this nanocrystal (0.32, 0.34) is closed to that of the ideal white light (0.33, 0.33). Correlated color temperature of the white light (5894 K) is within the range of vertical daylight. Lifetime (1.32 ms) corresponding to 5 D 0 energy level of the Eu 3+ is found to be far longer than conventional red counterparts of white light emitters. It suggests that the ZrO 2 :Eu 3+ nanocrystals synthesized by hydrothermal technique may find applications in simulating the vertical daylight of the Sun

  8. Effects of noise and parameter deviations in a bichromatic Raman white light cavity

    International Nuclear Information System (INIS)

    Sun Qingqing; Zubairy, M. Suhail; Shahriar, M. Selim

    2010-01-01

    We analyze the effects of noise and parameter deviations in a bichromatic Raman type white light cavity, with potential applications in precision measurements. The results show that the dispersion variation induced by parameter deviation can be controlled with an accuracy of 10 -4 . The laser phase noise decreases the dispersion magnitude while the amplitude noise increases it. Although we can always adjust the parameters to satisfy the white light condition, both types of noise make the cavity transmission curve uneven.

  9. Surface Topology Reconstruction From The White Light Interferogram By Means Of Prony Analysis

    Directory of Open Access Journals (Sweden)

    Khoma Anna

    2015-12-01

    Full Text Available The paper presents a new method of surface topology reconstruction from a white light interferogram. The method is based on interferogram modelling by complex exponents (Prony method. The compatibility of white light interferogram and Prony models has already been proven. Effectiveness of the method was tested by modelling and examining reconstruction of tilted and spherical surfaces, and by estimating the reconstruction accuracy.

  10. Semiconductive 3-D haloplumbate framework hybrids with high color rendering index white-light emission.

    Science.gov (United States)

    Wang, Guan-E; Xu, Gang; Wang, Ming-Sheng; Cai, Li-Zhen; Li, Wen-Hua; Guo, Guo-Cong

    2015-12-01

    Single-component white light materials may create great opportunities for novel conventional lighting applications and display systems; however, their reported color rendering index (CRI) values, one of the key parameters for lighting, are less than 90, which does not satisfy the demand of color-critical upmarket applications, such as photography, cinematography, and art galleries. In this work, two semiconductive chloroplumbate (chloride anion of lead(ii)) hybrids, obtained using a new inorganic-organic hybrid strategy, show unprecedented 3-D inorganic framework structures and white-light-emitting properties with high CRI values around 90, one of which shows the highest value to date.

  11. CORRELATION OF HARD X-RAY AND WHITE LIGHT EMISSION IN SOLAR FLARES

    Energy Technology Data Exchange (ETDEWEB)

    Kuhar, Matej; Krucker, Säm; Battaglia, Marina; Kleint, Lucia; Casadei, Diego [University of Applied Sciences and Arts Northwestern Switzerland, Bahnhofstrasse 6, 5210 Windisch (Switzerland); Oliveros, Juan Carlos Martinez; Hudson, Hugh S. [Space Sciences Laboratory, University of California, Berkeley, CA 94720-7450 (United States)

    2016-01-01

    A statistical study of the correlation between hard X-ray and white light emission in solar flares is performed in order to search for a link between flare-accelerated electrons and white light formation. We analyze 43 flares spanning GOES classes M and X using observations from the Reuven Ramaty High Energy Solar Spectroscopic Imager and Helioseismic and Magnetic Imager. We calculate X-ray fluxes at 30 keV and white light fluxes at 6173 Å summed over the hard X-ray flare ribbons with an integration time of 45 s around the peak hard-X ray time. We find a good correlation between hard X-ray fluxes and excess white light fluxes, with a highest correlation coefficient of 0.68 for photons with energy of 30 keV. Assuming the thick target model, a similar correlation is found between the deposited power by flare-accelerated electrons and the white light fluxes. The correlation coefficient is found to be largest for energy deposition by electrons above ∼50 keV. At higher electron energies the correlation decreases gradually while a rapid decrease is seen if the energy provided by low-energy electrons is added. This suggests that flare-accelerated electrons of energy ∼50 keV are the main source for white light production.

  12. 4th generation light source instrumentation

    International Nuclear Information System (INIS)

    Lumpkin, A.

    1998-01-01

    This working group on 4th Generation Light Source (4GLS) Instrumentation was a follow-up to the opening-discussion on Challenges in Beam Profiling. It was in parallel with the Feedback Systems session. We filled the SSRL Conference Room with about 25 participants. The session opened with an introduction by Lumpkin. The target beam parameter values for a few-angstrom, self-amplified spontaneous emissions (SASE) experiment and for a diffraction-limited soft x-ray storage ring source were addressed. Instrument resolution would of course need to be 2-3 times better than the value measured, if possible. The nominal targeted performance parameters are emittance (1-2π mm mrad), bunch length (100 fs), peak-current (l-5 kA), beam size (10 microm), beam divergence (1 microrad), energy spread (2 x 10 -4 ), and beam energy (10's of GeV). These are mostly the SASE values, and the possible parameters for a diffraction-limited soft x-ray source would be relaxed somewhat. Beam stability and alignment specifications in the sub-micron domain for either device are anticipated

  13. Development of White-Light Emitting Active Layers in Nitride Based Heterostructures for Phosphorless Solid State Lighting

    Energy Technology Data Exchange (ETDEWEB)

    Jan Talbot; Kailash Mishra

    2007-12-31

    This report provides a summary of research activities carried out at the University of California, San Diego and Central Research of OSRAM SYLVANIA in Beverly, MA partially supported by a research contract from US Department of Energy, DE-FC26-04NT422274. The main objective of this project was to develop III-V nitrides activated by rare earth ions, RE{sup 3+}, which could eliminate the need for phosphors in nitride-based solid state light sources. The main idea was to convert electron-hole pairs injected into the active layer in a LED die to white light directly through transitions within the energy levels of the 4f{sup n}-manifold of RE{sup 3+}. We focused on the following materials: Eu{sup 3+}(red), Tb{sup 3+}(green), Er{sup 3+}(green), Dy{sup 3+}(yellow) and Tm{sup 3+}(blue) in AlN, GaN and alloys of AlN and GaN. Our strategy was to explore candidate materials in powder form first, and then study their behavior in thin films. Thin films of these materials were to be deposited on sapphire substrates using pulsed laser deposition (PLD) and metal organic vapor phase epitaxy (MOVPE). The photo- and cathode-luminescence measurements of these materials were used to investigate their suitability for white light generation. The project proceeded along this route with minor modifications needed to produce better materials and to expedite our progress towards the final goal. The project made the following accomplishments: (1) red emission from Eu{sup 3+}, green from Tb{sup 3+}, yellow from Dy{sup 3+} and blue from Tm{sup 3+} in AlN powders; (2) red emission from Eu{sup 3+} and green emission from Tb{sup 3+} in GaN powder; (3) red emission from Eu{sup 3+} in alloys of GaN and AlN; (4) green emission from Tb{sup 3+} in GaN thin films by PLD; (5) red emission from Eu{sup 3+} and Tb{sup 3+} in GaN thin films deposited by MOVPE; (6) energy transfer from host to RE{sup 3+}; (7) energy transfer from Tb{sup 3+} to Eu{sup 3+} in AlN powders; (8) emission from AlN powder samples

  14. White light photoluminescence from ZnS films on porous Si substrates

    International Nuclear Information System (INIS)

    Wang Caifeng; Li Weibing; Li Qingshan; Hu Bo

    2010-01-01

    ZnS films were deposited on porous Si (PS) substrates using a pulsed laser deposition (PLD) technique. White light emission is observed in photoluminescence (PL) spectra, and the white light is the combination of blue and green emission from ZnS and red emission from PS. The white PL spectra are broad, intense in a visible band ranging from 450 to 700 nm. The effects of the excitation wavelength, growth temperature of ZnS films, PS porosity and annealing temperature on the PL spectra of ZnS/PS were also investigated. (semiconductor materials)

  15. SEMICONDUCTOR MATERIALS: White light photoluminescence from ZnS films on porous Si substrates

    Science.gov (United States)

    Caifeng, Wang; Qingshan, Li; Bo, Hu; Weibing, Li

    2010-03-01

    ZnS films were deposited on porous Si (PS) substrates using a pulsed laser deposition (PLD) technique. White light emission is observed in photoluminescence (PL) spectra, and the white light is the combination of blue and green emission from ZnS and red emission from PS. The white PL spectra are broad, intense in a visible band ranging from 450 to 700 nm. The effects of the excitation wavelength, growth temperature of ZnS films, PS porosity and annealing temperature on the PL spectra of ZnS/PS were also investigated.

  16. Fluorescent SiC for white light-emitting diodes

    DEFF Research Database (Denmark)

    Ou, Haiyan; Ou, Yiyu; Kamiyama, S.

    2012-01-01

    The strong photoluminescence from f-SiC was achieved after the optimization of the B and N concentrations. Surface nanostructures were successfully applied to enhance the extraction efficiency. f-SiC is a promising wavelength convertor for white LEDs....

  17. Collective dynamics of populations of weakly correlated filaments of incoherent white light

    International Nuclear Information System (INIS)

    Guo, Jinxin; Sheridan, John T; Saravanamuttu, Kalaichelvi

    2013-01-01

    We examined the dynamics of two populations of self-trapped filaments of spatially and temporally incoherent white light. The populations consisted of (i) independent filaments generated through self-trapping of incandescent speckles, and (ii) co-dependent filaments created through modulation instability of a broad incandescent beam. Both filament populations were positionally stable in conditions where individual pairs of self-trapped beams interact strongly. Both also acquired significantly broad intensity distributions, which were independent of their parent optical fields; a small but persistent number of high-intensity filaments was identified in both cases. These studies provide accessible routes to weakly correlated ensembles, insight into their collective behaviour such as self-stabilization and self-selected intensity distributions, and reveal intriguing similarities between the dynamics of two populations of different origins. (paper)

  18. Pulsed White Spectrum Neutron Generator for Explosive Detection

    International Nuclear Information System (INIS)

    King, Michael J.; Miller, Gill T.; Reijonen, Jani; Ji, Qing; Andresen, Nord; Gicquel, Frederic; Kavlas, Taneli; Leung, Ka-Ngo; Kwan, Joe

    2008-01-01

    Successful explosive material detection in luggage and similar sized containers is a critical issue in securing the safety of all airline passengers. Tensor Technology Inc. has recently developed a methodology that will detect explosive compounds with pulsed fast neutron transmission spectroscopy. In this scheme, tritium beams will be used to generate neutrons with a broad energy spectrum as governed by the T(t,2n)4He fission reaction that produces 0-9 MeV neutrons. Lawrence Berkeley National Laboratory (LBNL), in collaboration with Tensor Technology Inc., has designed and fabricated a pulsed white-spectrum neutron source for this application. The specifications of the neutron source are demanding and stringent due to the requirements of high yield and fast pulsing neutron emission, and sealed tube, tritium operation. In a unique co-axial geometry, the ion source uses ten parallel rf induction antennas to externally couple power into a toroidal discharge chamber. There are 20 ion beam extraction slits and 3 concentric electrode rings to shape and accelerate the ion beam into a titanium cone target. Fast neutron pulses are created by using a set of parallel-plate deflectors switching between +-1500 volts and deflecting the ion beams across a narrow slit. The generator is expected to achieve 5 ns neutron pulses at tritium ion beam energies between 80-120 kV. First experiments demonstrated ion source operation and successful beam pulsing

  19. Laser driven white light source for BRDF measurement

    DEFF Research Database (Denmark)

    Amdemeskel, Mekbib Wubishet; Thorseth, Anders; Dam-Hansen, Carsten

    2017-01-01

    In this paper, we will present a setup with laser driven light source (LDLS) for measuring a 2D bidirectional reflectance distribution function (BRDF). We have carried out measurements to acquire the BRDF of different samples based on our setup: which consists of a new laser driven broadband light...... source (UV-VIS-NIR), spectroradiometer and sample holder stepper motor in a dark UV-protected environment. Here, we introduced a special kind of light source which has a bright, stable, broad spectral range and well collimated light output to give a very good angular resolution. The experimental results...

  20. White light-emitting diodes (LEDs) using (oxy)nitride phosphors

    International Nuclear Information System (INIS)

    Xie, R-J; Hirosaki, N; Sakuma, K; Kimura, N

    2008-01-01

    (Oxy)nitride phosphors have attracted great attention recently because they are promising luminescent materials for phosphor-converted white light-emitting diodes (LEDs). This paper reports the luminescent properties of (oxy)nitride phosphors in the system of M-Si-Al-O-N (M = Li, Ca or Sr), and optical properties of white LEDs using a GaN-based blue LED and (oxy)nitride phosphors. The phosphors show high conversion efficiency of blue light, suitable emission colours and small thermal quenching. The bichromatic white LEDs exhibit high luminous efficacy (∼55 lm W -1 ) and the multi-phosphor converted white LEDs show high colour rendering index (Ra 82-95). The results indicate that (oxy)nitride phosphors demonstrate their superior suitability to use as down-conversion luminescent materials in white LEDs

  1. Spectral optimization simulation of white light based on the photopic eye-sensitivity curve

    Energy Technology Data Exchange (ETDEWEB)

    Dai, Qi, E-mail: qidai@tongji.edu.cn [College of Architecture and Urban Planning, Tongji University, 1239 Siping Road, Shanghai 200092 (China); Institute for Advanced Study, Tongji University, 1239 Siping Road, Shanghai 200092 (China); Key Laboratory of Ecology and Energy-saving Study of Dense Habitat (Tongji University), Ministry of Education, 1239 Siping Road, Shanghai 200092 (China); Hao, Luoxi; Lin, Yi; Cui, Zhe [College of Architecture and Urban Planning, Tongji University, 1239 Siping Road, Shanghai 200092 (China); Key Laboratory of Ecology and Energy-saving Study of Dense Habitat (Tongji University), Ministry of Education, 1239 Siping Road, Shanghai 200092 (China)

    2016-02-07

    Spectral optimization simulation of white light is studied to boost maximum attainable luminous efficacy of radiation at high color-rendering index (CRI) and various color temperatures. The photopic eye-sensitivity curve V(λ) is utilized as the dominant portion of white light spectra. Emission spectra of a blue InGaN light-emitting diode (LED) and a red AlInGaP LED are added to the spectrum of V(λ) to match white color coordinates. It is demonstrated that at the condition of color temperature from 2500 K to 6500 K and CRI above 90, such white sources can achieve spectral efficacy of 330–390 lm/W, which is higher than the previously reported theoretical maximum values. We show that this eye-sensitivity-based approach also has advantages on component energy conversion efficiency compared with previously reported optimization solutions.

  2. Spectral optimization simulation of white light based on the photopic eye-sensitivity curve

    International Nuclear Information System (INIS)

    Dai, Qi; Hao, Luoxi; Lin, Yi; Cui, Zhe

    2016-01-01

    Spectral optimization simulation of white light is studied to boost maximum attainable luminous efficacy of radiation at high color-rendering index (CRI) and various color temperatures. The photopic eye-sensitivity curve V(λ) is utilized as the dominant portion of white light spectra. Emission spectra of a blue InGaN light-emitting diode (LED) and a red AlInGaP LED are added to the spectrum of V(λ) to match white color coordinates. It is demonstrated that at the condition of color temperature from 2500 K to 6500 K and CRI above 90, such white sources can achieve spectral efficacy of 330–390 lm/W, which is higher than the previously reported theoretical maximum values. We show that this eye-sensitivity-based approach also has advantages on component energy conversion efficiency compared with previously reported optimization solutions

  3. Zero- and two-dimensional hybrid carbon phosphors for high colorimetric purity white light-emission.

    Science.gov (United States)

    Ding, Yamei; Chang, Qing; Xiu, Fei; Chen, Yingying; Liu, Zhengdong; Ban, Chaoyi; Cheng, Shuai; Liu, Juqing; Huang, Wei

    2018-03-01

    Carbon nanomaterials are promising phosphors for white light emission. A facile single-step synthesis method has been developed to prepare zero- and two-dimensional hybrid carbon phosphors for the first time. Zero-dimensional carbon dots (C-dots) emit bright blue luminescence under 365 nm UV light and two-dimensional nanoplates improve the dispersity and film forming ability of C-dots. As a proof-of-concept application, the as-prepared hybrid carbon phosphors emit bright white luminescence in the solid state, and the phosphor-coated blue LEDs exhibit high colorimetric purity white light-emission with a color coordinate of (0.3308, 0.3312), potentially enabling the successful application of white emitting phosphors in the LED field.

  4. Blue light filtered white light induces depression-like responses and temporary spatial learning deficits in rats.

    Science.gov (United States)

    Meng, Qinghe; Lian, Yuzheng; Jiang, Jianjun; Wang, Wei; Hou, Xiaohong; Pan, Yao; Chu, Hongqian; Shang, Lanqin; Wei, Xuetao; Hao, Weidong

    2018-04-18

    Ambient light has a vital impact on mood and cognitive functions. Blue light has been previously reported to play a salient role in the antidepressant effect via melanopsin. Whether blue light filtered white light (BFW) affects mood and cognitive functions remains unclear. The present study aimed to investigate whether BFW led to depression-like symptoms and cognitive deficits including spatial learning and memory abilities in rats, and whether they were associated with the light-responsive function in retinal explants. Male Sprague-Dawley albino rats were randomly divided into 2 groups (n = 10) and treated with a white light-emitting diode (LED) light source and BFW light source, respectively, under a standard 12 : 12 h L/D condition over 30 days. The sucrose consumption test, forced swim test (FST) and the level of plasma corticosterone (CORT) were employed to evaluate depression-like symptoms in rats. Cognitive functions were assessed by the Morris water maze (MWM) test. A multi-electrode array (MEA) system was utilized to measure electro-retinogram (ERG) responses induced by white or BFW flashes. The effect of BFW over 30 days on depression-like responses in rats was indicated by decreased sucrose consumption in the sucrose consumption test, an increased immobility time in the FST and an elevated level of plasma CORT. BFW led to temporary spatial learning deficits in rats, which was evidenced by prolonged escape latency and swimming distances in the spatial navigation test. However, no changes were observed in the short memory ability of rats treated with BFW. The micro-ERG results showed a delayed implicit time and reduced amplitudes evoked by BFW flashes compared to the white flash group. BFW induces depression-like symptoms and temporary spatial learning deficits in rats, which might be closely related to the impairment of light-evoked output signals in the retina.

  5. A phosphor-free white light-emitting diode using In2O3 : Tb transparent conductive light converter

    International Nuclear Information System (INIS)

    Chen, Lung-Chien; Tien, Ching-Ho; Liao, Wei-Chian

    2011-01-01

    Tb-doped indium oxide (In 2 O 3 : Tb) films were deposited on a GaN-based near-ultraviolet (NUV) light-emitting diode (LED) as a transparent conductive light converter to form a white LED. The transmittance of the In 2 O 3 : Tb film (Tb at 10 wt%) exceeded 80% in visible light and the resistivity was 0.325 Ω cm. The In 2 O 3 : Tb transparent conductive light converter was also employed on GaN-based LEDs. GaN-based NUV-LEDs with In 2 O 3 : Tb film (Tb at 10 wt%) produced forward biases of 3.42 V at an injection current of 20 mA. With increasing temperature, increasing Tb 3+ concentration and increasing injection current from 20 to 100 mA, the chromaticity coordinates barely changed in the white light area. Therefore, the GaN-based NUV-LED with In 2 O 3 : Tb film had a stable white light colour, when temperature and injection current changed, and is suitable for solid-state lighting.

  6. Attraction of Rhagoletis indifferens (Diptera: Tephitidae) to white light in the presence and absence of ammonia

    Science.gov (United States)

    Attraction of tephritid fruit flies to light and its role in fly biology and management has received little attention. Here, the objective was to show that western cherry fruit fly, Rhagoletis indifferens Curran (Diptera: Tephritidae), is attracted to white light in the presence and absence of ammo...

  7. Wireless high-speed data transmission with phosphorescent white-light LEDs

    NARCIS (Netherlands)

    Grubor, J.; Lee, S.C.J.; Langer, K-D.; Koonen, A.M.J.; Walewski, J.

    2007-01-01

    Wireless transmission exceeding 100 Mbit/s is demonstrated using a phosphorescent white-light LED in a lighting-like scenario. The data rate was achieved by detecting the blue part of the optical spectrum and applying discrete multi-tone modulation.

  8. Simulataneous Formation of InGaN Nanostructures with Varying Shapes for White Light Source Applications

    KAUST Repository

    Gasim, Anwar A.; Bhattacharya, Pallab K.; Cha, Dong Kyu; Ng, Tien Khee; Ooi, Boon S.

    2012-01-01

    Varying shapes of InGaN nanostructures were simultaneously formed on silicon epitaxially. The nanowires and nanomushrooms emit violet-blue light, and broad yellow-orange-red luminescence, respectively. The combination of which is promising for white light emission.

  9. White light emitting device based on single-phase CdS quantum dots

    Science.gov (United States)

    Li, Feng; Nie, Chao; You, Lai; Jin, Xiao; Zhang, Qin; Qin, Yuancheng; Zhao, Feng; Song, Yinglin; Chen, Zhongping; Li, Qinghua

    2018-05-01

    White light emitting diodes (WLEDs) based on quantum dots (QDs) are emerging as robust candidates for white light sources, however they are suffering from the problem of energy loss resulting from the re-absorption and self-absorption among the employed QDs of different peak wavelengths. It still remains a challenging task to construct WLEDs based on single-phase QD emitters. Here, CdS QDs with short synthesis times are introduced to the fabrication of WLEDs. With a short synthesis time, on one hand, CdS QDs with a small diameter with blue emission can be obtained. On the other hand, surface reconstruction barely has time to occur, and the surface is likely defect-ridden, which enables the existence of a broad emission covering the range of green, yellow and red regions. This is essential for the white light emission of CdS QDs, and is very important for WLED applications. The temporal evolution of the PL spectra for CdS QDs was obtained to investigate the influence of growth time on the luminescent properties. The CdS QDs with a growth time of 0.5 min exhibited a colour rendering index (CRI) of 79.5 and a correlated colour temperature (CCT) of 6238 K. With increasing reaction time, the colour coordinates of the CdS QDs will move away from the white light region in the CIE 1931 chromaticity diagram. By integrating the as prepared white light emission CdS QDs with a violet GaN chip, WLEDs were fabricated. The fabricated WLEDs exhibited a CRI of 87.9 and a CCT of 4619 K, which satisfy the demand of general illumination. The luminous flux and the luminous efficiency of the fabricated WLEDs, being less advanced than current commercial white light sources, can be further improved, meaning there is a need for much more in-depth studies on white light emission CdS QDs.

  10. Thermal, optical, and electrical engineering of an innovative tunable white LED light engine

    Science.gov (United States)

    Trivellin, Nicola; Meneghini, Matteo; Ferretti, Marco; Barbisan, Diego; Dal Lago, Matteo; Meneghesso, Gaudenzio; Zanoni, Enrico

    2014-02-01

    Color temperature, intensity and blue spectrum of the light affects the ganglion receptors in human brain stimulating the human nervous system. With this work we review different methods for obtaining tunable light emission spectra and propose an innovative white LED lighting system. By an in depth study of the thermal, electrical and optical characteristics of GaN and GaP based compound semiconductors for optoelectronics a specific tunable spectra has been designed. The proposed tunable white LED system is able to achieve high CRI (above 95) in a large CCT range (3000 - 5000K).

  11. Novel concepts for high-efficiency white organic light-emitting diodes

    Energy Technology Data Exchange (ETDEWEB)

    Schwartz, Gregor

    2007-07-01

    This work deals with novel concepts to realize high efficiency white OLEDs by combining fluorescent blue and phosphorescent green and orange emitters. A key point determining the maximum efficiency possible, as well as the device structure to be chosen to reach high efficiency, is the triplet exciton energy of the fluorescent blue emitter. If its triplet state is lower than that of the phosphorescent emitters, mutual exciton quenching can occur. This problem is solved by the first concept with spatial separation of the fluorescent blue from the phosphorescent emitters by a large-gap exciton blocking layer. To still realize exciton generation on both sides, the interlayer has to be ambipolar. On the other hand, if the triplet exciton energy of the fluorescent blue is higher than that of at least one of the phosphorescent emitters, appropriate arrangement of the emission layers makes a separation layer obsolete, since phosphorescence quenching does not occur anymore. Moreover, the intrinsically non-radiative triplet excitons of the fluorescent blue emitter may be harvested by the phosphor for light emission, which means that even 100% internal quantum efficiency is possible. The last chapter 6 deals with this second concept, where the main issue is to simultaneously achieve exciton harvesting as complete as possible and a balanced white emission spectrum by appropriately distributing singlet and triplet excitons to the used emitters. All emitters used in this work are commercially available and their molecular structure is disclosed in order to make the results transparent. (orig.)

  12. Pure white-light emitting ultrasmall organic-inorganic hybrid perovskite nanoclusters.

    Science.gov (United States)

    Teunis, Meghan B; Lawrence, Katie N; Dutta, Poulami; Siegel, Amanda P; Sardar, Rajesh

    2016-10-14

    Organic-inorganic hybrid perovskites, direct band-gap semiconductors, have shown tremendous promise for optoelectronic device fabrication. We report the first colloidal synthetic approach to prepare ultrasmall (∼1.5 nm diameter), white-light emitting, organic-inorganic hybrid perovskite nanoclusters. The nearly pure white-light emitting ultrasmall nanoclusters were obtained by selectively manipulating the surface chemistry (passivating ligands and surface trap-states) and controlled substitution of halide ions. The nanoclusters displayed a combination of band-edge and broadband photoluminescence properties, covering a major part of the visible region of the solar spectrum with unprecedentedly large quantum yields of ∼12% and photoluminescence lifetime of ∼20 ns. The intrinsic white-light emission of perovskite nanoclusters makes them ideal and low cost hybrid nanomaterials for solid-state lighting applications.

  13. GATEWAY Report Brief: Tunable-White Lighting at the ACC Care Center

    Energy Technology Data Exchange (ETDEWEB)

    None, None

    2016-09-30

    Summary of a GATEWAY program report that documented the performance of tunable-white LED lighting systems installed in several spaces within the ACC Care Center, a senior-care facility in Sacramento, CA. The project results included energy savings and improved lighting quality, as well as other possible health-related benefits that may have been attributable, at least in part, to the lighting changes.

  14. White light emission of carbon dots by creating different emissive traps

    International Nuclear Information System (INIS)

    Joseph, Julin; Anappara, Aji A.

    2016-01-01

    Here we report a facile and rapid synthetic strategy for white light emitting carbon dots (CDs) by creating inhomogeneity in the surface-moieties by carbonizing ethylene diamine tetra acetic acid (EDTA) and ethylene glycol (EG) which are having different functional groups. The aqueous solution of the as-synthesised nanoparticles exhibits broad-band emission at several excitation wavelengths, with CIE parameters in the white gamut. Furthermore, white light emission is demonstrated through remote-phosphor technology, by capping 365 nm UV chip with PMMA, after dispersing the polymer with CDs. The resulting emission from the white-LED reported colour parameters such as CIE (0.34, 0.38), CRI of 84 and CCT of 5078 K.

  15. White light emission of carbon dots by creating different emissive traps

    Energy Technology Data Exchange (ETDEWEB)

    Joseph, Julin; Anappara, Aji A., E-mail: aji@nitc.ac.in

    2016-10-15

    Here we report a facile and rapid synthetic strategy for white light emitting carbon dots (CDs) by creating inhomogeneity in the surface-moieties by carbonizing ethylene diamine tetra acetic acid (EDTA) and ethylene glycol (EG) which are having different functional groups. The aqueous solution of the as-synthesised nanoparticles exhibits broad-band emission at several excitation wavelengths, with CIE parameters in the white gamut. Furthermore, white light emission is demonstrated through remote-phosphor technology, by capping 365 nm UV chip with PMMA, after dispersing the polymer with CDs. The resulting emission from the white-LED reported colour parameters such as CIE (0.34, 0.38), CRI of 84 and CCT of 5078 K.

  16. Iranian Light Source Facility, A third generation light source laboratory

    Directory of Open Access Journals (Sweden)

    J Rahighi

    2015-09-01

    Full Text Available The Iranian Light Source Facility (ILSF project is the first large scale accelerator facility which is currently under planning in Iran. On the basis of the present design, circumference of the 3 GeV storage ring is 528 m. Beam current and natural beam emittance are 400 mA and 0.477 nm.rad, respectively. Some prototype accelerator components such as high power solid state radio frequency amplifiers, low level RF system, thermionic RF gun, H-type dipole and quadruple magnets, magnetic measurement laboratory and highly stable magnet power supplies have been constructed at ILSF R&D laboratory

  17. Online multispectral fluorescence lifetime values estimation and overlay onto tissue white-light video frames

    Science.gov (United States)

    Gorpas, Dimitris; Ma, Dinglong; Bec, Julien; Yankelevich, Diego R.; Marcu, Laura

    2016-03-01

    Fluorescence lifetime imaging has been shown to be a robust technique for biochemical and functional characterization of tissues and to present great potential for intraoperative tissue diagnosis and guidance of surgical procedures. We report a technique for real-time mapping of fluorescence parameters (i.e. lifetime values) onto the location from where the fluorescence measurements were taken. This is achieved by merging a 450 nm aiming beam generated by a diode laser with the excitation light in a single delivery/collection fiber and by continuously imaging the region of interest with a color CMOS camera. The interrogated locations are then extracted from the acquired frames via color-based segmentation of the aiming beam. Assuming a Gaussian profile of the imaged aiming beam, the segmentation results are fitted to ellipses that are dynamically scaled at the full width of three automatically estimated thresholds (50%, 75%, 90%) of the Gaussian distribution's maximum value. This enables the dynamic augmentation of the white-light video frames with the corresponding fluorescence decay parameters. A fluorescence phantom and fresh tissue samples were used to evaluate this method with motorized and hand-held scanning measurements. At 640x512 pixels resolution the area of interest augmented with fluorescence decay parameters can be imaged at an average 34 frames per second. The developed method has the potential to become a valuable tool for real-time display of optical spectroscopy data during continuous scanning applications that subsequently can be used for tissue characterization and diagnosis.

  18. KEPLER FLARES. II. THE TEMPORAL MORPHOLOGY OF WHITE-LIGHT FLARES ON GJ 1243

    Energy Technology Data Exchange (ETDEWEB)

    Davenport, James R. A.; Hawley, Suzanne L.; Johnson, Emily C.; Peraza, Jesus; Jansen, Tiffany C.; Larsen, Daniel M. [Department of Astronomy, University of Washington, P.O. Box 351580, Seattle, WA 98195 (United States); Hebb, Leslie [Department of Physics, Hobart and William Smith Colleges, 300 Pulteney Street, Geneva, NY 14456 (United States); Wisniewski, John P.; Malatesta, Michael; Keil, Marcus; Silverberg, Steven M.; Scheffler, Matthew S.; Berdis, Jodi R. [HL Dodge Department of Physics and Astronomy, University of Oklahoma, 440 W Brooks Street, Norman, OK 73019 (United States); Kowalski, Adam F. [NASA Goddard Space Flight Center, Code 671, Greenbelt, MD 20771 (United States); Hilton, Eric J., E-mail: jrad@astro.washington.edu [Universe Sandbox, 911 E. Pike Street #333, Seattle, WA 98122 (United States)

    2014-12-20

    We present the largest sample of flares ever compiled for a single M dwarf, the active M4 star GJ 1243. Over 6100 individual flare events, with energies ranging from 10{sup 29} to 10{sup 33} erg, are found in 11 months of 1 minute cadence data from Kepler. This sample is unique for its completeness and dynamic range. We have developed automated tools for finding flares in short-cadence Kepler light curves, and performed extensive validation and classification of the sample by eye. From this pristine sample of flares we generate a median flare template. This template shows that two exponential cooling phases are present during the white-light flare decay, providing fundamental constraints for models of flare physics. The template is also used as a basis function to decompose complex multi-peaked flares, allowing us to study the energy distribution of these events. Only a small number of flare events are not well fit by our template. We find that complex, multi-peaked flares occur in over 80% of flares with a duration of 50 minutes or greater. The underlying distribution of flare durations for events 10 minutes and longer appears to follow a broken power law. Our results support the idea that sympathetic flaring may be responsible for some complex flare events.

  19. KEPLER FLARES. II. THE TEMPORAL MORPHOLOGY OF WHITE-LIGHT FLARES ON GJ 1243

    International Nuclear Information System (INIS)

    Davenport, James R. A.; Hawley, Suzanne L.; Johnson, Emily C.; Peraza, Jesus; Jansen, Tiffany C.; Larsen, Daniel M.; Hebb, Leslie; Wisniewski, John P.; Malatesta, Michael; Keil, Marcus; Silverberg, Steven M.; Scheffler, Matthew S.; Berdis, Jodi R.; Kowalski, Adam F.; Hilton, Eric J.

    2014-01-01

    We present the largest sample of flares ever compiled for a single M dwarf, the active M4 star GJ 1243. Over 6100 individual flare events, with energies ranging from 10 29 to 10 33 erg, are found in 11 months of 1 minute cadence data from Kepler. This sample is unique for its completeness and dynamic range. We have developed automated tools for finding flares in short-cadence Kepler light curves, and performed extensive validation and classification of the sample by eye. From this pristine sample of flares we generate a median flare template. This template shows that two exponential cooling phases are present during the white-light flare decay, providing fundamental constraints for models of flare physics. The template is also used as a basis function to decompose complex multi-peaked flares, allowing us to study the energy distribution of these events. Only a small number of flare events are not well fit by our template. We find that complex, multi-peaked flares occur in over 80% of flares with a duration of 50 minutes or greater. The underlying distribution of flare durations for events 10 minutes and longer appears to follow a broken power law. Our results support the idea that sympathetic flaring may be responsible for some complex flare events

  20. Tailored white light emission in Eu3+/Dy3+ doped tellurite glass phosphors containing Al3+ ions

    Science.gov (United States)

    Walas, Michalina; Piotrowski, Patryk; Lewandowski, Tomasz; Synak, Anna; Łapiński, Marcin; Sadowski, Wojciech; Kościelska, Barbara

    2018-05-01

    Tellurite glass systems modified by addition of aluminum fluoride AlF3 have been successfully synthesized as host matrices for optically active rare earth ions RE3+ (RE3+ = Eu3+, Dy3+). Samples with different Eu3+ to Dy3+ molar ratio have been studied in order to determine possibility of white light emission via UV excitation. Structural investigations confirmed amorphous character of materials whereas spectroscopic studies brought more insight into glass network's nature. FTIR results shown presence of two features related to tellurite glass matrix (in 490-935 cm-1 spectral region) and another one (940-1250 cm-1) due to aluminum addition. Especially, Al-O and Te-O-Al bonds of AlO4 tetrahedrons have been found. AlO4 units are considered as glass formers that improve network's strength and thermal resistivity against devitrification. Based on XPS studies of Al3+ photoelectron band the existence of Al-O and also Al-F bonds have been examined. Moreover, signals originating from Eu3+ and Dy3+ have been found confirming their valence state. Luminescence results revealed possibility of simultaneous UV excitation of Eu3+ and Dy3+ ions. Excitation with λexc = 390 and 393 nm resulted in white light generation starting from warm white to neutral and cool white depending on Eu3+ concentration and used excitation wavelength. Additionally, increase of decay lifetime of Eu3+ induced by Al3+ presence have been revealed based on luminescence decay analysis. Thus, tellurite glass systems modified by AlF3 and doped with Eu3+/Dy3+ may be considered as promising candidates for white light emitting sources.

  1. A rapid excitation-emission matrix fluorometer utilizing supercontinuum white light and acousto-optic tunable filters

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Wenbo [Imaging Unit, Integrative Oncology Department, BC Cancer Agency Research Center, 675 West 10th Avenue, Vancouver, British Columbia V5Z 1L3 (Canada); Department of Dermatology and Skin Science, University of British Columbia, 835 West 10th Avenue, Vancouver, British Columbia V5Z 4E8 (Canada); Department of Biomedical Engineering, University of British Columbia, KAIS 5500, 2332 Main Mall, Vancouver, British Columbia V6T 1Z4 (Canada); Wu, Zhenguo; Zhao, Jianhua; Lui, Harvey; Zeng, Haishan, E-mail: hzeng@bccrc.ca [Imaging Unit, Integrative Oncology Department, BC Cancer Agency Research Center, 675 West 10th Avenue, Vancouver, British Columbia V5Z 1L3 (Canada); Department of Dermatology and Skin Science, University of British Columbia, 835 West 10th Avenue, Vancouver, British Columbia V5Z 4E8 (Canada)

    2016-06-15

    Scanning speed and coupling efficiency of excitation light to optic fibres are two major technical challenges that limit the potential of fluorescence excitation-emission matrix (EEM) spectrometer for on-line applications and in vivo studies. In this paper, a novel EEM system, utilizing a supercontinuum white light source and acousto-optic tunable filters (AOTFs), was introduced and evaluated. The supercontinuum white light, generated by pumping a nonlinear photonic crystal fiber with an 800 nm femtosecond laser, was efficiently coupled into a bifurcated optic fiber bundle. High speed EEM spectral scanning was achieved using AOTFs both for selecting excitation wavelength and scanning emission spectra. Using calibration lamps (neon and mercury argon), wavelength deviations were determined to vary from 0.18 nm to −0.70 nm within the spectral range of 500–850 nm. Spectral bandwidth for filtered excitation light broadened by twofold compared to that measured with monochromatic light between 650 nm and 750 nm. The EEM spectra for methanol solutions of laser dyes were successfully acquired with this rapid fluorometer using an integration time of 5 s.

  2. A rapid excitation-emission matrix fluorometer utilizing supercontinuum white light and acousto-optic tunable filters

    International Nuclear Information System (INIS)

    Wang, Wenbo; Wu, Zhenguo; Zhao, Jianhua; Lui, Harvey; Zeng, Haishan

    2016-01-01

    Scanning speed and coupling efficiency of excitation light to optic fibres are two major technical challenges that limit the potential of fluorescence excitation-emission matrix (EEM) spectrometer for on-line applications and in vivo studies. In this paper, a novel EEM system, utilizing a supercontinuum white light source and acousto-optic tunable filters (AOTFs), was introduced and evaluated. The supercontinuum white light, generated by pumping a nonlinear photonic crystal fiber with an 800 nm femtosecond laser, was efficiently coupled into a bifurcated optic fiber bundle. High speed EEM spectral scanning was achieved using AOTFs both for selecting excitation wavelength and scanning emission spectra. Using calibration lamps (neon and mercury argon), wavelength deviations were determined to vary from 0.18 nm to −0.70 nm within the spectral range of 500–850 nm. Spectral bandwidth for filtered excitation light broadened by twofold compared to that measured with monochromatic light between 650 nm and 750 nm. The EEM spectra for methanol solutions of laser dyes were successfully acquired with this rapid fluorometer using an integration time of 5 s.

  3. Fluorescent Silicon Carbide and its Applications in White Light-Emitting Diodes

    DEFF Research Database (Denmark)

    Ou, Yiyu

    light extraction efficiency are presented. White LEDs are the most promising techniques to replace the conventional lighting sources. A typical white LED consists of a Gallium Nitride (GaN) blue or Ultraviolet (UV) LED stack and a wavelengthconversion material. Silicon Carbide (SiC) has a wide optical...... rendering performance and a much longer material lifetime compared with the commonly used wavelength-conversion material like Phosphors. In this thesis, f-SiC with different doping concentrations are analyzed and optimized in order to enhance the quantum efficiency. On the other hand, semiconductor...

  4. Ultrabroad linewidth orange-emitting nanowires LED for high CRI laser-based white lighting and gigahertz communications

    KAUST Repository

    Janjua, Bilal

    2016-08-10

    Group-III-nitride laser diode (LD)-based solid-state lighting device has been demonstrated to be droop-free compared to light-emitting diodes (LEDs), and highly energy-efficient compared to that of the traditional incandescent and fluorescent white light systems. The YAG:Ce3+ phosphor used in LD-based solid-state lighting, however, is associated with rapid degradation issue. An alternate phosphor/LD architecture, which is capable of sustaining high temperature, high power density, while still intensity- and bandwidth-tunable for high color-quality remained unexplored. In this paper, we present for the first time, the proof-of-concept of the generation of high-quality white light using an InGaN-based orange nanowires (NWs) LED grown on silicon, in conjunction with a blue LD, and in place of the compound-phosphor. By changing the relative intensities of the ultrabroad linewidth orange and narrow-linewidth blue components, our LED/LD device architecture achieved correlated color temperature (CCT) ranging from 3000 K to above 6000K with color rendering index (CRI) values reaching 83.1, a value unsurpassed by the YAG-phosphor/blue-LD counterpart. The white-light wireless communications was implemented using the blue LD through on-off keying (OOK) modulation to obtain a data rate of 1.06 Gbps. We therefore achieved the best of both worlds when orange-emitting NWs LED are utilized as “active-phosphor”, while blue LD is used for both color mixing and optical wireless communications.

  5. White organic light-emitting diodes with Zn-complexes.

    Science.gov (United States)

    Kim, Dong-Eun; Shin, Hoon-Kyu; Kim, Nam-Kyu; Lee, Burm-Jong; Kwon, Young-Soo

    2014-02-01

    This paper reviews OLEDs fabricated using Zn-complexes. Zn(HPB)2, Zn(HPB)q, and Zn(phen)q were synthesized as new electroluminescence materials. The electron affinity (EA) and ionization potential (IP) of Zn complexes were also determined and devices were characterized. Zn complexes such as Zn(HPB)2, Zn(HPB)q, and Zn(phen)q were found to exhibit blue and yellow emissions with wavelengths of 455, 532, and 535 nm, respectively. On the other hand, Zn(HPB)2 and Zn(HPB)q were applied as hole-blocking materials. As a result, the OLED efficiency by using Zn(HPB)2 as a hole-blocking material was improved. In particular, the OLED property of Zn(HPB)2 was found to be better than that of Zn(HPB)q. Moreover, Zn(phen)q was used as an electron-transporting material and compared with Alq3. The performance of the device with Zn(phen)q as an electron-transporting material was improved compared with Alq3-based devices. The Zn complexes can possibly be used as hole-blocking and electron-transporting materials in OLED devices. A white emission was ultimately realized from the OLED devices using Zn-complexes as inter-layer components.

  6. Virtual 3D bladder reconstruction for augmented medical records from white light cystoscopy (Conference Presentation)

    Science.gov (United States)

    Lurie, Kristen L.; Zlatev, Dimitar V.; Angst, Roland; Liao, Joseph C.; Ellerbee, Audrey K.

    2016-02-01

    Bladder cancer has a high recurrence rate that necessitates lifelong surveillance to detect mucosal lesions. Examination with white light cystoscopy (WLC), the standard of care, is inherently subjective and data storage limited to clinical notes, diagrams, and still images. A visual history of the bladder wall can enhance clinical and surgical management. To address this clinical need, we developed a tool to transform in vivo WLC videos into virtual 3-dimensional (3D) bladder models using advanced computer vision techniques. WLC videos from rigid cystoscopies (1280 x 720 pixels) were recorded at 30 Hz followed by immediate camera calibration to control for image distortions. Video data were fed into an automated structure-from-motion algorithm that generated a 3D point cloud followed by a 3D mesh to approximate the bladder surface. The highest quality cystoscopic images were projected onto the approximated bladder surface to generate a virtual 3D bladder reconstruction. In intraoperative WLC videos from 36 patients undergoing transurethral resection of suspected bladder tumors, optimal reconstruction was achieved from frames depicting well-focused vasculature, when the bladder was maintained at constant volume with minimal debris, and when regions of the bladder wall were imaged multiple times. A significant innovation of this work is the ability to perform the reconstruction using video from a clinical procedure collected with standard equipment, thereby facilitating rapid clinical translation, application to other forms of endoscopy and new opportunities for longitudinal studies of cancer recurrence.

  7. Cerenkov light generated in optical fibres and other light pipes irradiated by electron beams

    International Nuclear Information System (INIS)

    Beddar, A.S.; Mackie, T.R.; Attix, F.H.

    1992-01-01

    The use of a small plastic scintillator coupled to an optical fibre bundle light pipe for the dosimetry of radiotherapy x-ray or electron beams in a phantom has been studied. Under such conditions, some light is generated by the direct action of the radiation on the optical fibres themselves, and this 'background' signal must be correctly accounted for. Electron beams were incident on fused silica optical fibres and other light pipes made of polymethylmethacrylate (PMMA), polystyrene and water. The observed light signal generated in all cases was found to depend strongly on the angle between the electron direction and the light pipe axis, and to correlate well with the angular characteristics uniquely associated with Cerenkov radiation. The use of a parallel fibre bundle light pipe, identical to the one that carries light from the scintillator, offers a suitable means of generating a similar background Cerenkov light signal that can be subtracted to obtain output from the scintillation dosimeter alone. (author)

  8. Optimization of Multiband White-Light Illuminants for Specified Color Temperatures

    Directory of Open Access Journals (Sweden)

    Snjezana Soltic

    2015-01-01

    Full Text Available This paper describes an effective approach for the optimization of multiband spectra to produce prospective white-light spectra having specific color temperatures. The optimization process employs a genetic algorithm known as differential evolution, which aims to minimize the color rendering differences between a prospective white-light spectrum and its corresponding reference illuminant. Color rendering is assessed by calculating the CIEDE2000 color difference (ΔE00 for 14 CIE test colors under the two sources. Optimized white-light spectra were matched to three CIE standard illuminants, that is, A (2856 K, D50 (5003 K, and D65 (6504 K. Optimal solutions for three- and four-band 25 and 50 nm Gaussian spectra are presented and analyzed, together with mixed 4-LED spectra that were optimized in the same way. In all cases, the simulated sources were shown to provide color rendering of such quality that ΔE00av ≤ 2.24 units. Such white-light sources would likely find wide acceptance in numerous lighting applications.

  9. Students’ conceptions on white light and implications for teaching and learning about colour

    Science.gov (United States)

    Haagen-Schützenhöfer, Claudia

    2017-07-01

    The quality of learning processes is mainly determined by the extent to which students’ conceptions are addressed and thus conceptual change is triggered. Colour phenomena are a topic within initial instruction of optics which is challenging. A physically adequate concept of white light is crucial for being able to grasp the processes underlying colour formation. Our previous research suggests that misconceptions on white light may influence the conceptual understanding of colour phenomena. For the design of a learning environment on light and colours, the literature was reviewed. Then an explorative interview study with participants (N  =  32), with and without instruction in introductory optics, was carried out. In addition, the representations used for white light in Austrian physics schoolbooks were analysed. Based on the results of the literature review, the interview study and the schoolbook analysis, a learning environment was designed and tested in teaching experiments. The results indicate that learners often lack an adequate concept of white light even after instruction in introductory optics. This seems to cause learning difficulties concerning colour phenomena. On the other hand, the evaluation of our learning environment showed that students are able to gain a good conceptual understanding of colour phenomena if instruction takes these content specific learning difficulties into account.

  10. Color Rendering Index Thermal Stability Improvement of Glass-Based Phosphor-Converted White Light-Emitting Diodes for Solid-State Lighting

    Directory of Open Access Journals (Sweden)

    Chun-Chin Tsai

    2014-01-01

    Full Text Available High color rendering index performance has been required for phosphor-converted warm-white light-emitting diodes (PC-WWLEDs in lighting industry. The characteristics of low-temperature fabricated phosphor (yellow: Ce3+:YAG, green: Tb3+:YAG, and red: CaAlClSiN3:Eu2+ doped glass were presented for applications to high color rendering index warm-white-light-emitting diodes. Color coordinates (x, y = (0.36, 0.29, quantum yield (QY = 55.6%, color rending index (CRI = 85.3, and correlated color temperature (CCT = 3923 K were characterized. Glass-based PC-WWLEDs was found able to maintain good thermal stability for long-time high-temperature operation. QY decay, CRI remenance, and chromaticity shift were also analyzed for glass- and silicone-based high-power PC-WLEDs by thermal aging at 150°C and 250°C for industrial test standard’s aging time 1008 hours. Better than the silicone’s, thermal stability of glass-based PC-WLEDs has been improved. The resulted high color rendering index (CRI glass phosphor potentially can be used as a phosphor layer for high-performance and low-cost PC-WLEDs used in next-generation indoor solid-state lighting applications.

  11. Synchronization System for Next Generation Light Sources

    Energy Technology Data Exchange (ETDEWEB)

    Zavriyev, Anton [MagiQ Technologies, Inc., Somerville, MA (United States)

    2014-03-27

    An alternative synchronization technique – one that would allow explicit control of the pulse train including its repetition rate and delay is clearly desired. We propose such a scheme. Our method is based on optical interferometry and permits synchronization of the pulse trains generated by two independent mode-locked lasers. As the next generation x-ray sources will be driven by a clock signal derived from a mode-locked optical source, our technique will provide a way to synchronize x-ray probe with the optical pump pulses.

  12. Making metals transparency for white light by surface plasmons

    Science.gov (United States)

    Peng, Ru-Wen; Huang, Xian-Rong; Fan, Ren-Hao; Li, Jia; Hu, Qing; Wang, Mu

    2012-02-01

    We demonstrate both experimentally and theoretically that metallic gratings consisting of narrow slits become transparent for extremely broad bandwidths under oblique incidence. This phenomenon can be explained by a concrete picture in which the incident wave drives free electrons on the conducting surfaces and part of the slit walls to form surface plasmons (SPs). The SPs then propagate on the slit walls but are abruptly discontinued by the bottom edges to form oscillating charges that emit the transmitted wave. This picture explicitly demonstrates the conversion between light and SPs and indicates clear guidelines for enhancing SP excitation and propagation. Making structured metals transparent may lead to a variety of applications. References: Xian-Rong Huang, Ru-Wen Peng, and Ren-Hao Fan, Phys. Rev. Lett. (2010)105, 243901; and Ren-Hao Fan, Ru-Wen Peng, Xian-Rong Huang, Jia Li, Qing Hu, and Mu Wang, manuscript prepared(2011).

  13. [Multiplayer white organic light-emitting diodes with different order and thickness of emission layers].

    Science.gov (United States)

    Xu, Wei; Lu, Fu-Han; Cao, Jin; Zhu, Wen-Qing; Jiang, Xue-Yin; Zhang, Zhi-Lin; Xu, Shao-Hong

    2008-02-01

    In multilayer OLED devices, the order and thickness of the emission layers have great effect on their spectrum. Based on the three basic colours of red, blue and green, a series of white organic light-emitting diodes(WOLEDS)with the structure of ITO/CuPc(12 nm)/NPB(50 nm)/EML/LiF(1 nm)/Al(100 nm) and a variety of emission layer's orders and thicknesses were fabricated. The blue emission material: 2-t-butyl-9,10-di-(2-naphthyl)anthracene (TBADN) doped with p-bis(p-N, N-diphenyl-amono-styryl)benzene(DSA-Ph), the green emission material: tris-[8-hydroxyquinoline]aluminum(Alq3) doped with C545, and the red emission material: tris-[8-hydroxyquinoline]aluminum( Alq3) doped with 4-(dicyanomethylene)-2-t-butyl-6-(1, 1, 7, 7-tetramethyljulolidyl-9-enyl)-4H-pyran (DCJTB) were used. By adjusting the order and thickness of each emission layer in the RBG structure, we got a white OLED with current efficiency of 5.60 cd x A(-1) and Commission Internationale De L'Eclairage (CIE) coordinates of (0. 34, 0.34) at 200 mA x cm(-2). Its maximum luminance reached 20 700 cd x m(-2) at current density of 400 mA x cm(-2). The results were analyzed on the basis of the theory of excitons' generation and diffusion. According to the theory, an equation was set up which relates EL spectra to the luminance efficiency, the thickness of each layer and the exciton diffusion length. In addition, in RBG structure with different thickness of red layer, the ratio of th e spectral intensity of red to that of blue was calculated. It was found that the experimental results are in agreement with the theoretical values.

  14. 2 Gbit/s data transmission from an unfiltered laser-based phosphor-converted white lighting communication system

    KAUST Repository

    Lee, Changmin; Shen, Chao; Oubei, Hassan M.; Cantore, Michael; Janjua, Bilal; Ng, Tien Khee; Farrell, Robert M.; El-Desouki, Munir M.; Speck, James S.; Nakamura, Shuji; Ooi, Boon S.; DenBaars, Steven P.

    2015-01-01

    We demonstrate data transmission of unfiltered white light generated by direct modulation of a blue gallium nitride (GaN) laser diode (LD) exciting YAG:Ce phosphors. 1.1 GHz of modulation bandwidth was measured without a limitation from the slow 3.8 MHz phosphor response. A high data transmission rate of 2 Gbit/s was achieved without an optical blue-filter using a non-return-to-zero on-off keying (NRZ-OOK) modulation scheme. The measured bit error rate (BER) of 3.50 × 10−3 was less than the forward error correction (FEC) limit of 3.8 × 10−3. The generated white light exhibits CIE 1931 chromaticity coordinates of (0.3628, 0.4310) with a color rendering index (CRI) of 58 and a correlated color temperature (CCT) of 4740 K when the LD was operated at 300 mA. The demonstrated laser-based lighting system can be used simultaneously for indoor broadband access and illumination applications with good color stability.

  15. 2 Gbit/s data transmission from an unfiltered laser-based phosphor-converted white lighting communication system

    KAUST Repository

    Lee, Changmin

    2015-11-05

    We demonstrate data transmission of unfiltered white light generated by direct modulation of a blue gallium nitride (GaN) laser diode (LD) exciting YAG:Ce phosphors. 1.1 GHz of modulation bandwidth was measured without a limitation from the slow 3.8 MHz phosphor response. A high data transmission rate of 2 Gbit/s was achieved without an optical blue-filter using a non-return-to-zero on-off keying (NRZ-OOK) modulation scheme. The measured bit error rate (BER) of 3.50 × 10−3 was less than the forward error correction (FEC) limit of 3.8 × 10−3. The generated white light exhibits CIE 1931 chromaticity coordinates of (0.3628, 0.4310) with a color rendering index (CRI) of 58 and a correlated color temperature (CCT) of 4740 K when the LD was operated at 300 mA. The demonstrated laser-based lighting system can be used simultaneously for indoor broadband access and illumination applications with good color stability.

  16. Aligned energy-level design for decreasing operation voltage of tandem white organic light-emitting diodes

    Energy Technology Data Exchange (ETDEWEB)

    Chang, Chih-Hao, E-mail: chc@saturn.yzu.edu.tw [Department of Photonics Engineering, Yuan Ze University, Chung-Li 32003, Taiwan, ROC (China); Wu, Zih-Jyun; Liang, Yi-Hu; Chang, Yu-Shuo; Chiu, Chuan-Hao; Tai, Cheng-Wei [Department of Photonics Engineering, Yuan Ze University, Chung-Li 32003, Taiwan, ROC (China); Chang, Hsin-Hua, E-mail: hhua3@mail.vnu.edu.tw [Department of Electro-Optical Engineering, Vanung University, Chung-Li 32061, Taiwan, ROC (China)

    2013-12-02

    In general, organic light-emitting devices (OLEDs) need to operate at higher current density levels to ensure an ample light flux. However, stressed operation will result in poor performance and limited device lifetime. Recently, a tandem structure has been proposed as a pivotal technique to meet the stringent lighting requirements for OLED commercialization, with a research focus on decreasing the concomitant higher operation voltage. Driving two connected emission units (EMUs) in a tandem structure often requires more than twice the driving voltage for a single EMU. This study investigates bipolar host materials and their effective employment in fabricating tandem white phosphorescent OLEDs (PhOLEDs). In addition, the design of a mechanism to align the energy level between the hole transport layer/emitting layer is shown to effectively mitigate operational voltages. In sharp contrast to devices using a unipolar host material, we demonstrate that the turn-on voltage of blue PhOLEDs could be decreased from 3.8 V to 2.7 V through utilizing a bipolar host. Furthermore, applying the proposed techniques to tandem white PhOLEDs produces a luminance of 10{sup 3} cd/m{sup 2} by a 10.1 V driving voltage. - Highlights: • The matched energy level between the hole transport/emitting layer lowers voltages. • Multiple conduction dopants were used to investigate charge generation layer. • Two-color emitters were used to quantify the charge generation strength.

  17. Aligned energy-level design for decreasing operation voltage of tandem white organic light-emitting diodes

    International Nuclear Information System (INIS)

    Chang, Chih-Hao; Wu, Zih-Jyun; Liang, Yi-Hu; Chang, Yu-Shuo; Chiu, Chuan-Hao; Tai, Cheng-Wei; Chang, Hsin-Hua

    2013-01-01

    In general, organic light-emitting devices (OLEDs) need to operate at higher current density levels to ensure an ample light flux. However, stressed operation will result in poor performance and limited device lifetime. Recently, a tandem structure has been proposed as a pivotal technique to meet the stringent lighting requirements for OLED commercialization, with a research focus on decreasing the concomitant higher operation voltage. Driving two connected emission units (EMUs) in a tandem structure often requires more than twice the driving voltage for a single EMU. This study investigates bipolar host materials and their effective employment in fabricating tandem white phosphorescent OLEDs (PhOLEDs). In addition, the design of a mechanism to align the energy level between the hole transport layer/emitting layer is shown to effectively mitigate operational voltages. In sharp contrast to devices using a unipolar host material, we demonstrate that the turn-on voltage of blue PhOLEDs could be decreased from 3.8 V to 2.7 V through utilizing a bipolar host. Furthermore, applying the proposed techniques to tandem white PhOLEDs produces a luminance of 10 3 cd/m 2 by a 10.1 V driving voltage. - Highlights: • The matched energy level between the hole transport/emitting layer lowers voltages. • Multiple conduction dopants were used to investigate charge generation layer. • Two-color emitters were used to quantify the charge generation strength

  18. Fabrication of white light-emitting diodes based on UV light-emitting diodes with conjugated polymers-(CdSe/ZnS) quantum dots as hybrid phosphors.

    Science.gov (United States)

    Jung, Hyunchul; Chung, Wonkeun; Lee, Chang Hun; Kim, Sung Hyun

    2012-07-01

    White light-emitting diodes (LEDs) were fabricated using GaN-based 380-nm UV LEDs precoated with the composite of blue-emitting polymer (poly[(9,9-dihexylfluorenyl-2,7-diyl)-alt-co-(2-methoxy-5-{2-ethylhexyloxy)-1 ,4-phenylene)]), yellow green-emitting polymer (poly[(9,9-dioctylfluorenyl-2,7-diyl)-co-(1,4-benzo-{2,1',3}-thiadiazole)]), and 605-nm red-emitting quantum dots (QDs). CdSe cores were obtained by solvothermal route using CdO, Se precursors and ZnS shells were synthesized by using diethylzinc, and hexamethyldisilathiane precursors. The optical properties of CdSe/ZnS QDs were characterized by UV-visible and photoluminescence (PL) spectra. The structural data and composition of the QDs were transmission electron microscopy (TEM), and EDX technique. The quantum yield and size of the QDs were 58.7% and about 6.7 nm, respectively. Three-band white light was generated by hybridizing blue (430 nm), green (535 nm), and red (605 nm) emission. The color-rendering index (CRI) of the device was extremely improved by introducing the QDs. The CIE-1931 chromaticity coordinate, color temperature, and CRI of a white LED at 20 mA were (0.379, 0.368), 3969 K, and 90, respectively.

  19. Highly efficient phosphor-converted white organic light-emitting diodes with moderate microcavity and light-recycling filters.

    Science.gov (United States)

    Cho, Sang-Hwan; Oh, Jeong Rok; Park, Hoo Keun; Kim, Hyoung Kun; Lee, Yong-Hee; Lee, Jae-Gab; Do, Young Rag

    2010-01-18

    We demonstrate the combined effects of a microcavity structure and light-recycling filters (LRFs) on the forward electrical efficiency of phosphor-converted white organic light-emitting diodes (pc-WOLEDs). The introduction of a single pair of low- and high-index layers (SiO(2)/TiO(2)) improves the blue emission from blue OLED and the insertion of blue-passing and yellow-reflecting LRFs enhances the forward yellow emission from the YAG:Ce(3+) phosphors layers. The enhancement of the luminous efficacy of the forward white emission is 1.92 times that of a conventional pc-WOLED with color coordinates of (0.34, 0.34) and a correlated color temperature of about 4800 K.

  20. White Polymer Light-Emitting Diodes Based on Exciplex Electroluminescence from Polymer Blends and a Single Polymer.

    Science.gov (United States)

    Liang, Junfei; Zhao, Sen; Jiang, Xiao-Fang; Guo, Ting; Yip, Hin-Lap; Ying, Lei; Huang, Fei; Yang, Wei; Cao, Yong

    2016-03-09

    In this Article, we designed and synthesized a series of polyfluorene derivatives, which consist of the electron-rich 4,4'-(9-alkyl-carbazole-3,6-diyl)bis(N,N-diphenylaniline) (TPA-Cz) in the side chain and the electron-deficient dibenzothiophene-5,5-dioxide (SO) unit in the main chain. The resulting copolymer PF-T25 that did not comprise the SO unit exhibited blue light-emission with the Commission Internationale de L'Eclairage coordinates of (0.16, 0.10). However, by physically blending PF-T25 with a blue light-emitting SO-based oligomer, a novel low-energy emission correlated to exciplex emerged due to the appropriate energy level alignment of TPA-Cz and the SO-based oligomers, which showed extended exciton lifetime as confirmed by time-resolved photoluminescent spectroscopy. The low-energy emission was also identified in copolymers consisting of SO unit in the main chain, which can effectively compensate for the high-energy emission to produce binary white light-emission. Polymer light-emitting diodes based on the exciplex-type single greenish-white polymer exhibit the peak luminous efficiency of 2.34 cd A(-1) and the maximum brightness of 12 410 cd m(-2), with Commission Internationale de L'Eclairage color coordinates (0.27, 0.39). The device based on such polymer showed much better electroluminescent stability than those based on blending films. These observations indicated that developing a single polymer with the generated exciplex emission can be a novel and effective molecular design strategy toward highly stable and efficient white polymer light-emitting diodes.

  1. Hybrid Structure White Organic Light Emitting Diode for Enhanced Efficiency by Varied Doping Rate.

    Science.gov (United States)

    Kim, Dong-Eun; Kang, Min-Jae; Park, Gwang-Ryeol; Kim, Nam-Kyu; Lee, Burm-Jong; Kwon, Young-Soo; Shin, Hoon-Kyu

    2016-03-01

    Novel materials based on Zn(HPB)2 and Ir-complexes were synthesized as blue or red emitters, respectively. White organic light emitting diodes were fabricated using the Zn(HPB)2 as a blue emitting layer, Ir-complexes as a red emitting layer and Alq3 as a green emitting layer. The obtained experimental results, were based on white OLEDs fabricated using double emission layers of Zn(HPB)2 and Alq3:Ir-complexes. The doping rate of the Ir-complexes was varied at 0.4%, 0.6%, 0.8% and 1.0%. When the doping rate of the Alq3:Ir-complexes was 0.6%, a white emission was achieved. The Commission Internationale de l'Eclairage coordinates of the device's white emission were (0.316, 0.331) at an applied voltage of 10.75 V.

  2. Ultrathin nondoped emissive layers for efficient and simple monochrome and white organic light-emitting diodes.

    Science.gov (United States)

    Zhao, Yongbiao; Chen, Jiangshan; Ma, Dongge

    2013-02-01

    In this paper, highly efficient and simple monochrome blue, green, orange, and red organic light emitting diodes (OLEDs) based on ultrathin nondoped emissive layers (EMLs) have been reported. The ultrathin nondoped EML was constructed by introducing a 0.1 nm thin layer of pure phosphorescent dyes between a hole transporting layer and an electron transporting layer. The maximum external quantum efficiencies (EQEs) reached 17.1%, 20.9%, 17.3%, and 19.2% for blue, green, orange, and red monochrome OLEDs, respectively, indicating the universality of the ultrathin nondoped EML for most phosphorescent dyes. On the basis of this, simple white OLED structures are also demonstrated. The demonstrated complementary blue/orange, three primary blue/green/red, and four color blue/green/orange/red white OLEDs show high efficiency and good white emission, indicating the advantage of ultrathin nondoped EMLs on constructing simple and efficient white OLEDs.

  3. Study on constant-step stress accelerated life tests in white organic light-emitting diodes.

    Science.gov (United States)

    Zhang, J P; Liu, C; Chen, X; Cheng, G L; Zhou, A X

    2014-11-01

    In order to obtain reliability information for a white organic light-emitting diode (OLED), two constant and one step stress tests were conducted with its working current increased. The Weibull function was applied to describe the OLED life distribution, and the maximum likelihood estimation (MLE) and its iterative flow chart were used to calculate shape and scale parameters. Furthermore, the accelerated life equation was determined using the least squares method, a Kolmogorov-Smirnov test was performed to assess if the white OLED life follows a Weibull distribution, and self-developed software was used to predict the average and the median lifetimes of the OLED. The numerical results indicate that white OLED life conforms to a Weibull distribution, and that the accelerated life equation completely satisfies the inverse power law. The estimated life of a white OLED may provide significant guidelines for its manufacturers and customers. Copyright © 2014 John Wiley & Sons, Ltd.

  4. Students' Conceptions on White Light and Implications for Teaching and Learning about Colour

    Science.gov (United States)

    Haagen-Schützenhöfer, Claudia

    2017-01-01

    The quality of learning processes is mainly determined by the extent to which students' conceptions are addressed and thus conceptual change is triggered. Colour phenomena are a topic within initial instruction of optics which is challenging. A physically adequate concept of white light is crucial for being able to grasp the processes underlying…

  5. White light emission from Er2O3 nano-powder excited by infrared radiation

    Science.gov (United States)

    Tabanli, Sevcan; Eryurek, Gonul; Di Bartolo, Baldassare

    2017-07-01

    Phosphors of Er2O3 nano-crystalline powders were synthesized by the thermal decomposition method. The structural properties of the nano-powders were investigated with XRD and HRTEM measurements. The cubic phase with a = 10.540 Å was the only phase observed. The average crystalline sizes and the widths of the grain size distribution curves were determined to be 27.2, 18.7 and 9.7 nm, respectively. The spectroscopic properties of the Er2O3 nano-powder were studied by measuring the luminescence, decay and rise patterns under 808 and 975 nm diode laser excitations. A peculiar effect of the pressure was observed since an optically active ion (Er) is part of the complex and not a dopant. A broad band of the white light emission combined with blue, green and red up-conversion emission bands of Er3+ ions were observed at 0.03 mbar pressure under both excitation wavelengths. Only, an intense broad band white light emission was observed from these nanocrystals at atmospheric pressure. Rising patterns show that the white light intensity reaches its maximum value more rapidly under 975 nm excitation although it decays slower than that of 808 nm excitation. The color quality parameters such as the color coordinate (CRI), correlated color temperature and the color rendering index were found to vary with both the excitation wavelength and the ambient pressure indicating that these nanocrystals could be considered good white light emitting source under the infrared excitations.

  6. Measurement of the influence of dispersion on white-light interferometry

    Czech Academy of Sciences Publication Activity Database

    Pavlíček, Pavel; Soubusta, Jan

    2004-01-01

    Roč. 43, č. 4 (2004), s. 766-770 ISSN 0003-6935 R&D Projects: GA MŠk LN00A015 Institutional research plan: CEZ:AV0Z1010921 Keywords : white-light interferometry * height profile * smooth surface Subject RIV: BH - Optics, Masers, Lasers Impact factor: 1.799, year: 2004

  7. Four-Parameter white blood cell differential counting based on light scattering measurements

    NARCIS (Netherlands)

    Terstappen, Leonardus Wendelinus Mathias Marie; de Grooth, B.G.; Visscher, K.; Kouterik, F.A.; Greve, Jan

    1988-01-01

    Measurement of the depolarized orthogonal light scattering in flow cytometry enables one to discriminate human eosinephilic granulocytes from neutrophilic granulocytes. We use this method to perform a four-parameter differential white blood cell analysis. A simple flow cytometer was built equipped

  8. High-efficient and brightness white organic light-emitting diodes operated at low bias voltage

    Science.gov (United States)

    Zhang, Lei; Yu, Junsheng; Yuan, Kai; Jian, Yadong

    2010-10-01

    White organic light-emitting diodes (OLEDs) used for display application and lighting need to possess high efficiency, high brightness, and low driving voltage. In this work, white OLEDs consisted of ambipolar 9,10-bis 2-naphthyl anthracene (ADN) as a host of blue light-emitting layer (EML) doped with tetrabutyleperlene (TBPe) and a thin codoped layer consisted of N, N'-bis(naphthalen-1-yl)-N,N'-bis(phenyl)-benzidine (NPB) as a host of yellow light-emitting layer doped with 4-(dicyanomethylene)-2-tert-butyl-6-(1,1,7,7-tetramethyljulolidin-4-yl-vinyl)-4H-pyran (DCJTB) were investigated. With appropriate tuning in the film thickness, position, and dopant concentration of the co-doped layer, a white OLED with a luminance yield of 10.02 cd/A with the CIE coordinates of (0.29, 0.33) has been achieved at a bias voltage of 9 V and a luminance level of over 10,000 cd/m2. By introducing the PIN structure with both HIL and bis(10- hydroxybenzo-quinolinato)-beryllium (BeBq2) ETL, the power efficiency of white OLED was improved.

  9. Prophylactic treatment of seasonal affective disorder (SAD) by using light visors : Bright white or infrared light?

    NARCIS (Netherlands)

    Meesters, Y; Beersma, DGM; Bouhuys, AL; van den Hoofdakker, RH

    1999-01-01

    Background: Thirty-eight patients with SAD participated in a light visor study addressing two questions. 1. Can the development of a depressive episode be prevent ed by daily exposure to bright light started before symptom onset in early fall and continued throughout the winter? 2. Does the light

  10. How to distinguish scattered and absorbed light from re-emitted light for white LEDs?

    NARCIS (Netherlands)

    Meretska, Maryna; Lagendijk, Aart; Thyrrestrup Nielsen, Henri; Mosk, Allard; IJzerman, Wilbert; Vos, Willem L.

    2017-01-01

    We have studied the light transport through phosphor diffuser plates that are used in commercial solid-state lighting modules (Fortimo). These polymer plates contain YAG:Ce+3 phosphor particles that scatter, absorb and re-emit incident light in the visible wavelength range (400-700 nm). To

  11. White light emission from fluorescent SiC with porous surface

    DEFF Research Database (Denmark)

    Lu, Weifang; Ou, Yiyu; Fiordaliso, Elisabetta Maria

    2017-01-01

    We report for the frst time a NUV light to white light conversion in a N-B co-doped 6H-SiC (fuorescent SiC) layer containing a hybrid structure. The surface of fuorescent SiC sample contains porous structures fabricated by anodic oxidation method. After passivation by 20nm thick Al2O3, the photol......We report for the frst time a NUV light to white light conversion in a N-B co-doped 6H-SiC (fuorescent SiC) layer containing a hybrid structure. The surface of fuorescent SiC sample contains porous structures fabricated by anodic oxidation method. After passivation by 20nm thick Al2O3...... the bulk fuorescent SiC layer. A high color rendering index of 81.1 has been achieved. Photoluminescence spectra in porous layers fabricated in both commercial n-type and lab grown N-B co-doped 6H-SiC show two emission peaks centered approximately at 460nm and 530nm. Such bluegreen emission phenomenon can......, the photoluminescence intensity from the porous layer was signifcant enhanced by a factor of more than 12. Using a porous layer of moderate thickness (~10µm), high-quality white light emission was realized by combining the independent emissions of blue-green emission from the porous layer and yellow emission from...

  12. High luminous flux from single crystal phosphor-converted laser-based white lighting system

    KAUST Repository

    Cantore, Michael

    2015-12-14

    The efficiency droop of light emitting diodes (LEDs) with increasing current density limits the amount of light emitted per wafer area. Since low current densities are required for high efficiency operation, many LED die are needed for high power white light illumination systems. In contrast, the carrier density of laser diodes (LDs) clamps at threshold, so the efficiency of LDs does not droop above threshold and high efficiencies can be achieved at very high current densities. The use of a high power blue GaN-based LD coupled with a single crystal Ce-doped yttrium aluminum garnet (YAG:Ce) sample was investigated for white light illumination applications. Under CW operation, a single phosphor-converted LD (pc-LD) die produced a peak luminous efficacy of 86.7 lm/W at 1.4 A and 4.24 V and a peak luminous flux of 1100 lm at 3.0 A and 4.85 V with a luminous efficacy of 75.6 lm/W. Simulations of a pc-LD confirm that the single crystal YAG:Ce sample did not experience thermal quenching at peak LD operating efficiency. These results show that a single pc-LD die is capable of emitting enough luminous flux for use in a high power white light illumination system.

  13. Preliminary measurement performance evaluation of a new white light interferometer for cylindrical surfaces

    International Nuclear Information System (INIS)

    Albertazzi, Armando Jr; Pont, Alex Dal

    2005-01-01

    This paper introduces a new design of a white light interferometer, suitable for measurement of cylindrical or quasi-cylindrical parts. A high precision 45 deg. conical mirror is used to direct collimated light radially, making it possible to measure in true cylindrical coordinates. The image of the measurand, distorted by the conical mirror, is projected in a high resolution digital camera. A mapping algorithm is used to reconstruct the cylindrical geometry from the distorted image. The rest of the interferometer is quite similar to a conventional white light interferometer: A flat reference mirror is scanned through the measurement range while an algorithm is searching for the maximum contrast position of the interference pattern. The performance evaluation of a configuration suitable for measurement of external cylindrical surfaces is also presented in this paper. A master cylinder was used as reference. Uncertainties of about 1.0 μm were found at the present stage of development

  14. Device Engineering and Degradation Mechanism Study of All-Phosphorescent White Organic Light-Emitting Diodes

    Science.gov (United States)

    Xu, Lisong

    As a possible next-generation solid-state lighting source, white organic light-emitting diodes (WOLEDs) have the advantages in high power efficiency, large area and flat panel form factor applications. Phosphorescent emitters and multiple emitting layer structures are typically used in high efficiency WOLEDs. However due to the complexity of the device structure comprising a stack of multiple layers of organic thin films, ten or more organic materials are usually required, and each of the layers in the stack has to be optimized to produce the desired electrical and optical functions such that collectively a WOLED of the highest possible efficiency can be achieved. Moreover, device degradation mechanisms are still unclear for most OLED systems, especially blue phosphorescent OLEDs. Such challenges require a deep understanding of the device operating principles and materials/device degradation mechanisms. This thesis will focus on achieving high-efficiency and color-stable all-phosphorescent WOLEDs through optimization of the device structures and material compositions. The operating principles and the degradation mechanisms specific to all-phosphorescent WOLED will be studied. First, we investigated a WOLED where a blue emitter was based on a doped mix-host system with the archetypal bis(4,6-difluorophenyl-pyridinato-N,C2) picolinate iridium(III), FIrpic, as the blue dopant. In forming the WOLED, the red and green components were incorporated in a single layer adjacent to the blue layer. The WOLED efficiency and color were optimized through variations of the mixed-host compositions to control the electron-hole recombination zone and the dopant concentrations of the green-red layers to achieve a balanced white emission. Second, a WOLED structure with two separate blue layers and an ultra-thin red and green co-doped layer was studied. Through a systematic investigation of the placement of the co-doped red and green layer between the blue layers and the material

  15. White light emission from exciplex using tris-(8-hydroxyquinoline)aluminum as chromaticity-tuning layer

    International Nuclear Information System (INIS)

    Feng, Jing; Li, Feng; Gao, Wenbao; Liu, Shiyong; Liu, Yu; Wang, Yue

    2001-01-01

    We demonstrate efficient organic white light-emitting devices (LEDs), using N,N prime-diphenyl-N,N prime-bis(1-naphthyl) - (1,1 prime-biphenyl)-4,4 prime-diamine (NPB) as the hole-transporting layer, 1,6-bis(2-hydroxyphenyl)pyridine boron complex [(dppy)BF] as the emitting layer, tris-(8-hydroxyquinoline)aluminum (Alq) as the electron-transporting and chromaticity-tuning layer. The white light comes from exciplex emission at the solid-state interface between (dppy)BF and NPB in addition to the exciton emission from NPB and (dppy)BF, respectively. The chromaticity of white emission can be tuned by adjusting the thickness of the Alq layer. The white LEDs with an Alq thickness of 15 nm exhibit a maximum luminescence of 2000 cd/m2 and efficiency of 0.58 lm/W, and the Commission Internationale De l'Eclairage coordinates of resulting emission vary from (0.29,0.33) to (0.31,0.35) with increasing forward bias from 10 to 25 V. The region is very close to the equienergy white point (0.33,0.33). [copyright] 2001 American Institute of Physics

  16. Simple single-emitting layer hybrid white organic light emitting with high color stability

    Science.gov (United States)

    Nguyen, C.; Lu, Z. H.

    2017-10-01

    Simultaneously achieving a high efficiency and color quality at luminance levels required for solid-state lighting has been difficult for white organic light emitting diodes (OLEDs). Single-emitting layer (SEL) white OLEDs, in particular, exhibit a significant tradeoff between efficiency and color stability. Furthermore, despite the simplicity of SEL white OLEDs being its main advantage, the reported device structures are often complicated by the use of multiple blocking layers. In this paper, we report a highly simplified three-layered white OLED that achieves a low turn-on voltage of 2.7 V, an external quantum efficiency of 18.9% and power efficiency of 30 lm/W at 1000 cd/cm2. This simple white OLED also shows good color quality with a color rendering index of 75, CIE coordinates (0.42, 0.46), and little color shifting at high luminance. The device consists of a SEL sandwiched between a hole transport layer and an electron transport layer. The SEL comprises a thermally activated delayer fluorescent molecule having dual functions as a blue emitter and as a host for other lower energy emitters. The improved color stability and efficiency in such a simple device structure is explained as due to the elimination of significant energy barriers at various organic-organic interfaces in the traditional devices having multiple blocking layers.

  17. The 4th Generation Light Source at Jefferson Lab

    International Nuclear Information System (INIS)

    Stephen Benson; George Biallas; James Boyce; Donald Bullard; James Coleman; David Douglas; H. Dylla; Richard Evans; Pavel Evtushenko; Albert Grippo; Christopher Gould; Joseph Gubeli; David Hardy; Carlos Hernandez-Garcia; Kevin Jordan; John Klopf; Steven Moore; George Neil; Thomas Powers; Joseph Preble; Daniel Sexton; Michelle Shinn; Christopher Tennant; Richard Walker; Shukui Zhang; Gwyn Williams

    2007-01-01

    A number of 'Grand Challenges' in Science have recently been identified in reports from The National Academy of Sciences, and the U.S. Dept. of Energy, Basic Energy Sciences. Many of these require a new generation of linac-based light source to study dynamical and non-linear phenomena in nanoscale samples. In this paper we present a summary of the properties of such light sources, comparing them with existing sources, and then describing in more detail a specific source at Jefferson Lab. Importantly, the JLab light source has developed some novel technology which is a critical enabler for other new light sources

  18. White organic light-emitting diodes with 9, 10-bis (2-naphthyl) anthracene

    Energy Technology Data Exchange (ETDEWEB)

    Guan Yunxia; Niu Lianbin [Key Laboratory of Optical Engineering, College of Physics and Information Technology, Chongqing Normal University, Chongqing 400047 (China)], E-mail: gyxybsy@126.com, E-mail: niulb03@126.com

    2009-03-01

    White organic light-emitting diodes were fabricated by 9, 10-bis (2-naphthyl) anthracene (ADN) doped with Rubrene with a structure of ITO/copper phthalocyanine (CuPc) / NPB /ADN: Rubrene /Alq{sub 3} /CsF/Mg:Ag/Ag. Multilayer organic devices using AND and Rubrene as an emitting layer produced white emissions with good chromaticity and luminous efficiency as high as 5.93 cd/A. This performance can be explained by Foerster energy transfer from the blue-emitting host to the orange-emitting dopant.

  19. White organic light-emitting diodes with 9, 10-bis (2-naphthyl) anthracene

    International Nuclear Information System (INIS)

    Guan Yunxia; Niu Lianbin

    2009-01-01

    White organic light-emitting diodes were fabricated by 9, 10-bis (2-naphthyl) anthracene (ADN) doped with Rubrene with a structure of ITO/copper phthalocyanine (CuPc) / NPB /ADN: Rubrene /Alq 3 /CsF/Mg:Ag/Ag. Multilayer organic devices using AND and Rubrene as an emitting layer produced white emissions with good chromaticity and luminous efficiency as high as 5.93 cd/A. This performance can be explained by Foerster energy transfer from the blue-emitting host to the orange-emitting dopant.

  20. Multiregion, multigroup collision probability method with white boundary condition for light water reactor thermalization calculations

    International Nuclear Information System (INIS)

    Ozgener, B.; Ozgener, H.A.

    2005-01-01

    A multiregion, multigroup collision probability method with white boundary condition is developed for thermalization calculations of light water moderated reactors. Hydrogen scatterings are treated by Nelkin's kernel while scatterings from other nuclei are assumed to obey the free-gas scattering kernel. The isotropic return (white) boundary condition is applied directly by using the appropriate collision probabilities. Comparisons with alternate numerical methods show the validity of the present formulation. Comparisons with some experimental results indicate that the present formulation is capable of calculating disadvantage factors which are closer to the experimental results than alternative methods

  1. White organic light-emitting devices incorporating nanoparticles of II-VI semiconductors

    International Nuclear Information System (INIS)

    Ahn, Jin H; Bertoni, Cristina; Dunn, Steve; Wang, Changsheng; Talapin, Dmitri V; Gaponik, Nikolai; Eychmueller, Alexander; Hua Yulin; Bryce, Martin R; Petty, Michael C

    2007-01-01

    A blue-green fluorescent organic dye and red-emitting nanoparticles, based on II-VI semiconductors, have been used together in the fabrication of white organic light-emitting devices. In this work, the materials were combined in two different ways: in the form of a blend, and as separate layers deposited on the opposite sides of the substrate. The blended-layer structure provided purer white emission. However, this device also exhibited a number of disadvantages, namely a high drive voltage, a low efficiency and some colour instability. These problems could be avoided by using a device structure that was fabricated using separate dye and nanoparticle layers

  2. White-light emission from porous-silicon-aluminium Schottky junctions

    International Nuclear Information System (INIS)

    Masini, G.; La Monica, S.; Maiello, G.

    1996-01-01

    Porous-silicon-based white-light-emitting devices are presented. The fabrication process on different substrates is described. The peculiarities of technological steps for device fabrication (porous-silicon formation and aluminium treatment) are underlined. Doping profile of the porous layer, current-voltage characteristics, time response, lifetime tests and electroluminescence emission spectrum of the device are presented. A model for electrical behaviour of Al/porous silicon Schottky junction is presented. Electroluminescence spectrum of the presented devices showed strong similarities with white emission from crystalline silicon junctions in the breakdown region

  3. Laser light absorption and harmonic generation due to self-generated magnetic fields

    International Nuclear Information System (INIS)

    Kruer, W.L.; Estabrook, K.G.

    1977-01-01

    It is shown that self-generated magnetic fields can play a significant role in laser light absorption. Even normally incident light will then be resonantly absorbed. Computer simulations and theoretical estimates for this absorption and the concomitant harmonic generation are given for parameters characteristic of some recent experiments

  4. Highly efficient tandem organic light-emitting devices employing an easily fabricated charge generation unit

    Science.gov (United States)

    Yang, Huishan; Yu, Yaoyao; Wu, Lishuang; Qu, Biao; Lin, Wenyan; Yu, Ye; Wu, Zhijun; Xie, Wenfa

    2018-02-01

    We have realized highly efficient tandem organic light-emitting devices (OLEDs) employing an easily fabricated charge generation unit (CGU) combining 1,4,5,8,9,11-hexaazatriphenylene-hexacarbonitrile with ultrathin bilayers of CsN3 and Al. The charge generation and separation processes of the CGU have been demonstrated by studying the differences in the current density-voltage characteristics of external-carrier-excluding devices. At high luminances of 1000 and 10000 cd/m2, the current efficiencies of the phosphorescent tandem device are about 2.2- and 2.3-fold those of the corresponding single-unit device, respectively. Simultaneously, an efficient tandem white OLED exhibiting high color stability and warm white emission has also been fabricated.

  5. Invariable optical properties of phosphor-free white light-emitting diode under electrical stress

    International Nuclear Information System (INIS)

    Hao, Long; Hao, Fang; Sheng-Li, Qi; Li-Wen, Sang; Wen-Yu, Cao; Jian, Yan; Jun-Jing, Deng; Zhi-Jian, Yang; Guo-Yi, Zhang

    2010-01-01

    This paper reports that a dual-wavelength white light-emitting diode is fabricated by using a metal-organic chemical vapor deposition method. Through a 200-hours' current stress, the reverse leakage current of this light-emitting diode increases with the aging time, but the optical properties remained unchanged despite the enhanced reverse leakage current. Transmission electron microscopy and cathodeluminescence images show that indium atoms were assembled in and around V-shape pits with various compositions, which can be ascribed to the emitted white light. Evolution of cathodeluminescence intensities under electron irradiation is also performed. Combining cathodeluminescence intensities under electron irradiation and above results, the increase of leakage channels and crystalline quality degradation are realized. Although leakage channels increase with aging, potential fluctuation caused by indium aggregation can effectively avoid the impact of leakage channels. Indium aggregation can be attributed to the mechanism of preventing optical degradation in phosphor-free white light-emitting diode. (condensed matter: electronic structure, electrical, magnetic, and optical properties)

  6. Structure and Ultrafast Dynamics of White-Light-Emitting CdSe Nanocrystals

    International Nuclear Information System (INIS)

    Bowers, Michael J.; McBride, James; Garrett, Maria Danielle; Sammons, Jessica A.; Dukes, Albert; Schreuder, Michael A.; Watt, Tony L.; Lupini, Andrew R.; Pennycook, Stephen J.; Rosenthal, Sandra

    2009-01-01

    White-light emission from ultrasmall CdSe nanocrystals offers an alternative approach to the realization of solid-state lighting as an appealing technology for consumers. Unfortunately, their extremely small size limits the feasibility of traditional methods for nanocrystal characterization. This paper reports the first images of their structure, which were obtained using aberration-corrected atomic number contrast scanning transmission electron microscopy (Z-STEM). With subangstrom resolution, Z-STEM is one of the few available methods that can be used to directly image the nanocrystal's structure. The initial images suggest that they are crystalline and approximately four lattice planes in diameter. In addition to the structure, for the first time, the exciton dynamics were measured at different wavelengths of the white-light spectrum using ultrafast fluorescence upconversion spectroscopy. The data suggest that a myriad of trap states are responsible for the broad-spectrum emission. It is hoped that the information presented here will provide a foundation for the future development and improvement of white-light-emitting nanocrystals.

  7. White organic light-emitting diodes based on electroplex from polyvinyl carbazole and carbazole oligomers blends

    International Nuclear Information System (INIS)

    Fei-Peng, Chen; Bin, Xu; Wen-Jing, Tian; Zu-Jin, Zhao; Ping, Lü; Chan, Im

    2010-01-01

    White organic light-emitting diodes with a blue emitting material fluorene-centred ethylene-liked carbazole oligomer (Cz6F) doped into polyvinyl carbazole (PVK) as the single light-emitting layer are reported. The optical properties of Cz6F, PVK, and PVK:Cz6F blends are studied. Single and double layer devices are fabricated by using PVK: Cz6F blends, and the device with the configuration of indium tin oxide (ITO)/PVK:Cz6F/tris(8-hydroxyquinolinate)aluminium (Alq 3 )/LiF/A1 exhibits white light emission with Commission Internationale de l'Éclairage chromaticity coordinates of (0.30, 0.33) and a brightness of 402 cd/m 2 . The investigation reveals that the white light is composed of a blue–green emission originating from the excimer of Cz6F molecules and a red emission from an electroplex from the PVK:Cz6F blend films

  8. White organic light-emitting diodes based on electroplex from polyvinyl carbazole and carbazole oligomers blends

    Science.gov (United States)

    Chen, Fei-Peng; Xu, Bin; Zhao, Zu-Jin; Tian, Wen-Jing; Lü, Ping; Im, Chan

    2010-03-01

    White organic light-emitting diodes with a blue emitting material fluorene-centred ethylene-liked carbazole oligomer (Cz6F) doped into polyvinyl carbazole (PVK) as the single light-emitting layer are reported. The optical properties of Cz6F, PVK, and PVK:Cz6F blends are studied. Single and double layer devices are fabricated by using PVK: Cz6F blends, and the device with the configuration of indium tin oxide (ITO)/PVK:Cz6F/tris(8-hydroxyquinolinate)aluminium (Alq3)/LiF/A1 exhibits white light emission with Commission Internationale de l'Éclairage chromaticity coordinates of (0.30, 0.33) and a brightness of 402 cd/m2. The investigation reveals that the white light is composed of a blue-green emission originating from the excimer of Cz6F molecules and a red emission from an electroplex from the PVK:Cz6F blend films.

  9. Adjusting White OLEDs with Yellow Light Emission Phosphor Dye and Ultrathin NPB Layer Structure

    Directory of Open Access Journals (Sweden)

    Jun Wang

    2013-01-01

    Full Text Available High efficiency white organic light emission devices were demonstrated with phosphor material dye bis[2-(4-tertbutylphenylbenzothiazolato-N,C2′]iridium (acetylacetonate and ultrathin layer structure. The ultra thin layer be composed of 4,4′-bis[N-1-naphthyl-N-phenyl-amino]biphenyl (NPB or 4,4′-N,N′-dicarbazole-biphenyl : NPB mixed layer with blue light emission. The emission spectra of devices could be adjusted by different phosphor doping concentrations and ultra thin layer structure. Warm white light emitting device could be obtained with 5 wt% doping concentration and power efficiency of 9.93 lm/W at 5 V. Pure white light with Commission Internationale de l'Eclairage (CIE coordinates of (0.33, 0.30 and external quantum efficiency of 4.49% could be achieved with ultra thin layer device structure and 3 wt% phosphor doped device.

  10. Fabrication of White Light-emitting Electrochemical Cells with Stable Emission from Exciplexes.

    Science.gov (United States)

    Uchida, Soichi; Takizawa, Daisuke; Ikeda, Satoru; Takeuchi, Hironori; Nishimura, Suzushi; Nishide, Hiroyuki; Nishikitani, Yoshinori

    2016-11-15

    The authors present an approach for fabricating stable white light emission from polymer light-emitting electrochemical cells (PLECs) having an active layer which consists of blue-fluorescent poly(9,9-di-n-dodecylfluorenyl-2,7-diyl) (PFD) and π-conjugated triphenylamine molecules. This white light emission originates from exciplexes formed between PFD and amines in electronically excited states. A device containing PFD, 4,4',4''-tris[2-naphthyl(phenyl)amino]triphenylamine (2-TNATA), Poly(ethylene oxide) and K2CF3SO3 showed white light emission with Commission internationale de l'éclairage (CIE) coordinates of (0.33, 0.43) and a Color Rendering Index (CRI) of Ra = 73 at an applied voltage of 3.5 V. Constant voltage measurements showed that the CIE coordinates of (0.27, 0.37), Ra of 67, and the emission color observed immediately after application of a voltage of 5 V were nearly unchanged and stable after 300 sec.

  11. White-Light Emission and Structural Distortion in New Corrugated Two-Dimensional Lead Bromide Perovskites.

    Science.gov (United States)

    Mao, Lingling; Wu, Yilei; Stoumpos, Constantinos C; Wasielewski, Michael R; Kanatzidis, Mercouri G

    2017-03-29

    Hybrid inorganic-organic perovskites are developing rapidly as high performance semiconductors. Recently, two-dimensional (2D) perovskites were found to have white-light, broadband emission in the visible range that was attributed mainly to the role of self-trapped excitons (STEs). Here, we describe three new 2D lead bromide perovskites incorporating a series of bifunctional ammonium dications as templates which also emit white light: (1) α-(DMEN)PbBr 4 (DMEN = 2-(dimethylamino)ethylamine), which adopts a unique corrugated layered structure in space group Pbca with unit cell a = 18.901(4) Å, b = 11.782(2) Å, and c = 23.680(5) Å; (2) (DMAPA)PbBr 4 (DMAPA = 3-(dimethylamino)-1-propylamine), which crystallizes in P2 1 /c with a = 10.717(2) Å, b = 11.735(2) Å, c = 12.127(2) Å, and β = 111.53(3)°; and (3) (DMABA)PbBr 4 (DMABA = 4-dimethylaminobutylamine), which adopts Aba2 with a = 41.685(8) Å, b = 23.962(5) Å, and c = 12.000(2) Å. Photoluminescence (PL) studies show a correlation between the distortion of the "PbBr 6 " octahedron in the 2D layer and the broadening of PL emission, with the most distorted structure having the broadest emission (183 nm full width at half-maximum) and longest lifetime (τ avg = 1.39 ns). The most distorted member α-(DMEN)PbBr 4 exhibits white-light emission with a color rendering index (CRI) of 73 which is similar to a fluorescent light source and correlated color temperature (CCT) of 7863 K, producing "cold" white light.

  12. White organic light emitting diodes based on fluorene-carbazole dendrimers

    International Nuclear Information System (INIS)

    Usluer, Özlem; Demic, Serafettin; Kus, Mahmut; Özel, Faruk; Serdar Sariciftci, Niyazi

    2014-01-01

    In this paper, we report on theProd. Type: FTP fabrication and characterization of blue and white light emitting devices based on two fluorene-carbazole containing dendrimers and para-sexiphenyl (6P) oligomers. Blue light emitting diodes were fabricated using 9′,9″-(9,9-dioctyl-9H-fluorene-2,7-diyl)bis-9′H-9,3′:6′,9″-tercarbazole (OFC-G2) and 9′,9″-(9,9′-spirobi[fluorene]-2,7-diyl)bis-9′H-9,3′:6′,9″-tercarbazole (SBFC-G2) dendrimers as a hole transport and emissive layer (EML) and 2,9-dimethyl-4,7-diphenyl-1,10-phenanthroline (BCP) as an electron transport layer. White light emitting diodes were fabricated using 6P and these two dendrimers as an EML. OLED device with the structure of ITO/PEDOT:PSS (50 nm)/OFC-G2 (40 nm)/6P (20 nm)/LiF:Al (0.5:100 nm) shows maximum luminance of nearly 1400 cd/m 2 and a Commission Internationale de l'Eclairage chromaticity coordinates of (0.27, 0.30) at 12 V. -- Highlights: • White organic light emitting diodes have been fabricated using two fluorene-carbazole dendrimers and para-sexiphenyl (6P) oligomers. • When only these two dendrimers are used as EML, OLED devices are emitted blue light. • The emission colors of OLED devices change from blue to white when 6P is coated on dendrimer films

  13. White organic light emitting diodes based on fluorene-carbazole dendrimers

    Energy Technology Data Exchange (ETDEWEB)

    Usluer, Özlem, E-mail: usluerozlem@yahoo.com.tr [Department of Chemistry, Muğla Sıtkı Koçman University, 48000 Muğla (Turkey); Demic, Serafettin [Department of Materials Science and Engineering, Izmir Katip Çelebi University, 35620 Çiğli, Izmir (Turkey); Kus, Mahmut, E-mail: mahmutkus1@gmail.com [Chemical Engineering Department and Advanced Technology R and D Center, Selçuk University, Konya (Turkey); Özel, Faruk [Chemical Engineering Department and Advanced Technology R and D Center, Selçuk University, Konya (Turkey); Serdar Sariciftci, Niyazi [Linz Institute for Organic Solar Cells (LIOS), Physical Chemistry, Johannes Kepler University, Altenbergerstr. 69, A-4040 Linz (Austria)

    2014-02-15

    In this paper, we report on theProd. Type: FTP fabrication and characterization of blue and white light emitting devices based on two fluorene-carbazole containing dendrimers and para-sexiphenyl (6P) oligomers. Blue light emitting diodes were fabricated using 9′,9″-(9,9-dioctyl-9H-fluorene-2,7-diyl)bis-9′H-9,3′:6′,9″-tercarbazole (OFC-G2) and 9′,9″-(9,9′-spirobi[fluorene]-2,7-diyl)bis-9′H-9,3′:6′,9″-tercarbazole (SBFC-G2) dendrimers as a hole transport and emissive layer (EML) and 2,9-dimethyl-4,7-diphenyl-1,10-phenanthroline (BCP) as an electron transport layer. White light emitting diodes were fabricated using 6P and these two dendrimers as an EML. OLED device with the structure of ITO/PEDOT:PSS (50 nm)/OFC-G2 (40 nm)/6P (20 nm)/LiF:Al (0.5:100 nm) shows maximum luminance of nearly 1400 cd/m{sup 2} and a Commission Internationale de l'Eclairage chromaticity coordinates of (0.27, 0.30) at 12 V. -- Highlights: • White organic light emitting diodes have been fabricated using two fluorene-carbazole dendrimers and para-sexiphenyl (6P) oligomers. • When only these two dendrimers are used as EML, OLED devices are emitted blue light. • The emission colors of OLED devices change from blue to white when 6P is coated on dendrimer films.

  14. Color Degradation of Textiles with Natural Dyes and of Blue Scale Standards Exposed to White LED Lamps:Evaluation of White LED Lamps for Effectiveness as Museum Lighting

    Science.gov (United States)

    Ishii, Mie; Moriyama, Takayoshi; Toda, Masahiro; Kohmoto, Kohtaro; Saito, Masako

    White light-emitting diodes (LED) are well suited for museum lighting because they emit neither UV nor IR radiation, which damage artifacts. The color degradation of natural dyes and blue scale standards (JIS L 0841) by white LED lamps are examined, and the performance of white LED lamps for museum lighting is evaluated. Blue scale standard grades 1-6 and silk fabrics dyed with 22 types of natural dyes classified as mid to highly responsive in a CIE technical report (CIE157:2004) were exposed to five types of white LED lamps using different luminescence methods and color temperatures. Color changes were measured at each 15000 lx·hr (500 lx at fabric surface × 300 hr) interval ten times. The accumulated exposure totaled 150000 lx·hr. The data on conventional white LED lamps and previously reported white fluorescent (W) and museum fluorescent (NU) lamps was evaluated. All the white LED lamps showed lower fading rates compared with a W lamp on a blue scale grade 1. The fading rate of natural dyes in total was the same between an NU lamp (3000 K) and a white LED lamp (2869 K). However, yellow natural dyes showed higher fading rates with the white LED lamp. This tendency is due to the high power characteristic of the LED lamp around 400-500 nm, which possibly contributes to the photo-fading action on the dyes. The most faded yellow dyes were Ukon (Curcuma longa L.) and Kihada (Phellodendron amurense Rupr.), and these are frequently used in historic artifacts such as kimono, wood-block prints, and scrolls. From a conservation point of view, we need to continue research on white LED lamps for use in museum lighting.

  15. Development of Advanced Manufacturing Methods for Warm White LEDs for General Lighting

    Energy Technology Data Exchange (ETDEWEB)

    Deshpande, Anirudha; Kolodin, Boris; Jacob, Cherian; Chowdhury, Ashfaqul; Kuenzler, Glenn; Sater, Karen; Aesram, Danny; Glaettli, Steven; Gallagher, Brian; Langer, Paul; Setlur, Anant; Beers, Bill

    2012-03-31

    GE Lighting Solutions will develop precise and efficient manufacturing techniques for the “remote phosphor” platform of warm-white LED products. In volume, this will be demonstrated to drive significant materials, labor and capital productivity to achieve a maximum possible 53% reduction in overall cost. In addition, the typical total color variation for these white LEDs in production will be well within the ANSI bins and as low as a 4-step MacAdam ellipse centered on the black body curve. Achievement of both of these objectives will be demonstrated while meeting a performance target of > 75 lm/W for a warm-white LED and a reliability target of <30% lumen drop / <2-step MacAdam ellipse shift, estimated over 50,000 hrs.

  16. Electrical aging effect of ZnS based quantum dots for white light-emitting diodes

    Science.gov (United States)

    Kim, Yohan; Ippen, Christian; Greco, Tonino; Jang, Ilwan; Park, Sungkyu; Oh, Min Suk; Han, Chul Jong; Lee, Jeongno; Wedel, Armin; Kim, Jiwan

    2014-03-01

    The present work reports cadmium-free colloidal ZnS:Al quantum dot (QD) based white quantum dot light-emitting diodes (QD-LEDs). The device was fabricated with a structure of ITO/PEDOT:PSS/PVK/QDs/TPBi/LiF/Al using synthesized ZnS:Al QDs which has 393 nm of peak wavelength and sub peaks in visible wavelength. White emission with high color rending index (CRI) was achieved by the combination of blue emission from PVK and ZnS:Al QDs, electroplex emission at the interface between PVK and ZnS:Al QDs, and Al traps/defects emission, which are controlled by electrical aging effect. The characteristic of our device shows the potential for spectrum tunable and Cd-free white QD-LEDs in the near future.

  17. Tunable light emission and similarities with garnet structure of Ce-doped LSCAS glass for white-light devices

    Energy Technology Data Exchange (ETDEWEB)

    Andrade, L.H.C., E-mail: luishca@uems.br [Grupo de Espectroscopia Optica e Fototermica, Universidade Estadual de Mato Grosso do Sul - UEMS, C.P. 351, Dourados, MS (Brazil); Lima, S.M. [Grupo de Espectroscopia Optica e Fototermica, Universidade Estadual de Mato Grosso do Sul - UEMS, C.P. 351, Dourados, MS (Brazil); Baesso, M.L.; Novatski, A.; Rohling, J.H. [Grupo de Estudos de Fenomenos Fototermicos, Departamento de Fisica, Universidade Estadual de Maringa, Av. Colombo 5790, 87020-900 Maringa, PR (Brazil); Guyot, Y.; Boulon, G. [Laboratoire de Physico-Chimie des Materiaux Luminescents, Universite Claude Bernard Lyon 1, UMR 5620 CNRS, 69622 Villeurbanne (France)

    2012-01-05

    Highlights: > Ce{sup 3+}-doped LSCAS glass exhibits broad, simultaneously blue and yellow emissions under UV excitation. > In this phosphor is possible to continuously tune the emission, covering the entire visible spectrum. > The ability to change the color temperature in accordance to the occasion is a feature of this glass system. - Abstract: In this paper, we report results concerning tunable light emission and color temperature in cerium-doped low-silica-calcium-alumino-silicate (LSCAS) glass for smart white-light devices. Spectroscopic results, analyzed using the CIE 1931 x-y chromatic diagram, show that this glass presents two broad emission bands centered at 475 and 540 nm, whose intensities can be tuned by the excitation wavelength. Moreover, the same emission can be achieved from a color temperature range from 3200 to 10,000 K, with a color-rendering index (CRI) of around 75% obtained by changing the optical path length of the sample. Our new phosphor LSCAS glass, which is a unique system that exhibits tunable yellow emission, combines all qualities for white-light devices.

  18. Enhancement of sensitivity and bandwidth of gravitational wave detectors using fast-light-based white light cavities

    International Nuclear Information System (INIS)

    Salit, M; Shahriar, M S

    2010-01-01

    The effect of gravitational waves (GWs) has been observed indirectly, by monitoring the change in the orbital frequency of neutron stars in a binary system as they lose energy via gravitational radiation. However, GWs have not yet been observed directly. The initial LIGO apparatus has not yet observed GWs. The advanced LIGO (AdLIGO) will use a combination of improved techniques in order to increase the sensitivity. Along with power recycling and a higher power laser source, the AdLIGO will employ signal recycling (SR). While SR would increase sensitivity, it would also reduce the bandwidth significantly. Previously, we and others have investigated, theoretically and experimentally, the feasibility of using a fast-light-based white light cavity (WLC) to circumvent this constraint. However, in the previous work, it was not clear how one would incorporate the white light cavity effect. Here, we first develop a general model for Michelson-interferometer-based GW detectors that can be easily adapted to include the effects of incorporating a WLC into the design. We then describe a concrete design of a WLC constructed as a compound mirror, to replace the signal recycling mirror. This design is simple, robust, completely non-invasive, and can be added to the AdLIGO system without changing any other optical elements. We show a choice of parameters for which the signal sensitivity as well as the bandwidth are enhanced significantly over what is planned for the AdLIGO, covering the entire spectrum of interest for gravitational waves

  19. Zinc oxide nanorods/polymer hybrid heterojunctions for white light emitting diodes

    Science.gov (United States)

    Willander, M.; Nur, O.; Zaman, S.; Zainelabdin, A.; Bano, N.; Hussain, I.

    2011-06-01

    Zinc oxide (ZnO) with its deep level defect emission covering the whole visible spectrum holds promise for the development of intrinsic white lighting sources with no need of using phosphors for light conversion. ZnO nanorods (NRs) grown on flexible plastic as substrate using a low temperature approach (down to 50 °C) were combined with different organic semiconductors to form hybrid junction. White electroluminescence (EL) was observed from these hybrid junctions. The configuration used for the hybrid white light emitting diodes (LEDs) consists of two-layers of polymers on the flexible plastic with ZnO NRs on the top. The inorganic/organic hybrid heterojunction has been fabricated by spin coating the p-type polymer poly (3,4-ethylenedioxythiophene) poly(styrenesulfonate) (PEDOT : PSS) for hole injection with an ionization potential of 5.1 eV and poly(9, 9-dioctylfluorene) (PFO) is used as blue emitting material with a bandgap of 3.3 eV. ZnO NRs are grown on top of the organic layers. Two other configurations were also fabricated; these are using a single MEH PPV (red-emitting polymer) instead of the PFO and the third configuration was obtained from a blend of the PFO and the MEH PPV. The white LEDs were characterized by scanning electron microscope, x-ray diffraction (XRD), current-voltage (I-V) characteristics, room temperature photoluminescence (PL) and EL. The EL spectrum reveals a broad emission band covering the range from 420 to 800 nm, and the emissions causing this white luminescence were identified.

  20. Zinc oxide nanorods/polymer hybrid heterojunctions for white light emitting diodes

    International Nuclear Information System (INIS)

    Willander, M; Nur, O; Zaman, S; Zainelabdin, A; Bano, N; Hussain, I

    2011-01-01

    Zinc oxide (ZnO) with its deep level defect emission covering the whole visible spectrum holds promise for the development of intrinsic white lighting sources with no need of using phosphors for light conversion. ZnO nanorods (NRs) grown on flexible plastic as substrate using a low temperature approach (down to 50 0 C) were combined with different organic semiconductors to form hybrid junction. White electroluminescence (EL) was observed from these hybrid junctions. The configuration used for the hybrid white light emitting diodes (LEDs) consists of two-layers of polymers on the flexible plastic with ZnO NRs on the top. The inorganic/organic hybrid heterojunction has been fabricated by spin coating the p-type polymer poly (3,4-ethylenedioxythiophene) poly(styrenesulfonate) (PEDOT : PSS) for hole injection with an ionization potential of 5.1 eV and poly(9, 9-dioctylfluorene) (PFO) is used as blue emitting material with a bandgap of 3.3 eV. ZnO NRs are grown on top of the organic layers. Two other configurations were also fabricated; these are using a single MEH PPV (red-emitting polymer) instead of the PFO and the third configuration was obtained from a blend of the PFO and the MEH PPV. The white LEDs were characterized by scanning electron microscope, x-ray diffraction (XRD), current-voltage (I-V) characteristics, room temperature photoluminescence (PL) and EL. The EL spectrum reveals a broad emission band covering the range from 420 to 800 nm, and the emissions causing this white luminescence were identified.

  1. Multispectral digital lensless holographic microscopy: from femtosecond laser to white light LED

    International Nuclear Information System (INIS)

    Garcia-Sucerquia, J

    2015-01-01

    The use of femtosecond laser radiation and super bright white LED in digital lensless holographic microscopy is presented. For the ultrafast laser radiation two different configurations of operation of the microscope are presented and the dissimilar performance of each one analyzed. The microscope operating with a super bright white light LED in combination with optical filters shows very competitive performance as it is compared with more expensive optical sources. The broadband emission of both radiation sources allows the multispectral imaging of biological samples to obtain spectral responses and/or full color images of the microscopic specimens; sections of the head of a Drosophila melanogaster fly are imaged in this contribution. The simple, solid, compact, lightweight, and reliable architecture of digital lensless holographic microscopy operating with broadband light sources to image biological specimens exhibiting micrometer-sized details is evaluated in the present contribution. (paper)

  2. Medium pressure mercury discharge for use as an intense white light source

    International Nuclear Information System (INIS)

    Kitsinelis, S; Devonshire, R; Stone, D A; Tozer, R C

    2005-01-01

    In this paper, we demonstrate the possibilities that exist in developing a high brightness white light source. The lamp employs mercury at a few Torr and is operated with short pulses of the order of 1 μs at a frequency of 10 kHz. The emission spectrum is atomic in nature and the white light is the outcome of a relative enhancement of the mercury yellow lines at 577 and 579 nm with respect to the rest of the visible lines, which shifts the colour coordinates of the source towards the black body locus of the chromaticity diagram. The pulse operation of a lamp containing mercury at a vapour pressure of 20 Torr offers a greater near-UV and visible output compared to a phosphor-uncoated, low-pressure pulsed compact mercury discharge

  3. A development optical course based on optical fiber white light interference

    Science.gov (United States)

    Jiang, Haili; Sun, Qiuhua; Zhao, Yancheng; Li, Qingbo

    2017-08-01

    The Michelson interferometer is a very important instrument in optical part for college physics teaching. But most students only know the instrument itself and don't know how to use it in practical engineering problems. A case about optical fiber white light interference based on engineering practice was introduced in the optical teaching of college physics and then designed a development course of university physical optics part. This system based on low-coherence white light interferometric technology can be used to measure distribution strain or temperature. It also could be used in the case of temperature compensation mode.This teaching design can use the knowledge transfer rule to enable students to apply the basic knowledge in the university physics to the new knowledge domain, which can promote the students' ability of using scientific methods to solve complex engineering problems.

  4. White light spectral interferometer for measuring dispersion in the visible-near infrared

    Science.gov (United States)

    Arosa, Yago; Rodríguez Fernández, Carlos Damian; Algnamat, Bilal S.; López-Lago, Elena; de la Fuente, Raul

    2017-08-01

    We have designed a spectrally resolved interferometer to measure the refractive index of transparent samples over a wide spectral band from 400 to 1550 nm. The measuring device consists of a Michelson interferometer whose output is analyzed by means of three fiber spectrometers. The first one is a homemade prism spectrometer, which obtains the interferogram produced by the sample over 400 to 1050 nm; the second one is a homemade transmission grating spectrometer thought to measure the interferogram in the near infrared spectral band from 950 to 1550 nm; the last one is a commercial Czerny-Turner spectrometer used to make high precision measurements of the displacement between the Michelson mirrors also using white light interferometry. The whole system is illuminated by a white light source with an emission spectrum similar to black body. We have tested the instrument with solid and liquids samples achieving accuracy to the fourth decimal on the refractive index after fitting it to a Cauchy formula

  5. Vibration compensated high-resolution scanning white-light Linnik-interferometer

    Science.gov (United States)

    Tereschenko, Stanislav; Lehmann, Peter; Gollor, Pascal; Kuehnhold, Peter

    2017-06-01

    We present a high-resolution Linnik scanning white-light interferometer (SWLI) with integrated distance measuring interferometer (DMI) for close-to-machine applications in the presence of environmental vibrations. The distance, measured by DMI during the depth-scan, is used for vibration compensation of SWLI signals. The reconstruction of the white-light interference signals takes place after measurement by reordering the captured images in accordance with their real positions obtained by the DMI and subsequent trigonometrical approximation. This system is the further development of our previously presented Michelson-interferometer. We are able to compensate for arbitrary vibrations with frequencies up to several kilohertz and amplitudes in the lower micrometer range. Completely distorted SWLI signals can be reconstructed and the surface topography can be obtained with high accuracy. We demonstrate the feasibility of the method by examples of practical measurements with and without vibrational disturbances.

  6. Noise analysis of the measurement of group delay in Fourier white-light interferometric cross correlation

    International Nuclear Information System (INIS)

    Laude, Vincent

    2002-01-01

    The problem of noise analysis in measuring the group delay introduced by a dispersive optical element by use of white-light interferometric cross correlation is investigated. Two noise types, detection noise and position noise, are specifically analyzed. Detection noise is shown to be highly sensitive to the spectral content of the white-light source at the frequency considered and to the temporal acquisition window. Position noise, which arises from the finite accuracy of the measurement of the scanning mirror's position, can severely damage the estimation of the group delay. Such is shown to be the case for fast Fourier transform-based estimation algorithms. A new algorithm that is insensitive to scanning delay errors is proposed, and subfemtosecond accuracy is obtained without any postprocessing

  7. Optimal nitrogen and phosphorus codoping carbon dots towards white light-emitting device

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, Feng; Wang, Yaling; Miao, Yanqin; Yang, Yongzhen, E-mail: yyztyut@126.com, E-mail: liuxuguang@tyut.edu.cn [Key Laboratory of Interface Science and Engineering in Advanced Materials, Taiyuan University of Technology, Ministry of Education, Taiyuan 030024 (China); Research Center on Advanced Materials Science and Technology, Taiyuan University of Technology, Taiyuan 030024 (China); He, Yuheng; Liu, Xuguang, E-mail: yyztyut@126.com, E-mail: liuxuguang@tyut.edu.cn [Key Laboratory of Interface Science and Engineering in Advanced Materials, Taiyuan University of Technology, Ministry of Education, Taiyuan 030024 (China); College of Chemistry and Chemical Engineering, Taiyuan University of Technology, Taiyuan 030024 (China)

    2016-08-22

    Through a one-step fast microwave-assisted approach, nitrogen and phosphorus co-doped carbon dots (N,P-CDs) were synthesized using ammonium citrate (AC) as a carbon source and phosphates as additive reagent. Under the condition of an optimal reaction time of 140 s, the influence of additive with different N and P content on fluorescent performance of N,P-CDs was further explored. It was concluded that high nitrogen content and moderate phosphorus content are necessary for obtaining high quantum yield (QY) N,P-CDs, among which the TAP-CDs (CDs synthesized using ammonium phosphate as additive reagent) show high quantum yield (QY) of 62% and red-green-blue (RGB) spectral composition of 51.67%. Besides, the TAP-CDs exhibit satisfying thermal stability within 180 °C. By virtue of good optical and thermal properties of TAP-CDs, a white light-emitting device (LED) was fabricated by combining ultraviolet chip with TAP-CDs as phosphor. The white LED emits bright warm-white light with the CIE chromaticity coordinate of (0.38, 0.35) and the corresponding color temperature (CCT) of 4450 K, indicating the potential of TAP-CDs phosphor in white LED.

  8. Dy:Eu doped CaBAl glasses for white light applications

    Science.gov (United States)

    Lodi, T. A.; Sandrini, M.; Medina, A. N.; Barboza, M. J.; Pedrochi, F.; Steimacher, A.

    2018-02-01

    The combination of Eu3+ and Dy3+ in co-doped glassy materials provides interesting applicability for white light emission devices. In this work, Dy:Eu doped Calcium Boroaluminate (CaBAl) glasses were prepared by conventional melting quenching, with 3 wt% of Dy2O3 and Eu2O3 content varying from 0 to 3 wt%, and results of absorption spectra, photoluminescence and photoluminescence lifetime are discussed in terms of Eu2O3 content. The photoluminescence of the samples was studied under excitation of 365 and 405 nm light source. The 365 nm excitation shows favor to the Dy3+ ion emission. The results of photoluminescence lifetime at 575 nm (Dy3+) shows a decrease due to Eu2O3 addition, which suggests an energy transfer from Dy3+ (donor) to the Eu3+ (acceptor). On the other hand, under excitation of 405 nm, the photoluminescence lifetime at 575 nm (Dy3+) shows no significant changes due to Eu2O3 amount, which indicates that the energy transfer from Dy3+ to Eu3+ (under λexc = 405 nm) is negligible. However, the results of photoluminescence under 405 nm excitation present a white yellowish emission in the CIE diagram, which shifts to red with Eu2O3 addition. The combination of a Blue LED (BL) emission with the emission of the samples was also studied in the CIE diagram, in order to improve light emission and to obtain ideal White Light (WL). The results show that by modifying the emission intensity of BL, it is possible to achieve a route for smart lighting, close to the circadian light cycle.

  9. Fish freshness estimation using eye image processing under white and UV lightings

    Science.gov (United States)

    Kanamori, Katsuhiro; Shirataki, Yuri; Liao, Qiuhong; Ogawa, Yuichi; Suzuki, Tetsuhito; Kondo, Naoshi

    2017-05-01

    A non-destructive method of estimating the freshness of fish is required for appropriate price setting and food safety. In particular, for determining the possibility of eating raw fish (sashimi), freshness estimation is critical. We studied such an estimation method by capturing images of fish eyes and performing image processing using the temporal changes of the luminance of pupil and iris. To detect subtle non-visible changes of these features, we used UV (375 nm) light illumination in addition to visible white light illumination. Polarization and two-channel LED techniques were used to remove strong specular reflection from the cornea of the eye and from clear-plastic wrap used to cover the fish to maintain humidity. Pupil and iris regions were automatically detected separately by image processing after the specular reflection removal process, and two types of eye contrast were defined as the ratio of mean and median pixel values of each region. Experiments using 16 Japanese dace (Tribolodon hakonensis) at 23° and 85% humidity for 24 hours were performed. The eye contrast of raw fish increase non-linearly in the initial period and then decreased; however, that of frozen-thawed fish decreased linearly throughout 24 hours, regardless of the lighting. Interestingly, the eye contrast using UV light showed a higher correlation with time than that using white light only in the case of raw fish within the early 6- hour period postmortem. These results show the possibility of estimating fish freshness in the initial stage when fish are eaten raw using white and UV lightings.

  10. The POLIS interferometer for ponderomotive squeezed light generation

    Energy Technology Data Exchange (ETDEWEB)

    Calloni, Enrico [Dipartimento di Fisica, Università degli Studi di Napoli “Federico II”, Napoli (Italy); INFN, Sezione di Napoli (Italy); Conte, Andrea [Dipartimento di Fisica, Università di Roma “Sapienza”, Roma (Italy); INFN, Sezione di Roma1 (Italy); De Laurentis, Martina, E-mail: martina.delaurentis@na.infn.it [Dipartimento di Fisica, Università degli Studi di Napoli “Federico II”, Napoli (Italy); INFN, Sezione di Napoli (Italy); Naticchioni, Luca [Dipartimento di Fisica, Università di Roma “Sapienza”, Roma (Italy); INFN, Sezione di Roma1 (Italy); Puppo, Paola [INFN, Sezione di Roma1 (Italy); Ricci, Fulvio [Dipartimento di Fisica, Università di Roma “Sapienza”, Roma (Italy); INFN, Sezione di Roma1 (Italy)

    2016-07-11

    POLIS (POnderomotive LIght Squeezer) is a suspended interferometer, presently under construction, devoted to the generation of ponderomotive squeezed light and to the study of the interaction of non classical quantum states of light and macroscopic objects. The interferometer is a Michelson whose half-meter long arms are constituted by high-finesse cavities, suspended to a seismic isolation chain similar to the Virgo SuperAttenuator. The mass of the suspended cavity mirrors are chosen to be tens of grams: this value is sufficiently high to permit the use of the well-tested Virgo suspension techniques but also sufficiently small to generate the coupling among the two phase quadratures with a limited amount of light in the cavity, of the order of few tens of kW. In this short paper the main features of the interferometer are shown, together with the expected sensitivity and squeezing factor.

  11. Energy Transfer between Conjugated Colloidal Ga2O3 and CdSe/CdS Core/Shell Nanocrystals for White Light Emitting Applications

    Directory of Open Access Journals (Sweden)

    Paul C. Stanish

    2016-02-01

    Full Text Available Developing solid state materials capable of generating homogeneous white light in an energy efficient and resource-sustainable way is central to the design of new and improved devices for various lighting applications. Most currently-used phosphors depend on strategically important rare earth elements, and rely on a multicomponent approach, which produces sub-optimal quality white light. Here, we report the design and preparation of a colloidal white-light emitting nanocrystal conjugate. This conjugate is obtained by linking colloidal Ga2O3 and II–VI nanocrystals in the solution phase with a short bifunctional organic molecule (thioglycolic acid. The two types of nanocrystals are electronically coupled by Förster resonance energy transfer owing to the short separation between Ga2O3 (energy donor and core/shell CdSe/CdS (energy acceptor nanocrystals, and the spectral overlap between the photoluminescence of the donor and the absorption of the acceptor. Using steady state and time-resolved photoluminescence spectroscopies, we quantified the contribution of the energy transfer to the photoluminescence spectral power distribution and the corresponding chromaticity of this nanocrystal conjugate. Quantitative understanding of this new system allows for tuning of the emission color and the design of quasi-single white light emitting inorganic phosphors without the use of rare-earth elements.

  12. Energy Transfer between Conjugated Colloidal Ga2O3 and CdSe/CdS Core/Shell Nanocrystals for White Light Emitting Applications

    Science.gov (United States)

    Stanish, Paul C.; Radovanovic, Pavle V.

    2016-01-01

    Developing solid state materials capable of generating homogeneous white light in an energy efficient and resource-sustainable way is central to the design of new and improved devices for various lighting applications. Most currently-used phosphors depend on strategically important rare earth elements, and rely on a multicomponent approach, which produces sub-optimal quality white light. Here, we report the design and preparation of a colloidal white-light emitting nanocrystal conjugate. This conjugate is obtained by linking colloidal Ga2O3 and II–VI nanocrystals in the solution phase with a short bifunctional organic molecule (thioglycolic acid). The two types of nanocrystals are electronically coupled by Förster resonance energy transfer owing to the short separation between Ga2O3 (energy donor) and core/shell CdSe/CdS (energy acceptor) nanocrystals, and the spectral overlap between the photoluminescence of the donor and the absorption of the acceptor. Using steady state and time-resolved photoluminescence spectroscopies, we quantified the contribution of the energy transfer to the photoluminescence spectral power distribution and the corresponding chromaticity of this nanocrystal conjugate. Quantitative understanding of this new system allows for tuning of the emission color and the design of quasi-single white light emitting inorganic phosphors without the use of rare-earth elements. PMID:28344289

  13. Hybrid white organic light-emitting devices based on phosphorescent iridium-benzotriazole orange-red and fluorescent blue emitters

    Energy Technology Data Exchange (ETDEWEB)

    Xia, Zhen-Yuan, E-mail: xiazhenyuan@hotmail.com [Key Laboratory for Advanced Materials and Institute of Fine Chemicals, East China University of Science and Technology, Shanghai 200237 (China); Su, Jian-Hua [Key Laboratory for Advanced Materials and Institute of Fine Chemicals, East China University of Science and Technology, Shanghai 200237 (China); Chang, Chi-Sheng; Chen, Chin H. [Display Institute, Microelectronics and Information Systems Research Center, National Chiao Tung University, Hsinchu, Taiwan 300 (China)

    2013-03-15

    We demonstrate that high color purity or efficiency hybrid white organic light-emitting devices (OLEDs) can be generated by integrating a phosphorescent orange-red emitter, bis[4-(2H-benzotriazol-2-yl)-N,N-diphenyl-aniline-N{sup 1},C{sup 3}] iridium acetylacetonate, Ir(TBT){sub 2}(acac) with fluorescent blue emitters in two different emissive layers. The device based on deep blue fluorescent material diphenyl-[4-(2-[1,1 Prime ;4 Prime ,1 Double-Prime ]terphenyl-4-yl-vinyl)-phenyl]-amine BpSAB and Ir(TBT){sub 2}(acac) shows pure white color with the Commission Internationale de L'Eclairage (CIE) coordinates of (0.33,0.30). When using sky-blue fluorescent dopant N,N Prime -(4,4 Prime -(1E,1 Prime E)-2,2 Prime -(1,4-phenylene)bis(ethene-2,1-diyl) bis(4,1-phenylene))bis(2-ethyl-6-methyl-N-phenylaniline) (BUBD-1) and orange-red phosphor with a color-tuning phosphorescent material fac-tris(2-phenylpyridine) iridium (Ir(ppy){sub 3} ), it exhibits peak luminance yield and power efficiency of 17.4 cd/A and 10.7 lm/W, respectively with yellow-white color and CIE color rendering index (CRI) value of 73. - Highlights: Black-Right-Pointing-Pointer An iridium-based orange-red phosphor Ir(TBT){sub 2}(acac) was applied in hybrid white OLEDs. Black-Right-Pointing-Pointer Duel- and tri-emitter WOLEDs were achieved with either high color purity or efficiency performance. Black-Right-Pointing-Pointer Peak luminance yield of tri-emitter WOLEDs was 17.4 cd/A with yellow-white color and color rendering index (CRI) value of 73.

  14. Hybrid white organic light-emitting devices based on phosphorescent iridium–benzotriazole orange–red and fluorescent blue emitters

    International Nuclear Information System (INIS)

    Xia, Zhen-Yuan; Su, Jian-Hua; Chang, Chi-Sheng; Chen, Chin H.

    2013-01-01

    We demonstrate that high color purity or efficiency hybrid white organic light-emitting devices (OLEDs) can be generated by integrating a phosphorescent orange–red emitter, bis[4-(2H-benzotriazol-2-yl)-N,N-diphenyl-aniline-N 1 ,C 3 ] iridium acetylacetonate, Ir(TBT) 2 (acac) with fluorescent blue emitters in two different emissive layers. The device based on deep blue fluorescent material diphenyl-[4-(2-[1,1′;4′,1″]terphenyl-4-yl-vinyl)-phenyl]-amine BpSAB and Ir(TBT) 2 (acac) shows pure white color with the Commission Internationale de L'Eclairage (CIE) coordinates of (0.33,0.30). When using sky-blue fluorescent dopant N,N′-(4,4′-(1E,1′E)-2,2′-(1,4-phenylene)bis(ethene-2,1-diyl) bis(4,1-phenylene))bis(2-ethyl-6-methyl-N-phenylaniline) (BUBD-1) and orange–red phosphor with a color-tuning phosphorescent material fac-tris(2-phenylpyridine) iridium (Ir(ppy) 3 ), it exhibits peak luminance yield and power efficiency of 17.4 cd/A and 10.7 lm/W, respectively with yellow-white color and CIE color rendering index (CRI) value of 73. - Highlights: ► An iridium-based orange–red phosphor Ir(TBT) 2 (acac) was applied in hybrid white OLEDs. ► Duel- and tri-emitter WOLEDs were achieved with either high color purity or efficiency performance. ► Peak luminance yield of tri-emitter WOLEDs was 17.4 cd/A with yellow-white color and color rendering index (CRI) value of 73.

  15. Low-intensity blue-enriched white light (750 lux) and standard bright light (10 000 lux) are equally effective in treating SAD. A randomized controlled study

    NARCIS (Netherlands)

    Meesters, Ybe; Dekker, Vera; Schlangen, Luc J. M.; Bos, Elske H.; Ruiter, Martine J.

    2011-01-01

    Background: Photoreceptor cells containing melanopsin play a role in the phase-shifting effects of short-wavelength light. In a previous study, we compared the standard light treatment (SLT) of SAD with treatment using short-wavelength blue-enriched white light (BLT). Both treatments used the same

  16. Measuring the Dispersion in Laser Cavity Mirrors using White-Light Interferometry

    Science.gov (United States)

    2008-03-01

    mirrors. Two AlGaInP (aluminum gallium indium phosphide ) diode lasers are aligned such that one is polarized vertically while one is polarized...linear crystals, where the index of refraction depends on beam intensity. Short pulses with high peak intensities are well 14 suited to induce the...MEASURING THE DISPERSION OF LASER CAVITY MIRRORS USING WHITE-LIGHT INTERFEROMETRY THESIS Allison S

  17. White light scanner-based repeatability of 3-dimensional digitizing of silicon rubber abutment teeth impressions.

    Science.gov (United States)

    Jeon, Jin-Hun; Lee, Kyung-Tak; Kim, Hae-Young; Kim, Ji-Hwan; Kim, Woong-Chul

    2013-11-01

    The aim of this study was to evaluate the repeatability of the digitizing of silicon rubber impressions of abutment teeth by using a white light scanner and compare differences in repeatability between different abutment teeth types. Silicon rubber impressions of a canine, premolar, and molar tooth were each digitized 8 times using a white light scanner, and 3D surface models were created using the point clouds. The size of any discrepancy between each model and the corresponding reference tooth were measured, and the distribution of these values was analyzed by an inspection software (PowerInspect 2012, Delcamplc., Birmingham, UK). Absolute values of discrepancies were analyzed by the Kruskal-Wallis test and multiple comparisons (α=.05). The discrepancy between the impressions for the canine, premolar, and molar teeth were 6.3 µm (95% confidence interval [CI], 5.4-7.2), 6.4 µm (95% CI, 5.3-7.6), and 8.9 µm (95% CI, 8.2-9.5), respectively. The discrepancy of the molar tooth impression was significantly higher than that of other tooth types. The largest variation (as mean [SD]) in discrepancies was seen in the premolar tooth impression scans: 26.7 µm (95% CI, 19.7-33.8); followed by canine and molar teeth impressions, 16.3 µm (95% CI, 15.3-17.3), and 14.0 µm (95% CI, 12.3-15.7), respectively. The repeatability of the digitizing abutment teeth's silicon rubber impressions by using a white light scanner was improved compared to that with a laser scanner, showing only a low mean discrepancy between 6.3 µm and 8.9 µm, which was in an clinically acceptable range. Premolar impression with a long and narrow shape showed a significantly larger discrepancy than canine and molar impressions. Further work is needed to increase the digitizing performance of the white light scanner for deep and slender impressions.

  18. Improvement of white organic light emitting diode performances by an annealing process

    International Nuclear Information System (INIS)

    Sepeai, Suhaila; Salleh, Muhamad Mat; Yahaya, Muhammad; Umar, Akrajas Ali

    2009-01-01

    White organic light emitting diode (OLED) devices with the structure ITO/PHF:rubrene/Al, in which PHF (poly(9,9-di-n-hexylfluorenyl-2,7-diyl)) is used as blue light emitting host and rubrene (5,6,11,12-tetraphenylnapthacene) as an orange dye dopant, have been fabricated. Indium tin oxide (ITO) coated-glass and aluminium were used as anode and cathode, respectively. The devices were fabricated with various rubrene-dopant to obtain a white light emission. The OLED device that composed of several concentrations of rubrene-doped PHF film was prepared in this study. It was found that the concentration of rubrene in the PHF-rubrene thin film matrix plays a key role in producing the white color emission. In a typical result, the device composed of 0.06 wt.% rubrene-dopant produced the white light emission with the Commission Internationale de L'Eclairage (CIE) coordinate of (0.30,0.33). The turn-on voltage and the brightness were found to be as low as 14.0 V and as high as 6540 cd/m 2 , respectively. The annealing technique at relatively low temperature (50 o C, 100 o C, and 150 o C) was then used to optimize the performance of the device. In a typical result, the turn-on voltage of the device could be successfully reduced and the brightness could be increased using the annealing technique. At an optimum condition, for example, annealed at 150 o C, the turn-on voltage as low as 8.0 V and the brightness as high as 9040 cd/m 2 were obtained. The mechanism for the improvement of the device performance upon annealing will be discussed.

  19. Improvement of white organic light emitting diode performances by an annealing process

    Energy Technology Data Exchange (ETDEWEB)

    Sepeai, Suhaila, E-mail: suhaila_sepeai@yahoo.co [Solar Energy Research Institute, Universiti Kebangsaan Malaysia, 43600 UKM Bangi Selangor (Malaysia); Salleh, Muhamad Mat, E-mail: mms@pkrisc.cc.ukm.m [Institute Of Microengineering And Nanoelectronic, Universiti Kebangsaan Malaysia, 43600 UKM Bangi Selangor (Malaysia); Yahaya, Muhammad; Umar, Akrajas Ali [Institute Of Microengineering And Nanoelectronic, Universiti Kebangsaan Malaysia, 43600 UKM Bangi Selangor (Malaysia)

    2009-06-30

    White organic light emitting diode (OLED) devices with the structure ITO/PHF:rubrene/Al, in which PHF (poly(9,9-di-n-hexylfluorenyl-2,7-diyl)) is used as blue light emitting host and rubrene (5,6,11,12-tetraphenylnapthacene) as an orange dye dopant, have been fabricated. Indium tin oxide (ITO) coated-glass and aluminium were used as anode and cathode, respectively. The devices were fabricated with various rubrene-dopant to obtain a white light emission. The OLED device that composed of several concentrations of rubrene-doped PHF film was prepared in this study. It was found that the concentration of rubrene in the PHF-rubrene thin film matrix plays a key role in producing the white color emission. In a typical result, the device composed of 0.06 wt.% rubrene-dopant produced the white light emission with the Commission Internationale de L'Eclairage (CIE) coordinate of (0.30,0.33). The turn-on voltage and the brightness were found to be as low as 14.0 V and as high as 6540 cd/m{sup 2}, respectively. The annealing technique at relatively low temperature (50 {sup o}C, 100 {sup o}C, and 150 {sup o}C) was then used to optimize the performance of the device. In a typical result, the turn-on voltage of the device could be successfully reduced and the brightness could be increased using the annealing technique. At an optimum condition, for example, annealed at 150 {sup o}C, the turn-on voltage as low as 8.0 V and the brightness as high as 9040 cd/m{sup 2} were obtained. The mechanism for the improvement of the device performance upon annealing will be discussed.

  20. Combination of carbon dot and polymer dot phosphors for white light-emitting diodes.

    Science.gov (United States)

    Sun, Chun; Zhang, Yu; Sun, Kai; Reckmeier, Claas; Zhang, Tieqiang; Zhang, XiaoYu; Zhao, Jun; Wu, Changfeng; Yu, William W; Rogach, Andrey L

    2015-07-28

    We realized white light-emitting diodes with high color rendering index (85-96) and widely variable color temperatures (2805-7786 K) by combining three phosphors based on carbon dots and polymer dots, whose solid-state photoluminescence self-quenching was efficiently suppressed within a polyvinyl pyrrolidone matrix. All three phosphors exhibited dominant absorption in the UV spectral region, which ensured the weak reabsorption and no energy transfer crosstalk. The WLEDs showed excellent color stability against the increasing current because of the similar response of the tricolor phosphors to the UV light variation.

  1. Real and virtual propagation dynamics of angular accelerating white light beams

    CSIR Research Space (South Africa)

    Vetter, C

    2017-08-01

    Full Text Available light modulators. References and links 1. H. Rubinsztein-Dunlop, A. Forbes, M. Berry, M. Dennis, D. L. Andrews, M. Mansuripur, C. Denz, C. Alpmann, P. Banzer, T. Bauer, E. Karimi, L. Marrucci, M. Padgett, M. Ritsch-Marte, N.M. Litchinitser, N. P. Bigelow...–678 (2008). 16. N. K. Efremidis and D. N. Christodoulides, “Abruptly autofocusing waves,” Opt. Lett. 35, 4045–4047 (2010). 17. R. Steiger, S. Bernet, and M. Ritsch-Marte, “Slm-based off-axis fourier filtering in microscopy with white light illumination,” Opt...

  2. Enhanced efficiency in single-host white organic light-emitting diode by triplet exciton conversion

    International Nuclear Information System (INIS)

    Wu, Qingyang; Zhang, Shiming; Yue, Shouzhen; Zhang, Zhensong; Xie, Guohua; Zhao, Yi; Liu, Shiyong

    2013-01-01

    The authors observe that the external quantum efficiency (EQE) of the Iridium (III) bis(4-phenylthieno [3,2-c]pyridinato-N,C 2′ )acetylacetonate (PO-01) based yellow organic light-emitting diode (OLED) is significantly increased by uniformly co-doping Iridium (III)bis[(4,6-difluorophenyl)-pyridinato-N,C 2− ] (FIrpic) and PO-01 into the same wide band-gap host of N,N ′ -dicarbazolyl-3, 5-benzene (mCP). Detailed investigation indicates that the efficiency enhancement is ascribed to effective triplet exciton gathering by FIrpic, followed by energy transfer to PO-01. Compared to the control device, which has maximum EQE of 10.5%, an improved maximum EQE of 13.2% is obtained in the optimization white device based on FIrpic and PO-01 emission according to this principle. This work makes it easier for a single host white OLED to simultaneously harvest high efficiency in both blue and yellow units. Comprehensive experimental results show that this phenomenon can also be found and utilized in other popular hosts to realize more efficient white devices. -- Highlights: • This work makes easier for a single host white OLED to harvest high efficiency in both blue and yellow units. • Efficiency enhancement is ascribed to effective triplet exciton gathering by FIrpic, followed by energy transfer to PO-01. • This phenomenon can also be found and utilized in other popular hosts to realize more efficient white devices

  3. Enhanced efficiency in single-host white organic light-emitting diode by triplet exciton conversion

    Energy Technology Data Exchange (ETDEWEB)

    Wu, Qingyang, E-mail: wqy1527@163.com [State Key laboratory on Integrated Optoelectronics, College of Electronic Science and Engineering, Jilin University, Changchun 130012 (China); Zhang, Shiming [State Key laboratory on Integrated Optoelectronics, College of Electronic Science and Engineering, Jilin University, Changchun 130012 (China); Département of Chemical Engineering, École Polytechnique de Montréal, Montréal, Québec, Canada H3C3J7 (Canada); Yue, Shouzhen; Zhang, Zhensong [State Key laboratory on Integrated Optoelectronics, College of Electronic Science and Engineering, Jilin University, Changchun 130012 (China); Xie, Guohua [Institut für Angewandte Photophysik, Technische Universtität Dresden, Dresden 01062 (Germany); Zhao, Yi; Liu, Shiyong [State Key laboratory on Integrated Optoelectronics, College of Electronic Science and Engineering, Jilin University, Changchun 130012 (China)

    2013-11-15

    The authors observe that the external quantum efficiency (EQE) of the Iridium (III) bis(4-phenylthieno [3,2-c]pyridinato-N,C{sup 2′})acetylacetonate (PO-01) based yellow organic light-emitting diode (OLED) is significantly increased by uniformly co-doping Iridium (III)bis[(4,6-difluorophenyl)-pyridinato-N,C{sup 2−}] (FIrpic) and PO-01 into the same wide band-gap host of N,N{sup ′}-dicarbazolyl-3, 5-benzene (mCP). Detailed investigation indicates that the efficiency enhancement is ascribed to effective triplet exciton gathering by FIrpic, followed by energy transfer to PO-01. Compared to the control device, which has maximum EQE of 10.5%, an improved maximum EQE of 13.2% is obtained in the optimization white device based on FIrpic and PO-01 emission according to this principle. This work makes it easier for a single host white OLED to simultaneously harvest high efficiency in both blue and yellow units. Comprehensive experimental results show that this phenomenon can also be found and utilized in other popular hosts to realize more efficient white devices. -- Highlights: • This work makes easier for a single host white OLED to harvest high efficiency in both blue and yellow units. • Efficiency enhancement is ascribed to effective triplet exciton gathering by FIrpic, followed by energy transfer to PO-01. • This phenomenon can also be found and utilized in other popular hosts to realize more efficient white devices.

  4. Strong white light emission from a processed porous silicon and its photoluminescence mechanism

    International Nuclear Information System (INIS)

    Karacali, T.; Cicek, K.

    2011-01-01

    We have prepared various porous silicon (PS) structures with different surface conditions (any combination of oxidation, carbonization as well as thermal annealing) to increase the intensity of photoluminescence (PL) spectrum in the visible range. Strong white light (similar to day-light) emission was achieved by carrying out thermal annealing at 1100 deg. C after surface modification with 1-decene of anodic oxidized PS structures. Temperature-dependent PL measurements were first performed by gradually increasing the sample temperature from 10 to 300 K inside a cryostat. Then, we analyzed the measured spectrum of all prepared samples. After the analysis, we note that throughout entire measured spectrum, only two main peaks corresponding to blue and green-orange emission lines (which can be interpreted by quantum size effect and/or configuration coordinate model) were seem to be predominant for all temperature range. To further reveal and analysis these peaks, finally, measured data were inputted into the formula of activation energy of thermal excitation. We found that activation energies of blue and green-orange lines were approximately 49.3 and 44.6 meV, respectively. - Highlights: →Light emitting devices based on silicon technology are of great interest in illumination and display applications. → We have achieved strong white light (similar to day-light) emission from porous silicon. → The most important impact of carbonization on porous silicon and post annealing is the enhancement of room temperature luminescence.

  5. Novel Low Cost Organic Vapor Jet Printing of Striped High Efficiency Phosphorescent OLEDs for White Lighting

    Energy Technology Data Exchange (ETDEWEB)

    Mike Hack

    2008-12-31

    In this program, Universal Display Corporation and University of Michigan proposed to integrate three innovative concepts to meet the DOE's Solid State Lighting (SSL) goals: (1) high-efficiency phosphorescent organic light emitting device (PHOLED{trademark}) technology, (2) a white lighting design that is based on a series of red, green and blue OLED stripes, and (3) the use of a novel cost-effective, high rate, mask-less deposition process called organic vapor jet printing (OVJP). Our PHOLED technology offers up to four-times higher power efficiency than other OLED approaches for general lighting. We believe that one of the most promising approaches to maximizing the efficiency of OLED lighting sources is to produce stripes of the three primary colors at such a pitch (200-500 {mu}m) that they appear as a uniform white light to an observer greater than 1 meter (m) away from the illumination source. Earlier work from a SBIR Phase 1 entitled 'White Illumination Sources Using Striped Phosphorescent OLEDs' suggests that stripe widths of less than 500 {mu}m appear uniform from a distance of 1m without the need for an external diffuser. In this program, we intend to combine continued advances in this PHOLED technology with the striped RGB lighting design to demonstrate a high-efficiency, white lighting source. Using this background technology, the team has focused on developing and demonstrating the novel cost-effective OVJP process to fabricate these high-efficiency white PHOLED light sources. Because this groundbreaking OVJP process is a direct printing approach that enables the OLED stripes to be printed without a shadow mask, OVJP offers very high material utilization and high throughput without the costs and wastage associated with a shadow mask (i.e. the waste of material that deposits on the shadow mask itself). As a direct printing technique, OVJP also has the potential to offer ultra-high deposition rates (> 1,000 Angstroms/second) for any size or

  6. Accuracy of 3D white light scanning of abutment teeth impressions: evaluation of trueness and precision.

    Science.gov (United States)

    Jeon, Jin-Hun; Kim, Hae-Young; Kim, Ji-Hwan; Kim, Woong-Chul

    2014-12-01

    This study aimed to evaluate the accuracy of digitizing dental impressions of abutment teeth using a white light scanner and to compare the findings among teeth types. To assess precision, impressions of the canine, premolar, and molar prepared to receive all-ceramic crowns were repeatedly scanned to obtain five sets of 3-D data (STL files). Point clouds were compared and error sizes were measured (n=10 per type). Next, to evaluate trueness, impressions of teeth were rotated by 10°-20° and scanned. The obtained data were compared with the first set of data for precision assessment, and the error sizes were measured (n=5 per type). The Kruskal-Wallis test was performed to evaluate precision and trueness among three teeth types, and post-hoc comparisons were performed using the Mann-Whitney U test with Bonferroni correction (α=.05). Precision discrepancies for the canine, premolar, and molar were 3.7 µm, 3.2 µm, and 7.3 µm, respectively, indicating the poorest precision for the molar (Pimpressions of abutment teeth using a white light scanner was assessed to be a highly accurate method and provided discrepancy values in a clinically acceptable range. Further study is needed to improve digitizing performance of white light scanning in axial wall.

  7. Electroplex emission at PVK/Bphen interface for application in white organic light-emitting diodes

    International Nuclear Information System (INIS)

    Wen Liang; Li Fushan; Xie Jiangxing; Wu Chaoxing; Zheng Yong; Chen Dongling; Xu Sheng; Guo Tailiang; Qu Bo; Chen Zhijian; Gong Qihuang

    2011-01-01

    White organic light-emitting diode (WOLED) with a structure of ITO/poly(N-vinylcarbazole) (PVK)/4,7-diphenyl-1, 10-phenanthroline (Bphen)/tris(8-hydroxyquinoline)aluminum (Alq 3 )/LiF/Al has been fabricated via the thermal evaporation technique. The electroluminescence (EL) spectrum of the as-fabricated WOLED covers from 380 to 700 nm of the visible light region with a wide blue emission from PVK and an interesting new red emission. The red emission at 613 nm in EL spectra of the WOLED was attributed to electroplex emission at PVK/Bphen interface since it was not observed in photoluminescence spectra. The WOLED showed a Commission International De l'Eclairage coordinate of (0.31, 0.32), which is very close to the standard white coordinate (0.33, 0.33). - Highlights: → A white organic light-emitting diode was fabricated by vacuum deposition. → A new red emission at 613 nm was observed in the electroluminescence spectra. → Red emission comes from electroplex instead of exciplex at PVK/Bphen interface. → The device has a CIE coordinate of (0.31, 0.32).

  8. Enhancement of white light OLED efficiency by combining both internal and external light extraction structures

    Science.gov (United States)

    Kao, I.-Ling; Ku, Chun-Neng; Chen, Yi-Ping; Lin, Ding-Zheng

    2012-09-01

    We proposed an internal nanostructure with a high reflective index planarization layer to solve the optical loss due to the reflective index mismatch between ITO and glass substrate. In our experiments, we found the electrical property of OLED device was significantly influenced by the internal nanostructures without planarization layer. Moreover, the internal extraction structure (IES) is not necessarily beneficial for light extraction. Therefore, we proposed a new substrate combine both internal and external extraction structure (EES) to extract trapping light. We successfully developed a high refractive index (N 1.7) planarization material with flat surface (RMS roughness < 2 nm), and improved about 70% device efficiency compared to traditional glass substrate.

  9. Permanent magnet based dipole magnets for next generation light sources

    Directory of Open Access Journals (Sweden)

    Takahiro Watanabe

    2017-07-01

    Full Text Available We have developed permanent magnet based dipole magnets for the next generation light sources. Permanent magnets are advantageous over electromagnets in that they consume less power, are physically more compact, and there is a less risk of power supply failure. However, experience with electromagnets and permanent magnets in the field of accelerators shows that there are still challenges to replacing main magnets of accelerators for light sources with permanent magnets. These include the adjustability of the magnetic field, the temperature dependence of permanent magnets, and the issue of demagnetization. In this paper, we present a design for magnets for future light sources, supported by experimental and numerical results.

  10. Gigabit-per-second white light-based visible light communication using near-ultraviolet laser diode and red-, green-, and blue-emitting phosphors

    KAUST Repository

    Lee, Changmin

    2017-07-12

    Data communication based on white light generated using a near-ultraviolet (NUV) laser diode (LD) pumping red-, green-, and blue-emitting (RGB) phosphors was demonstrated for the first time. A III-nitride laser diode (LD) on a semipolar (2021) substrate emitting at 410 nm was used for the transmitter. The measured modulation bandwidth of the LD was 1 GHz, which was limited by the avalanche photodetector. The emission from the NUV LD and the RGB phosphor combination measured a color rendering index (CRI) of 79 and correlated color temperature (CCT) of 4050 K, indicating promise of this approach for creating high quality white lighting. Using this configuration, data was successfully transmitted at a rate of more than 1 Gbps. This NUV laser-based system is expected to have lower background noise from sunlight at the LD emission wavelength than a system that uses a blue LD due to the rapid fall off in intensity of the solar spectrum in the NUV spectral region.

  11. Gigabit-per-second white light-based visible light communication using near-ultraviolet laser diode and red-, green-, and blue-emitting phosphors.

    Science.gov (United States)

    Lee, Changmin; Shen, Chao; Cozzan, Clayton; Farrell, Robert M; Speck, James S; Nakamura, Shuji; Ooi, Boon S; DenBaars, Steven P

    2017-07-24

    Data communication based on white light generated using a near-ultraviolet (NUV) laser diode (LD) pumping red-, green-, and blue-emitting (RGB) phosphors was demonstrated for the first time. A III-nitride laser diode (LD) on a semipolar (2021¯)  substrate emitting at 410 nm was used for the transmitter. The measured modulation bandwidth of the LD was 1 GHz, which was limited by the avalanche photodetector. The emission from the NUV LD and the RGB phosphor combination measured a color rendering index (CRI) of 79 and correlated color temperature (CCT) of 4050 K, indicating promise of this approach for creating high quality white lighting. Using this configuration, data was successfully transmitted at a rate of more than 1 Gbps. This NUV laser-based system is expected to have lower background noise from sunlight at the LD emission wavelength than a system that uses a blue LD due to the rapid fall off in intensity of the solar spectrum in the NUV spectral region.

  12. Tunable and white light emitting AlPO4 mesoporous glass by design of inorganic/organic luminescent species

    Directory of Open Access Journals (Sweden)

    Jin He

    2015-04-01

    Full Text Available The realization of tunable and white light emitting sources employed by UV-LED with single-host phosphors has been an exciting development in the search for high luminous efficiency and excellent color rendering index white-light source. A tunable and white light emitting mesoporous glass was prepared by utilizing both inorganic/organic (Europium/coumarin luminescent species in the meso-structure. The tunable and white light emission was deliberately designed by CIE calculation based on the individual emission spectra, which was realized by tailoring the emission of Eu2+/Eu3+ ions and coumarin 535 in sol-gel AlPO4 mesoporous glass. This simple and versatile procedure is not limited in the combination of rare earth and organic dye and is therefore extendable to other luminescent species in meso-structure for color-tunable efficient solid-state lighting sources.

  13. Organic light-emitting diodes with direct contact-printed red, green, blue, and white light-emitting layers

    Science.gov (United States)

    Chen, Sun-Zen; Peng, Shiang-Hau; Ting, Tzu-Yu; Wu, Po-Shien; Lin, Chun-Hao; Chang, Chin-Yeh; Shyue, Jing-Jong; Jou, Jwo-Huei

    2012-10-01

    We demonstrate the feasibility of using direct contact-printing in the fabrication of monochromatic and polychromatic organic light-emitting diodes (OLEDs). Bright devices with red, green, blue, and white contact-printed light-emitting layers with a respective maximum luminance of 29 000, 29 000, 4000, and 18 000 cd/m2 were obtained with sound film integrity by blending a polymeric host into a molecular host. For the red OLED as example, the maximum luminance was decreased from 29 000 to 5000 cd/m2 as only the polymeric host was used, or decreased to 7000 cd/m2 as only the molecular host was used. The markedly improved device performance achieved in the devices with blended hosts may be attributed to the employed polymeric host that contributed a good film-forming character, and the molecular host that contributed a good electroluminescence character.

  14. Design of a dynamic biofilm imaging cell for white-light interferometric microscopy

    Science.gov (United States)

    Larimer, Curtis; Brann, Michelle; Suter, Jonathan D.; Addleman, R. Shane

    2017-11-01

    In microbiology research, there is a strong need for next-generation imaging and sensing instrumentation that will enable minimally invasive and label-free investigation of soft, hydrated structures, such as in bacterial biofilms. White-light interferometry (WLI) can provide high-resolution images of surface topology without the use of fluorescent labels but is not typically used to image biofilms because there is insufficient refractive index contrast to induce reflection from the biofilm's interface. The soft structure and water-like bulk properties of hydrated biofilms make them difficult to characterize in situ, especially in a nondestructive manner. We build on our prior description of static biofilm imaging and describe the design of a dynamic growth flow cell that enables monitoring of the thickness and topology of live biofilms over time using a WLI microscope. The microfluidic system is designed to grow biofilms in dynamic conditions and to create a reflective interface on the surface while minimizing disruption of fragile structures. The imaging cell was also designed to accommodate limitations imposed by the depth of focus of the microscope's objective lens. Example images of live biofilm samples are shown to illustrate the ability of the flow cell and WLI instrument to (1) support bacterial growth and biofilm development, (2) image biofilm structure that reflects growth in flow conditions, and (3) monitor biofilm development over time nondestructively. In future work, the apparatus described here will enable surface metrology measurements (roughness, surface area, etc.) of biofilms and may be used to observe changes in biofilm structure in response to changes in environmental conditions (e.g., flow velocity, availability of nutrients, and presence of biocides). This development will open opportunities for the use of WLI in bioimaging.

  15. Organic Light-Emitting Diode with Color Tunable between Bluish-White Daylight and Orange-White Dusk Hue

    Directory of Open Access Journals (Sweden)

    Shih-Yun Liao

    2014-01-01

    Full Text Available The varying color of sunlight diurnally exhibits an important effect on circadian rhythm of living organisms. The bluish-white daylight that is suitable for work shows a color temperature as high as 9,000 K, while the homey orange-white dusk hue is as low as 2,000 K. We demonstrate in this report the feasibility of using organic light-emitting diode (OLED technology to fabricate sunlight-style illumination with a very wide color temperature range. The color temperature can be tuned from 2,300 K to 9,300 K, for example, by changing the applied voltage from 3 to 11 V for the device composing red and yellow emitters in the first emissive layer and blue emitter in the second. Unlike the prior arts, the color-temperature span can be made much wider without any additional carrier modulation layer, which should enable a more cost effective fabrication. For example, the color-temperature span is 7,000 K for the above case, while it is 1,700 K upon the incorporation of a nanoscale hole modulation layer in between the two emissive layers. The reason why the present device can effectively regulate the shifting of recombination zone is because the first emissive layer itself possesses an effective hole modulation barrier of 0.2 eV. This also explains why the incorporation of an extra hole modulation layer with a 0.7 eV barrier did not help extend the desirable color-temperature span since excessive holes may be blocked.

  16. A Heuristic Approach to Remove the Background Intensity on White-light Solar Images. I. STEREO /HI-1 Heliospheric Images

    Energy Technology Data Exchange (ETDEWEB)

    Stenborg, Guillermo; Howard, Russell A. [Space Science Division, U.S. Naval Research Laboratory, Washington, DC 20375 (United States)

    2017-04-10

    White-light coronal and heliospheric imagers observe scattering of photospheric light from both dust particles (the F-Corona) and free electrons in the corona (the K-corona). The separation of the two coronae is thus vitally important to reveal the faint K-coronal structures (e.g., streamers, co-rotating interaction regions, coronal mass ejections, etc.). However, the separation of the two coronae is very difficult, so we are content in defining a background corona that contains the F- and as little K- as possible. For both the LASCO-C2 and LASCO-C3 coronagraphs aboard the Solar and Heliospheric Observatory ( SOHO ) and the white-light imagers of the SECCHI suite aboard the Solar Terrestrial Relationships Observatory ( STEREO ), a time-dependent model of the background corona is generated from about a month of similar images. The creation of such models is possible because the missions carrying these instruments are orbiting the Sun at about 1 au. However, the orbit profiles for the upcoming Solar Orbiter and Solar Probe Plus missions are very different. These missions will have elliptic orbits with a rapidly changing radial distance, hence invalidating the techniques in use for the SOHO /LASCO and STEREO /SECCHI instruments. We have been investigating techniques to generate background models out of just single images that could be used for the Solar Orbiter Heliospheric Imager and the Wide-field Imager for the Solar Probe Plus packages on board the respective spacecraft. In this paper, we introduce a state-of-the-art, heuristic technique to create the background intensity models of STEREO /HI-1 data based solely on individual images, report on new results derived from its application, and discuss its relevance to instrumental and operational issues.

  17. Sub-Poissonian-light generation by postselection from twin beams

    Czech Academy of Sciences Publication Activity Database

    Peřina Jr., J.; Haderka, O.; Michálek, Václav

    2013-01-01

    Roč. 21, č. 16 (2013), 19387-19394 ISSN 1094-4087 R&D Projects: GA ČR GAP205/12/0382 Institutional support: RVO:68378271 Keywords : twin beams * Sub-Poissonian-light generation Subject RIV: BH - Optics, Masers, Lasers Impact factor: 3.525, year: 2013

  18. True Yellow Light-Emitting Diodes as Phosphor for Tunable Color-Rendering Index Laser-Based White Light

    KAUST Repository

    Janjua, Bilal; Ng, Tien Khee; Zhao, Chao; Prabaswara, Aditya; Consiglio, Giuseppe Bernardo; Priante, Davide; Shen, Chao; Elafandy, Rami T.; Anjum, Dalaver H.; Alhamoud, Abdullah A.; Alatawi, Abdullah A.; Yang, Yang; Alyamani, Ahmed Y.; El-Desouki, Munir M.; Ooi, Boon S.

    2016-01-01

    An urgent challenge for the lighting research community is the lack of efficient optical devices emitting in between 500 and 600 nm, resulting in the “green-yellow gap”. In particular, true green (∼555 nm) and true yellow (∼590 nm), along with blue and red, constitute four technologically important colors. The III-nitride material system, being the most promising choice of platform to bridge this gap, still suffers from high dislocation density and poor crystal quality in realizing high-power, efficient devices. Particularly, the high polarization fields in the active region of such 2D quantum confined structures prevent efficient recombination of carriers. Here we demonstrate a true yellow nanowire (NW) light emitting diode (LED) with peak emission of 588 nm at 29.5 A/cm2 (75 mA in a 0.5 × 0.5 mm2 device) and a low turn-on voltage of ∼2.5 V, while having an internal quantum efficiency of 39%, and without “efficiency droop” up to an injection current density of 29.5 A/cm2. By mixing yellow light from a NW LED in reflective configuration with that of a red, green, and blue laser diode (LD), white light with a correlated color temperature of ∼6000 K and color-rendering index of 87.7 was achieved. The nitride-NW-based device offers a robust, long-term stability for realizing yellow light emitters for tunable color-rendering index solid-state lighting, on a scalable, low-cost, foundry-compatible titanium/silicon substrate, suitable for industry uptake.

  19. True Yellow Light-Emitting Diodes as Phosphor for Tunable Color-Rendering Index Laser-Based White Light

    KAUST Repository

    Janjua, Bilal

    2016-10-11

    An urgent challenge for the lighting research community is the lack of efficient optical devices emitting in between 500 and 600 nm, resulting in the “green-yellow gap”. In particular, true green (∼555 nm) and true yellow (∼590 nm), along with blue and red, constitute four technologically important colors. The III-nitride material system, being the most promising choice of platform to bridge this gap, still suffers from high dislocation density and poor crystal quality in realizing high-power, efficient devices. Particularly, the high polarization fields in the active region of such 2D quantum confined structures prevent efficient recombination of carriers. Here we demonstrate a true yellow nanowire (NW) light emitting diode (LED) with peak emission of 588 nm at 29.5 A/cm2 (75 mA in a 0.5 × 0.5 mm2 device) and a low turn-on voltage of ∼2.5 V, while having an internal quantum efficiency of 39%, and without “efficiency droop” up to an injection current density of 29.5 A/cm2. By mixing yellow light from a NW LED in reflective configuration with that of a red, green, and blue laser diode (LD), white light with a correlated color temperature of ∼6000 K and color-rendering index of 87.7 was achieved. The nitride-NW-based device offers a robust, long-term stability for realizing yellow light emitters for tunable color-rendering index solid-state lighting, on a scalable, low-cost, foundry-compatible titanium/silicon substrate, suitable for industry uptake.

  20. InP/ZnS nanocrystals for colour conversion in white light emitting diodes

    DEFF Research Database (Denmark)

    Shirazi, Roza

    In this work a comprehensive study of a colloidal InP/ZnS nanocrystals (NC) as the colour conversion material for white light emitting diodes (WLED) is shown. Studied nanocrystals were synthesised by wet chemistry using one pot, hot injection method. A quantum efficiency (QE) of photoluminescence......, radiative and non-radiative recombination rates were determined and QE of 63% for the population of NCs that emit light was derived. A search for source of exciton losses in bright nanocrystals temperature resolved TRPL was studied and it revealed carrier trapping most likely at core-shell interface as well...... as at the surface and which competes with bright and dark exciton states. A presence of long-lived dark excitons and trapped charges lead to strong Auger recombination at high (relative to the trapping times) excitation. A colour conversion efficiency of the nanocrystals upon light absorption and in a process...

  1. Output blue light evaluation for phosphor based smart white LED wafer level packages.

    Science.gov (United States)

    Kolahdouz, Zahra; Rostamian, Ali; Kolahdouz, Mohammadreza; Ma, Teng; van Zeijl, Henk; Zhang, Kouchi

    2016-02-22

    This study presents a blue light detector for evaluating the output light of phosphor based white LED package. It is composed of a silicon stripe-shaped photodiode designed and implemented in a 2 μm BiCMOS process which can be used for wafer level integration of different passive and active devices all in just 5 lithography steps. The final device shows a high selectivity to blue light. The maximum responsivity at 480 nm is matched with the target blue LED illumination. The designed structure have better responsivity compared to simple photodiode structure due to reducing the effect of dead layer formation close to the surface because of implantation. It has also a two-fold increase in the responsivity and quantum efficiency compared to previously similar published sensors.

  2. Extreme sensitivity to ultraviolet light in the fungal pathogen causing white-nose syndrome of bats.

    Science.gov (United States)

    Palmer, Jonathan M; Drees, Kevin P; Foster, Jeffrey T; Lindner, Daniel L

    2018-01-02

    Bat white-nose syndrome (WNS), caused by the fungal pathogen Pseudogymnoascus destructans, has decimated North American hibernating bats since its emergence in 2006. Here, we utilize comparative genomics to examine the evolutionary history of this pathogen in comparison to six closely related nonpathogenic species. P. destructans displays a large reduction in carbohydrate-utilizing enzymes (CAZymes) and in the predicted secretome (~50%), and an increase in lineage-specific genes. The pathogen has lost a key enzyme, UVE1, in the alternate excision repair (AER) pathway, which is known to contribute to repair of DNA lesions induced by ultraviolet (UV) light. Consistent with a nonfunctional AER pathway, P. destructans is extremely sensitive to UV light, as well as the DNA alkylating agent methyl methanesulfonate (MMS). The differential susceptibility of P. destructans to UV light in comparison to other hibernacula-inhabiting fungi represents a potential "Achilles' heel" of P. destructans that might be exploited for treatment of bats with WNS.

  3. Monte Carlo analysis of a control technique for a tunable white lighting system

    DEFF Research Database (Denmark)

    Chakrabarti, Maumita; Thorseth, Anders; Jepsen, Jørgen

    2017-01-01

    A simulated colour control mechanism for a multi-coloured LED lighting system is presented. The system achieves adjustable and stable white light output and allows for system-to-system reproducibility after application of the control mechanism. The control unit works using a pre-calibrated lookup...... table for an experimentally realized system, with a calibrated tristimulus colour sensor. A Monte Carlo simulation is used to examine the system performance concerning the variation of luminous flux and chromaticity of the light output. The inputs to the Monte Carlo simulation, are variations of the LED...... peak wavelength, the LED rated luminous flux bin, the influence of the operating conditions, ambient temperature, driving current, and the spectral response of the colour sensor. The system performance is investigated by evaluating the outputs from the Monte Carlo simulation. The outputs show...

  4. Microwave-assisted one-step synthesis of white light-emitting carbon dot suspensions

    Science.gov (United States)

    Vanessa, Hinterberger; Wenshuo, Wang; Cornelia, Damm; Simon, Wawra; Martin, Thoma; Wolfgang, Peukert

    2018-06-01

    In this contribution, we demonstrate that an aqueous solution with adjustable fluorescent color, including white light emission, can be achieved by a rapid one-step microwave synthesis method resulting in a mixture of blue-emitting carbon dots (CDs) and the yellow-emitting 2,3-diaminophenazine (DAP). Aqueous mixtures of o-phenylene-diamine (oPD) and citric acid (CA) are used as precursors. The resulting product structures are analyzed by FT-IR and NMR spectroscopy and the size of the resulting CDs is determined by atomic force microscopy to be 1.1 ± 0.3 nm. The synthesized solution exhibits two fluorescence emission peaks at 430 and 560 nm, which were found to originate from the CDs and DAP, respectively. The intensity ratio of both fluorescence peaks depends on pH, which is driven by the protonation state of DAP. In consequence, the fluorescence emission color of the CD solution can be tuned precisely and reproducibly from blue to white to yellow by careful control of the pH. Finally, at a pH level of 5.4, at which there is equal blue and yellow emission intensity, a white light emitting solution can be successfully produced in a very fast and simple synthesis procedure.

  5. High color rendering index white organic light-emitting diode using levofloxacin as blue emitter

    International Nuclear Information System (INIS)

    Miao Yan-Qin; Zhang Ai-Qin; Li Yuan-Hao; Wang Hua; Jia Hu-Sheng; Liu Xu-Guang; Gao Zhi-Xiang; Tsuboi Taijuf

    2015-01-01

    Levofloxacin (LOFX), which is well-known as an antibiotic medicament, was shown to be useful as a 452-nm blue emitter for white organic light-emitting diodes (OLEDs). In this paper, the fabricated white OLED contains a 452-nm blue emitting layer (thickness of 30 nm) with 1 wt% LOFX doped in CBP (4,4’-bis(carbazol-9-yl)biphenyl) host and a 584-nm orange emitting layer (thickness of 10 nm) with 0.8 wt% DCJTB (4-(dicyanomethylene)-2-tert-butyl-6-(1,1,7, 7-tetramethyljulolidin-4-yl-vinyl)-4H-pyran) doped in CBP, which are separated by a 20-nm-thick buffer layer of TPBi (2,2’,2”-(benzene-1,3,5-triyl)-tri(1-phenyl-1H-benzimidazole). A high color rendering index (CRI) of 84.5 and CIE chromaticity coordinates of (0.33, 0.32), which is close to ideal white emission CIE (0.333, 0.333), are obtained at a bias voltage of 14 V. Taking into account that LOFX is less expensive and the synthesis and purification technologies of LOFX are mature, these results indicate that blue fluorescence emitting LOFX is useful for applications to white OLEDs although the maximum current efficiency and luminance are not high. The present paper is expected to become a milestone to using medical drug materials for OLEDs. (paper)

  6. Semipolar GaN-based laser diodes for Gbit/s white lighting communication: devices to systems

    KAUST Repository

    Lee, Changmin; Shen, Chao; Farrell, Robert M.; Nakamura, Shuji; Ooi, Boon S.; Bowers, John E.; DenBaars, Steven P.; Speck, James S.; Cozzan, Clayton; Alyamani, Ahmed Y.

    2018-01-01

    diodes than the conventional c-plane counterparts. In addition, we demonstrate the first novel white lighting communication system by using our near-ultraviolet (NUV) LDs and pumping red-, green-, and blueemitting phosphors. This system satisfies both

  7. Molecular Beam Epitaxy-Grown InGaN Nanomushrooms and Nanowires for White Light Source Applications

    KAUST Repository

    Gasim, Anwar A.; Bhattacharya, Pallab K.; Cha, Dong Kyu; Ng, Tien Khee; Ooi, Boon S.

    2012-01-01

    We report the observation of coexisting InGaN nanomushrooms and nanowires grown via MBE. Photoluminescence characterization shows that the nanostructures emit yellow and blue light, respectively. The combined emission is promising for white-LEDs.

  8. Quantitative Light Fluorescence (QLF and Polarized White Light (PWL assessments of dental fluorosis in an epidemiological setting

    Directory of Open Access Journals (Sweden)

    Pretty Iain A

    2012-05-01

    Full Text Available Abstract Background To determine if a novel dual camera imaging system employing both polarized white light (PWL and quantitative light induced fluorescence imaging (QLF is appropriate for measuring enamel fluorosis in an epidemiological setting. The use of remote and objective scoring systems is of importance in fluorosis assessments due to the potential risk of examiner bias using clinical methods. Methods Subjects were recruited from a panel previously characterized for fluorosis and caries to ensure a range of fluorosis presentation. A total of 164 children, aged 11 years (±1.3 participated following consent. Each child was examined using the novel imaging system, a traditional digital SLR camera, and clinically using the Dean’s and Thylstrup and Fejerskov (TF Indices on the upper central and lateral incisors. Polarized white light and SLR images were scored for both Dean’s and TF indices by raters and fluorescence images were automatically scored using software. Results Data from 164 children were available with a good distribution of fluorosis severity. The automated software analysis of QLF images demonstrated significant correlations with the clinical examinations for both Dean’s and TF index. Agreement (measured by weighted Kappa’s between examiners scoring clinically, from polarized photographs and from SLR images ranged from 0.56 to 0.92. Conclusions The study suggests that the use of a digital imaging system to capture images for either automated software analysis, or remote assessment by raters is suitable for epidemiological work. The use of recorded images enables study archiving, assessment by multiple examiners, remote assessment and objectivity due to the blinding of subject status.

  9. Study and Implementation of White Power-LED Based Indoor Lighting Application for the Healthcare Sector

    Science.gov (United States)

    Chakraborty, A.; Ganguly, R.

    With the current technological growth in the field of device fabrication, white power-LED's are available for solid state lighting applications. This is a paradigm shift from electrical lighting to electronic lighting. The implemented systems are showing some promise by saving a considerable amount of energy as well as providing a good and acceptable illumination level. However, the `useful life' of such devices is an important parameter. If the proper device is not chosen, the desired reliability and performance will not be obtained. In the present work, different parameters associated with reliability of such LED's are studied. Four different varieties of LED's are put to test the `useful life' as per IESNA LM 79 standard. From the results obtained, the proper LED is chosen for further application. Subsequently, lighting design is done for a hospital waiting room (indoor application) with 24 × 7 lighting requirements for replacement of existing CFLs there. The calculations show that although the initial cost is higher for LED based lighting, yet the savings on energy and replacement of the lamp results in a payback time of less than a year.

  10. White emission from organic light-emitting diodes with a super-thin BCP layer

    Energy Technology Data Exchange (ETDEWEB)

    Hao Jingang [Key Laboratory of Luminescence and Optical Information, Ministry of Education, Institute of Optoelectronic Technology, Beijing Jiaotong University, Beijing 100044 (China); Deng Zhenbo [Key Laboratory of Luminescence and Optical Information, Ministry of Education, Institute of Optoelectronic Technology, Beijing Jiaotong University, Beijing 100044 (China)]. E-mail: zbdeng@center.njtu.edu.cn; Yang Shengyi [Key Laboratory of Luminescence and Optical Information, Ministry of Education, Institute of Optoelectronic Technology, Beijing Jiaotong University, Beijing 100044 (China)

    2007-01-15

    We report a method to achieve white emission from organic light-emitting diodes (OLEDs) in which a super-thin (3 nm) hole blocking layer, 2,9-dimethyl-4,7-diphenyl-1,10-phenanthroline (BCP), was inserted between electron-transport layer 8-hydroxyquinoline aluminum (Alq{sub 3}) and 4-(dicyanomethylene)-2-t-butyl-6(1,1,7,7-tetramethyljulolidyl-9-enyl) -4H-pyran (DCJTB) doped poly-vinlycarbazole (PVK) layer. The BCP layer can not only confine exciton in the emitting layer but also control energy transfer proportion from PVK to Alq{sub 3} and then from Alq{sub 3} to DCJTB through BCP layer. In this way, pure white emission with CIE coordinate of (0.32, 0.32) was obtained and it was voltage independent. The brightness reached 270 cd/m{sup 2} at 18 V with an efficiency of 0.166 cd/A.

  11. Lambertian white top-emitting organic light emitting device with carbon nanotube cathode

    Science.gov (United States)

    Freitag, P.; Zakhidov, Al. A.; Luessem, B.; Zakhidov, A. A.; Leo, K.

    2012-12-01

    We demonstrate that white organic light emitting devices (OLEDs) with top carbon nanotube (CNT) electrodes show almost no microcavity effect and exhibit essentially Lambertian emission. CNT top electrodes were applied by direct lamination of multiwall CNT sheets onto white small molecule OLED stack. The devices show an external quantum efficiency of 1.5% and high color rendering index of 70. Due to elimination of the cavity effect, the devices show good color stability for different viewing angles. Thus, CNT electrodes are a viable alternative to thin semitransparent metallic films, where the strong cavity effect causes spectral shift and non-Lambertian angular dependence. Our method of the device fabrication is simple yet effective and compatible with virtually any small molecule organic semiconductor stack. It is also compatible with flexible substrates and roll-to-roll fabrication.

  12. White emission from organic light-emitting diodes with a super-thin BCP layer

    International Nuclear Information System (INIS)

    Hao Jingang; Deng Zhenbo; Yang Shengyi

    2007-01-01

    We report a method to achieve white emission from organic light-emitting diodes (OLEDs) in which a super-thin (3 nm) hole blocking layer, 2,9-dimethyl-4,7-diphenyl-1,10-phenanthroline (BCP), was inserted between electron-transport layer 8-hydroxyquinoline aluminum (Alq 3 ) and 4-(dicyanomethylene)-2-t-butyl-6(1,1,7,7-tetramethyljulolidyl-9-enyl) -4H-pyran (DCJTB) doped poly-vinlycarbazole (PVK) layer. The BCP layer can not only confine exciton in the emitting layer but also control energy transfer proportion from PVK to Alq 3 and then from Alq 3 to DCJTB through BCP layer. In this way, pure white emission with CIE coordinate of (0.32, 0.32) was obtained and it was voltage independent. The brightness reached 270 cd/m 2 at 18 V with an efficiency of 0.166 cd/A

  13. Real-time Image Generation for Compressive Light Field Displays

    International Nuclear Information System (INIS)

    Wetzstein, G; Lanman, D; Hirsch, M; Raskar, R

    2013-01-01

    With the invention of integral imaging and parallax barriers in the beginning of the 20th century, glasses-free 3D displays have become feasible. Only today—more than a century later—glasses-free 3D displays are finally emerging in the consumer market. The technologies being employed in current-generation devices, however, are fundamentally the same as what was invented 100 years ago. With rapid advances in optical fabrication, digital processing power, and computational perception, a new generation of display technology is emerging: compressive displays exploring the co-design of optical elements and computational processing while taking particular characteristics of the human visual system into account. In this paper, we discuss real-time implementation strategies for emerging compressive light field displays. We consider displays composed of multiple stacked layers of light-attenuating or polarization-rotating layers, such as LCDs. The involved image generation requires iterative tomographic image synthesis. We demonstrate that, for the case of light field display, computed tomographic light field synthesis maps well to operations included in the standard graphics pipeline, facilitating efficient GPU-based implementations with real-time framerates.

  14. Eu/Tb ions co-doped white light luminescence Y2O3 phosphors

    International Nuclear Information System (INIS)

    Tu Dong; Liang Yujun; Liu Rong; Li Daoyi

    2011-01-01

    Y 2 O 3 :Eu 3+ , Tb 3+ phosphors with white emission are prepared with different doping concentration of Eu 3+ and Tb 3+ ions and synthesizing temperatures from 750 to 950 deg. C by the co-precipitation method. The resulted phosphors were characterized by X-ray diffraction (XRD) and photoluminescence (PL) spectroscopy. The results of XRD indicate that the crystallinity of the synthesized samples increases with enhancing the firing temperature. The photoluminescence spectra indicate the Eu 3+ and Tb 3+ co-doped Y 2 O 3 phosphors show five main emission peaks: three at 590, 611 and 629 nm originate from Eu 3+ and two at 481 and 541 nm originate from Tb 3+ , under excitation of 250-320 nm irradition. The white light luminescence color could be changed by varying the excitation wavelength. Different concentrations of Eu 3+ and Tb 3+ ions were induced into the Y 2 O 3 lattice and the energy transfer from Tb 3+ →Eu 3+ ions in these phosphors was found. The Commission International de l'Eclairage (CIE) chromaticity shows that the Y 2 O 3 :Eu 3+ , Tb 3+ phosphors can obtain an intense white emission. - Highlights: → Novel phosphors Y 2 O 3 :Eu 3+ , Tb 3+ have been synthesized by co-precipitation method. → Samples emit white light with excellent color coordinates under UV excitation. → Luminescence color could be changed by varying the excitation wavelength. → Energy transfer from Tb 3+ →Eu 3+ ions in these phosphors was found.

  15. Theoretical characterization of a class of orange dopants for white-light-emitting single polymers

    International Nuclear Information System (INIS)

    Hu, Bo; Yao, Chan; Wang, Qingwei; Zhang, Hao; Yu, Jiankang

    2012-01-01

    New single-polymer white electroluminescent systems containing two individual emission species − polyfluorene as a blue host and 2,1,3-benzothiadiazole(BTD) derivative as an orange dopant − have been designed and investigated on the basis of the quantum chemical calculations. Calculations show that the change of chemical composition along the backbone in BTD-based derivative yields modifications to the electronic and optical properties. Furthermore, by introducing electron-donating groups [−CH 3 , –OCH 3 , and –NH 2 ] on terminal N,N-disubstituted amino groups, desirable orange emission can be obtained and may be further combined with polyfluorene to form white light. Also, we estimate the reorganization energies upon cation or anion formation as one of the important parameters of mobility with the charge hopping model to determine whether the molecular structural changes may improve the hole/electron transport. The electrostatic surface potentials are finally taken into account to evaluate stability. -- Graphical abstract: New single-polymer white electroluminescent systems containing two individual emission species − polyfluorene as a blue host and 2,1,3-benzothiadiazole(BTD) derivative as an orange dopant − have been designed and investigated on the basis of the quantum chemical calculations. Highlights: ► The change of chemical composition along the backbone yields modifications to the electronic and optical properties. ► Introducing [–CH 3 , –OCH 3 , and –NH 2 ] on terminal N,N-disubstituted amino groups, desirable orange emission can be obtained. ► Desirable orange emission may be further combined with polyfluorene to form white light. ► Designed BTD-based derivatives can function as good hole or ambipolar transport materials in the OLEDs. ► According to the calculated electrostatic surface potentials, OMC-PZ has better stability than that of OMC-PZT.

  16. Evaluation of anogenital injuries using white and UV-light among adult volunteers following consensual sexual intercourse.

    Science.gov (United States)

    Joki-Erkkilä, Minna; Rainio, Juha; Huhtala, Heini; Salonen, Aki; Karhunen, Pekka J

    2014-09-01

    New clinical forensic examination techniques for sexual assaults have not been introduced over the last few decades. We evaluated the benefit of ultraviolet light compared to white light for detecting minor anogenital injuries and scars, following consensual sexual intercourse among adult volunteers. A prospective study comparing female genital findings utilising white and ultraviolet light. A colposcopy with photographic documentation was used. Personal invitation to healthcare students, hospital employees or acquaintances to volunteer for a gynecological examination, with a focus on clinical forensic aspects. Eighty-eight adult female volunteers were recruited for the study. The examination was performed after consensual intercourse. Age ranged from 20 to 52 years (median 26.5 years). Presence of acute findings and scars in the genital area using white and UV-light. Acute genital injury rate was 14.8% under white light colposcopy and 23.0% using UV light. Submucosal hemorrhages in the genital area were documented significantly better under UV-light than white light (14.9% vs. 6.8%; p=0.016), whereas petechiaes (4.5%) and abrasions (2.3%) were detected using either method. UV-light revealed significantly more often delivery-associated genital scars compared to white light (39.8% vs. 31.8%; p=0.016). Furthermore, 10 out of 31 (33.3%) women had no residual anogenital skin or mucosal surface findings, despite a prior episiotomy or rupture of the vaginal outlet wall during delivery, supporting its enormous ability to heal even after major trauma. UV-light may provide additional value for the evaluation of physical findings in clinical forensic examinations after sexual assault, and is especially useful in detecting otherwise invisible early submucosal hemorrhages and scars. Copyright © 2014 Elsevier Ireland Ltd. All rights reserved.

  17. Photoluminescence properties of white light emitting La2O3:Dy3+ nanocrystals

    Science.gov (United States)

    Reenabati Devi, Konsam; Dorendrajit Singh, Shougaijam; David Singh, Th.

    2018-01-01

    White light emitting nanocrystalline La2O3:Dy3+ phosphors with different concentration (0.5-2 at.%) were synthesized by simple precipitation method. X-ray diffraction (XRD) pattern indicates all the samples crystallizes in the hexagonal phase. Average crystallite sizes of the samples calculated from XRD data were found to be in the range of 20-55 nm. Transmission electron microscopy, selected area electron diffraction, energy dispersive analysis of X-ray and photoluminescence (PL) of the samples are also reported. Strong PL excitation peak due to charge transfer band was observed at 230 nm. Photoluminescence emission peaks observed at 486 and 575 nm were probably attributed to 4F9/2-6H15/2 and 4F9/2-6H13/2 of Dy3+ ions respectively. Optimum luminescence intensity is found at 1 at.% Dy3+ doped La2O3 sample. Further, Commission Internationale de l'é clairage (CIE, 1931) co-ordinates and correlated color temperature (CCT) of the doped sample were calculated to investigate the phosphors' performance and technical applicability of the emitted light respectively. CCT of the 0.5 and 1 at.% samples is 5894 K (white light), within the range of vertical daylight, which makes the synthesised samples promising nanophosphor and may find application in simulating vertical daylight of the Sun.

  18. Progress in characterizing the multidimensional color quality properties of white LED light sources

    Science.gov (United States)

    Teunissen, Kees; Hoelen, Christoph

    2016-03-01

    With the introduction of solid state light sources, the variety in emission spectra is almost unlimited. However, the set of standardized parameters to characterize a white LED light source, such as correlated color temperature (CCT) and CIE general color rendering index (Ra), is known to be limited and insufficient for describing perceived differences between light sources. Several characterization methods have been proposed over the past decades, but their contribution to perceived color quality has not always been validated. To gain more insight in the relevant characteristics of the emission spectra for specific applications, we have conducted a perception experiment to rate the attractiveness of three sets of objects, including fresh food, packaging materials and skin tones. The objects were illuminated with seven different combinations of Red, Green, Blue, Amber and White LEDs, all with the same CCT and illumination level, but with differences in Ra and color saturation. The results show that, in general, object attractiveness does not correlate well with Ra, but shows a positive correlation with saturation increase for two out of three applications. There is no clear relation between saturation and skin tone attractiveness, partly due to differences in preference between males and females. A relative gamut area index (Ga) represents the average change in saturation and a complementary color vector graphic shows the direction and magnitude of chromatic differences for the eight CIE-1974 test-color samples. Together with the CIE general color rendering index (Ra) they provide useful information for designing and optimizing application specific emission spectra.

  19. A white organic light emitting diode based on anthracene-triphenylamine derivatives

    Science.gov (United States)

    Jiang, Quan; Qu, Jianjun; Yu, Junsheng; Tao, Silu; Gan, Yuanyuan; Jiang, Yadong

    2010-10-01

    White organic lighting-diode (WOLED) can be used as flat light sources, backlights for liquid crystal displays and full color displays. Recently, a research mainstream of white OLED is to develop the novel materials and optimize the structure of devices. In this work a WOLED with a structure of ITO/NPB/PAA/Alq3: x% rubrene/Alq3/Mg: Ag, was fabricated. The device has two light-emitting layers. NPB is used as a hole transport layer, PAA as a blue emitting layer, Alq3: rubrene host-guest system as a yellow emitting layer, and Alq3 close to the cathode as an electron transport layer. In the experiment, the doping concentration of rubrene was optimized. WOLED 1 with 4% rubrene achieved a maximum luminous efficiency of 1.80 lm/W, a maximum luminance of 3926 cd/m2 and CIE coordinates of (0.374, 0.341) .WOLED 2 with 2% rubrene achieved a maximum luminous efficiency of 0.65 lm/W, a maximum luminance of 7495cd/m2 and CIE coordinates of (0.365,0.365).

  20. Diamond Light Source - A Next Generation SR Facility

    International Nuclear Information System (INIS)

    Materlik, G.

    2004-01-01

    After the very successful start and the by now almost 10 years operation of the 3rd generation x-ray sources ESRF, APS and Spring-8 smaller storage rings are being planned and constructed with properties emphasising applications with photon energies around the 10 keV spectral region. In the UK the Government and the medical foundation Wellcome Trust have decided to build the Diamond Light Source Facility in the South of Oxfordshire right next to the Rutherford Appleton Laboratory. The joint venture company Diamond Light Source Limited has been created to plan, construct, and operate this facility. (author)

  1. Nanopatterned yttrium aluminum garnet phosphor incorporated film for high-brightness GaN-based white light emitting diodes

    International Nuclear Information System (INIS)

    Cho, Joong-yeon; Park, Sang-Jun; Ahn, Jinho; Lee, Heon

    2014-01-01

    In this study, we fabricated high-brightness white light emitting diodes (LEDs) by developing a nanopatterned yttrium aluminum garnet (YAG) phosphor-incorporated film. White light can be obtained by mixing blue light from a GaN-based LED and yellow light of the YAG phosphor-incorporated film. If white light sources can be fabricated by exciting proper yellow phosphor using blue light, then these sources can be used instead of the conventional fluorescent lamps with a UV source, for backlighting of displays. In this work, a moth-eye structure was formed on the YAG phosphor-incorporated film by direct spin-on glass (SOG) printing. The moth-eye structures have been investigated to improve light transmittance in various optoelectronic devices, including photovoltaic solar cells, light emitting diodes, and displays, because of their anti-reflection property. Direct SOG printing, which is a simple, easy, and relatively inexpensive process, can be used to fabricate nanoscale structures. After direct SOG printing, the moth-eye structure with a diameter of 220 nm was formed uniformly on the YAG phosphor-incorporated film. As a result of moth-eye patterning on the YAG phosphor-incorporated film, the light output power of a white LED with a patterned YAG phosphor-incorporated film increased to up to 13% higher than that of a white LED with a non-patterned film. - Highlights: • GaN-based high-brightness white LED was prepared using patterned YAG phosphor-incorporated films. • Direct hydrogen silsesquioxane printing was used to form moth-eye patterns on the YAG films. • The electroluminescence intensity of the white LED was enhanced by up to 14.9%

  2. Nanopatterned yttrium aluminum garnet phosphor incorporated film for high-brightness GaN-based white light emitting diodes

    Energy Technology Data Exchange (ETDEWEB)

    Cho, Joong-yeon; Park, Sang-Jun [Department of Materials Science and Engineering, Korea University, Seoul 136-713 (Korea, Republic of); Ahn, Jinho, E-mail: jhahn@hanyang.ac.kr [Department of Material Science and Engineering, Hanyang University, Seoul 133-791 (Korea, Republic of); Lee, Heon, E-mail: heonlee@korea.ac.kr [Department of Materials Science and Engineering, Korea University, Seoul 136-713 (Korea, Republic of)

    2014-11-03

    In this study, we fabricated high-brightness white light emitting diodes (LEDs) by developing a nanopatterned yttrium aluminum garnet (YAG) phosphor-incorporated film. White light can be obtained by mixing blue light from a GaN-based LED and yellow light of the YAG phosphor-incorporated film. If white light sources can be fabricated by exciting proper yellow phosphor using blue light, then these sources can be used instead of the conventional fluorescent lamps with a UV source, for backlighting of displays. In this work, a moth-eye structure was formed on the YAG phosphor-incorporated film by direct spin-on glass (SOG) printing. The moth-eye structures have been investigated to improve light transmittance in various optoelectronic devices, including photovoltaic solar cells, light emitting diodes, and displays, because of their anti-reflection property. Direct SOG printing, which is a simple, easy, and relatively inexpensive process, can be used to fabricate nanoscale structures. After direct SOG printing, the moth-eye structure with a diameter of 220 nm was formed uniformly on the YAG phosphor-incorporated film. As a result of moth-eye patterning on the YAG phosphor-incorporated film, the light output power of a white LED with a patterned YAG phosphor-incorporated film increased to up to 13% higher than that of a white LED with a non-patterned film. - Highlights: • GaN-based high-brightness white LED was prepared using patterned YAG phosphor-incorporated films. • Direct hydrogen silsesquioxane printing was used to form moth-eye patterns on the YAG films. • The electroluminescence intensity of the white LED was enhanced by up to 14.9%.

  3. Warm White Light-Emitting Diodes Based on a Novel Orange Cationic Iridium(III) Complex.

    Science.gov (United States)

    Tang, Huaijun; Meng, Guoyun; Chen, Zeyu; Wang, Kaimin; Zhou, Qiang; Wang, Zhengliang

    2017-06-16

    A novel orange cationic iridium(III) complex [(TPTA)₂Ir(dPPOA)]PF₆ (TPTA: 3,4,5-triphenyl-4 H -1,2,4-triazole, dPPOA: N,N-diphenyl-4-(5-(pyridin-2-yl)-1,3,4-oxadiazol-2-yl)aniline) was synthesized and used as a phosphor in light-emitting diodes (LEDs). [(TPTA)₂Ir(dPPOA)]PF₆ has high thermal stability with a decomposition temperature ( T d ) of 375 °C, and its relative emission intensity at 100 °C is 88.8% of that at 25°C. When only [(TPTA)₂Ir(dPPOA)]PF₆ was used as a phosphor at 6.0 wt % in silicone and excited by a blue GaN (GaN: gallium nitride) chip (450 nm), an orange LED was obtained. A white LED fabricated by a blue GaN chip (450 nm) and only yellow phosphor Y₃Al₅O 12 :Ce 3+ (YAG:Ce) (1.0 wt % in silicone) emitted cold white light, its CIE (CIE: Commission International de I'Eclairage ) value was (0.32, 0.33), color rendering index (CRI) was 72.2, correlated color temperature (CCT) was 6877 K, and luminous efficiency ( η L ) was 128.5 lm∙W -1 . Such a cold white LED became a neutral white LED when [(TPTA)₂Ir(dPPOA)]PF₆ was added at 0.5 wt %; its corresponding CIE value was (0.35, 0.33), CRI was 78.4, CCT was 4896 K, and η L was 85.2 lm∙W -1 . It further became a warm white LED when [(TPTA)₂Ir(dPPOA)]PF₆ was added at 1.0 wt %; its corresponding CIE value was (0.39, 0.36), CRI was 80.2, CCT was 3473 K, and η L was 46.1 lm∙W -1 . The results show that [(TPTA)₂Ir(dPPOA)]PF₆ is a promising phosphor candidate for fabricating warm white LEDs.

  4. Comparison of the heat generation of light curing units.

    Science.gov (United States)

    Bagis, Bora; Bagis, Yildirim; Ertas, Ertan; Ustaomer, Seda

    2008-02-01

    The aim of this study was to evaluate the heat generation of three different types of light curing units. Temperature increases were recorded from a distance of 1 mm from a thermocouple to the tip of three different types of light curing units including one quartz-tungsten halogen (QTH), one plasma arc (PAC), and one light emitting diode (LED) unit. An experimental model was designed to fix the 1 mm distance between the tip of the light curing units and the thermocouple wire. Temperature changes were recorded in 10 second intervals up to 40 seconds. (10, 20, 30, and 40 seconds). Temperature measurements were repeated three times for every light curing unit after a one hour standby period. Statistical analysis of the results was performed using the analysis of variance (ANOVA) and the Bonferroni Test. The highest temperature rises (54.4+/-1.65 degrees C) occurred during activation of a PAC light curing unit for every test period (pdamage to the pulp.

  5. Morning sleep inertia in alertness and performance: effect of cognitive domain and white light conditions.

    Directory of Open Access Journals (Sweden)

    Nayantara Santhi

    Full Text Available The transition from sleep to wakefulness entails a temporary period of reduced alertness and impaired performance known as sleep inertia. The extent to which its severity varies with task and cognitive processes remains unclear. We examined sleep inertia in alertness, attention, working memory and cognitive throughput with the Karolinska Sleepiness Scale (KSS, the Psychomotor Vigilance Task (PVT, n-back and add tasks, respectively. The tasks were administered 2 hours before bedtime and at regular intervals for four hours, starting immediately after awakening in the morning, in eleven participants, in a four-way cross-over laboratory design. We also investigated whether exposure to Blue-Enhanced or Bright Blue-Enhanced white light would reduce sleep inertia. Alertness and all cognitive processes were impaired immediately upon awakening (p<0.01. However, alertness and sustained attention were more affected than cognitive throughput and working memory. Moreover, speed was more affected than accuracy of responses. The light conditions had no differential effect on performance except in the 3-back task (p<0.01, where response times (RT at the end of four hours in the two Blue-Enhanced white light conditions were faster (200 ms than at wake time. We conclude that the effect of sleep inertia varies with cognitive domain and that it's spectral/intensity response to light is different from that of sleepiness. That is, just increasing blue-wavelength in light may not be sufficient to reduce sleep inertia. These findings have implications for critical professions like medicine, law-enforcement etc., in which, personnel routinely wake up from night-time sleep to respond to emergency situations.

  6. Efficiency and stability of a phosphor-conversion white light source using a blue laser diode

    Directory of Open Access Journals (Sweden)

    G. Ledru

    2014-10-01

    Full Text Available A white light source using direct phosphor-conversion excited by a blue laser diode is presented. In this preliminary study we have investigated the influence of phosphor’s thickness and operating current of the laser diode over the (x, y chromaticity coordinates, Correlated Color Temperature (CCT and Color Rendering Index (CRI. The best values found were 4000 K and 94. A 40 lm/W luminous efficacy was achieved together with a CRI close to 90 for an operating current of 0.8 A. Those values, to the best of our knowledge, were not previously reported in the literature.

  7. The Concept of Fashion Design on the Basis of Color Coordination Using White LED Lighting

    Science.gov (United States)

    Mizutani, Yumiko; Taguchi, Tsunemasa

    This thesis focuses on the development of fashion design, especially a dress coordinated with White LED Lighting (=LED). As for the design concept a fusion of the advanced science and local culture was aimed for. For such a reason this development is a very experimental one. Here in particular I handled an Imperial Court dinner dress for the last Japanese First Lady, Mrs. Akie Abe who wore it at the Imperial Court dinner for the Indonesian First Couple held on November 2006 to. This dress made by Prof. T. Taguchi and I open up a new field in the dress design.

  8. Polaron Self-localization in White-light Emitting Hybrid Perovskites

    OpenAIRE

    Cortecchia, Daniele; Yin, Jun; Bruno, Annalisa; Lo, Shu-Zee Alencious; Gurzadyan, Gagik G.; Mhaisalkar, Subodh; Brédas, Jean-Luc; Soci, Cesare

    2016-01-01

    Two-dimensional (2D) perovskites with general formula $APbX_4$ are attracting increasing interest as solution processable, white-light emissive materials. Recent studies have shown that their broadband emission is related to the formation of intra-gap color centers; however, the nature and dynamics of the emissive species have remained elusive. Here we show that the broadband photoluminescence of the 2D perovskites $(EDBE)PbCl_4$ and $(EDBE)PbBr_4$ stems from the localization of small polaron...

  9. Color selectivity of surface-plasmon holograms illuminated with white light.

    Science.gov (United States)

    Ozaki, Miyu; Kato, Jun-ichi; Kawata, Satoshi

    2013-09-20

    By using the optical frequency dependence of surface-plasmon polaritons, color images can be reconstructed from holograms illuminated with white light. We report details on the color selectivity of the color holograms. The selectivity is tuned by the thickness of a dielectric film covering a plasmonic metal film. When the dielectric is SiO(2) and the metal is silver, the appropriate thicknesses are 25 and 55 nm, respectively. In terms of spatial color uniformity, holograms made of silver-film corrugations are better than holograms recorded on photographic film on a flat silver surface.

  10. Clean Cities Strategic Planning White Paper: Light Duty Vehicle Fuel Economy

    Energy Technology Data Exchange (ETDEWEB)

    Saulsbury, Bo [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Hopson, Dr Janet L [Univ. of Tennessee, Knoxville, TN (United States); Greene, David [Univ. of Tennessee, Knoxville, TN (United States); Gibson, Robert [Univ. of Tennessee, Knoxville, TN (United States)

    2015-04-01

    Increasing the energy efficiency of motor vehicles is critical to achieving national energy goals of reduced petroleum dependence, protecting the global climate, and promoting continued economic prosperity. Even with fuel economy and greenhouse gas emissions standards and various economic incentives for clean and efficient vehicles, providing reliable and accurate fuel economy information to the public is important to achieving these goals. This white paper reviews the current status of light-duty vehicle fuel economy in the United States and the role of the Department of Energy (DOE) Clean Cities Program in disseminating fuel economy information to the public.

  11. Quantitative description of charge-carrier transport in a white organic light-emitting diode

    Science.gov (United States)

    Schober, M.; Anderson, M.; Thomschke, M.; Widmer, J.; Furno, M.; Scholz, R.; Lüssem, B.; Leo, K.

    2011-10-01

    We present a simulation model for the analysis of charge-carrier transport in organic thin-film devices, and apply it to a three-color white hybrid organic light-emitting diode (OLED) with fluorescent blue and phosphorescent red and green emission. We simulate a series of single-carrier devices, which reconstruct the OLED layer sequence step by step. Thereby, we determine the energy profiles for hole and electron transport, show how to discern bulk from interface limitation, and identify trap states.

  12. Inhibition of white light of 86Rb+ absorption in the root apex of corn

    International Nuclear Information System (INIS)

    McKendree, W.L.; Smith, R.C.

    1990-01-01

    Measurements of cell lengths made at 0.5 millimeter intervals in median longitudinal sections of the primary roots of corn (Zea mays) were used to construct a growth curve. The region 1.5 to 4.0 millimeters from the apex contained the largest number of elongating cells. Absorption of 86 Rb + was measured using intact, dark-grown corn seedlings. Following uptake and exchange, the terminal 8.0 millimeters of each root was cut into four 2.0 millimeter segments. Maximum 86 Rb + uptake occurred in the region from 0.0 to 4.0 millimeter from the root tip. Washing the intact primary root in fresh 2.0 millimolar CaSO 4 for 2 hours prior to uptake augmented the rate of 86 Rb + uptake in all regions. Illumination with white light during washing caused a reduction of 86 Rb + uptake as compared with controls washing in darkness, and the region of greatest light response was the region of elongation. Removal of the coleoptile prior to washing did not prevent the light inhibition of subsequent 86 Rb + uptake. Removal of the root cap prior to washing in light partially reversed the light-induced inhibition of the washing response

  13. Color-converted remote phosphor prototype of a multiwavelength excitable borosilicate glass for white light-emitting diodes

    International Nuclear Information System (INIS)

    Tian Hua; Qiu Kun; Song Jun; Wang Da-Jian; Liu Ji-Wen

    2012-01-01

    We report a unique red light-emitting Eu-doped borosilicate glass to convert color for warm white light-emitting diodes. This glass can be excited from 394 nm-peaked near ultraviolet light, 466 nm-peaked blue light, to 534 nm-peaked green light to emit the desired red light with an excellent transmission in the wavelength range of 400–700 nm which makes this glass suitable for color conversion without a great cost of luminous power loss. In particular, when assembling this glass for commercial white light-emitting diodes, the tested results show that the color rendering index is improved to 84 with a loss of luminous power by 12 percent at average, making this variety of glass promising for inorganic “remote-phosphor” color conversion

  14. Dynamic generation of light states with discrete symmetries

    Science.gov (United States)

    Cordero, S.; Nahmad-Achar, E.; Castaños, O.; López-Peña, R.

    2018-01-01

    A dynamic procedure is established within the generalized Tavis-Cummings model to generate light states with discrete point symmetries, given by the cyclic group Cn. We consider arbitrary dipolar coupling strengths of the atoms with a one-mode electromagnetic field in a cavity. The method uses mainly the matter-field entanglement properties of the system, which can be extended to any number of three-level atoms. An initial state constituted by the superposition of two states with definite total excitation numbers, |ψ〉 M1,and |ψ〉 M 2, is considered. It can be generated by the proper selection of the time of flight of an atom passing through the cavity. We demonstrate that the resulting Husimi function of the light is invariant under cyclic point transformations of order n =| M1-M2| .

  15. Ca8Mg(SiO4)4Cl2:Ce3+, Tb3+: A potential single-phased phosphor for white-light-emitting diodes

    International Nuclear Information System (INIS)

    Zhu Ge; Wang Yuhua; Ci Zhipeng; Liu Bitao; Shi Yurong; Xin Shuangyu

    2012-01-01

    A single-phased white-light-emitting phosphor Ca 8 Mg(SiO 4 ) 4 Cl 2 :Ce 3+ , Tb 3+ (CMSC:Ce 3+ , Tb 3+ ) is synthesized by a high temperature solid-state reaction method, and its photoluminescence properties are investigated. The obtained phosphor exhibits a strong excitation band between 250 and 410 nm, matching well with the dominant emission band of a UV light-emitting-diode (LED) chip. Energy transfer from Ce 3+ to Tb 3+ ions has been investigated and demonstrated to be a resonant type via a dipole–dipole mechanism. The energy transfer efficiency as well as the critical distance is also estimated. Furthermore, the phosphors can generate light from yellow-green through white and eventually to blue by properly tuning the relative ratio of Ce 3+ to Tb 3+ ions grounded on the principle of energy transfer. The results show that this phosphor has potential applications as a single-phased phosphor for UV white-light LEDs. - Highlights: ► The luminescence properties of Ca 8 Mg(SiO 4 ) 4 Cl 2 :Ce 3+ , Tb 3+ were investigated for the first time. ► The strong absorption of phosphors matches well with the emission band of UV LED chips. ► The energy transfer from Ce 3+ to Tb 3+ in Ca 8 Mg(SiO 4 ) 4 Cl 2 was investigated in detail. ► The white light (CIE=(0.29, 0.34)) is generated by tuning the relative ratio of Ce 3+ to Tb 3+ .

  16. White light photothermal lens spectrophotometer for the determination of absorption in scattering samples.

    Science.gov (United States)

    Marcano, Aristides; Alvarado, Salvador; Meng, Junwei; Caballero, Daniel; Moares, Ernesto Marín; Edziah, Raymond

    2014-01-01

    We developed a pump-probe photothermal lens spectrophotometer that uses a broadband arc-lamp and a set of interference filters to provide tunable, nearly monochromatic radiation between 370 and 730 nm as the pump light source. This light is focused onto an absorbing sample, generating a photothermal lens of millimeter dimensions. A highly collimated monochromatic probe light from a low-power He-Ne laser interrogates the generated lens, yielding a photothermal signal proportional to the absorption of light. We measure the absorption spectra of scattering dye solutions using the device. We show that the spectra are not affected by the presence of scattering, confirming that the method only measures the absorption of light that results in generation of heat. By comparing the photothermal spectra with the usual absorption spectra determined using commercial transmission spectrophotometers, we estimate the quantum yield of scattering of the sample. We discuss applications of the device for spectroscopic characterization of samples such as blood and gold nanoparticles that exhibit a complex behavior upon interaction with light.

  17. White light emission from organic-inorganic hererostructure devices by using CdSe quantum dots as emitting layer

    International Nuclear Information System (INIS)

    Tang Aiwei; Teng Feng; Gao Yinhao; Li Dan; Zhao Suling; Liang Chunjun; Wang Yongsheng

    2007-01-01

    In this paper, white light emission was obtained from organic-inorganic heterostructure devices by using CdSe quantum dots as emitting layer, in which CdSe quantum dots were synthesized via a colloidal chemical approach by using CdO and Se powder as precursors. Photoluminescence of CdSe quantum dots demonstrated a white emission with a full wavelength at half maximum (FWHM) of about 200 nm under ambient conditions, and the white emission could be observed in both multilayer device ITO/PEDOT:PSS/CdSe/BCP/Alq 3 /Al and single-layer device: ITO/PEDOT:PSS/CdSe/Al. The broad emission was attributed to the inhomogeneous broadening. The CIE coordinates of the multilayer device were x=0.35 and y=0.40. The white-light-emitting diodes with CdSe quantum dots as the emitting layer are potentially useful in lighting applications

  18. Host-free, yellow phosphorescent material in white organic light-emitting diodes

    Energy Technology Data Exchange (ETDEWEB)

    Lee, Meng-Ting; Chu, Miao-Tsai; Lin, Jin-Sheng; Tseng, Mei-Rurng, E-mail: osolomio.ac89g@nctu.edu.t [Material and Chemical Research Laboratories, Industrial Technology Research Institute (ITRI), Hsinchu, Taiwan 310 (China)

    2010-11-10

    A white organic light-emitting diode (WOLED) with a high power efficiency has been demonstrated by dispersing a host-free, yellow phosphorescent material in between double blue phosphorescent emitters. The device performance achieved a comparable value to that of using a complicated host-guest doping system to form the yellow emitter in WOLEDs. Based on this device concept as well as the molecular engineering of blue phosphorescent host material and light-extraction film, a WOLED with a power efficiency of 65 lm W{sup -1} at a practical brightness of 1000 cd m{sup -2} with Commission Internationale d'Echariage coordinates (CIE{sub x,y}) of (0.37, 0.47) was achieved. (fast track communication)

  19. [White organic light emitting device with dyestuff DCJTB blended in polymer].

    Science.gov (United States)

    Zhang, Yan-Fei; Xu, Zheng; Zhang, Fu-Jun; Wang, Yong; Zhao, Su-Ling

    2008-04-01

    The Alq3 and DCJTB were blended with poly (N-vinylcarbazole) (PVK) in different weight ratios and spin coated into films. Multilayer devices with the light emitting layer PVK : Alq3 : DCJTB were fabricated, and their structure was ITO/ PVK : Alq3 : DCJTB/ BCP/Alq3/LiF/Al in which BCP and Alq3 were employed as the hole-blocking and electron-transporting layers respectively, PVK is the blue light-emitting as well as hole-transporting layer. The mass proportion of PVK relative to Alq3 was tuned while the quality ratio of PVK to DCJTB remained (100 : 1). Finally, fairly pure and stabile white emission was achieved when PVK : Alq3 : DCJTB was 100 : 5 : 1. The CIE coordinate was (0.33, 0.36) at 14 V, which is very stable at various biases (10-14 V).

  20. White-light-emitting diode based on a single-layer polymer

    Science.gov (United States)

    Wang, B. Z.; Zhang, X. P.; Liu, H. M.

    2013-05-01

    A broad-band light-emitting diode was achieved in a single-layer device based on pure poly(9,9'-dioctylfluorene-co-bis-N,N'-(4-butylphenyl)-bis-N,N'-phenyl-1,4-phenylenediamine) (PFB). Electromer emission was observed in the red with a center wavelength of about 620 nm in electroluminescence (EL) spectrum. This kind of emission exhibits strong dependence on the thickness of the PFB layer, so that the shape of the EL spectrum may be adjusted through changing the thickness of the active polymer layer to balance between the intrinsic PFB emission in the blue and the electromer emission in the red. Thus, white light emission may be achieved from such a single-layer single-material diode.

  1. Steady full colour white organic light-emitting devices consisting of an ultrathin red fluorescent layer

    International Nuclear Information System (INIS)

    Wen Wen; Yu Junsheng; Li Lu; Wang Jun; Jiang Yadong

    2009-01-01

    White organic light-emitting devices were fabricated using an ultrathin red fluorescent dye of 3-(dicyanomethylene)-5, 5-dimethyl-1-(4-dimethylamino-styryl)cyclohexene inserted in tris(8-quinolinolato) aluminium layer as a red and green emitting layer (EML) and a thin 4, 4'-bis(2, 2'-diphenylvinyl)-1, 1'-diphenyl (DPVBi) layer as blue EML. A maximum power efficiency of 2.4 lm W -1 at 5.5 V and a maximum luminance of 16 690 cd m -2 at 18.5 V were obtained. Pure white emission with a good colour rendering index of 80 was achieved as low as 5 V. The Commission Internationale de l'Eclairage (CIE) coordinates near (0.330, 0.300) show a slight variation of (-0.020, +0.002) in a wide range of voltages. The achievement of full colour white emission at low-operation voltages and high-colour stability is attributed to the confining emission zone function of the thin EML and direct carrier trapping in the ultrathin layer.

  2. Steady full colour white organic light-emitting devices consisting of an ultrathin red fluorescent layer

    Energy Technology Data Exchange (ETDEWEB)

    Wen Wen; Yu Junsheng; Li Lu; Wang Jun; Jiang Yadong [State Key Laboratory of Electronic Thin Films and Integrated Devices, School of Optoelectronic Information, University of Electronic Science and Technology of China (UESTC), Chengdu 610054 (China)], E-mail: jsyu@uestc.edu.cn

    2009-01-07

    White organic light-emitting devices were fabricated using an ultrathin red fluorescent dye of 3-(dicyanomethylene)-5, 5-dimethyl-1-(4-dimethylamino-styryl)cyclohexene inserted in tris(8-quinolinolato) aluminium layer as a red and green emitting layer (EML) and a thin 4, 4'-bis(2, 2'-diphenylvinyl)-1, 1'-diphenyl (DPVBi) layer as blue EML. A maximum power efficiency of 2.4 lm W{sup -1} at 5.5 V and a maximum luminance of 16 690 cd m{sup -2} at 18.5 V were obtained. Pure white emission with a good colour rendering index of 80 was achieved as low as 5 V. The Commission Internationale de l'Eclairage (CIE) coordinates near (0.330, 0.300) show a slight variation of (-0.020, +0.002) in a wide range of voltages. The achievement of full colour white emission at low-operation voltages and high-colour stability is attributed to the confining emission zone function of the thin EML and direct carrier trapping in the ultrathin layer.

  3. Highly efficient blue and warm white organic light-emitting diodes with a simplified structure

    International Nuclear Information System (INIS)

    Li, Xiang-Long; Chen, Dongcheng; Cai, Xinyi; Liu, Ming; Cao, Yong; Su, Shi-Jian; Ouyang, Xinhua; Ge, Ziyi

    2016-01-01

    Two blue fluorescent emitters were utilized to construct simplified organic light-emitting diodes (OLEDs) and the remarkable difference in device performance was carefully illustrated. A maximum current efficiency of 4.84 cd A"−"1 (corresponding to a quantum efficiency of 4.29%) with a Commission Internationale de l’Eclairage (CIE) coordinate of (0.144, 0.127) was achieved by using N,N-diphenyl-4″-(1-phenyl-1H-benzo[d]imidazol-2-yl)-[1, 1′:4′, 1″-terphenyl]-4-amine (BBPI) as a non-doped emission layer of the simplified blue OLEDs without carrier-transport layers. In addition, simplified fluorescent/phosphorescent (F/P) hybrid warm white OLEDs without carrier-transport layers were fabricated by utilizing BBPI as (1) the blue emitter and (2) the host of a complementary yellow phosphorescent emitter (PO-01). A maximum current efficiency of 36.8 cd A"−"1 and a maximum power efficiency of 38.6 lm W"−"1 were achieved as a result of efficient energy transfer from the host to the guest and good triplet exciton confinement on the phosphorescent molecules. The blue and white OLEDs are among the most efficient simplified fluorescent blue and F/P hybrid white devices, and their performance is even comparable to that of most previously reported complicated multi-layer devices with carrier-transport layers. (paper)

  4. Efficient non-doped phosphorescent orange, blue and white organic light-emitting devices

    Science.gov (United States)

    Yin, Yongming; Yu, Jing; Cao, Hongtao; Zhang, Letian; Sun, Haizhu; Xie, Wenfa

    2014-10-01

    Efficient phosphorescent orange, blue and white organic light-emitting devices (OLEDs) with non-doped emissive layers were successfully fabricated. Conventional blue phosphorescent emitters bis [4,6-di-fluorophenyl]-pyridinato-N,C2'] picolinate (Firpic) and Bis(2,4-difluorophenylpyridinato) (Fir6) were adopted to fabricate non-doped blue OLEDs, which exhibited maximum current efficiency of 7.6 and 4.6 cd/A for Firpic and Fir6 based devices, respectively. Non-doped orange OLED was fabricated utilizing the newly reported phosphorescent material iridium (III) (pbi)2Ir(biq), of which manifested maximum current and power efficiency of 8.2 cd/A and 7.8 lm/W. The non-doped white OLEDs were achieved by simply combining Firpic or Fir6 with a 2-nm (pbi)2Ir(biq). The maximum current and power efficiency of the Firpic and (pbi)2Ir(biq) based white OLED were 14.8 cd/A and 17.9 lm/W.

  5. Next generation smart window display using transparent organic display and light blocking screen.

    Science.gov (United States)

    Kim, Gyeong Woo; Lampande, Raju; Choe, Dong Cheol; Ko, Ik Jang; Park, Jin Hwan; Pode, Ramchandra; Kwon, Jang Hyuk

    2018-04-02

    Transparent organic light emitting diodes (TOLED) have widespread applications in the next-generation display devices particularly in the large size transparent window and interactive displays. Herein, we report high performance and stable attractive smart window displays using facile process. Advanced smart window display is realized by integrating the high performance light blocking screen and highly transparent white OLED panel. The full smart window display reveals a maximum transmittance as high as 64.2% at the wavelength of 600 nm and extremely good along with tunable ambient contrast ratio (171.94:1) compared to that of normal TOLED (4.54:1). Furthermore, the performance decisive light blocking screen has demonstrated an excellent optical and electrical characteristics such as i) high transmittance (85.56% at 562nm) at light-penetrating state, ii) superior absorbance (2.30 at 562nm) in light interrupting mode, iii) high optical contrast (85.50 at 562 nm), iv) high optical stability for more than 25,000 cycle of driving, v) fast switching time of 1.9 sec, and vi) low driving voltage of 1.7 V. The experimental results of smart window display are also validated using optical simulation. The proposed smart window display technology allows us to adjust the intensity of daylight entering the system quickly and conveniently.

  6. Assessment of the SRI Gasification Process for Syngas Generation with HTGR Integration -- White Paper

    Energy Technology Data Exchange (ETDEWEB)

    A.M. Gandrik

    2012-04-01

    This white paper is intended to compare the technical and economic feasibility of syngas generation using the SRI gasification process coupled to several high-temperature gas-cooled reactors (HTGRs) with more traditional HTGR-integrated syngas generation techniques, including: (1) Gasification with high-temperature steam electrolysis (HTSE); (2) Steam methane reforming (SMR); and (3) Gasification with SMR with and without CO2 sequestration.

  7. Full phosphorescent white-light organic light-emitting diodes with improved color stability and efficiency by fine tuning primary emission contributions

    Directory of Open Access Journals (Sweden)

    Wang Hua

    2014-02-01

    Full Text Available In this paper, a novel type of white-light organic light emitting diode (OLED with high color stability was reported, in which the yellow-light emission layer of (4,4′-N,N′-dicarbazolebiphenyl (CBP : tris(2-phenylquinoline-C2,N′iridium(III (Ir(2-phq3 was sandwiched by double blue-light emission layers of 1,1-bis-[(di-4-tolylaminopheny1]cyclohexane (TAPC : bis[4,6-(di-fluorophenyl-pyridinato-N,C2′]picolinate (FIrpic and tris[3-(3-pyridylmesityl]borane (3TPYMB:FIrpic. And, it exhibited the maximum current efficiency of 33.1 cd/A, the turn-on voltage at about 3 V and the maximum luminance in excess of 20000 cd/m2. More important, it realized very stable white-light emission, and its CIE(x, y coordinates only shift from (0.34, 0.37 to (0.33, 0.37 as applied voltage increased from 5 V to 12 V. It is believed that the new scheme in emission layer of white-light OLED can fine tune the contribution of primary emission with applied voltage changed, resulting in high quality white-light OLED.

  8. Full phosphorescent white-light organic light-emitting diodes with improved color stability and efficiency by fine tuning primary emission contributions

    Energy Technology Data Exchange (ETDEWEB)

    Hua, Wang, E-mail: wmsu2008@sinano.ac.cn, E-mail: wanghua001@tyut.edu.cn; Du, Xiaogang [Key Laboratory of Interface Science and Engineering in Advanced Materials, Taiyuan University of Technology, Ministry of Education, Taiyuan 030024 (China); Research Center of Advanced Materials Science and Technology, Taiyuan University of Technology, Taiyuan 030024 (China); Su, Wenming, E-mail: wmsu2008@sinano.ac.cn, E-mail: wanghua001@tyut.edu.cn; Zhang, Dongyu [Printable Electronics Research Centre, Suzhou Institute of Nano-Tech and Nano-Bionics, CAS, suzhou 215123 (China); Lin, Wenjing [Key Laboratory of Interface Science and Engineering in Advanced Materials, Taiyuan University of Technology, Ministry of Education, Taiyuan 030024 (China); Research Center of Advanced Materials Science and Technology, Taiyuan University of Technology, Taiyuan 030024 (China); Printable Electronics Research Centre, Suzhou Institute of Nano-Tech and Nano-Bionics, CAS, suzhou 215123 (China)

    2014-02-15

    In this paper, a novel type of white-light organic light emitting diode (OLED) with high color stability was reported, in which the yellow-light emission layer of (4,4{sup ′}-N,N{sup ′}-dicarbazole)biphenyl (CBP) : tris(2-phenylquinoline-C2,N{sup ′})iridium(III) (Ir(2-phq){sub 3}) was sandwiched by double blue-light emission layers of 1,1-bis-[(di-4-tolylamino)pheny1]cyclohexane (TAPC) : bis[4,6-(di-fluorophenyl)-pyridinato-N,C2{sup ′}]picolinate (FIrpic) and tris[3-(3-pyridyl)mesityl]borane (3TPYMB):FIrpic. And, it exhibited the maximum current efficiency of 33.1 cd/A, the turn-on voltage at about 3 V and the maximum luminance in excess of 20000 cd/m{sup 2}. More important, it realized very stable white-light emission, and its CIE(x, y) coordinates only shift from (0.34, 0.37) to (0.33, 0.37) as applied voltage increased from 5 V to 12 V. It is believed that the new scheme in emission layer of white-light OLED can fine tune the contribution of primary emission with applied voltage changed, resulting in high quality white-light OLED.

  9. Full phosphorescent white-light organic light-emitting diodes with improved color stability and efficiency by fine tuning primary emission contributions

    Science.gov (United States)

    Hua, Wang; Du, Xiaogang; Su, Wenming; Lin, Wenjing; Zhang, Dongyu

    2014-02-01

    In this paper, a novel type of white-light organic light emitting diode (OLED) with high color stability was reported, in which the yellow-light emission layer of (4,4'-N,N'-dicarbazole)biphenyl (CBP) : tris(2-phenylquinoline-C2,N')iridium(III) (Ir(2-phq)3) was sandwiched by double blue-light emission layers of 1,1-bis-[(di-4-tolylamino)pheny1]cyclohexane (TAPC) : bis[4,6-(di-fluorophenyl)-pyridinato-N,C2']picolinate (FIrpic) and tris[3-(3-pyridyl)mesityl]borane (3TPYMB):FIrpic. And, it exhibited the maximum current efficiency of 33.1 cd/A, the turn-on voltage at about 3 V and the maximum luminance in excess of 20000 cd/m2. More important, it realized very stable white-light emission, and its CIE(x, y) coordinates only shift from (0.34, 0.37) to (0.33, 0.37) as applied voltage increased from 5 V to 12 V. It is believed that the new scheme in emission layer of white-light OLED can fine tune the contribution of primary emission with applied voltage changed, resulting in high quality white-light OLED.

  10. Color optimization of conjugated-polymer/InGaN hybrid white light emitting diodes by incomplete energy transfer

    International Nuclear Information System (INIS)

    Chang, Chi-Jung; Lai, Chun-Feng; Madhusudhana Reddy, P.; Chen, Yung-Lin; Chiou, Wei-Yung; Chang, Shinn-Jen

    2015-01-01

    By using the wavelength conversion method, white light emitting diodes (WLEDs) were produced by applying mixtures of polysiloxane and fluorescent polymers on InGaN based light emitting diodes. UV curable organic–inorganic hybrid materials with high refractive index (1.561), compromised optical, thermal and mechanical properties was used as encapsulants. Red light emitting fluorescent FABD polymer (with 9,9-dioctylfluorene (F), anthracene (A) and 2,1,3-benzothiadiazole (B), and 4,7-bis(2-thienyl)-2,1,3-benzothiadiazole (D) repeating units) and green light emitting fluorescent FAB polymer were used as wavelength converters. The encapsulant/fluorescent polymer mixture and InGaN produce the white light by incomplete energy transfer mechanism. WLEDs with high color rendering index (CRI, about 93), and tunable correlated color temperature (CCT) properties can be produced by controlling the composition and chemical structures of encapsulating polymer and fluorescent polymer in hybrid materials, offering cool-white and neutral-white LEDs. - Highlights: • Highly efficient white light-emitting diodes (WLEDs) were produced. • Conjugated-polymer/InGaN hybrid WLEDs by incomplete energy transfer mechanism. • WLEDs with high color-rendering index and tunable correlated color temperature. • Polysiloxane encapsulant with superior optical, mechanical and thermal properties

  11. Status and prospect of third-generation light sources

    International Nuclear Information System (INIS)

    Kihara, Motohiro

    1997-01-01

    The third generation synchrotron radiation facilities, of which the constructions are advanced in the world, the present status in Japan centering around the SPring-8 which started the operation recently, and the expected researches are reported. Also the future prospect is described. PF (2.5 GeV), SRS (2 GeV) and NSLS (2.5 GeV) were the second generation facilities in Japan, Europe and USA, respectively. The new technology for the third generation appeared in latter 1970s, and one of them is 'inserted light source'. The epoch-making development is the concept of low emittance ring. The third generation facilities are the new facilities which enable high brilliance synchrotron radiation by combining undulator with this low emittance ring. The features of the third generation synchrotron radiation are shown. The third generation facilities in X-ray and soft X-ray regions in operation and planning stage in the world are listed. In Japan, the SPring-8 on the largest scale in the world was completed, and the plans of University of Tokyo and Tohoku University are presented. These are explained. As the expected researches using the third generation facilities, the research on phase type X-ray CT, the utilization of micro-beam and others are mentioned. (K.I.)

  12. Effect of Annealing Time of YAG:Ce3+ Phosphor on White Light Chromaticity Values

    Science.gov (United States)

    Abd, Husnen R.; Hassan, Z.; Ahmed, Naser M.; Almessiere, Munirah Abdullah; Omar, A. F.; Alsultany, Forat H.; Sabah, Fayroz A.; Osman, Ummu Shuhada

    2018-02-01

    Yttrium and aluminium nitrate phosphors doped with cerium nitrate and mixed with urea (fuel) are prepared by using microwave-induced combustion synthesis according to the formula Y(3-0.06)Al5O12:0.06Ce3+ (YAG:Ce3+) to produce white light emitting diodes by conversion from blue indium gallium nitride-light emitting diode chips. The sintering time with fixed temperature (1050°C) for phosphor powder was optimized and found to be 5 h. The crystallinity, structure, chemical composition, luminescent properties with varying currents densities and chromaticity were characterized by x-ray diffraction, field emission-scanning electron microscopy, transmission electron microscopy, energy dispersive spectroscopy, photoluminescence emission, electroluminescence and standard CIE 1931 chromaticity diagram, respectively. The energy levels of Ce3+ in YAG were discussed based on its absorption and excitation spectra. The results show that the obtained YAG:Ce3+ phosphor sintered for 5 h has good crystallinity with pure phase, low agglomerate with spherical shaped particles and strong yellow emission, offering cool-white LED with tuneable correlated color temperature and a good color rendering index compared to those prepared by sintering for 2 h and as-prepared phosphor powders.

  13. Suppression of Hydrogen Emission in an X-class White-light Solar Flare

    Energy Technology Data Exchange (ETDEWEB)

    Procházka, Ondrej; Milligan, Ryan O.; Mathioudakis, Mihalis [Astrophysics Research Centre, Queen’s University Belfast, Northern Ireland (United Kingdom); Allred, Joel C. [NASA Goddard Space Flight Center, Greenbelt, MD 20771 (United States); Kowalski, Adam F. [Department of Astrophysical and Planetary Sciences, University of Colorado Boulder, 2000 Colorado Avenue, Boulder, CO 80305 (United States); Kotrč, Pavel, E-mail: oprochazka01@qub.ac.uk [Astronomical Institute, The Czech Academy of Sciences, 25165 Ondřejov (Czech Republic)

    2017-03-01

    We present unique NUV observations of a well-observed X-class flare from NOAA 12087 obtained at the Ondřejov Observatory. The flare shows a strong white-light continuum but no detectable emission in the higher Balmer and Lyman lines. Reuven Ramaty High-Energy Solar Spectroscopic Imager and Fermi observations indicate an extremely hard X-ray spectrum and γ -ray emission. We use the RADYN radiative hydrodynamic code to perform two types of simulations: one where an energy of 3 × 10{sup 11} erg cm{sup −2} s{sup −1} is deposited by an electron beam with a spectral index of ≈3, and a second where the same energy is applied directly to the photosphere. The combination of observations and simulations allows us to conclude that the white-light emission and the suppression or complete lack of hydrogen emission lines is best explained by a model where the dominant energy deposition layer is located in the lower layers of the solar atmosphere, rather than the chromosphere.

  14. Highly efficient phosphorescent blue and white organic light-emitting devices with simplified architectures

    Energy Technology Data Exchange (ETDEWEB)

    Chang, Chih-Hao, E-mail: chc@saturn.yzu.edu.tw [Department of Photonics Engineering, Yuan Ze University, Chung-Li, Taiwan 32003 (China); Ding, Yong-Shung; Hsieh, Po-Wei; Chang, Chien-Ping; Lin, Wei-Chieh [Department of Photonics Engineering, Yuan Ze University, Chung-Li, Taiwan 32003 (China); Chang, Hsin-Hua, E-mail: hhua3@mail.vnu.edu.tw [Department of Electro-Optical Engineering, Vanung University, Chung-Li, Taiwan 32061 (China)

    2011-09-01

    Blue phosphorescent organic light-emitting devices (PhOLEDs) with quantum efficiency close to the theoretical maximum were achieved by utilizing a double-layer architecture. Two wide-triplet-gap materials, 1,3-bis(9-carbazolyl)benzene and 1,3,5-tri[(3-pyridyl)-phen-3-yl]benzene, were employed in the emitting and electron-transport layers respectively. The opposite carrier-transport characteristics of these two materials were leveraged to define the exciton formation zone and thus increase the probability of recombination. The efficiency at practical luminance (100 cd/m{sup 2}) was as high as 20.8%, 47.7 cd/A and 31.2 lm/W, respectively. Furthermore, based on the design concept of this simplified architecture, efficient warmish-white PhOLEDs were developed. Such two-component white organic light-emitting devices exhibited rather stable colors over a wide brightness range and yielded electroluminescence efficiencies of 15.3%, 33.3 cd/A, and 22.7 lm/W in the forward directions.

  15. Efficient white organic light-emitting devices based on blue, orange, red phosphorescent dyes

    International Nuclear Information System (INIS)

    Chen Ping; Duan Yu; Xie Wenfa; Zhao Yi; Hou Jingying; Liu Shiyong; Zhang Liying; Li Bin

    2009-01-01

    We demonstrate efficient white organic light-emitting devices (WOLEDs) based on an orange phosphorescent iridium complex bis(2-(2-fluorphenyl)-1,3-benzothiozolato-N, C 2' )iridium(acetylacetonate) in combination with blue phosphorescent dye bis[(4, 6-difluorophenyl)-pyridinato-N,C 2 )](picolinato) Ir(III) and red phosphorescent dye bis[1-(phenyl)isoquinoline] iridium (III) acetylanetonate. By introducing a thin layer of 4, 7-diphenyl-1,10-phenanthroline between blue and red emission layers, the diffusion of excitons is confined and white light can be obtained. WOLEDs with the interlayer all have a higher colour rendering index (>82) than the device without it (76). One device has the maximum current efficiency of 17.6 cd A -1 and a maximum luminance of 39 050 cd m -2 . The power efficiency is 8.7 lm W -1 at 100 cd m -2 . Furthermore, the device has good colour stability and the CIE coordinates just change from (0.394, 0.425) to (0.390, 0.426) with the luminance increasing from 630 to 4200 cd m -2 .

  16. Can 3D light localization be reached in ‘white paint’?

    International Nuclear Information System (INIS)

    Sperling, T; Schertel, L; Aubry, G J; Maret, G; Ackermann, M; Aegerter, C M

    2016-01-01

    When waves scatter multiple times in 3D random media, a disorder driven phase transition from diffusion to localization may occur (Anderson 1958 Phys. Rev. 109 1492–505; Abrahams et al 1979 Phys. Rev. Lett. 42 673–6). In ‘The question of classical localization: a theory of white paint?’ Anderson suggested the possibility to observe light localization in TiO 2 samples (Anderson 1985 Phil. Mag. B 52 505–9). We recently claimed the observation of localization effects measuring photon time of flight (ToF) distributions (Störzer et al 2006 Phys. Rev. Lett. 96 063904) and evaluating transmission profiles (TPs) (Sperling et al 2013 Nat. Photonics 7 48–52) in such TiO 2 samples. Here we present a careful study of the long time tail of ToF distributions and the long time behavior of the TP width for very thin samples and different turbidities that questions the localization interpretation. We further show new data that allow an alternative consistent explanation of these previous data by a fluorescence process. An adapted diffusion model including an appropriate exponential fluorescence decay accounts for the shape of the ToF distributions and the TP width. These observations question whether the strong localization regime can be reached with visible light scattering in polydisperse TiO 2 samples, since the disorder parameter can hardly be increased any further in such a ‘white paint’ material. (paper)

  17. Reduction of chromatic aberration influences in vertical scanning white-light interferometry

    International Nuclear Information System (INIS)

    Lehmann, Peter; Kühnhold, Peter; Xie, Weichang

    2014-01-01

    Vertical scanning white-light interferometry (SWLI) is a well-established method that is widely used in high precision surface topography measurement. However, SWLI results show characteristic slope-dependent errors due to dispersion effects and lateral chromatic aberrations of the optical imaging system. In this paper, we present methods to characterize these systematic errors related to dispersion and lateral colour. Lateral colour leads to field-dependent systematic discrepancies of the topography data obtained from the envelope position of a low-coherence interference signal and the data resulting from its interference phase. Hence, an erroneous fringe order obtained from the envelope position leads to a 2π phase jump and thus to a so-called ghost step in the measured topography. Our first approach to solve this problem is based on the measurement of a surface standard of well-known geometry. By comparison of measurement results related to the envelope position and the phase of SWLI signals, the systematic error is estimated and a numerical error compensation method is proposed. Both experimental and simulation results confirm the validity of this numerical method. In addition, using an improved design of a white-light Michelson interferometer we demonstrate experimentally that lateral chromatic aberrations and dispersion influences can be reduced also in a physical way. In this context, a conventional long working distance microscope objective is used which was not originally designed for a Michelson interference microscope. (paper)

  18. Highly efficient phosphorescent blue and white organic light-emitting devices with simplified architectures

    International Nuclear Information System (INIS)

    Chang, Chih-Hao; Ding, Yong-Shung; Hsieh, Po-Wei; Chang, Chien-Ping; Lin, Wei-Chieh; Chang, Hsin-Hua

    2011-01-01

    Blue phosphorescent organic light-emitting devices (PhOLEDs) with quantum efficiency close to the theoretical maximum were achieved by utilizing a double-layer architecture. Two wide-triplet-gap materials, 1,3-bis(9-carbazolyl)benzene and 1,3,5-tri[(3-pyridyl)-phen-3-yl]benzene, were employed in the emitting and electron-transport layers respectively. The opposite carrier-transport characteristics of these two materials were leveraged to define the exciton formation zone and thus increase the probability of recombination. The efficiency at practical luminance (100 cd/m 2 ) was as high as 20.8%, 47.7 cd/A and 31.2 lm/W, respectively. Furthermore, based on the design concept of this simplified architecture, efficient warmish-white PhOLEDs were developed. Such two-component white organic light-emitting devices exhibited rather stable colors over a wide brightness range and yielded electroluminescence efficiencies of 15.3%, 33.3 cd/A, and 22.7 lm/W in the forward directions.

  19. ITO/metal/ITO anode for efficient transparent white organic light-emitting diodes

    Science.gov (United States)

    Joo, Chul Woong; Lee, Jonghee; Sung, Woo Jin; Moon, Jaehyun; Cho, Nam Sung; Chu, Hye Yong; Lee, Jeong-Ik

    2015-02-01

    We report on the characteristics of enhanced and balanced white-light emission of transparent organic light emitting diodes (TOLEDs) by introducing anode that has a stack structure of ITO/metal/ITO (IMI). We have investigated an anode that has a stack structure of IMI. IMI anodes are typically composed of a thin Ag layer (˜15 nm) sandwiched between two ITO layers (˜50 nm). By inserting an Ag layer it was possible to achieve sheet resistance lower than 3 Ω/sq. and transmittance of 86% at a wavelength of 550 nm. The Ag insert can act as a reflective component. With its counterpart, a transparent cathode made of a thin Ag layer (˜15 nm), micro-cavities (MC) can be effectively induced in the OLED, leading to improved performance. Using an IMI anode, it was possible to significantly increase the current efficiencies. The current efficiencies of the top and the bottom of the IMI TOLED increased to 23.0 and 15.6 cd/A, respectively, while those of the white TOLED with the ITO anode were 20.7 and 5.1 cd/A, respectively. A 30% enhancement in the overall current efficiency was achieved by taking advantage of the MC effect and the low sheet resistance.

  20. Broadband white light emission from Ce:AlN ceramics: High thermal conductivity down-converters for LED and laser-driven solid state lighting

    Directory of Open Access Journals (Sweden)

    A. T. Wieg

    2016-12-01

    Full Text Available We introduce high thermal conductivity aluminum nitride (AlN as a transparent ceramic host for Ce3+, a well-known active ion dopant. We show that the Ce:AlN ceramics have overlapping photoluminescent (PL emission peaks that cover almost the entire visible range resulting in a white appearance under 375 nm excitation without the need for color mixing. The PL is due to a combination of intrinsic AlN defect complexes and Ce3+ electronic transitions. Importantly, the peak intensities can be tuned by varying the Ce concentration and processing parameters, causing different shades of white light without the need for multiple phosphors or light sources. The Commission Internationale de l’Eclairage coordinates calculated from the measured spectra confirm white light emission. In addition, we demonstrate the viability of laser driven white light emission by coupling the Ce:AlN to a readily available frequency tripled Nd-YAG laser emitting at 355 nm. The high thermal conductivity of these ceramic down-converters holds significant promise for producing higher power white light sources than those available today.

  1. High color rendering index white organic light-emitting diode using levofloxacin as blue emitter

    Science.gov (United States)

    Miao, Yan-Qin; Gao, Zhi-Xiang; Zhang, Ai-Qin; Li, Yuan-Hao; Wang, Hua; Jia, Hu-Sheng; Liu, Xu-Guang; Tsuboi, Taijuf

    2015-05-01

    Levofloxacin (LOFX), which is well-known as an antibiotic medicament, was shown to be useful as a 452-nm blue emitter for white organic light-emitting diodes (OLEDs). In this paper, the fabricated white OLED contains a 452-nm blue emitting layer (thickness of 30 nm) with 1 wt% LOFX doped in CBP (4,4’-bis(carbazol-9-yl)biphenyl) host and a 584-nm orange emitting layer (thickness of 10 nm) with 0.8 wt% DCJTB (4-(dicyanomethylene)-2-tert-butyl-6-(1,1,7,7-tetramethyljulolidin-4-yl-vinyl)-4H-pyran) doped in CBP, which are separated by a 20-nm-thick buffer layer of TPBi (2,2’,2”-(benzene-1,3,5-triyl)-tri(1-phenyl-1H-benzimidazole). A high color rendering index (CRI) of 84.5 and CIE chromaticity coordinates of (0.33, 0.32), which is close to ideal white emission CIE (0.333, 0.333), are obtained at a bias voltage of 14 V. Taking into account that LOFX is less expensive and the synthesis and purification technologies of LOFX are mature, these results indicate that blue fluorescence emitting LOFX is useful for applications to white OLEDs although the maximum current efficiency and luminance are not high. The present paper is expected to become a milestone to using medical drug materials for OLEDs. Project supported by the Program for New Century Excellent Talents in University of Ministry of Education of China (Grant No. NCET-13-0927), the International Science & Technology Cooperation Program of China (Grant No. 2012DFR50460), the National Natural Science Foundation of China (Grant Nos. 21101111 and 61274056), and the Shanxi Provincial Key Innovative Research Team in Science and Technology, China (Grant No. 2012041011).

  2. Using light and melatonin in the management of New Zealand White rabbits

    Directory of Open Access Journals (Sweden)

    T. M. Mousa-Balabel

    2011-01-01

    Full Text Available Lighting system is a stimulant for reproduction in some species (Horses and an inhibitor for others (Sheep. This study started on September 1st and planned to study the effects of different lighting regimes and melatonin treatment on the receptivity and performance of 78 (60-does and 18-bucks New Zealand White rabbits, which were reared in a private Rabbitary in Menuofia Governorate, Egypt. These rabbits were randomly assigned to six treatment groups of 10 does and three bucks for each (8, 10, 12, 14 and 16 hours light (HL and melatonin- treated. Ejaculate traits, sexual activity of bucks, sexual receptivity and reproductive performance of does were recorded. Results revealed that exposure of rabbits to long photoperiods (14 and 16HL or treatment with melatonin improved the quantity and quality of ejaculate traits and buck sexual activity. Moreover, does sexual receptivity, feed intake, litter size and weight at birth and weaning were increased by long photoperiods (14 and 16HL or treatment with melatonin. On the other hand, gestation period and pre-weaning mortality rate were decreased. It can be concluded that application of long photoperiods is beneficial to rabbit producers and 14 HL : 10 hours dark is optimal for satisfying the biological requirements of the rabbits. Finally, the light schedules can be used for biostimulation instead of melatonin.

  3. Pathogen reduction by ultraviolet C light effectively inactivates human white blood cells in platelet products.

    Science.gov (United States)

    Pohler, Petra; Müller, Meike; Winkler, Carla; Schaudien, Dirk; Sewald, Katherina; Müller, Thomas H; Seltsam, Axel

    2015-02-01

    Residual white blood cells (WBCs) in cellular blood components induce a variety of adverse immune events, including nonhemolytic febrile transfusion reactions, alloimmunization to HLA antigens, and transfusion-associated graft-versus-host disease (TA-GVHD). Pathogen reduction (PR) methods such as the ultraviolet C (UVC) light-based THERAFLEX UV-Platelets system were developed to reduce the risk of transfusion-transmitted infection. As UVC light targets nucleic acids, it interferes with the replication of both pathogens and WBCs. This preclinical study aimed to evaluate the ability of UVC light to inactivate contaminating WBCs in platelet concentrates (PCs). The in vitro and in vivo function of WBCs from UVC-treated PCs was compared to that of WBCs from gamma-irradiated and untreated PCs by measuring cell viability, proliferation, cytokine secretion, antigen presentation in vitro, and xenogeneic GVHD responses in a humanized mouse model. UVC light was at least as effective as gamma irradiation in preventing GVHD in the mouse model. It was more effective in suppressing T-cell proliferation (>5-log reduction in the limiting dilution assay), cytokine secretion, and antigen presentation than gamma irradiation. The THERAFLEX UV-Platelets (MacoPharma) PR system can substitute gamma irradiation for TA-GVHD prophylaxis in platelet (PLT) transfusion. Moreover, UVC treatment achieves suppression of antigen presentation and inhibition of cytokine accumulation during storage of PCs, which has potential benefits for transfusion recipients. © 2014 AABB.

  4. Enhancing Color Purity and Stable Efficiency of White Organic Light Diodes by Using Hole-Blocking Layer

    Directory of Open Access Journals (Sweden)

    Chien-Jung Huang

    2014-01-01

    Full Text Available The organic light-emitting diodes with triple hole-blocking layer (THBL formation sandwich structure which generate white emission were fabricated. The 5,6,11,12-tetraphenylnapthacene (Rubrene, (4,4′-N,N′-dicarbazolebiphenyl (CBP, and 4,4′-bis(2,2′diphenylvinil-1,1′-biphenyl (DPVBi were used as emitting materials in the device. The function of CBP layer is not only an emitting layer but also a hole-blocking layer (HBL, and the Rubrene was doped into the CBP. The optimal configuration structure was indium tin oxide (ITO/Molybdenum trioxide (MoO3 (5 nm/[4,4-bis[N-(1-naphthyl-N-phenylamino]biphenyl (NPB (35 nm/CBP (HBL1 (5 nm/DPVBi (I (10 nm/CBP (HBL2 : Rubrene (4 : 1 (3 nm/DPVBi (II (30 nm/CBP (HBL3 (2 nm/4,7-diphenyl-1,10-phenanthroline (BPhen (10 nm/Lithium fluoride (LiF/aluminum (Al. The result showed that the device with Rubrene doped in CBP (HBL2 exhibited a stable white emission with the color coordinates of (0.322, 0.368, and the coordinate with the slight shift of ±Δx,y = (0.001, 0.011 for applied voltage of 8–12 V was observed.

  5. Efficient polymer white-light-emitting diodes with a single-emission layer of fluorescent polymer blend

    International Nuclear Information System (INIS)

    Niu Qiaoli; Xu Yunhua; Jiang Jiaxing; Peng Junbiao; Cao Yong

    2007-01-01

    Efficient polymer white-light-emitting diodes (WPLEDs) have been fabricated with a single layer of fluorescent polymer blend. The device structure consists of ITO/PEDOT/PVK/emissive layer/Ba/Al. The emissive layer is a blend of poly(9,9-dioctylfluorene) (PFO), phenyl-substituted PPV derivative (P-PPV) and a copolymer of 9,9-dioctylfluorene and 4,7-di(4-hexylthien-2-yl)-2,1,3-benzothiadiazole (PFO-DHTBT), which, respectively, emits blue, green and red light. The emission of pure and efficient white light was implemented by tuning the blend weight ratio of PFO: P-PPV: PFO-DHTBT to 96:4:0.4. The maximum current efficiency and luminance are, respectively, 7.6 cd/A at 6.7 V and 11930 cd/m 2 at 11.2 V. The CIE coordinates of white-light emission were stable with the drive voltages

  6. Power generation versus fuel production in light water hybrid reactors

    International Nuclear Information System (INIS)

    Greenspan, E.

    1977-06-01

    The economic potentials of fissile-fuel-producing light-water hybrid reactors (FFP-LWHR) and of fuel-self-sufficient (FSS) LWHR's are compared. A simple economic model is constructed that gives the capital investment allowed for the hybrid reactor so that the cost of electricity generated in the hybrid based energy system equals the cost of electricity generated in LWR's. The power systems considered are LWR, FSS-LWHR, and FFP-LWHR plus LWR, both with and without plutonium recycling. The economic potential of FFP-LWHR's is found superior to that of FSS-LWHR's. Moreover, LWHR's may compete, economically, with LWR's. Criteria for determining the more economical approach to hybrid fuel or power production are derived for blankets having a linear dependence between F and M. The examples considered favor the power generation rather than fuel production

  7. Defect induced photoluminescence in MoS2 quantum dots and effect of Eu3+/Tb3+ co-doping towards efficient white light emission

    Science.gov (United States)

    Haldar, Dhrubaa; Ghosh, Arnab; Bose, Saptasree; Mondal, Supriya; Ghorai, Uttam Kumar; Saha, Shyamal K.

    2018-05-01

    Intensive research has been carried out on optical properties of MoS2 quantum dots for versatile applications in photo catalytic, sensing and optoelectronic devices. However, white light generation from MoS2 quantum dots particularly using doping effect is relatively unexplored. Herein we report successful synthesis of Europium (Eu)/Terbium (Tb) co-doped MoS2 quantum dots to achieve white light for potential applications in optoelectronic devices. The dopant ions are introduced into the host lattice to retain the emission colors to cover the entire range of visible light of solar spectrum. Perfect white light (CIE = 0.31, 0.33) with high intensity (quantum yield = 28.29%) is achieved in these rare earth elements co-doped quantum dot system. A new peak is observed in the NIR region which is attributed to the defects present in MoS2 quantum dots. Temperature dependent study has been carried out to understand the origin of this new peak in the NIR region. It is seen that the 'S' defects in the QDs cause the appearance of this peak which shows a blue shift at higher temperature.

  8. Coronal mass ejection kinematics deduced from white light (Solar Mass Ejection Imager) and radio (Wind/WAVES) observations

    Science.gov (United States)

    Reiner, M. J.; Jackson, B. V.; Webb, D. F.; Mizuno, D. R.; Kaiser, M. L.; Bougeret, J.-L.

    2005-09-01

    White-light and radio observations are combined to deduce the coronal and interplanetary kinematics of a fast coronal mass ejection (CME) that was ejected from the Sun at about 1700 UT on 2 November 2003. The CME, which was associated with an X8.3 solar flare from W56°, was observed by the Mauna Loa and Solar and Heliospheric Observatory (SOHO) Large-Angle Spectrometric Coronograph (LASCO) coronagraphs to 14 R⊙. The measured plane-of-sky speed of the LASCO CME was 2600 km s-1. To deduce the kinematics of this CME, we use the plane-of-sky white light observations from both the Solar Mass Ejection Imager (SMEI) all-sky camera on board the Coriolis spacecraft and the SOHO/LASCO coronagraph, as well as the frequency drift rate of the low-frequency radio data and the results of the radio direction-finding analysis from the WAVES experiment on the Wind spacecraft. In agreement with the in situ observations for this event, we find that both the white light and radio observations indicate that the CME must have decelerated significantly beginning near the Sun and continuing well into the interplanetary medium. More specifically, by requiring self-consistency of all the available remote and in situ data, together with a simple, but not unreasonable, assumption about the general characteristic of the CME deceleration, we were able to deduce the radial speed and distance time profiles for this CME as it propagated from the Sun to 1 AU. The technique presented here, which is applicable to mutual SMEI/WAVES CME events, is expected to provide a more complete description and better quantitative understanding of how CMEs propagate through interplanetary space, as well as how the radio emissions, generated by propagating CME/shocks, relate to the shock and CME. This understanding can potentially lead to more accurate predictions for the onset times of space weather events, such as those that were observed during this unique period of intense solar activity.

  9. Low driving voltage blue, green, yellow, red and white organic light-emitting diodes with a simply double light-emitting structure.

    Science.gov (United States)

    Zhang, Zhensong; Yue, Shouzhen; Wu, Yukun; Yan, Pingrui; Wu, Qingyang; Qu, Dalong; Liu, Shiyong; Zhao, Yi

    2014-01-27

    Low driving voltage blue, green, yellow, red and white phosphorescent organic light-emitting diodes (OLEDs) with a common simply double emitting layer (D-EML) structure are investigated. Our OLEDs without any out-coupling schemes as well as n-doping strategies show low driving voltage, e.g. white OLED, respectively. This work demonstrates that the low driving voltages and high efficiencies can be simultaneously realized with a common simply D-EML structure.

  10. Suppressed speckle contrast of blue light emission out of white lamp with phosphors excited by blue laser diodes for high-brightness lighting applications

    Science.gov (United States)

    Kinoshita, Junichi; Ikeda, Yoshihisa; Takeda, Yuji; Ueno, Misaki; Kawasaki, Yoji; Matsuba, Yoshiaki; Heike, Atsushi

    2012-11-01

    The speckle contrast of blue light emission out of high-brightness white lamps using phosphors excited by InGaN/GaN blue laser diodes is evaluated as a measure of coherence. As a result, speckle contrast of as low as 1.7%, the same level as a blue light emitting diode, is obtained. This implies that the original blue laser light can be converted into incoherent light through lamp structures without any dynamic mechanisms. This unique speckle-free performance is considered to be realized by multiple scattering inside the lamp structure, the multi-longitudinal mode operation of the blue laser diodes, and the use of multiple laser diodes. Such almost-incoherent white lamps can be applied for general lighting without any nuisance of speckle noise and should be categorized as lamps rather than lasers in terms of laser safety regulation.

  11. Speckles generated by skewed, short-coherence light beams

    International Nuclear Information System (INIS)

    Brogioli, D; Salerno, D; Ziano, R; Mantegazza, F; Croccolo, F

    2011-01-01

    When a coherent laser beam impinges on a random sample (e.g. a colloidal suspension), the scattered light exhibits characteristic speckles. If the temporal coherence of the light source is too short, then the speckles disappear, along with the possibility of performing homodyne or heterodyne scattering detection or photon correlation spectroscopy. Here we investigate the scattering of a so-called ‘skewed coherence beam’, i.e. a short-coherence beam modified such that the field is coherent within slabs that are skewed with respect to the wave fronts. We show that such a beam generates speckles and can be used for heterodyne scattering detection, despite its short temporal coherence. Moreover, we show that the heterodyne signal is not affected by multiple scattering. We suggest that the phenomenon presented here can be used as a means of carrying out heterodyne scattering measurement with any short-coherence radiation, including x-rays. (paper)

  12. Highly efficient white organic light-emitting devices consisting of undoped ultrathin yellow phosphorescent layer

    Energy Technology Data Exchange (ETDEWEB)

    Liu, Shengqiang [State Key Laboratory of Electronic Thin Films and Integrated Devices, School of Optoelectronic Information, University of Electronic Science and Technology of China (UESTC), Chengdu 610054 (China); Yu, Junsheng, E-mail: jsyu@uestc.edu.cn [State Key Laboratory of Electronic Thin Films and Integrated Devices, School of Optoelectronic Information, University of Electronic Science and Technology of China (UESTC), Chengdu 610054 (China); Ma, Zhu; Zhao, Juan [State Key Laboratory of Electronic Thin Films and Integrated Devices, School of Optoelectronic Information, University of Electronic Science and Technology of China (UESTC), Chengdu 610054 (China)

    2013-02-15

    High-efficiency white organic light-emitting devices (WOLEDs) based on an undoped ultrathin yellow light-emitting layer and a doped blue light-emitting layer were demonstrated. While the thickness of blue light-emitting layer, formed by doping a charge-trapping phosphor, iridium(III) bis(4 Prime ,6 Prime -difluorophenylpyridinato)tetrakis(1-pyrazolyl)borate (FIr6) in a wide bandgap host, was kept constant, the thickness of neat yellow emissive layer of novel phosphorescent material, bis[2-(4-tertbutylphenyl)benzothiazolato-N,C{sup 2 Prime }]iridium (acetylacetonate) [(t-bt){sub 2}Ir(acac)] was varied to optimize the device performance. The optimized device exhibited maximum luminance, current efficiency and power efficiency of 24,000 cd/m{sup 2} (at 15.2 V), 79.0 cd/A (at 1550 cd/m{sup 2}) and 40.5 lm/W (at 1000 cd/m{sup 2}), respectively. Besides, the white-light emission covered a wide range of visible spectrum, and the Commission Internationale de l'Eclairage coordinates were (0.32, 0.38) with a color temperature of 5800 K at 8 V. Moreover, high external quantum efficiency was also obtained in the high-efficiency WOLEDs. The performance enhancement was attributed to the proper thickness of (t-bt){sub 2}Ir(acac) layer that enabled adequate current density and enough phosphorescent dye to trap electrons. - Highlights: Black-Right-Pointing-Pointer Highly efficient WOLEDs based on two complementary layers were fabricated. Black-Right-Pointing-Pointer The yellow emissive layer was formed by utilizing undoping system. Black-Right-Pointing-Pointer The blue emissive layer was made by host-guest doping system. Black-Right-Pointing-Pointer The thickness of the yellow emissive layer was varied to make device optimization. Black-Right-Pointing-Pointer The optimized device achieved high power efficiency of 40.5 lm/W.

  13. White light emission from an exciplex interface with a single emitting layer (Conference Presentation)

    Science.gov (United States)

    Bernal, Wilson; Perez-Gutierrez, Enrique; Agular, Andres; Barbosa G, J. Oracio C.; Maldonado, Jose L.; Meneses-Nava, Marco Antonio; Rodriguez Rivera, Mario A.; Rodriguez, Braulio

    2017-02-01

    Efficient solid state lighting devices based in inorganic emissive materials are now available in the market meanwhile for organic emissive materials still a lot of research work is in its way. [1,2] In this work a new organic emissive material based on carbazole, N-(4-Ethynylphenyl) carba-zole-d4 (6-d4), is used as electron-acceptor and commercial PEDOT:PSS as the electron-donor to obtain white emission. Besides the HOMO-LUMO levels of materials the white emission showed dependence on the films thicknesses and applied voltages. In here it is reported that by diminishing the thickness of the PEDOT:PSS layer, from 60 to 35 nm, and by keeping the derivative carbazole layer constant at 100 nm the electro-luminescence (EL) changed from emissive exciton states to the mixture of emissive exciton and exciplex states. [3] For the former thicknesses no white light was obtained meanwhile for the later the EL spectra broadened due to the emission of exciplex states. Under this condition, the best-achieved CIE coordinate was (0.31,0.33) with a driving voltage of 8 V. To lower the driving voltage of the devices a thin film of LiF was added between the derivative of carbazol and cathode but the CIE coordinates changed. The best CIE coordinates for this case were (0.29, 0.34) and (0.32, 0.37) with driving voltage of about 6.5 V. Acknowledgments: CeMie-Sol/27 (Mexico) 207450 References [1] Timothy L Dawson, Society of Dyers and Colourists, Color. Technol., 126, 1-10 (2010), doi: 10.1111/j.1478-4408.2010.00220.x [2] G. M. Farinola, R. Ragni, Journal of Solid State Lighting, 2:9 (2015), doi: 10.1186/s40539-015-0028-7. [3] E. Angioni, et al, J. Mater. Chem. C, 2016, 4, 3851, doi: 10.1039/c6tc00750c.

  14. White organic light-emitting diodes based on doped and ultrathin Rubrene layer

    Science.gov (United States)

    Li, Yi; Jiang, Yadong; Wen, Wen; Yu, Junsheng

    2010-10-01

    Based on a yellow fluorescent dye of 5, 6, 11, 12-tetraphenylnaphthacene (Rubrene), WOLEDs were fabricated, with doping structure and ultrathin layer structure utilized in the devices. By doping Rubrene into blue-emitting N,N'-bis-(1- naphthyl)-N,N'-biphenyl-1,1'-biphenyl-4,4'-diamine (NPB), the device with a structure of indium-tin-oxide (ITO)/NPB (40 nm)/NPB:Rubrene (0.25 wt%, 7 nm)/2,9-dimethyl-4,7-diphenyl-1,10-phenanthroline (BCP) (30 nm)/Mg:Ag exhibited a warm white light with Commissions Internationale De L'Eclairage (CIE) coordinates of (0.38, 0.41) at 12 V. The electroluminescent spectrum of the OLED consisted of blue and yellow fluorescent emissions, the intensity of blue emission increased gradually relative to the orange emission with increasing voltage. This is mainly due to the recombination zone shifted towards the anode side as the transmission rate of electrons grows faster than that of holes under higher bias voltage. A maximum luminance of 7300 cd/m2 and a maximum power efficiency of 0.57 lm/W were achieved. Comparatively, by utilizing ultrathin dopant layer, the device with a structure of ITO/NPB (40 nm)/Rubrene (0.3 nm)/NPB (7 nm)/BCP (30 nm)/Mg:Ag achieved a low turn-on voltage of 3 V and a more stable white light. The peaks of EL spectra located at 430 and 560 nm corresponding to the CIE coordinates of (0.32, 0.32) under bias voltage ranging from 5 to 15 V. A maximum luminance of 5630 cd/m2 and a maximum power efficiency of 0.6 lm/W were achieved. The balanced spectra were attributed to the stable confining of charge carriers and exciton by the thin emitting layers. Hence, with simple device structure and fabricating process, the device with ultrathin layer achieved low turn-on voltage, stable white light emitting and higher power efficiency.

  15. New generation of light sources: Present and future

    International Nuclear Information System (INIS)

    Couprie, M.E.

    2014-01-01

    Spectroscopy and imaging in the VUV–X-ray domain are very sensitive tools for the investigation of the properties of matter [1–3]. Time-resolved studies enable to follow the movies of ultra-fast reactions. More than fifty years after the laser discovery [4], VUVX light sources are actively developed around the world. Among them, high order harmonics generated in gas, X-ray lasers, synchrotron radiation, free electron lasers are providing a wide offer, from laboratory size sources to large scale facilities, with various features, suitable for different types of experiments. The properties of these sources are here reviewed. Quest of new performances and flexibility is also discussed

  16. Non-doped white organic light-emitting diodes based on aggregation-induced emission

    Energy Technology Data Exchange (ETDEWEB)

    Chen Shuming; Kwok, Hoi Sing [Center for Display Research, Department of Electronic and Computer Engineering, Hong Kong University of Science and Technology, Clear Water Bay, Kowloon (Hong Kong); Zhao Zujin; Tang, Ben Zhong, E-mail: eekwok@ust.h [Department of Chemistry, Hong Kong University of Science and Technology, Clear Water Bay, Kowloon (Hong Kong)

    2010-03-10

    Non-doped white organic light-emitting diodes (WOLEDs) based on newly synthesized bluish-green light-emitting material 1,3,6,8-tetrakis [4-(1,2,2-triphenylvinyl)phenyl]pyrene (TTPEPy) and red light-emitting material 4-(4-(1,2,2-triphenylvinyl)phenyl)-7-(5-(4-(1,2,2-triphenylvinyl) phenyl)thiophen-2-yl)benzo[c][1,2,5]thiadiazole (BTPETTD) have been demonstrated. A maximum efficiency of 7.4 cd A{sup -1}, 4 lm W{sup -1} and brightness of 18 000 cd m{sup -2} have been achieved by employing 3 nm thick 4, 4'-bis [N-(1-naphthyl-1-)-N-phenyl-amino]- biphenyl (NPB) as an electron-blocking layer. The WOLEDs exhibit a high colour rendering index of 90 and moderate colour stability with 1931 Commision International de L'Eclairage coordinates changing from (0.41, 0.41) to (0.38, 0.40) over a wide range of driving voltages. Moreover, the non-doped WOLEDs enjoy a reduced efficiency roll-off due to their nature of aggregation-induced emission.

  17. Non-doped white organic light-emitting diodes based on aggregation-induced emission

    International Nuclear Information System (INIS)

    Chen Shuming; Kwok, Hoi Sing; Zhao Zujin; Tang, Ben Zhong

    2010-01-01

    Non-doped white organic light-emitting diodes (WOLEDs) based on newly synthesized bluish-green light-emitting material 1,3,6,8-tetrakis [4-(1,2,2-triphenylvinyl)phenyl]pyrene (TTPEPy) and red light-emitting material 4-(4-(1,2,2-triphenylvinyl)phenyl)-7-(5-(4-(1,2,2-triphenylvinyl) phenyl)thiophen-2-yl)benzo[c][1,2,5]thiadiazole (BTPETTD) have been demonstrated. A maximum efficiency of 7.4 cd A -1 , 4 lm W -1 and brightness of 18 000 cd m -2 have been achieved by employing 3 nm thick 4, 4'-bis [N-(1-naphthyl-1-)-N-phenyl-amino]- biphenyl (NPB) as an electron-blocking layer. The WOLEDs exhibit a high colour rendering index of 90 and moderate colour stability with 1931 Commision International de L'Eclairage coordinates changing from (0.41, 0.41) to (0.38, 0.40) over a wide range of driving voltages. Moreover, the non-doped WOLEDs enjoy a reduced efficiency roll-off due to their nature of aggregation-induced emission.

  18. Morning Sleep Inertia in Alertness and Performance: Effect of Cognitive Domain and White Light Conditions

    Science.gov (United States)

    Santhi, Nayantara; Groeger, John A.; Archer, Simon N.; Gimenez, Marina; Schlangen, Luc J. M.; Dijk, Derk-Jan

    2013-01-01

    The transition from sleep to wakefulness entails a temporary period of reduced alertness and impaired performance known as sleep inertia. The extent to which its severity varies with task and cognitive processes remains unclear. We examined sleep inertia in alertness, attention, working memory and cognitive throughput with the Karolinska Sleepiness Scale (KSS), the Psychomotor Vigilance Task (PVT), n-back and add tasks, respectively. The tasks were administered 2 hours before bedtime and at regular intervals for four hours, starting immediately after awakening in the morning, in eleven participants, in a four-way cross-over laboratory design. We also investigated whether exposure to Blue-Enhanced or Bright Blue-Enhanced white light would reduce sleep inertia. Alertness and all cognitive processes were impaired immediately upon awakening (pinertia varies with cognitive domain and that it’s spectral/intensity response to light is different from that of sleepiness. That is, just increasing blue-wavelength in light may not be sufficient to reduce sleep inertia. These findings have implications for critical professions like medicine, law-enforcement etc., in which, personnel routinely wake up from night-time sleep to respond to emergency situations. PMID:24260280

  19. Minimal-post-processing 320-Gbps true random bit generation using physical white chaos.

    Science.gov (United States)

    Wang, Anbang; Wang, Longsheng; Li, Pu; Wang, Yuncai

    2017-02-20

    Chaotic external-cavity semiconductor laser (ECL) is a promising entropy source for generation of high-speed physical random bits or digital keys. The rate and randomness is unfortunately limited by laser relaxation oscillation and external-cavity resonance, and is usually improved by complicated post processing. Here, we propose using a physical broadband white chaos generated by optical heterodyning of two ECLs as entropy source to construct high-speed random bit generation (RBG) with minimal post processing. The optical heterodyne chaos not only has a white spectrum without signature of relaxation oscillation and external-cavity resonance but also has a symmetric amplitude distribution. Thus, after quantization with a multi-bit analog-digital-convertor (ADC), random bits can be obtained by extracting several least significant bits (LSBs) without any other processing. In experiments, a white chaos with a 3-dB bandwidth of 16.7 GHz is generated. Its entropy rate is estimated as 16 Gbps by single-bit quantization which means a spectrum efficiency of 96%. With quantization using an 8-bit ADC, 320-Gbps physical RBG is achieved by directly extracting 4 LSBs at 80-GHz sampling rate.

  20. Enabling Lambertian-Like Warm White Organic Light-Emitting Diodes with a Yellow Phosphor Embedded Flexible Film

    Directory of Open Access Journals (Sweden)

    Cheng-Chang Chen

    2014-01-01

    Full Text Available We demonstrate in this report a new constructive method of fabricating white organic light-emitting devices (OLEDs with a flexible plastic film embedded with yellow phosphor. The flexible film is composed of polydimethylsiloxane (PDMS and fabricated by using spin coating followed by peeling technology. From the results, the resultant electroluminescent spectrum shows the white OLED to have chromatic coordinates of 0.38 and 0.54 and correlated color temperature of 4200 K. The warm white OLED exhibits the yield of 10.3 cd/A and the luminous power efficiency of 5.4 lm/W at a luminance of 1000 cd/m2. A desirable Lambertian-like far-field pattern is detected from the white OLEDs with the yellow phosphor containing PDMS film. This method is simple, reproducible, and cost-effective, proving to be a highly feasible approach to realize white OLED.

  1. Red, green, blue and white light upconversion emission in Yb3+/Tm3+/Ho3+ co-doped tellurite glasses

    International Nuclear Information System (INIS)

    Desirena, H; De la Rosa, E; Meza, O; Salas, P

    2011-01-01

    Several Yb 3+ /Tm 3+ /Ho 3+ co-doped transparent TeO 2 -ZnO-Na 2 O-Yb 2 O 3 -Ho 2 O 3 -Tm 2 O 3 glasses were prepared and luminescence properties were characterized. Simultaneous red, green and blue (RGB) emission were obtained after excitation at 970 nm. Colour emission was tuned from multicolour to white light with colour coordinate (0.32, 0.33) matching very well with the white reference (0.33, 0.33). Changes in colour emission were obtained by varying the intensity ratios between RGB bands that are strongly concentration dependent because of the interaction of co-dopants. The colour tunability, high quality of white light and high intensity of the emitted signal make these transparent glasses excellent candidates for applications in solid-state lighting.

  2. Broadening of white-light continuum by filamentation in BK7 glass at its zero-dispersion point

    International Nuclear Information System (INIS)

    Jiang, Jiaming; Zhong, Yue; Zheng, Yinghui; Zeng, Zhinan; Ge, Xiaochun; Li, Ruxin

    2015-01-01

    Broadening of white-light continuum is observed by filamentation of near-infrared femtosecond laser pulses with peak power exceeding the megawatt level in BK7 glass with the presence of the zero-dispersion point. The simulated results show that, due to the low dispersion at the zero-dispersion point, the broadening of white-light continuum can be wider and the filament can persist in propagating stably longer distance. - Highlights: • We observed the white-light continuum by filamentation at the zero-dispersion point. • Peak power significantly exceeding the critical value of self-focusing was used. • Wider spectral broadening was obtained around the zero-dispersion point

  3. Simple process of hybrid white quantum dot/organic light-emitting diodes by using quantum dot plate and fluorescence

    Science.gov (United States)

    Lee, Ho Won; Lee, Ki-Heon; Lee, Jae Woo; Kim, Jong-Hoon; Yang, Heesun; Kim, Young Kwan

    2015-02-01

    In this work, the simple process of hybrid quantum dot (QD)/organic light-emitting diode (OLED) was proposed to apply a white illumination light by using QD plate and organic fluorescence. Conventional blue fluorescent OLEDs were firstly fabricated and then QD plates of various concentrations, which can be controlled of UV-vis absorption and photoluminescence spectrum, were attached under glass substrate of completed blue devices. The suggested process indicates that we could fabricate the white device through very simple process without any deposition of orange or red organic emitters. Therefore, this work would be demonstrated that the potential simple process for white applications can be applied and also can be extended to additional research on light applications.

  4. Multi-solution processes of small molecule for flexible white organic light-emitting diodes

    Energy Technology Data Exchange (ETDEWEB)

    Tsai, Yu-Sheng, E-mail: ystsai@nfu.edu.tw [Institute of Electro-optical and Materials Science, National Formosa University, Yunlin 63201, Taiwan, ROC (China); Chittawanij, Apisit; Hong, Lin-Ann; Guo, Siou-Wei [Institute of Electro-optical and Materials Science, National Formosa University, Yunlin 63201, Taiwan, ROC (China); Wang, Ching-Chiun [Department of Solid State Lighting Technology, Mechanical and Systems Research Laboratories, Industrial Technology Research Institute, Hsinchu 31040, Taiwan, ROC (China); Juang, Fuh-Shyang [Institute of Electro-optical and Materials Science, National Formosa University, Yunlin 63201, Taiwan, ROC (China); Lai, Shih-Hsiang [Department of Solid State Lighting Technology, Mechanical and Systems Research Laboratories, Industrial Technology Research Institute, Hsinchu 31040, Taiwan, ROC (China); Lin, Yang-Ching [Institute of Electro-optical and Materials Science, National Formosa University, Yunlin 63201, Taiwan, ROC (China)

    2016-04-01

    Most small molecule organic light emitting diode (SM-OLED) device structures are made in one layer using solution-based processing because the solution is usually a high dissolvent material that easily attacks the layer below it. We demonstrate a simple and reliable stamping technique for fabricating multi-solution process flexible white SM-OLEDs. The structure is anode/spin-hole injection layer/spin-emitting layer/stamping-electron transport layer/cathode. Poly(di-methyl silane) (PDMS) stamp is used for transferring electron transport layer. An intermediate ultraviolet-ozone surface treatment is introduced to temporarily modify the PDMS stamp surface. Then, the solution-based electron transport layer film can therefore be uniformly formed on top of the PDMS surface. After that the electron transport layer film on the PDMS stamp is transfer-printed onto the emitting layer with suitable heating and pressing. A solution-based processing is successfully established to efficiently fabricate flexible white SM-OLEDs. The SM-OLEDs were obtained at the current density of 20 mA/cm{sup 2}, luminance of 1062 cd/m{sup 2}, current efficiency of 5.57 cd/A, and Commission internationale de l'éclairage coordinate of (0.32, 0.35). - Highlights: • All solution-processed small molecule materials (emitting layer, electron transport layer). • Poly(di-methylsilane) (PDMS) stamp is subsequently used for stamping transfer. • The flexible white SM-OLEDs are based on solution-processes with a low-cost method.

  5. Multi-solution processes of small molecule for flexible white organic light-emitting diodes

    International Nuclear Information System (INIS)

    Tsai, Yu-Sheng; Chittawanij, Apisit; Hong, Lin-Ann; Guo, Siou-Wei; Wang, Ching-Chiun; Juang, Fuh-Shyang; Lai, Shih-Hsiang; Lin, Yang-Ching

    2016-01-01

    Most small molecule organic light emitting diode (SM-OLED) device structures are made in one layer using solution-based processing because the solution is usually a high dissolvent material that easily attacks the layer below it. We demonstrate a simple and reliable stamping technique for fabricating multi-solution process flexible white SM-OLEDs. The structure is anode/spin-hole injection layer/spin-emitting layer/stamping-electron transport layer/cathode. Poly(di-methyl silane) (PDMS) stamp is used for transferring electron transport layer. An intermediate ultraviolet-ozone surface treatment is introduced to temporarily modify the PDMS stamp surface. Then, the solution-based electron transport layer film can therefore be uniformly formed on top of the PDMS surface. After that the electron transport layer film on the PDMS stamp is transfer-printed onto the emitting layer with suitable heating and pressing. A solution-based processing is successfully established to efficiently fabricate flexible white SM-OLEDs. The SM-OLEDs were obtained at the current density of 20 mA/cm"2, luminance of 1062 cd/m"2, current efficiency of 5.57 cd/A, and Commission internationale de l'éclairage coordinate of (0.32, 0.35). - Highlights: • All solution-processed small molecule materials (emitting layer, electron transport layer). • Poly(di-methylsilane) (PDMS) stamp is subsequently used for stamping transfer. • The flexible white SM-OLEDs are based on solution-processes with a low-cost method.

  6. White organic light-emitting diodes with 4 nm metal electrode

    Energy Technology Data Exchange (ETDEWEB)

    Lenk, Simone; Schwab, Tobias; Schubert, Sylvio; Müller-Meskamp, Lars; Leo, Karl; Reineke, Sebastian [Institut für Angewandte Photophysik, Technische Universität Dresden, George-Bähr-Straße 1, 01069 Dresden (Germany); Gather, Malte C. [Institut für Angewandte Photophysik, Technische Universität Dresden, George-Bähr-Straße 1, 01069 Dresden (Germany); Organic Semiconductor Centre, SUPA, School of Physics and Astronomy, University of St Andrews, North Haugh, St Andrews KY16 9SS (United Kingdom)

    2015-10-19

    We investigate metal layers with a thickness of only a few nanometers as anode replacement for indium tin oxide (ITO) in white organic light-emitting diodes (OLEDs). The ultrathin metal electrodes prove to be an excellent alternative that can, with regard to the angular dependence and efficiency of the OLED devices, outperform the ITO reference. Furthermore, unlike ITO, the thin composite metal electrodes are readily compatible with demanding architectures (e.g., top-emission or transparent OLEDs, device unit stacking, etc.) and flexible substrates. Here, we compare the sheet resistance of both types of electrodes on polyethylene terephthalate for different bending radii. The electrical performance of ITO breaks down at a radius of 10 mm, while the metal electrode remains intact even at radii smaller than 1 mm.

  7. Measurement of chromatic dispersion of microstructured polymer fibers by white-light spectral interferometry

    DEFF Research Database (Denmark)

    Hlubina, Petr; Ciprian, Dalibor; Frosz, Michael Henoch

    2009-01-01

    We present a white-light spectral interferometric method for measuring the chromatic dispersion of microstructured fibers made of polymethyl methacrylate (PMMA). The method uses an unbalanced Mach-Zehnder interferometer with the fiber of known length placed in one of the interferometer arms...... of the method by measuring the wavelength dependence of the differential group refractive index of a pure silica fiber. We apply a five-term power series fit to the measured data and confirm by its differentiation that the chromatic dispersion of pure silica glass agrees well with theory. Second, we measure...... the chromatic dispersion for the fundamental mode supported by two different PMMA microstructured fibers, the multimode fiber and the large-mode area one....

  8. White organic light emitting devices with hybrid emissive layers combining phosphorescence and fluorescence

    Energy Technology Data Exchange (ETDEWEB)

    Lei Gangtie; Chen Xiaolan; Wang Lei; Zhu Meixiang; Zhu Weiguo [Key Lab of Environmental-friendly Chemistry and Application of Ministry of Education, College of Chemistry, Xiangtan University, Xiangtan 411105 (China); Wang Liduo; Qiu Yong [Key Lab of Organic-Optoelectronics and Molecular Sciences of Ministry of Education, Department of Chemistry, Tsinghua University, Beijing 100084 (China)], E-mail: lgt@xtu.edu.cn

    2008-05-21

    We fabricated a white organic light-emitting diode (WOLED) by hybrid emissive layers which combined phosphorescence with fluorescence. In this device, the thin layer of 4-(dicyanomethylene)-2-(t-butyl)-6-(1, 1, 7, 7-tetramethyljulolidyl-9-enyl)-4H-pyran played the role of undoped red emissive layer which was inserted between two blue phosphorescence emissive layers. The blue phosphorescent dye was bis[(4, 6-difluorophenyl)-pyridinato-N, C{sup 2}] (picolinato) Ir(III), which was doped in the host material, N, N'-dicarbazolyl-1, 4-dimethene-benzene. The WOLED showed stable Commission Internationale de L'Eclairage coordinates and a high efficency of 9.6 cd A{sup -1} when the current density was 1.8 A m{sup -2}. The maximum luminance of the device achieved was 17 400 cd m{sup -2} when the current density was 3000 A m{sup -2}.

  9. Efficient red, green, blue and white organic light-emitting diodes with same exciplex host

    Science.gov (United States)

    Chang, Chih-Hao; Wu, Szu-Wei; Huang, Chih-Wei; Hsieh, Chung-Tsung; Lin, Sung-En; Chen, Nien-Po; Chang, Hsin-Hua

    2016-03-01

    Recently, exciplex had drawn attention because of its potential for efficient electroluminescence or for use as a host in organic light-emitting diodes (OLEDs). In this study, four kinds of hole transport material/electron transport material combinations were examined to verify the formation of exciplex and the corresponding energy bandgaps. We successfully demonstrated that the combination of tris(4-carbazoyl-9-ylphenyl)amine (TCTA) and 3,5,3‧,5‧-tetra(m-pyrid-3-yl)phenyl[1,1‧]biphenyl (BP4mPy) could form a stable exciplex emission with an adequate energy gap. Using exciplex as a host in red, green, and blue phosphorescent OLEDs with an identical trilayer architecture enabled effective energy transfer from exciplex to emitters, achieving corresponding efficiencies of 8.8, 14.1, and 15.8%. A maximum efficiency of 11.3% and stable emission was obtained in white OLEDs.

  10. Measurements of refractive indices and thermo-optical coefficients using a white-light Michelson interferometer.

    Science.gov (United States)

    Rocha, A C P; Silva, J R; Lima, S M; Nunes, L A O; Andrade, L H C

    2016-08-20

    A dispersive white-light Michelson interferometer was used to determine the wavelength dependence of the refractive index (n) in the visible range from 425 to 775 nm and the thermo-optical coefficient (dn/dT) of fused silica (FS) and borosilicate glass (BK7). For FS, the values obtained for n and dn/dT at 546 nm were 1.46079 and 11.3×10-6  K-1, respectively, while the values for BK7 glass were 1.51825 and 2.2×10-6  K-1, respectively, which is in good agreement with the literature. The accuracy of the methodology used for n was almost 10-6, enabling precise spectroscopic characterization of materials across a wide spectral range.

  11. Effect of input spectrum on the spectral switch characteristics in a white-light Michelson interferometer.

    Science.gov (United States)

    Brundavanam, Maruthi M; Viswanathan, Nirmal K; Rao, D Narayana

    2009-12-01

    We report here a detailed experimental study to demonstrate the effect of source spectral characteristics such as spectral bandwidth (Deltalambda), peak wavelength (lambda(0)), and shape of the spectrum on the spectral shifts and spectral switches measured due to temporal correlation in a white-light Michelson interferometer operated in the spectral domain. Behavior of the spectral switch characteristics such as the switch position, switch amplitude, and switch symmetry are discussed in detail as a function of optical path difference between the interfering beams. The experimental results are compared with numerical calculations carried out using interference law in the spectral domain with modified source spectral characteristics. On the basis of our results we feel that our study is of critical importance in the selection of source spectral characteristics to further improve the longitudinal resolution or the measurement sensitivity in spectral-domain optical coherence tomography and microscopy.

  12. White organic light-emitting diodes with 4 nm metal electrode

    Science.gov (United States)

    Lenk, Simone; Schwab, Tobias; Schubert, Sylvio; Müller-Meskamp, Lars; Leo, Karl; Gather, Malte C.; Reineke, Sebastian

    2015-10-01

    We investigate metal layers with a thickness of only a few nanometers as anode replacement for indium tin oxide (ITO) in white organic light-emitting diodes (OLEDs). The ultrathin metal electrodes prove to be an excellent alternative that can, with regard to the angular dependence and efficiency of the OLED devices, outperform the ITO reference. Furthermore, unlike ITO, the thin composite metal electrodes are readily compatible with demanding architectures (e.g., top-emission or transparent OLEDs, device unit stacking, etc.) and flexible substrates. Here, we compare the sheet resistance of both types of electrodes on polyethylene terephthalate for different bending radii. The electrical performance of ITO breaks down at a radius of 10 mm, while the metal electrode remains intact even at radii smaller than 1 mm.

  13. Vibrational and spectroscopic analysis of white light emitting Bi2SiO5 nanophosphor

    Science.gov (United States)

    Kumari, Pushpa; Dwivedi, Y.

    2017-06-01

    A series of Dy3 + ion activated Bi2SiO5 nanophosphors were synthesized by the hydrothermal and coprecipitation methods. Various structural and optical characterizations were made using X-ray diffraction, Scanning and Transmission electron microscopy, UV-Visible-Infrared absorption, Raman Spectroscopy, Photoluminescence, Time resolved luminescence techniques etc. Dy3 + ion doped samples yields characteristic bright yellow and blue emissions, on resonant excitation with 349 nm and 386 nm. The intensity ratio of the yellow/blue peaks was found to be function of Dy ion concentration and synthesis method. We have achieved white colour emission at 1.5 mol% Dy concentration, CIE coordinate (0.36, 0.4) of which fall well within gamut of white light. The time-resolved fluorescence reveals decrease in radiative lifetime values with increasing Dy3 + ions concentration. A comparison between the samples synthesized by different methods, and Dy ion concentrations has been made and detail photo-physics involved is presented in the article.

  14. White organic light emitting diodes based on DCM dye sandwiched in 2-methyl-8-hydroxyquinolinolatolithium

    Energy Technology Data Exchange (ETDEWEB)

    Kumar, Amit [Center for Organic Electronics, Polymeric and Soft Materials Section, National Physical Laboratory (Council of Scientific and Industrial Research), Dr. K.S. Krishnan Road, New Delhi 110012 (India); Department of Chemistry, M.D. University, Rohtak, Haryana 124001 (India); Srivastava, Ritu, E-mail: ritu@mail.nplindia.ernet.i [Center for Organic Electronics, Polymeric and Soft Materials Section, National Physical Laboratory (Council of Scientific and Industrial Research), Dr. K.S. Krishnan Road, New Delhi 110012 (India); Bawa, Sukhwant S. [Center for Organic Electronics, Polymeric and Soft Materials Section, National Physical Laboratory (Council of Scientific and Industrial Research), Dr. K.S. Krishnan Road, New Delhi 110012 (India); Singh, Devender; Singh, Kapoor [Department of Chemistry, M.D. University, Rohtak, Haryana 124001 (India); Chauhan, Gayatri [Center for Organic Electronics, Polymeric and Soft Materials Section, National Physical Laboratory (Council of Scientific and Industrial Research), Dr. K.S. Krishnan Road, New Delhi 110012 (India); Singh, Ishwar [Department of Chemistry, M.D. University, Rohtak, Haryana 124001 (India); Kamalasanan, Modeeparampil N. [Center for Organic Electronics, Polymeric and Soft Materials Section, National Physical Laboratory (Council of Scientific and Industrial Research), Dr. K.S. Krishnan Road, New Delhi 110012 (India)

    2010-08-15

    Stable white electroluminescence (EL) has been achieved from organic LED, in which an ultrathin 4-(dicyanomethylene)-2-methyl-6-(p-dimethyl-aminostyryl)-4H-pyran (DCM) dye layer has been inserted in between two 2-methyl-8-hydroxyquinolinolatolithium [LiMeq] emitter layer and by optimizing the position of the DCM dye layer from the {alpha}-NPD/LiMeq interface. Electroluminescence spectra, current-voltage-luminescence (I-V-L) characteristics of the devices have been studied by changing the position of the dye layer. As the distance of DCM layer from {alpha}-NPD/LiMeq interface is increased, the intensity of host emission enhances rapidly. Introduction of thin layer of DCM in emissive layer increases the turn on voltage. The best Commission International de L' Eclairage (CIE) coordinates i.e. (0.32, 0.33) were obtained with device structure ITO/{alpha}-NPD(30 nm) /LiMeq(10 nm)/DCM(1 nm)/LiMeq(25 nm)/BCP(6 nm)/Alq{sub 3}(28 nm)/LiF(1 nm)/Al(100 nm). The EL spectrum covers the whole visible spectra range 400-700 nm. The color rendering index (CRI) for our best white light (Device 4) is 47.4. The device shows very good color stability in terms of CIE coordinates with voltages. The maximum luminescence 1240 cd/m{sup -2} has been achieved at 19 V.

  15. Optimization of white organic light emitting diodes based on emitting layer charge carrier conduction properties

    International Nuclear Information System (INIS)

    Baek, H I; Lee, C H

    2008-01-01

    We have fabricated white organic light emitting diodes (OLEDs) with multi-emitting layer (EML) structures in which 4,4'-N,N'-dicarbazole-biphenyl (CBP) layers doped with the phosphorescent dopants fac-tris(2-phenylpyridine) iridium (Ir(ppy) 3 ) and bis(2-(2'-benzo[4,5-a]thienyl)pyridinato-N,C3')iridium(acetylacetonate) (btp 2 Ir(acac)) and the fluorescent dopant 4,4'-bis[2-{4-(N,N-diphenylamino) phenyl}vinyl]biphenyl (DPAVBi) were used as green (G), red (R) and blue (B) EMLs, respectively. A higher efficiency was expected with the R/G/B EML sequence from the hole transport layer interface than with the G/R/B sequence because of the differences in the charge carrier conduction properties of the EMLs doped with phosphorescent dopants and the luminance balance between the phosphorescent and fluorescent emissions. A high efficiency of 18.3 cd A -1 (an external quantum efficiency of 8.5%) at 100 cd m -2 and good colour stability were achieved with the R/G/B EML sequence as expected, with an additional non-doped CBP interlayer used between the G and B EMLs. In addition, the OLED with this sequence was found to have the longest lifetime of the white devices we tested

  16. Optimization of white organic light emitting diodes based on emitting layer charge carrier conduction properties

    Energy Technology Data Exchange (ETDEWEB)

    Baek, H I; Lee, C H [School of Electrical Engineering and Computer Science and Inter-University Semiconductor Research Center, Seoul National University, Seoul 151-744 (Korea, Republic of)], E-mail: hibaek75@snu.ac.kr

    2008-05-21

    We have fabricated white organic light emitting diodes (OLEDs) with multi-emitting layer (EML) structures in which 4,4'-N,N'-dicarbazole-biphenyl (CBP) layers doped with the phosphorescent dopants fac-tris(2-phenylpyridine) iridium (Ir(ppy){sub 3}) and bis(2-(2'-benzo[4,5-a]thienyl)pyridinato-N,C3')iridium(acetylacetonate) (btp{sub 2}Ir(acac)) and the fluorescent dopant 4,4'-bis[2-{l_brace}4-(N,N-diphenylamino) phenyl{r_brace}vinyl]biphenyl (DPAVBi) were used as green (G), red (R) and blue (B) EMLs, respectively. A higher efficiency was expected with the R/G/B EML sequence from the hole transport layer interface than with the G/R/B sequence because of the differences in the charge carrier conduction properties of the EMLs doped with phosphorescent dopants and the luminance balance between the phosphorescent and fluorescent emissions. A high efficiency of 18.3 cd A{sup -1} (an external quantum efficiency of 8.5%) at 100 cd m{sup -2} and good colour stability were achieved with the R/G/B EML sequence as expected, with an additional non-doped CBP interlayer used between the G and B EMLs. In addition, the OLED with this sequence was found to have the longest lifetime of the white devices we tested.

  17. Phase extracting algorithms analysis in the white-light spectral interferometry

    Science.gov (United States)

    Guo, Tong; Li, Bingtong; Li, Minghui; Chen, Jinping; Fu, Xing; Hu, Xiaotang

    2018-01-01

    As an optical testing method, white-light spectral interferometry has the characteristics of non-contact, high precision. The phase information can be obtained by analyzing the spectral interference signal of the tested sample, and then the absolute distance is calculated. Fourier transform method, temporal phase-shifting method, spatial phase-shifting method and envelope method can be used to extract the phase information of the spectral interference signal. In this paper, the performance of four methods to extract phase information is simulated and analyzed by using the ideal spectral interference signal. It turns out that temporal phase-shifting method has the performance of high precision, the results of Fourier transform method and envelop method are distorted at the edge of the signal, and spatial phase-shifting method has the worst precision. Adding different levels of white noise to the ideal signal, temporal phase-shifting method is most accurate, while Fourier transform method and envelope method are relatively poor. Finally, the absolute distance measurement experiment is carried out on the constructed test system, and the results are consistent with the simulation ones.

  18. All-inorganic white light emitting devices based on ZnO nanocrystals

    Energy Technology Data Exchange (ETDEWEB)

    Nannen, Ekaterina

    2012-09-21

    Semiconductor nanaocrystals (NCs) are very promising candidates for lightweight large-area rollable displays and light emitting devices (LEDs). They are expected to combine the efficiency, robustness and color tunability of conventional semiconductor LEDs with the flexible fabrication techniques known from OLED technology, since the NCs are compatible with solution processing and therefore can be deposited on virtually any substrates including glass and plastic. Today, NC-LEDs consist of chemically synthesized QDs embedded in organic charge injection and transport layers. The organic layers limit the robustness of the NC-LEDs and result in significant constrictions within the device fabrication procedure, such as organic evaporation steps, inert (i.e. humidity and oxygen free) atmosphere and obligatory encapsulation. These limitations during the production process as well as complex chemical synthesis route of the implemented NCs and organic components lead to high fabrication costs and low turnover. So far, only prototype devices have been introduced by several research groups and industrial companies. Still, the main concern retarding NC-LEDs from market launch is the high content of toxic heavy metals like Cd in the active nanocrystalline light emitting material. Within this work, possible environmentally safe and ambient-air-compatible alternatives to conventional QDs and organics were explored, with the main focus on design and fabrication of completely inorganic white NC-LEDs with commercial ZnO nanoparticles as an active light emitting material. While the electrical transport properties through the NC-network of the commercially available VP AdNano {sup registered} ZnO2O particles were already to some extent explored, their optical properties and therefore suitability as an active light emitter in NC-LEDs were not studied so far. (orig.)

  19. Efficient textured colour conversion layer of a down-converted white organic light-emitting diode by transfer imprinting

    International Nuclear Information System (INIS)

    Zhu, Wenqing; Xiao, Teng; Qian, Bingjie; Sun, Liangliang

    2015-01-01

    In this paper, we demonstrated an efficient textured colour conversion layer (CCL) of a down-converted white organic light-emitting diode (WOLED), which was fabricated by a very simple transfer imprinting method based on silicon wafer. The textured CCL not only helped to extract wave-guided light in the device, but also had an outstanding performance in enhancing the colour conversion rate, which was 1.75 times greater than that of flat CCL. Compared to flat CCL, the lower-doped textured CCL produced better white emission and higher efficiency simultaneously. Moreover, the WOLED with textured CCL also exhibited good colour stability at various voltages. (paper)

  20. Smart design to resolve spectral overlapping of phosphor-in-glass for high-powered remote-type white light-emitting devices.

    Science.gov (United States)

    Lee, Jin Seok; Arunkumar, P; Kim, Sunghoon; Lee, In Jae; Lee, Hyungeui; Im, Won Bin

    2014-02-15

    The white light-emitting diode (WLED) is a state-of-the-art solid state technology, which has replaced conventional lighting systems due to its reduced energy consumption, its reliability, and long life. However, the WLED presents acute challenges in device engineering, due to its lack of color purity, efficacy, and thermal stability of the lighting devices. The prime cause for inadequacies in color purity and luminous efficiency is the spectral overlapping of red components with yellow/green emissions when generating white light by pumping a blue InGaN chip with yellow YAG:Ce³⁺ phosphor, where red phosphor is included, to compensate for deficiencies in the red region. An innovative strategy was formulated to resolve this spectral overlapping by alternatively arranging phosphor-in-glass (PiG) through cutting and reassembling the commercial red CaAlSiN₃:Eu²⁺ and green Lu₃Al₅O₁₂:Ce³⁺ PiG. PiGs were fabricated using glass frits with a low softening temperature of 600°C, which exhibited excellent thermal stability and high transparency, improving life time even at an operating temperature of 200°C. This strategy overcomes the spectral overlapping issue more efficiently than the randomly mixed and patented stacking design of multiple phosphors for a remote-type WLED. The protocol for the current design of PiG possesses excellent thermal and chemical stability with high luminous efficiency and color purity is an attempt to make smarter solid state lighting for high-powered remote-type white light-emitting devices.

  1. Modulation of the photoluminescence in carbon dots through surface modification: from mechanism to white light-emitting diodes

    Science.gov (United States)

    Zhu, Jinyang; Shao, He; Bai, Xue; Zhai, Yue; Zhu, Yongsheng; Chen, Xu; Pan, Gencai; Dong, Biao; Xu, Lin; Zhang, Hanzhuang; Song, Hongwei

    2018-06-01

    Carbon dots (CDs) have emerged as a new type of fluorescent material because of their unique optical advantages, such as high photoluminescence quantum yields (QYs), excellent photo-stability, excitation-dependent emissions, and low toxicity. However, the photoluminescence mechanism for CDs remains unclear, which limits their further practical application. Here, CDs were synthesized via a solvothermal route from citric acid and urea. Through the oxidation and reduction treatment of pristine CDs, the origin of the photoluminescence and the involved mechanism were revealed. We found that the blue/green/red emissions originated from three diverse emitting states, i.e. the intrinsic state, and C=O- and C=N-related surface states, respectively. Based on the as-prepared CDs, a pH sensor depending on the radiometric luminescence detection was developed. Furthermore, we constructed CD/PVP (PVP, polyvinylpyrrolidone) composite films, which exhibited white light emission with photoluminescence QYs of 15.3%. The white light emission with different correlated color temperatures (CCTs), from 4807 K to 3319 K, was obtained by simply changing the amount of PVP solution. Benefiting from the white light-emitting solid-state films, single-component white light-emitting diodes were fabricated with an average color rendering index value (Ra) of 80.0, luminous efficiency of 10.2 lm W‑1, and good working stability, thus indicating a promising potential for practical lighting applications.

  2. Flexible white phosphorescent organic light emitting diodes based on multilayered graphene/PEDOT:PSS transparent conducting film

    Energy Technology Data Exchange (ETDEWEB)

    Wu, Xiaoxiao; Li, Fushan, E-mail: fushanli@hotmail.com; Wu, Wei; Guo, Tailiang, E-mail: gtl_fzu@hotmail.com

    2014-03-01

    Highlights: • A double-layered graphene/PEDOT:PSS film was fabricated by spray-coating. • A white flexible phosphorescent OLED was fabricated based on this film. • The white flexible OLED presented pure white light emission. • The flexible OLEDs showed a stable white emission during bending test. - Abstract: A double-layered graphene/poly(3,4-ethylenedioxythiophene):poly(styrenesulfonate) (PEDOT:PSS) conductive film was prepared, in which the PEDOT:PSS layer was obtained by using spray-coating technique. A flexible white phosphorescent organic light-emitting devices based on the graphene/PEDOT:PSS conductive film was fabricated. Phosphorescent material tris(2-phenylpyridine) iridium (Ir(ppy){sub 3}) and the fluorescent dye 5,6,11,12-tetraphenylnapthacene (Rubrene) were co-doped into 4,4′-N,N′-dicarbazole-biphenyl (CBP) host. N,N′-diphenyl-N,N′-bis(1-naphthyl)-(1,1′-biphenyl)-4,4′-diamine (NPB) and 4,7-diphenyl-1,10-phenanthroline (Bphen) were used as hole-transporting and electron-transporting layer, respectively, and 4,4′-bis(2,2′-diphenylvinyl)-1,1′-biphenyl (DPVBi) was used as blue light-emitting layer. The device presented pure white light emission with a Commission Internationale De I’Eclairage coordinates of (0.31, 0.33) and exhibited an excellent light-emitting stability during the bending cycle test with a radius of curvature of 10 mm.

  3. Flexible white phosphorescent organic light emitting diodes based on multilayered graphene/PEDOT:PSS transparent conducting film

    International Nuclear Information System (INIS)

    Wu, Xiaoxiao; Li, Fushan; Wu, Wei; Guo, Tailiang

    2014-01-01

    Highlights: • A double-layered graphene/PEDOT:PSS film was fabricated by spray-coating. • A white flexible phosphorescent OLED was fabricated based on this film. • The white flexible OLED presented pure white light emission. • The flexible OLEDs showed a stable white emission during bending test. - Abstract: A double-layered graphene/poly(3,4-ethylenedioxythiophene):poly(styrenesulfonate) (PEDOT:PSS) conductive film was prepared, in which the PEDOT:PSS layer was obtained by using spray-coating technique. A flexible white phosphorescent organic light-emitting devices based on the graphene/PEDOT:PSS conductive film was fabricated. Phosphorescent material tris(2-phenylpyridine) iridium (Ir(ppy) 3 ) and the fluorescent dye 5,6,11,12-tetraphenylnapthacene (Rubrene) were co-doped into 4,4′-N,N′-dicarbazole-biphenyl (CBP) host. N,N′-diphenyl-N,N′-bis(1-naphthyl)-(1,1′-biphenyl)-4,4′-diamine (NPB) and 4,7-diphenyl-1,10-phenanthroline (Bphen) were used as hole-transporting and electron-transporting layer, respectively, and 4,4′-bis(2,2′-diphenylvinyl)-1,1′-biphenyl (DPVBi) was used as blue light-emitting layer. The device presented pure white light emission with a Commission Internationale De I’Eclairage coordinates of (0.31, 0.33) and exhibited an excellent light-emitting stability during the bending cycle test with a radius of curvature of 10 mm

  4. Health-friendly high-quality white light using violet-green-red laser and InGaN nanowires-based true yellow nanowires light-emitting diodes

    KAUST Repository

    Janjua, Bilal

    2017-02-16

    White light based on blue laser - YAG: Ce phosphor has the advantage of implementing solid-state lighting and optical wireless communications combined-functionalities in a single lamp. However, the blue light was found to disrupt melatonin production, and therefore the human circadian rhythm in general; while the yellow phosphor is susceptible to degradation by laser irradiation and also lack tunability in color rendering index (CRI). In this investigation, by using a violet laser, which has 50% less impact on circadian response, as compared to blue light, and an InGaN-quantum-disks nanowires-based light-emitting diode (NWs-LED), we address both issues simultaneously. The white light is therefore generated using violet-green-red lasers, in conjunction with a yellow NWs-LED realized using molecular beam epitaxy technique, on titanium-coated silicon substrates. Unlike the conventional quantum-well-based LED, the NWs-LED showed efficiency-droop free behavior up to 9.8 A/cm with peak output power of 400 μW. A low turn-on voltage of ∼2.1 V was attributed to the formation of conducting titanium nitride layer at NWs nucleation site and improved fabrication process in the presence of relatively uniform height distribution. The 3D quantum confinement and the reduced band bending improve carriers-wavefunctions overlap, resulting in an IQE of ∼39 %. By changing the relative intensities of the individual color components, CRI of >85 was achieved with tunable correlated color temperature (CCT), thus covering the desired room lighting conditions. Our architecture provides important considerations in designing smart solid-state lighting while addressing the harmful effect of blue light.

  5. Health-friendly high-quality white light using violet-green-red laser and InGaN nanowires-based true yellow nanowires light-emitting diodes

    Science.gov (United States)

    Janjua, Bilal; Ng, Tien K.; Zhao, Chao; Anjum, Dalaver H.; Prabaswara, Aditya; Consiglio, Giuseppe Bernardo; Shen, Chao; Ooi, Boon S.

    2017-02-01

    White light based on blue laser - YAG: Ce3+ phosphor has the advantage of implementing solid-state lighting and optical wireless communications combined-functionalities in a single lamp. However, the blue light was found to disrupt melatonin production, and therefore the human circadian rhythm in general; while the yellow phosphor is susceptible to degradation by laser irradiation and also lack tunability in color rendering index (CRI). In this investigation, by using a violet laser, which has 50% less impact on circadian response, as compared to blue light, and an InGaN-quantum-disks nanowires-based light-emitting diode (NWs-LED), we address both issues simultaneously. The white light is therefore generated using violet-green-red lasers, in conjunction with a yellow NWs-LED realized using molecular beam epitaxy technique, on titanium-coated silicon substrates. Unlike the conventional quantum-well-based LED, the NWs-LED showed efficiency-droop free behavior up to 9.8 A/cm2 with peak output power of 400 μW. A low turn-on voltage of 2.1 V was attributed to the formation of conducting titanium nitride layer at NWs nucleation site and improved fabrication process in the presence of relatively uniform height distribution. The 3D quantum confinement and the reduced band bending improve carriers-wavefunctions overlap, resulting in an IQE of 39 %. By changing the relative intensities of the individual color components, CRI of >85 was achieved with tunable correlated color temperature (CCT), thus covering the desired room lighting conditions. Our architecture provides important considerations in designing smart solid-state lighting while addressing the harmful effect of blue light.

  6. One-dimensional organic lead halide perovskites with efficient bluish white-light emission

    Science.gov (United States)

    Yuan, Zhao; Zhou, Chenkun; Tian, Yu; Shu, Yu; Messier, Joshua; Wang, Jamie C.; van de Burgt, Lambertus J.; Kountouriotis, Konstantinos; Xin, Yan; Holt, Ethan; Schanze, Kirk; Clark, Ronald; Siegrist, Theo; Ma, Biwu

    2017-01-01

    Organic-inorganic hybrid metal halide perovskites, an emerging class of solution processable photoactive materials, welcome a new member with a one-dimensional structure. Herein we report the synthesis, crystal structure and photophysical properties of one-dimensional organic lead bromide perovskites, C4N2H14PbBr4, in which the edge sharing octahedral lead bromide chains [PbBr4 2-]∞ are surrounded by the organic cations C4N2H14 2+ to form the bulk assembly of core-shell quantum wires. This unique one-dimensional structure enables strong quantum confinement with the formation of self-trapped excited states that give efficient bluish white-light emissions with photoluminescence quantum efficiencies of approximately 20% for the bulk single crystals and 12% for the microscale crystals. This work verifies once again that one-dimensional systems are favourable for exciton self-trapping to produce highly efficient below-gap broadband luminescence, and opens up a new route towards superior light emitters based on bulk quantum materials.

  7. Intrinsic white-light emission from zinc oxide nanorods heterojunctions on large-area substrates

    Science.gov (United States)

    Willander, Magnus; Nur, O.; Zaman, S.; Zainelabdin, A.; Amin, G.; Sadaf, J. R.; Israr, M. Q.; Bano, N.; Hussain, I.; Alvi, N. H.

    2011-02-01

    Zinc oxide (ZnO) and especially in the nanostructure form is currently being intensively investigated world wide for the possibility of developing different new photonic devices. We will here present our recent findings on the controlled low temperature chemical growth of ZnO nanorods (NRs) on different large area substrates. Many different heterojunctions of ZnO NRs and p-substrates including those of crystalline e.g. p-GaN, p-SiC or amorphous nature e.g. p-polymer coated plastic and p-polymer coated paper will be shown. Moreover, the effect of the p-electrode of these heterojunctions on tuning the emitted wavelength and changing the light quality will be discussed. An example using ZnO NR/p-GaN will be shown and the electrical and electro-optical characteristics will be analyzed. For these heterojunctions the effect of post growth annealing and its effect on the electroluminescence (EL) spectrum will be shown. Finally, intrinsic white light emitting diodes based on ZnO NRs on foldable and disposable amorphous substrates (plastic and paper) will also be presented.

  8. Pulsed Ultraviolet Light Reduces Immunoglobulin E Binding to Atlantic White Shrimp (Litopenaeus setiferus Extract

    Directory of Open Access Journals (Sweden)

    Si-Yin Chung

    2011-06-01

    Full Text Available Pulsed ultraviolet light (PUV, a novel food processing and preservation technology, has been shown to reduce allergen levels in peanut and soybean samples. In this study, the efficacy of using PUV to reduce the reactivity of the major shrimp allergen, tropomyosin (36-kDa, and to attenuate immunoglobulin E (IgE binding to shrimp extract was examined. Atlantic white shrimp (Litopenaeus setiferus extract was treated with PUV (3 pulses/s, 10 cm from light source for 4 min. Tropomyosin was compared in the untreated, boiled, PUV-treated and [boiled+PUV]-treated samples, and changes in the tropomyosin levels were determined by sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE. IgE binding of the treated extract was analyzed via immunoblot and enzyme-linked immunosorbent assay (ELISA using pooled human plasma containing IgE antibodies against shrimp allergens. Results showed that levels of tropomyosin and IgE binding were reduced following PUV treatment. However, boiling increased IgE binding, while PUV treatment could offset the increased allergen reactivity caused by boiling. In conclusion, PUV treatment reduced the reactivity of the major shrimp allergen, tropomyosin, and decreased the IgE binding capacity of the shrimp extract.

  9. Solution-processed white organic light-emitting devices based on small-molecule materials

    International Nuclear Information System (INIS)

    Wang Dongdong; Wu Zhaoxin; Zhang Xinwen; Wang Dawei; Hou Xun

    2010-01-01

    We investigated solution-processed films of 4,4'-bis(2,2-diphenylvinyl)-1,1'-bibenyl (DPVBi) and its blends with N,N'-bis(3-methylphenyl)-(1,1'-biphenyl)-4,4'-diamine (TPD) by atomic force microscopy (AFM). The AFM result shows that the solution-processed films are pin-free and their morphology is smooth enough to be used in OLEDs. We have developed a solution-processed white organic light-emitting device (WOLEDs) based on small-molecules, in which the light-emitting layer (EML) was formed by spin-coating the solution of small-molecules on top of the solution-processed hole-transporting layer. This WOLEDs, in which the EML consists of co-host (DPVBi and TPD), the blue dopant (4,4'-bis[2-(4-(N,N-diphenylamino)phenyl)vinyl]biphenyl) and the yellow dye (5,6,11,12-tetraphenylnaphtacene), has a current efficiency of 6.0 cd/A at a practical luminance of 1000 cd/m 2 , a maximum luminance of 22500 cd/m 2 , and its color coordinates are quite stable. Our research shows a possible approach to achieve efficient and low-cost small-molecule-based WOLEDs, which avoids the complexities of the co-evaporation process of multiple dopants and host materials in vacuum depositions.

  10. [Effects of white organic light-emitting devices using color conversion films on electroluminescence spectra].

    Science.gov (United States)

    Hou, Qing-Chuan; Wu, Xiao-Ming; Hua, Yu-Lin; Qi, Qing-Jin; Li, Lan; Yin, Shou-Gen

    2010-06-01

    The authors report a novel white organic light-emitting device (WOLED), which uses a strategy of exciting organic/ inorganic color conversion film with a blue organic light-emitting diode (OLED). The luminescent layer of the blue OLED was prepared by use of CBP host blended with a blue highly fluorescent dye N-BDAVBi. The organic/inorganic color conversion film was prepared by dispersing a mixture of red pigment VQ-D25 and YAG : Ce3+ phosphor in PMMA. The authors have achieved a novel WOLED with the high color stability by optimizing the thickness and fluorescent pigment concentration of the color conversion film. When the driving voltage varied between 6 and 14 V, the color coordinates (CIE) varied slightly from (0.354, 0.304) to (0.357, 0.312) and the maximum current efficiency is about 5.8 cd x A(-1) (4.35 mA x cm(-2)), the maximum brightness is 16 800 cd x m(-2) at the operating voltage of 14 V.

  11. Luminescent properties of Na2CaSiO4:Eu2+ and its potential application in white light emitting diodes

    International Nuclear Information System (INIS)

    Wang, Zhijun; Li, Panlai; Li, Ting; Zhang, Xing; Li, Qingxuan; Yang, Zhiping; Guo, Qinglin

    2013-01-01

    Graphical abstract: Na 2 CaSiO 4 :Eu 2+ phosphor can be effectively excited by an ultraviolet and near-ultraviolet light, and produce a bright blue emission centered at 436 nm. The CIE chromaticity coordinations (x, y) of Na 2 CaSiO 4 :Eu 2+ (NSCE)/Li 2 SrSiO 4 :Eu 2+ (LSSE) vary with the molar ratio of the two constituents. When NSCE/LSSE is 1:3, the CIE chromaticity coordination is (0.332, 0.346), which is close to that of the natural sunlight (0.33, 0.33). The results indicate that Na 2 CaSiO 4 :Eu 2+ may be a promising blue phosphor for UV chip-based multi-phosphor converted white light emitting diodes. Highlights: ► Na 2 CaSiO 4 :Eu 2+ shows the blue emission with a peak at 436 nm and broad excitation band in the UV/n-UV range. ► White light with CIE coordinates (0.332, 0.346) is generated by mixing the blue phosphor with the Li 2 SrSiO 4 :Eu 2+ yellow phosphor. ► Na 2 CaSiO 4 :Eu 2+ would be a promising blue phosphor candidate for UV chip-based multi-phosphor converted white LEDs. - Abstract: A novel blue phosphor Na 2 CaSiO 4 :Eu 2+ is synthesized by a high temperature solid-state reaction, and its luminescent properties are systematically studied. Na 2 CaSiO 4 :Eu 2+ can be effectively excited by the 354 nm radiation, and create blue emission (436 nm). The emission intensity of Na 2 CaSiO 4 :Eu 2+ is influenced by the Eu 2+ doping content, and the optimal doping content is 1.5%, and the concentration quenching mechanism of Eu 2+ in Na 2 CaSiO 4 can be attributed to the multipolar interaction. The white light with CIE coordinates (0.332, 0.346) is generated by mixing the blue phosphor Na 2 CaSiO 4 :Eu 2+ with the yellow phosphor Li 2 SrSiO 4 :Eu 2+ . The results indicate that Na 2 CaSiO 4 :Eu 2+ may be a potential blue emitting phosphor for UV chip-based multi-phosphor converted white light emitting diodes

  12. Origin of colour stability in blue/orange/blue stacked phosphorescent white organic light-emitting diodes

    International Nuclear Information System (INIS)

    Kim, Sung Hyun; Jang, Jyongsik; Yook, Kyoung Soo; Lee, Jun Yeob

    2009-01-01

    The origin of colour stability in phosphorescent white organic light-emitting diodes (PHWOLEDs) with a blue/orange/blue stacked emitting structure was studied by monitoring the change in a recombination zone. A balanced recombination zone shift between the blue and the orange light-emitting layers was found to be responsible for the colour stability in the blue/orange/blue stacked PHWOLEDs.

  13. Settlement of reactive power compensation in the light of white certificates

    Science.gov (United States)

    Zajkowski, Konrad

    2017-10-01

    The article discusses the problem of the determination of savings on active energy as a result of a reactive power compensation. Statutory guidance on the required energy audit to obtain white certificates in the European Union was followed. The analysis was made on the basis of the Polish Law. The paper presents a detailed analytical method and an estimation method taking into account the impact on the line, the transformer and the generator. According to the relevant guidelines in the European Union, the reduction of CO2 emissions by calculating the saving of active power should be determined. The detailed method and an estimation method proposed for the determination of savings on active energy as a result of the reactive power compensation carried out possess some errors and inconvenience. The detailed method requires knowledge of the network topology and a determination of reactive power Q at each point of the network. The estimation method of analysis is easy in execution, especially if the consumer of energy is the main or the most significant purchaser of electricity in the network. Unfortunately, this latter method can be used only for activities that do not require high computational accuracy. The results obtained by this method are approximate values that can be used for the calculation of economic indicators. The estimation method is suitable for determining the number of white certificates when a power audit concerns a recipient of electricity, the structure of which is a large number of divisions scattered at many different locations in the power system.

  14. Dye-sensitized solar cells for efficient power generation under ambient lighting

    Science.gov (United States)

    Freitag, Marina; Teuscher, Joël; Saygili, Yasemin; Zhang, Xiaoyu; Giordano, Fabrizio; Liska, Paul; Hua, Jianli; Zakeeruddin, Shaik M.; Moser, Jacques-E.; Grätzel, Michael; Hagfeldt, Anders

    2017-06-01

    Solar cells that operate efficiently under indoor lighting are of great practical interest as they can serve as electric power sources for portable electronics and devices for wireless sensor networks or the Internet of Things. Here, we demonstrate a dye-sensitized solar cell (DSC) that achieves very high power-conversion efficiencies (PCEs) under ambient light conditions. Our photosystem combines two judiciously designed sensitizers, coded D35 and XY1, with the copper complex Cu(II/I)(tmby) as a redox shuttle (tmby, 4,4‧,6,6‧-tetramethyl-2,2‧-bipyridine), and features a high open-circuit photovoltage of 1.1 V. The DSC achieves an external quantum efficiency for photocurrent generation that exceeds 90% across the whole visible domain from 400 to 650 nm, and achieves power outputs of 15.6 and 88.5 μW cm-2 at 200 and 1,000 lux, respectively, under illumination from a model Osram 930 warm-white fluorescent light tube. This translates into a PCE of 28.9%.

  15. Control of a White Organic Light Emitting Diode emission parameters using a single doped RGB active layer

    Energy Technology Data Exchange (ETDEWEB)

    Pereira, D. [Departamento de Ciência dos Materiais e i3N – Instituto de Nanoestruturas, Nanomodelação e Nanofabricação, Faculdade de Ciências e Tecnologia, Universidade Nova de Lisboa, Campus da Caparica, 2829-516 Caparica (Portugal); Pinto, A.; Califórnia, A.; Gomes, J. [CeNTI – Centro de Nanotecnologia, Materiais Técnicos, Funcionais e Inteligentes, Rua Fernando Mesquita 2785, 4760-034 Vila Nova de Famalicão (Portugal); Pereira, L., E-mail: luiz@ua.pt [Departmento de Física e i3N – Instituto de Nanoestruturas, Nanomodelação e Nanofabricação, Universidade de Aveiro, 3810-193 Aveiro (Portugal)

    2016-09-15

    Highlights: • A simple WOLED for Solid State Lighting is proposed with high color stability. • Energy transfer and electroluminescence dynamics of a single RGB layer for WOLEDs. • White shade modulation and stability over large emitting areas and applied voltages. - Abstract: Solid State Lighting technologies based on Organic Light Emitting Diodes, became an interesting focus due to their unique properties. The use of a unique RGB active layer for white emission, although simple in theory, shows difficulty to stabilize both CIE coordinates and color modulation. In this work, a WOLED using a simple RGB layer, was developed achieving a high color stability and shade modulation. The RGB matrix comprises a blue host material NPB, doped with two guests, a green (Coumarin 153) and a red (DCM1) in low concentrations. The RGB layer carrier dynamics allows for the white emission in low device complexity and high stability. This was also shown independent of the white shade, obtained through small changes in the red dopant resulting in devices ranging from warm to cool white i.e. an easy color tuning. A detailed analysis of the opto-electrical behavior is made.

  16. Control of a White Organic Light Emitting Diode emission parameters using a single doped RGB active layer

    International Nuclear Information System (INIS)

    Pereira, D.; Pinto, A.; Califórnia, A.; Gomes, J.; Pereira, L.

    2016-01-01

    Highlights: • A simple WOLED for Solid State Lighting is proposed with high color stability. • Energy transfer and electroluminescence dynamics of a single RGB layer for WOLEDs. • White shade modulation and stability over large emitting areas and applied voltages. - Abstract: Solid State Lighting technologies based on Organic Light Emitting Diodes, became an interesting focus due to their unique properties. The use of a unique RGB active layer for white emission, although simple in theory, shows difficulty to stabilize both CIE coordinates and color modulation. In this work, a WOLED using a simple RGB layer, was developed achieving a high color stability and shade modulation. The RGB matrix comprises a blue host material NPB, doped with two guests, a green (Coumarin 153) and a red (DCM1) in low concentrations. The RGB layer carrier dynamics allows for the white emission in low device complexity and high stability. This was also shown independent of the white shade, obtained through small changes in the red dopant resulting in devices ranging from warm to cool white i.e. an easy color tuning. A detailed analysis of the opto-electrical behavior is made.

  17. A Next Generation Light Source Facility at LBNL

    International Nuclear Information System (INIS)

    Corlett, J.N.; Austin, B.; Baptiste, K.M.; Byrd, J.M.; Denes, P.; Donahue, R.; Doolittle, L.; Falcone, R.W.; Filippetto, D.; Fournier, S.; Li, D.; Padmore, H.A.; Papadopoulos, C.; Pappas, C.; Penn, G.; Placidi, M.; Prestemon, S.; Prosnitz, D.; Qiang, J.; Ratti, A.; Reinsch, M.; Sannibale, F.; Schlueter, R.; Schoenlein, R.W.; Staples, J.W.; Vecchione, T.; Venturini, M.; Wells, R.; Wilcox, R.; Wurtele, J.; Charman, A.; Kur, E.; Zholents, A.A.

    2011-01-01

    The Next Generation Light Source (NGLS) is a design concept, under development at LBNL, for a multibeamline soft x-ray FEL array powered by a ∼2 GeV superconducting linear accelerator, operating with a 1 MHz bunch repetition rate. The CW superconducting linear accelerator is supplied by a high-brightness, high-repetition-rate photocathode electron gun. Electron bunches are distributed from the linac to the array of independently configurable FEL beamlines with nominal bunch rates up to 100 kHz in each FEL, and with even pulse spacing. Individual FELs may be configured for EEHG, HGHG, SASE, or oscillator mode of operation, and will produce high peak and average brightness x-rays with a flexible pulse format, with pulse durations ranging from sub-femtoseconds to hundreds of femtoseconds.

  18. Development of next-generation light water reactor

    International Nuclear Information System (INIS)

    Ishibashi, Fumihiko; Yasuoka, Makoto

    2010-01-01

    The Next-Generation Light Water Reactor Development Program, a national project in Japan, was inaugurated in April 2008. The primary objective of this program is to meet the need for the replacement of existing nuclear power plants in Japan after 2030. With the aim of setting a global standard design, the reactor to be developed offers greatly improved safety, reliability, and economic efficiency through several innovative technologies, including a reactor core system with uranium enrichment of 5 to 10%, a seismic isolation system, long-life materials, advanced water chemistry, innovative construction techniques, optimized passive and active safety systems, innovative digital technologies, and so on. In the first three years, a plant design concept with these innovative features is to be established and the effectiveness of the program will be reevaluated. The major part of the program will be completed in 2015. Toshiba is actively engaged in both design studies and technology development as a founding member of this program. (author)

  19. The potential and limitations of third generation light sources

    International Nuclear Information System (INIS)

    Hormes, Josef

    2011-01-01

    To date, 3rd generation Light Sources, i.e. electron storage rings where mainly radiation from insertion devices (wigglers and undulators) is used for synchrotron radiation experiments are the 'workhorses' for basic and applied VUV/X-ray research. Several machine parameters. i.e. the energy of the electrons, the emittance and the circumference of the machine, together with the specification of the corresponding insertion devices determine the 'quality' of a facility and a specific beamline. In this talk, several of these aspects are discussed mainly from a users' point of view, i.e. what are the required specifications to carry out 'state-of-the-art' experiments in various areas, e.g. protein crystallography, Resonant Elastic and Inelastic X-ray Scattering (REIXS), Micro-/nanospectroscopy, and time resolved experiments in the femtosecond time domain. (author)

  20. A Next Generation Light Source Facility at LBNL

    Energy Technology Data Exchange (ETDEWEB)

    Corlett, J.N.; Austin, B.; Baptiste, K.M.; Byrd, J.M.; Denes, P.; Donahue, R.; Doolittle, L.; Falcone, R.W.; Filippetto, D.; Fournier, S.; Li, D.; Padmore, H.A.; Papadopoulos, C.; Pappas, C.; Penn, G.; Placidi, M.; Prestemon, S.; Prosnitz, D.; Qiang, J.; Ratti, A.; Reinsch, M.; Sannibale, F.; Schlueter, R.; Schoenlein, R.W.; Staples, J.W.; Vecchione, T.; Venturini, M.; Wells, R.; Wilcox, R.; Wurtele, J.; Charman, A.; Kur, E.; Zholents, A.A.

    2011-03-23

    The Next Generation Light Source (NGLS) is a design concept, under development at LBNL, for a multibeamline soft x-ray FEL array powered by a ~;;2 GeV superconducting linear accelerator, operating with a 1 MHz bunch repetition rate. The CW superconducting linear accelerator is supplied by a high-brightness, highrepetition- rate photocathode electron gun. Electron bunches are distributed from the linac to the array of independently configurable FEL beamlines with nominal bunch rates up to 100 kHz in each FEL, and with even pulse spacing. Individual FELs may be configured for EEHG, HGHG, SASE, or oscillator mode of operation, and will produce high peak and average brightness x-rays with a flexible pulse format, with pulse durations ranging from sub-femtoseconds to hundreds of femtoseconds.

  1. Light third-generation squarks from flavour gauge messengers

    International Nuclear Information System (INIS)

    Brümmer, Felix; McGarrie, Moritz; Weiler, Andreas

    2014-01-01

    We study models of gauge-mediated supersymmetry breaking with a gauged horizontal SU(3) F symmetry acting on the quark superfields. If SU(3) F is broken non-supersymmetrically by F-term vacuum expectation values, the massive gauge bosons and gauginos become messengers for SUSY breaking mediation. These gauge messenger fields induce a flavour-dependent, negative contribution to the soft masses of the squarks at one loop. In combination with the soft terms from standard gauge mediation, one obtains large and degenerate first- and second-generation squark masses, while the stops and sbottoms are light. We discuss the implications of this mechanism for the superparticle spectrum and for flavour precision observables. We also provide an explicit realization in a model with simultaneous SUSY and SU(3) F breaking

  2. Light third-generation squarks from flavour gauge messengers

    International Nuclear Information System (INIS)

    Bruemmer, Felix; McGarrie, Moritz; Univ. of the Witwatersrand, Johannesburg; Weiler, Andreas; CERN - European Organization for Nuclear Research, Geneva

    2014-04-01

    We study models of gauge-mediated supersymmetry breaking with a gauged horizontal SU(3) F symmetry acting on the quark superfields. If SU(3) F is broken non-supersymmetrically by F-term vacuum expectation values, the massive gauge bosons and gauginos become messengers for SUSY breaking mediation. These gauge messenger fields induce a flavour-dependent, negative contribution to the soft masses of the squarks at one loop. In combination with the soft terms from standard gauge mediation, one obtains large and degenerate first- and second-generation squark masses, while the stops and sbottoms are light. We discuss the implications of this mechanism for the superparticle spectrum and for flavour precision observables. We also provide an explicit realization in a model with simultaneous SUSY and SU(3) F breaking.

  3. White paper on perspectives of biofuels in Denmark - with focus on 2nd generation bioethanol; Hvidbog om perspektiver for biobraendstoffer i Danmark - med fokus paa 2. generations bioethanol

    Energy Technology Data Exchange (ETDEWEB)

    Larsen, Gy.; Foghmar, J.

    2009-11-15

    The white paper presents the perspectives - both options and barriers - for a Danish focus on production and use of biomass, including sustainable 2nd generation bioethanol, for transport. The white paper presents the current knowledge of biofuels and bioethanol and recommendations for a Danish strategy. (ln)

  4. Autofluorescence endoscopy: feasibility of detection of GI neoplasms unapparent to white light endoscopy with an evolving technology

    NARCIS (Netherlands)

    Haringsma, J.; Tytgat, G. N.; Yano, H.; Iishi, H.; Tatsuta, M.; Ogihara, T.; Watanabe, H.; Sato, N.; Marcon, N.; Wilson, B. C.; Cline, R. W.

    2001-01-01

    Case studies are presented of fluorescence endoscopy in the upper and lower GI tract to illustrate the ability to detect early-stage lesions that were not observable with white light endoscopy or those in which the assessment of the stage or extension of the lesion were equivocal. A new fluorescence

  5. Introduction of Red-Green-Blue Fluorescent Dyes into a Metal-Organic Framework for Tunable White Light Emission.

    Science.gov (United States)

    Wen, Yuehong; Sheng, Tianlu; Zhu, Xiaoquan; Zhuo, Chao; Su, Shaodong; Li, Haoran; Hu, Shengmin; Zhu, Qi-Long; Wu, Xintao

    2017-10-01

    The unique features of the metal-organic frameworks (MOFs), including ultrahigh porosities and surface areas, tunable pores, endow the MOFs with special utilizations as host matrices. In this work, various neutral and ionic guest dye molecules, such as fluorescent brighteners, coumarin derivatives, 4-(dicyanomethylene)-2-methyl-6-(p-dimethylaminostyryl)-4H-pyran (DCM), and 4-(p-dimethylaminostyryl)-1-methylpyridinium (DSM), are encapsulated in a neutral MOF, yielding novel blue-, green-, and red-phosphors, respectively. Furthermore, this study introduces the red-, green-, and blue-emitting dyes into a MOF together for the first time, producing white-light materials with nearly ideal Commission International ed'Eclairage (CIE) coordinates, high color-rendering index values (up to 92%) and quantum yields (up to 26%), and moderate correlated color temperature values. The white light is tunable by changing the content or type of the three dye guests, or the excitation wavelength. Significantly, the introduction of blue-emitting guests in the methodology makes the available MOF host more extensive, and the final white-light output more tunable and high-quality. Such strategy can be widely adopted to design and prepare white-light-emitting materials. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  6. Do chestnut, northern red, and white oak germinant seedlings respond similary to light treatments? II. Gas exchange and chlorophyll responses

    Science.gov (United States)

    Joanne Rebbeck; Amy Scherzer; Kurt. Gottschalk

    2012-01-01

    Understanding differences in physiological and growth strategies in low-light environments among upland oak species may help managers address the challenges of oaks' poor regeneration. Gas exchange and chlorophyll content were measured for northern red oak (Quercus rubra L.), chestnut oak (Quercus prinus L.), and white oak (...

  7. Subjective quality of videos displayed with local backlight dimming at different peak white and ambient light levels

    DEFF Research Database (Denmark)

    Mantel, Claire; Korhonen, Jari; Forchhammer, Søren

    2015-01-01

    In this paper the influence of ambient light and peak white (maximum brightness) of a display on the subjective quality of videos shown with local backlight dimming is examined. A subjective experiment investigating those factors is set-up using high contrast test sequences. The results are firstly...

  8. White light emission and color tunability of dysprosium doped barium silicate glasses

    Energy Technology Data Exchange (ETDEWEB)

    Mishra, Lokesh; Sharma, Anchal; Vishwakarma, Amit K.; Jha, Kaushal [Department of Applied Physics, Delhi Technological University, Delhi 110042 (India); Jayasimhadri, M., E-mail: jayaphysics@yahoo.com [Department of Applied Physics, Delhi Technological University, Delhi 110042 (India); Ratnam, B.V.; Jang, Kiwan [Department of Physics, Changwon National University, Changwon 641-77 (Korea, Republic of); Rao, A.S.; Sinha, R.K. [Department of Applied Physics, Delhi Technological University, Delhi 110042 (India)

    2016-01-15

    The present work elucidates the synthesis of Dy{sup 3+} doped barium silicate glasses, along with the subsequent studies performed to evaluate its viability in solid state lighting applications. The synthesized photonic glasses were investigated via X-Ray Diffraction, Scanning Electron Microscopy and Fourier Transform Infrared Spectroscopy. The photoluminescence properties were examined under ultraviolet (UV)/near UV (NUV) excitation. Photoluminescence spectrum exhibited characteristic emission bands at λ{sub em}=483 nm (blue) and λ{sub em}=576 nm (yellow) which are ascribed to the {sup 4}F{sub 9/2}→{sup 6}H{sub 15/2} and {sup 4}F{sub 9/2}→{sup 6}H{sub 13/2} transitions of Dy{sup 3+} ion, respectively. The chromaticity coordinates under excitation of λ{sub ex}=348 nm are (0.31, 0.34), which lies in the white region of CIE 1931 chromaticity diagram and are in excellent proximity with the standard equal energy white illuminant (0.333, 0.333). The calculated correlated color temperature and the yellow to blue (Y/B) ratio are found to be 6602 K and 1.12, respectively for the optimized sample. The synthesized photonic glass also offered the possibility of tuning the color as exemplified through the variation in CIE coordinates, correlated color temperature and the Y/B ratio. The results confirm the possibility of color tunability from the proposed glass and may be useful for various photonic device applications. - Highlights: • Successfully synthesized Dy{sup 3+} doped barium silicate glasses. • Structural properties thoroughly discussed by using XRD and FT-IR. • Photoluminescence and colorimetry properties have been investigated. • Y/B ratio and the reason for color tunability have been successfully explained. • CIE coordinates of Dy{sup 3+}:BBS glass confirm its suitability for w-LEDs.

  9. K2 Ultracool Dwarfs Survey. II. The White Light Flare Rate of Young Brown Dwarfs

    Science.gov (United States)

    Gizis, John E.; Paudel, Rishi R.; Mullan, Dermott; Schmidt, Sarah J.; Burgasser, Adam J.; Williams, Peter K. G.

    2017-08-01

    We use Kepler K2 Campaign 4 short-cadence (one-minute) photometry to measure white light flares in the young, moving group brown dwarfs 2MASS J03350208+2342356 (2M0335+23) and 2MASS J03552337+1133437 (2M0355+11), and report on long-cadence (thirty-minute) photometry of a superflare in the Pleiades M8 brown dwarf CFHT-PL-17. The rotation period (5.24 hr) and projected rotational velocity (45 km s-1) confirm 2M0335+23 is inflated (R≥slant 0.20 {R}⊙ ) as predicted for a 0.06 {M}⊙ , 24 Myr old brown dwarf βPic moving group member. We detect 22 white light flares on 2M0335+23. The flare frequency distribution follows a power-law distribution with slope -α =-1.8+/- 0.2 over the range 1031 to 1033 erg. This slope is similar to that observed in the Sun and warmer flare stars, and is consistent with lower-energy flares in previous work on M6-M8 very-low-mass stars; taking the two data sets together, the flare frequency distribution for ultracool dwarfs is a power law over 4.3 orders of magnitude. The superflare (2.6× {10}34 erg) on CFHT-PL-17 shows higher-energy flares are possible. We detect no flares down to a limit of 2× {10}30 erg in the nearby L5γ AB Dor moving group brown dwarf 2M0355+11, consistent with the view that fast magnetic reconnection is suppressed in cool atmospheres. We discuss two multi-peaked flares observed in 2M0335+23, and argue that these complex flares can be understood as sympathetic flares, in which fast-mode magnetohydrodynamic waves similar to extreme-ultraviolet waves in the Sun trigger magnetic reconnection in different active regions.

  10. White organic light-emitting devices with high color purity and stability

    International Nuclear Information System (INIS)

    Bai, Yajie; Liu, Su; Li, Hairong; Liu, Chunjuan; Wang, Jinshun; Chang, Jinxian

    2014-01-01

    A white organic light-emitting device (WOLED) with dual-emitting layers was presented, in which the blue fluorescent dye 2,5,8,11-terta-tertbutylperylene (TBPe) was doped in 2-methyl-9, 10-di(2-naphthyl)-anthracene (MADN) as a blue-emitting layer, while 5,6,11,12-tetraphenylnaphthacene (rubrene, Rb) was doped in the above-mentioned materials as a yellow-emitting layer. The fabricated monochromatic devices using the blue- and yellow-emitting layer have demonstrated that the direct charge trapping mechanism is the dominant emission mechanism in the yellow OLED. Studies on the WOLEDs with dual-emitting layers have shown that the performances of these devices are strongly susceptible to the thickness of the emitting layer and the stack order of two emitting layers. Structure of ITO(160 nm)/NPB(30 nm)/MADN: 5 wt%TBPe: 3 wt%Rb(10 nm)/MADN: 5 wt%TBPe(20 nm)/BCP (10 nm)/Alq 3 (20 nm)/Al(100 nm) was determined to be the most favorable WOLED. The maximum luminance of 16 000 cd cm −2  at the applied voltage of 13.4 V and Commission International de 1′Eclairage (CIE) coordinates of (0.3263, 0.3437) which is closer to the standard white light (CIE (0.33, 0.33)) than the most recent reported WOLEDs were obtained. Moreover, there is just slight variation of CIE coordinates (ΔCIE x, y = 0.0171, 0.0167; corresponding Δu′v′ = 0.0119) when the current density increases from 10 to 100 mA cm −2 . It reveals that the emissive dopant Rb acts as charge traps to improve electron–hole balance, provides sites for electron–hole recombination and thus makes carriers distribute more evenly in the dual-emitting layers which broaden the recombination zone and improve the stability of the CIE coordinates. (paper)

  11. White organic light-emitting devices with high color purity and stability

    Science.gov (United States)

    Bai, Yajie; Liu, Su; Li, Hairong; Liu, Chunjuan; Wang, Jinshun; Chang, Jinxian

    2014-04-01

    A white organic light-emitting device (WOLED) with dual-emitting layers was presented, in which the blue fluorescent dye 2,5,8,11-terta-tertbutylperylene (TBPe) was doped in 2-methyl-9, 10-di(2-naphthyl)-anthracene (MADN) as a blue-emitting layer, while 5,6,11,12-tetraphenylnaphthacene (rubrene, Rb) was doped in the above-mentioned materials as a yellow-emitting layer. The fabricated monochromatic devices using the blue- and yellow-emitting layer have demonstrated that the direct charge trapping mechanism is the dominant emission mechanism in the yellow OLED. Studies on the WOLEDs with dual-emitting layers have shown that the performances of these devices are strongly susceptible to the thickness of the emitting layer and the stack order of two emitting layers. Structure of ITO(160 nm)/NPB(30 nm)/MADN: 5 wt%TBPe: 3 wt%Rb(10 nm)/MADN: 5 wt%TBPe(20 nm)/BCP (10 nm)/Alq3(20 nm)/Al(100 nm) was determined to be the most favorable WOLED. The maximum luminance of 16 000 cd cm-2 at the applied voltage of 13.4 V and Commission International de 1‧Eclairage (CIE) coordinates of (0.3263, 0.3437) which is closer to the standard white light (CIE (0.33, 0.33)) than the most recent reported WOLEDs were obtained. Moreover, there is just slight variation of CIE coordinates (ΔCIEx, y = 0.0171, 0.0167; corresponding Δu‧v‧ = 0.0119) when the current density increases from 10 to 100 mA cm-2. It reveals that the emissive dopant Rb acts as charge traps to improve electron-hole balance, provides sites for electron-hole recombination and thus makes carriers distribute more evenly in the dual-emitting layers which broaden the recombination zone and improve the stability of the CIE coordinates.

  12. Coherent interference effects and squeezed light generation in optomechanical systems

    Science.gov (United States)

    Qu, Kenan

    My Ph.D. dissertation is on the fundamental effects in optomechanical systems (OMS) and their important applications. The OMS are based on the possibility of the mechanical motion produced by few photons incident on the mechanical device. This dissertation presents several applications of the OMS in the area of storage of light in long-lived phonons, single mode optomechanical Ramsey interferometry, and generation of large amount of squeezing in the output radiation. The long-lived phonons can be monitored and controlled via optical means as was experimentally demonstrated. To show this, I develop the theory of transient electromagnetically induced transparency (EIT). For further applications like state transfer, especially over very different frequency regimes, I consider double-cavity OMS, where the two cavities can correspond to different spectral domains, yet the state transfer is possible via phonons. The state transfer is based on a new effect, electromagnetically induced absorption (EIA), where one uses a second control field from the other cavity to produce an absorption peak inside the EIT window. All these involve the interference of various path ways via which a final state is reached. The following chapter shows how Fano-like interference can arise in OMS. A Fano asymmetry parameter for OMS was defined. The last two chapters deal with the question if OMS can be efficient generators of squeezed light. I show by blue and red tuning the two cavities in a double-cavity OMS, one can generate effectively a two-mode parametric interaction which yields two-mode squeezed output with the squeezing magnitude of the order of 10dB. This requires a bath temperature of 10mK. Such temperatures obtained by using Helium dilution refrigerator are routinely used with superconducting OMS. The major part of this dissertation is devoted to the dispersive optomechanical interaction. However, the interaction can also be dissipative, where the mechanical displacement modulates

  13. Transfer from blue light or green light to white light partially reverses changes in ocular refraction and anatomy of developing guinea pigs.

    Science.gov (United States)

    Qian, Yi-Feng; Liu, Rui; Dai, Jin-Hui; Chen, Min-Jie; Zhou, Xing-Tao; Chu, Ren-Yuan

    2013-09-26

    Relative to the broadband white light (BL), postnatal guinea pigs develop myopia in a monochromic middle-wavelength light (ML, 530 nm) environment and develop hyperopia in a monochromic short-wavelength light (SL, 430 nm) environment. We investigated whether transfer from SL or ML to BL leads to recuperation of ocular refraction and anatomy of developing guinea pigs. Two-week-old guinea pigs were given (a) SL for 20 weeks, (b) SL recuperation (SLR, SL for 10 weeks then BL for 10 weeks), (c) ML for 20 weeks, (d) ML recuperation (MLR, ML for 10 weeks then BL for 10 weeks), or (e) BL for 20 weeks. Two weeks after transfer from ML to BL (MLR group), ocular refraction increased from 1.95 ± 0.35 D to 2.58 ± 0.24 D, and vitreous length decreased from 3.48 ± 0.06 mm to 3.41 ± 0.06 mm. Two weeks after transfer from SL to BL (SLR group), ocular refraction decreased from 5.65 ± 0.61 D to 4.33 ± 0.49 D, and vitreous length increased from 3.18 ± 0.07 mm to 3.26 ± 0.11 mm. The MLR and SLR groups had final ocular refractions that were significantly different from those of the ML and SL groups at 20 weeks (ML vs. MLR: p < 0.0001; SL vs. SLR: p < 0.0001) but were still significantly different from the BL group (BL vs. MLR: p = 0.0120; BL vs. SLR: p = 0.0010). These results suggest that recuperation was not complete after return to BL for 10 weeks.

  14. Electron-transporting layer doped with cesium azide for high-performance phosphorescent and tandem white organic light-emitting devices

    Science.gov (United States)

    Yu, Yaoyao; Chen, Xingming; Jin, Yu; Wu, Zhijun; Yu, Ye; Lin, Wenyan; Yang, Huishan

    2017-07-01

    Cesium azide was employed as an effective n-dopant in the electron-transporting layer (ETL) of organic light-emitting devices (OLEDs) owing to its low deposition temperature and high ambient stability. By doping cesium azide onto 4,7-diphenyl-1,10-phenanthroline, a green phosphorescent OLED having best efficiencies of 66.25 cd A-1, 81.22 lm W-1 and 18.82% was realized. Moreover, the efficiency roll-off from 1000 cd m-2 to 10 000 cd m-2 is only 12.9%, which is comparable with or even lower than that of devices utilizing the co-host system. Physical mechanisms for the improvement of device performance were studied in depth by analyzing the current density-voltage (J-V) characteristics of the electron-only devices. In particular, by comparing the J-V characteristics of the electron-only devices instead of applying the complicated ultraviolet photoelectron spectrometer measurements, we deduced the decrease in barrier height for electron injection at the ETL/cathode contact. Finally, an efficient tandem white OLED utilizing the n-doped layer in the charge generation unit (CGU) was constructed. As far as we know, this is the first report on the application of this CGU for fabricating tandem white OLEDs. The emissions of the tandem device are all in the warm white region from 1213 cd m-2 to 10870 cd m-2, as is beneficial to the lighting application.

  15. Structural optimization for remote white light-emitting diodes with quantum dots and phosphor: packaging sequence matters.

    Science.gov (United States)

    Xie, Bin; Chen, Wei; Hao, Junjie; Wu, Dan; Yu, Xingjian; Chen, Yanhua; Hu, Run; Wang, Kai; Luo, Xiaobing

    2016-12-26

    White light-emitting diodes (WLEDs) with quantum dots (QDs) and phosphor have attracted tremendous attentions due to their excellent color rendering ability. In the packaging process, QDs layer and phosphor-silicone layer tend to be separated to reduce the reabsorption losses, and to maintain the stability of QDs surface ligands. This study investigated the packaging sequence between QDs and phosphor on the optical and thermal performances of WLEDs. The output optical power and PL spectra were measured and analyzed, and the temperature fields were simulated and validated experimentally by infrared thermal imager. It was found that when driven by 60 mA, the QDs-on-phosphor type WLEDs achieved luminous efficiency (LE) of 110 lm/W, with color rendering index (CRI) of Ra = 92 and R9 = 80, while the phosphor-on-QDs type WLEDs demonstrated lower LE of 68 lm/W, with Ra = 57 and R9 = 24. Moreover, the QDs-on-phosphor type WLEDs generated less heat than that of another, consequently the highest temperature in the QDs-on-phosphor type was lower than another, and the temperature difference can reach 12.3°C. Therefore, in terms of packaging sequence, the QDs-on-phosphor type is an optimal packaging architecture for higher optical efficiency, better color rendering ability and lower device temperature.

  16. Design of a High-Power White Light Source with Colloidal Quantum Dots and Non-Rare-Earth Phosphors

    Science.gov (United States)

    Bicanic, Kristopher T.

    This thesis describes the design process of a high-power white light source, using novel phosphor and colloidal quantum dot materials. To incorporate multiple light emitters, we generalized and extended a down-converting layer model. We employed a phosphor mixture comprising of YAG:Ce and K2TiF 6:Mn4+ powders to illustrate the effectiveness of the model. By incorporating experimental photophysical results from the phosphors and colloidal quantum dots, we modeled our system and chose the design suitable for high-power applications. We report a reduction in the correlated color temperature by 600K for phosphor and quantum dot systems, enabling the creation of a warm white light emission at power densities up to 5 kW/cm 2. Furthermore, at this high-power, their emission achieves the digital cinema initiative (DCI) requirements with a luminescence efficacy improvement up to 32% over the stand-alone ceramic YAG:Ce phosphor.

  17. Bidirectional reflectance distribution function of Spectralon white reflectance standard illuminated by incoherent unpolarized and plane-polarized light.

    Science.gov (United States)

    Bhandari, Anak; Hamre, Børge; Frette, Øvynd; Zhao, Lu; Stamnes, Jakob J; Kildemo, Morten

    2011-06-01

    A Lambert surface would appear equally bright from all observation directions regardless of the illumination direction. However, the reflection from a randomly scattering object generally has directional variation, which can be described in terms of the bidirectional reflectance distribution function (BRDF). We measured the BRDF of a Spectralon white reflectance standard for incoherent illumination at 405 and 680 nm with unpolarized and plane-polarized light from different directions of incidence. Our measurements show deviations of the BRDF for the Spectralon white reflectance standard from that of a Lambertian reflector that depend both on the angle of incidence and the polarization states of the incident light and detected light. The non-Lambertian reflection characteristics were found to increase more toward the direction of specular reflection as the angle of incidence gets larger.

  18. A comparison of white light laryngostroboscopy versus autofluorescence endoscopy in the evaluation of vocal fold pathology.

    Science.gov (United States)

    Caffier, Philipp P; Schmidt, Bernd; Gross, Manfred; Karnetzky, Klaus; Nawka, Tadeus; Rotter, Andreas; Seipelt, Matthias; Sedlmaier, Benedikt

    2013-07-01

    To prove the diagnostic value of autofluorescence endoscopy (AFE) and white light laryngostroboscopy (WLS) versus the gold standard microlaryngoscopy with histopathological examination in differential diagnostics of laryngeal lesions for experienced phoniatricians and laryngologists, using the PENTAX SAFE-3000 system. Exploratory cohort study. High-resolution rigid WLS was executed in 32 consecutive patients with initial manifestation of benign, precancerous, and malignant vocal fold lesions. Fiberoptic blue light AFE (SAFE-3000; λ = 408 nm) was subsequently performed by an experienced endoscopist in a blinded study setting. Findings were rated based on objective WLS and AFE parameters (e.g., phonatory vibration, mucosal wave propagation, and loss of autofluorescence). The clinically assumed WLS and AFE diagnoses were compared with the final histopathology of biopsied material taken during microlaryngoscopy. In reference to histopathological diagnosis, WLS achieved a higher sensitivity (100% vs. 94%), specificity (94% vs. 69%), and accuracy (97% vs. 81%) than AFE diagnostics. The concordance between both endoscopic techniques was 87.5% (28/32 patients); additional AFE benefits were not detectable. Significant loss of autofluorescence was observed in malignant findings clinically clearly diagnosed by WLS, but also in chronic inflammation, severe dysplasia, granulomas, vascular polyps, and glottal papillomatosis. The evaluation of vocal fold pathology by the clinically experienced examiner precisely applying WLS appears to be more reliable than diagnostics of mucosal tissue changes by means of AFE via the SAFE-3000 system as a relatively nonspecific method. Microlaryngoscopy with histopathological examination and phonomicrosurgical excision of pathologic changes remains the gold standard. © 2012 The American Laryngological, Rhinological and Otological Society, Inc.

  19. Color-tunable and stable-efficiency white organic light-emitting diode fabricated with fluorescent-phosphorescent emission layers

    International Nuclear Information System (INIS)

    Yang, Su-Hua; Shih, Po-Jen; Wu, Wen-Jie; Huang, Yi-Hua

    2013-01-01

    White organic light emitting diodes (OLEDs) were fabricated for color-tunable lighting applications. Fluorescent and phosphorescent hybrid emission layers (EMLs) were used to enhance the luminance and stability of the devices, which have blue-EML/CBP interlayer/green-EML/phosphorescent-sensitized-EML/red-EML structures. The influence of the composition and structure of the EMLs on the electroluminescence properties of the devices were investigated from the viewpoint of their emission spectra. The possible exciton harvesting, diffusion, transport, and annihilation processes occurring in the EMLs were also evaluated. A maximum luminance intensity of 7400 cd/m 2 and a highly stable current efficiency of 3.2 cd/A were obtained. Good color tunability was achieved for the white OLEDs; the chromatic coordinates linearly shifted from pure white (0.300, 0.398) to cold white (0.261, 0.367) when the applied voltage was varied from 10 to 14 V. -- Highlights: • Exciton harvesting, diffusion, transport, and annihilation processes were evaluated. • The electroluminescence properties were investigated from the viewpoint of the emission spectra. • Good color tunability and stable-efficiency were achieved for the white OLEDs

  20. Dopant effects on charge transport to enhance performance of phosphorescent white organic light emitting diodes

    Energy Technology Data Exchange (ETDEWEB)

    Zhu, Liping; Chen, Jiangshan; Ma, Dongge, E-mail: mdg1014@ciac.ac.cn [State Key Laboratory of Polymer Physics and Chemistry, Changchun Institute of Applied Chemistry, Chinese Academy of Sciences, University of Chinese Academy of Sciences, Changchun 130022 (China)

    2015-11-07

    We compared the performance of phosphorescent white organic light emitting diodes (WOLEDs) with red-blue-green and green-blue-red sequent emissive layers. It was found that the influence of red and green dopants on electron and hole transport in emissive layers leads to the large difference in the efficiency of fabricated WOLEDs. This improvement mechanism is well investigated by the current density-voltage characteristics of single-carrier devices based on dopant doped emissive layers and the comparison of electroluminescent and photoluminescence spectra, and attributed to the different change of charge carrier transport by the dopants. The optimized device achieves a maximum power efficiency, current efficiency, and external quantum efficiency of 37.0 lm/W, 38.7 cd/A, and 17.7%, respectively, which are only reduced to 32.8 lm/W, 38.5 cd/A, and 17.3% at 1000 cd/m{sup 2} luminance. The critical current density is as high as 210 mA/cm{sup 2}. It can be seen that the efficiency roll-off in phosphorescent WOLEDs can be well improved by effectively designing the structure of emissive layers.

  1. Monitoring bacterial biofilms with a microfluidic flow chip designed for imaging with white-light interferometry

    Energy Technology Data Exchange (ETDEWEB)

    Brann, Michelle; Suter, Jonathan D.; Addleman, R. Shane; Larimer, Curtis

    2017-07-01

    There is a need for imaging and sensing instrumentation that can monitor transitions in biofilm structure in order to better understand biofilm development and emergent properties such as anti-microbial resistance. Herein, we expanded on our previously reported technique for measuring and monitoring the thickness and topology of live biofilms using white-light interferometry (WLI). A flow cell designed for WLI enabled the use of this non-disruptive imaging method for the capture of high resolution three-dimensional profile images of biofilm growth over time. The fine axial resolution (3 nm) and wide field of view (>1 mm by 1 mm) enabled detection of biofilm formation as early as three hours after inoculation of the flow cell with a live bacterial culture (Pseudomonas fluorescens). WLI imaging facilitated monitoring the early stages of biofilm development and subtle variations in the structure of mature biofilms. Minimally-invasive imaging enabled monitoring of biofilm structure with surface metrology metrics (e.g., surface roughness). The system was used to observe a transition in biofilm structure that occurred in response to expsoure to a common antiseptic. In the future, WLI and the biofilm imaging cell described herein may be used to test the effectiveness of biofilm-specific therapies to combat common diseases associated with biofilm formation such as cystic fibrosis and periodontitis.

  2. Characterization of Nb SRF cavity materials by white light interferometry and replica techniques

    Energy Technology Data Exchange (ETDEWEB)

    Xu, Chen [Thomas Jefferson National Accelerator Facility, Newport News, VA 23606 (United States); The Applied Science Department, The College of William and Mary, Williamsburg, VA 23185 (United States); Reece, Charles [Thomas Jefferson National Accelerator Facility, Newport News, VA 23606 (United States); Kelley, Michael, E-mail: mkelley@jlab.org [Thomas Jefferson National Accelerator Facility, Newport News, VA 23606 (United States); The Applied Science Department, The College of William and Mary, Williamsburg, VA 23185 (United States)

    2013-06-01

    Much work has shown that the topography of the interior surface is an important contributor to the performance of Nb superconducting radiofrequency (SRF) accelerator cavities. Micron-scale topography is implicated in non-linear loss mechanisms that limit the useful accelerating gradient range and impact cryogenic cost. Aggressive final chemical treatments in cavity production seek to reliably obtain “smoothest” surfaces with superior performance. Process development suffers because the cavity interior surface cannot be viewed directly without cutting out pieces, rendering the cavities unavailable for further study. Here we explore replica techniques as an alternative, providing imprints of cavity internal surface that can be readily examined. A second matter is the topography measurement technique used. Atomic force microscopy (AFM) has proven successful, but too time intensive for routine use in this application. We therefore introduce white light interferometry (WLI) as an alternative approach. We examined real surfaces and their replicas, using AFM and WLI. We find that the replica/WLI is promising to provide the large majority of the desired information, recognizing that a trade-off is being made between best lateral resolution (AFM) and the opportunity to examine much more surface area (WLI).

  3. Non-destructive forensic latent fingerprint acquisition with chromatic white light sensors

    Science.gov (United States)

    Leich, Marcus; Kiltz, Stefan; Dittmann, Jana; Vielhauer, Claus

    2011-02-01

    Non-destructive latent fingerprint acquisition is an emerging field of research, which, unlike traditional methods, makes latent fingerprints available for additional verification or further analysis like tests for substance abuse or age estimation. In this paper a series of tests is performed to investigate the overall suitability of a high resolution off-the-shelf chromatic white light sensor for the contact-less and non-destructive latent fingerprint acquisition. Our paper focuses on scanning previously determined regions with exemplary acquisition parameter settings. 3D height field and reflection data of five different latent fingerprints on six different types of surfaces (HDD platter, brushed metal, painted car body (metallic and non-metallic finish), blued metal, veneered plywood) are experimentally studied. Pre-processing is performed by removing low-frequency gradients. The quality of the results is assessed subjectively; no automated feature extraction is performed. Additionally, the degradation of the fingerprint during the acquisition period is observed. While the quality of the acquired data is highly dependent on surface structure, the sensor is capable of detecting the fingerprint on all sample surfaces. On blued metal the residual material is detected; however, the ridge line structure dissolves within minutes after fingerprint placement.

  4. Spectroscopic refractometer for transparent and absorbing liquids by reflection of white light near the critical angle

    International Nuclear Information System (INIS)

    Sánchez-Pérez, C.; García-Valenzuela, A.

    2012-01-01

    We propose and evaluate a spectroscopic refractometer device to measure the refractive index dispersion of transparent and absorbing solutions. The angle-dependent reflectivity of a white beam of light in an internal reflection configuration around the critical angle is spectrally analyzed. The refractive index in a wavelength range from 400 nm to 900 nm is obtained from the angle-reflectivity curve around the critical angle at each wavelength. The device does not use angle scanning mechanisms, decreasing considerably the complexity of the instrument in comparison to previous proposals. As a result, the measurements are obtained relatively fast. Nevertheless, a good experimental resolution in refractive index of about Δn ≈ 10 −4 at all the wavelengths is achieved in the case of transparent solutions. The calibration procedure of the device is discussed in detail. We also present measurements of the refractive index dispersion of rhodamine 6G-methanol solutions, which has a strong absorption band in the visible spectra.

  5. Low-voltage and high-efficiency white organic light emitting devices with carrier balance

    International Nuclear Information System (INIS)

    Wei Fuxiang; Huang, Y.; Fang, L.

    2010-01-01

    White organic light emitting devices with the structure of ITO/m-MTDATA:x%4F-TCNQ/NPB/TBADN:EBDP:DCJTB/Bphen:Liq/LiF/Al have been demonstrated in this paper. High-mobility m-MTDATA:4F-TCNQ is added into the region between ITO and NBP to increase hole injection and transport. The high-mobility Bphen:Liq layer is added into the region between cathode and emission layers to lower cathode barrier and facilitate carrier injection. In the meanwhile, an effective carrier balance (number of holes is equal to number of electrons) between holes and electrons is considered to be one of the most important factors for improving OLEDs. During the experiment, by modulating the doping concentration of 4F-TCNQ, we can control hole injection and transport to make the carriers reach a high-level balance. The maximum current efficiency and power efficiency of devices were 9.3 cd/A and 4.6 lm/A, respectively.

  6. STRUCTURE AND DYNAMICS OF THE 2010 JULY 11 ECLIPSE WHITE-LIGHT CORONA

    International Nuclear Information System (INIS)

    Pasachoff, J. M.; Rusin, V.; Saniga, M.

    2011-01-01

    The white-light corona (WLC) during the total solar eclipse on 2010 July 11 was observed by several teams in the Moon's shadow stretching across the Pacific Ocean and a number of isolated islands. We present a comparison of the WLC as observed by eclipse teams located on the Tatakoto Atoll in French Polynesia and on Easter Island, 83 minutes later, combined with near-simultaneous space observations. The eclipse was observed at the beginning of the solar cycle, not long after solar minimum. Nevertheless, the solar corona shows a plethora of different features (coronal holes, helmet streamers, polar rays, very faint loops and radial-oriented thin streamers, a coronal mass ejection, and a puzzling 'curtain-like' object above the north pole). Comparing the observations from the two sites enables us to detect some dynamic phenomena. The eclipse observations are further compared with a hairy-ball model of the magnetic field and near-simultaneous images from the Atmospheric Imaging Assembly on NASA's Solar Dynamics Observatory, the Extreme Ultraviolet Imager on NASA's Solar Terrestrial Relations Observatory, the Sun Watcher, using Active Pixel System Detector and Image Processing on ESA's PRoject for Onboard Autonomy, and the Naval Research Laboratory's Large Angle and Spectrometric Coronagraph on ESA's Solar and Heliospheric Observatory. The Ludendorff flattening coefficient is 0.156, matching the expected ellipticity of coronal isophotes at 2 Rs un , for this rising phase of the solar-activity cycle.

  7. Hybrid white organic light emitting diodes with low efficiency roll-off, stable color and extreme brightness

    Energy Technology Data Exchange (ETDEWEB)

    Liu, Baiquan; Zou, Jianhua [Institute of Polymer Optoelectronic Materials and Devices, South China University of Technology, Guangzhou 510640 (China); State Key Laboratory of Luminescent Materials and Devices, Guangzhou 510640 (China); Su, Yueju; Gao, Dongyu [New Vision Opto-Electronic Technology Co., Ltd, Guangzhou 510640 (China); Lan, Linfeng [Institute of Polymer Optoelectronic Materials and Devices, South China University of Technology, Guangzhou 510640 (China); State Key Laboratory of Luminescent Materials and Devices, Guangzhou 510640 (China); Tao, Hong, E-mail: tao.h@scut.edu.cn [Institute of Polymer Optoelectronic Materials and Devices, South China University of Technology, Guangzhou 510640 (China); State Key Laboratory of Luminescent Materials and Devices, Guangzhou 510640 (China); Peng, Junbiao [Institute of Polymer Optoelectronic Materials and Devices, South China University of Technology, Guangzhou 510640 (China); State Key Laboratory of Luminescent Materials and Devices, Guangzhou 510640 (China)

    2014-07-01

    Highly efficient and bright hybrid white organic light emitting diodes (WOLEDs) based on simple architectures have been successfully fabricated and characterized. The optimized device can reach a maximum forward-viewing power efficiency (PE) of 20.2 lm/W, a peak forward-viewing current efficiency (CE) of 30.7 cd/A, an extremely high brightness of 95,683 cd/m{sup 2}, and a Commission International de l’E clairage chromaticity coordinates of (0. 436, 0.425) at 12 V. Even at the illumination-relevant brightness of 1000 cd/m{sup 2}, a forward-viewing PE of 17.0 lm/W and CE of 30.7 cd/A are obtained. Moreover, it is found that the device not only suffers slight efficiency roll-off but also exhibits a stable color during a large range of brightness, indicating that the device can satisfy the future commercial requirements. Undoubtedly, the results will be beneficial to the design of both material and device architecture for high-performance WOLEDs and next-generation solid-state lighting sources. - Highlights: • A simple HWOLED with B/O/B structure has been successfully developed. • A extremely high brigthness of 95,683 cd/m{sup 2} is obtained. • A high forward-viewing CE of 30.7 cd/A and PE of 20.2 lm/W are achieved. • Efficiency roll-off is very low and color is relatively stable.

  8. Optimizing white light luminescence in Dy3+-doped Lu3Ga5O12 nano-garnets

    International Nuclear Information System (INIS)

    Haritha, P.; Linganna, K.; Venkatramu, V.; Martín, I. R.; Monteseguro, V.; Rodríguez-Mendoza, U. R.; Babu, P.; León-Luis, S. F.; Jayasankar, C. K.; Lavín, V.

    2014-01-01

    Trivalent dysprosium-doped Lu 3 Ga 5 O 12 nano-garnets have been prepared by sol-gel method and characterized by X-ray powder diffraction, high-resolution transmission electron microscopy, dynamic light scattering, and laser excited spectroscopy. Under a cw 457 nm laser excitation, the white luminescence properties of Lu 3 Ga 5 O 12 nano-garnets have been studied as a function of the optically active Dy 3+ ion concentration and at low temperature. Decay curves for the 4 F 9/2 level of Dy 3+ ion exhibit non-exponential nature for all the Dy 3+ concentrations, which have been well-fitted to a generalized energy transfer model for a quadrupole-quadrupole interaction between Dy 3+ ions without diffusion. From these data, a simple rate-equations model can be applied to predict that intense white luminescence could be obtained from 1.8 mol% Dy 3+ ions-doped nano-garnets, which is in good agreement with experimental results. Chromaticity color coordinates and correlated color temperatures have been determined as a function of temperature and are found to be within the white light region for all Dy 3+ concentrations. These results indicate that 2.0 mol% Dy 3+ ions doped nano-garnet could be useful for white light emitting device applications

  9. White polymer light-emitting diodes based on star-shaped polymers with an orange dendritic phosphorescent core.

    Science.gov (United States)

    Zhu, Minrong; Li, Yanhu; Cao, Xiaosong; Jiang, Bei; Wu, Hongbin; Qin, Jingui; Cao, Yong; Yang, Chuluo

    2014-12-01

    A series of new star-shaped polymers with a triphenylamine-based iridium(III) dendritic complex as the orange-emitting core and poly(9,9-dihexylfluorene) (PFH) chains as the blue-emitting arms is developed towards white polymer light-emitting diodes (WPLEDs). By fine-tuning the content of the orange phosphor, partial energy transfer and charge trapping from the blue backbone to the orange core is realized to achieve white light emission. Single-layer WPLEDs with the configuration of ITO (indium-tin oxide)/poly(3,4-ethylenedioxythiophene):poly(styrenesulfonate) (PEDOT:PSS)/polymer/CsF/Al exhibit a maximum current efficiency of 1.69 cd A(-1) and CIE coordinates of (0.35, 0.33), which is very close to the pure white-light point of (0.33, 0.33). To the best of our knowledge, this is the first report on star-shaped white-emitting single polymers that simultaneously consist of fluorescent and phosphorescent species. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  10. White-light full-field OCT resolution improvement by image sensor colour balance adjustment: numerical simulation

    International Nuclear Information System (INIS)

    Kalyanov, A L; Lychagov, V V; Ryabukho, V P; Smirnov, I V

    2012-01-01

    The possibility of improving white-light full-field optical coherence tomography (OCT) resolution by image sensor colour balance tuning is shown numerically. We calculated the full-width at half-maximum (FWHM) of a coherence pulse registered by a silicon colour image sensor under various colour balance settings. The calculations were made for both a halogen lamp and white LED sources. The results show that the interference pulse width can be reduced by the proper choice of colour balance coefficients. The reduction is up to 18%, as compared with a colour image sensor with regular settings, and up to 20%, as compared with a monochrome sensor. (paper)

  11. Comparative Study of Lettuce and Radish Grown Under Red and Blue Light-Emitting Diodes (LEDs) and White Fluorescent Lamps

    Science.gov (United States)

    Mickens, Matthew A.

    2012-01-01

    Growing vegetable crops in space will be an essential part of sustaining astronauts during long-term missions. To drive photosynthesis, red and blue light-emitting diodes (LEDs) have attracted attention because of their efficiency, longevity, small size, and safety. In efforts to optimize crop production, there have also been recent interests in analyzing the subtle effects of green light on plant growth, and to determine if it serves as a source of growth enhancement or suppression. A comparative study was performed on two short cycle crops of lettuce (Outredgeous) and radish (Cherry Bomb) grown under two light treatments. The first treatment being red and blue LEDs, and the second treatment consisting of white fluorescent lamps which contain a portion of green light. In addition to comparing biomass production, physiological characterizations were conducted on how the light treatments influence morphology, water use, chlorophyll content, and the production of A TP within plant tissues.

  12. Review of third and next generation synchrotron light sources

    International Nuclear Information System (INIS)

    Bilderback, Donald H; Elleaume, Pascal; Weckert, Edgar

    2005-01-01

    Synchrotron radiation (SR) is having a very large impact on interdisciplinary science and has been tremendously successful with the arrival of third generation synchrotron x-ray sources. But the revolution in x-ray science is still gaining momentum. Even though new storage rings are currently under construction, even more advanced rings are under design (PETRA III and the ultra high energy x-ray source) and the uses of linacs (energy recovery linac, x-ray free electron laser) can take us further into the future, to provide the unique synchrotron light that is so highly prized for today's studies in science in such fields as materials science, physics, chemistry and biology, for example. All these machines are highly reliant upon the consequences of Einstein's special theory of relativity. The consequences of relativity account for the small opening angle of synchrotron radiation in the forward direction and the increasing mass an electron gains as it is accelerated to high energy. These are familiar results to every synchrotron scientist. In this paper we outline not only the origins of SR but discuss how Einstein's strong character and his intuition and excellence have not only marked the physics of the 20th century but provide the foundation for continuing accelerator developments into the 21st century

  13. Fabrication of Si/ZnS radial nanowire heterojunction arrays for white light emitting devices on Si substrates.

    Science.gov (United States)

    Katiyar, Ajit K; Sinha, Arun Kumar; Manna, Santanu; Ray, Samit K

    2014-09-10

    Well-separated Si/ZnS radial nanowire heterojunction-based light-emitting devices have been fabricated on large-area substrates by depositing n-ZnS film on p-type nanoporous Si nanowire templates. Vertically oriented porous Si nanowires on p-Si substrates have been grown by metal-assisted chemical etching catalyzed using Au nanoparticles. Isolated Si nanowires with needle-shaped arrays have been made by KOH treatment before ZnS deposition. Electrically driven efficient white light emission from radial heterojunction arrays has been achieved under a low forward bias condition. The observed white light emission is attributed to blue and green emission from the defect-related radiative transition of ZnS and Si/ZnS interface, respectively, while the red arises from the porous surface of the Si nanowire core. The observed white light emission from the Si/ZnS nanowire heterojunction could open up the new possibility to integrate Si-based optical sources on a large scale.

  14. Utilization of solvothermally grown InP/ZnS quantum dots as wavelength converters for fabrication of white light-emitting diodes.

    Science.gov (United States)

    Jang, Eun-Pyo; Yang, Heesun

    2013-09-01

    This work reports on a simple solvothermal synthesis of InP/ZnS core/shell quantum dots (QDs) using a much safer and cheaper phosphorus precursor of tris(dimethylamino)phosphine than the most popularly chosen tris(trimethylsilyl)phosphine. The band gap of InP QDs is facilely controlled by varying the solvothermal core growth time (4 vs. 6 h) with a fixed temperature of 150 degrees C, and the successive solvothermal ZnS shelling at 220 degrees C for 6 h results in green- and yellow-emtting InP/ZnS QD with emission quantum yield of 41-42%. The broad size distribution of as-synthesized InP/ZnS QDs, which appears to be inherent in the current solvothermal approach, is improved by a size-selective sorting procedure, and the emission properties of the resulting size-sorted QD fractions are investigated. To produce white emission for general lighting source, a blue light-emitting diode (LED) is combined with non-size-soroted green or yellow QDs as wavelength converters. Furthermore, the QD-LED that includes a blend of green and yellow QDs is fabricated to generate a white lighting source with an enhanced color rendering performance, and its electroluminescent properties are characterized in detail.

  15. Low-intensity blue-enriched white light (750 lux) and standard bright light (10,000 lux) are equally effective in treating SAD. A randomized controlled study.

    Science.gov (United States)

    Meesters, Ybe; Dekker, Vera; Schlangen, Luc J M; Bos, Elske H; Ruiter, Martine J

    2011-01-28

    Photoreceptor cells containing melanopsin play a role in the phase-shifting effects of short-wavelength light. In a previous study, we compared the standard light treatment (SLT) of SAD with treatment using short-wavelength blue-enriched white light (BLT). Both treatments used the same illuminance (10,000 lux) and were equally highly effective. It is still possible, however, that neither the newly-discovered photoreceptor cells, nor the biological clock play a major role in the therapeutic effects of light on SAD. Alternatively, these effects may at least be partly mediated by these receptor cells, which may have become saturated as a result of the high illuminances used in the therapy. This randomized controlled study compares the effects of low-intensity BLT to those of high-intensity SLT. In a 22-day design, 22 patients suffering from a major depression with a seasonal pattern (SAD) were given light treatment (10,000 lux) for two weeks on workdays. Subjects were randomly assigned to either of the two conditions, with gender and age evenly distributed over the groups. Light treatment either consisted of 30 minutes SLT (5000 °K) with the EnergyLight® (Philips, Consumer Lifestyle) with a vertical illuminance of 10,000 lux at eye position or BLT (17,000 °K) with a vertical illuminance of 750 lux using a prototype of the EnergyLight® which emitted a higher proportion of short-wavelengths. All participants completed questionnaires concerning mood, activation and sleep quality on a daily basis. Mood and energy levels were also assessed on a weekly basis by means of the SIGH-SAD and other assessment tools. On day 22, SIGH-SAD ratings were significantly lower than on day 1 (SLT 65.2% and BLT 76.4%). On the basis of all assessments no statistically significant differences were found between the two conditions. With sample size being small, conclusions can only be preliminary. Both treatment conditions were found to be highly effective. The therapeutic effects of low

  16. Low-intensity blue-enriched white light (750 lux and standard bright light (10 000 lux are equally effective in treating SAD. A randomized controlled study

    Directory of Open Access Journals (Sweden)

    Bos Elske H

    2011-01-01

    Full Text Available Abstract Background Photoreceptor cells containing melanopsin play a role in the phase-shifting effects of short-wavelength light. In a previous study, we compared the standard light treatment (SLT of SAD with treatment using short-wavelength blue-enriched white light (BLT. Both treatments used the same illuminance (10 000 lux and were equally highly effective. It is still possible, however, that neither the newly-discovered photoreceptor cells, nor the biological clock play a major role in the therapeutic effects of light on SAD. Alternatively, these effects may at least be partly mediated by these receptor cells, which may have become saturated as a result of the high illuminances used in the therapy. This randomized controlled study compares the effects of low-intensity BLT to those of high-intensity SLT. Method In a 22-day design, 22 patients suffering from a major depression with a seasonal pattern (SAD were given light treatment (10 000 lux for two weeks on workdays. Subjects were randomly assigned to either of the two conditions, with gender and age evenly distributed over the groups. Light treatment either consisted of 30 minutes SLT (5000°K with the EnergyLight® (Philips, Consumer Lifestyle with a vertical illuminance of 10 000 lux at eye position or BLT (17 000°K with a vertical illuminance of 750 lux using a prototype of the EnergyLight® which emitted a higher proportion of short-wavelengths. All participants completed questionnaires concerning mood, activation and sleep quality on a daily basis. Mood and energy levels were also assessed on a weekly basis by means of the SIGH-SAD and other assessment tools. Results On day 22, SIGH-SAD ratings were significantly lower than on day 1 (SLT 65.2% and BLT 76.4%. On the basis of all assessments no statistically significant differences were found between the two conditions. Conclusion With sample size being small, conclusions can only be preliminary. Both treatment conditions were found

  17. Electricity generation using white and red wine lees in air cathode microbial fuel cells

    Science.gov (United States)

    Pepe Sciarria, Tommy; Merlino, Giuseppe; Scaglia, Barbara; D'Epifanio, Alessandra; Mecheri, Barbara; Borin, Sara; Licoccia, Silvia; Adani, Fabrizio

    2015-01-01

    Microbial fuel cell (MFC) is a useful biotechnology to produce electrical energy from different organic substrates. This work reports for the first time results of the application of single chamber MFCs to generate electrical energy from diluted white wine (WWL) and red wine (RWL) lees. Power obtained was of 8.2 W m-3 (262 mW m-2; 500 Ω) and of 3.1 W m-3 (111 mW m-2; 500Ω) using white and red wine lees, respectively. Biological processes lead to a reduction of chemical oxygen (TCOD) and biological oxygen demand (BOD5) of 27% and 83% for RWL and of 90% and 95% for WWL, respectively. These results depended on the degradability of organic compounds contained, as suggest by BOD5/TCOD of WWL (0.93) vs BOD5/TCOD of RWL (0.33), and to the high presence of polyphenols in RWL that inhibited the process. Coulombic efficiency (CE) of 15 ± 0%, for WWL, was in line with those reported in the literature for other substrates, i.e. CE of 14.9 ± 11.3%. Different substrates led to different microbial consortia, particularly at the anode. Bacterial species responsible for the generation of electricity, were physically connected to the electrode, where the direct electron transfer took place.

  18. Blue-Light Therapy following Mild Traumatic Brain Injury: Effects on White Matter Water Diffusion in the Brain

    Directory of Open Access Journals (Sweden)

    Sahil Bajaj

    2017-11-01

    Full Text Available Mild traumatic brain injury (mTBI is a common and often inconspicuous wound that is frequently associated with chronic low-grade symptoms and cognitive dysfunction. Previous evidence suggests that daily blue wavelength light therapy may be effective at reducing fatigue and improving sleep in patients recovering from mTBI. However, the effects of light therapy on recovering brain structure remain unexplored. In this study, we analyzed white matter diffusion properties, including generalized fractional anisotropy, and the quantity of water diffusion in isotropic (i.e., isotropic diffusion and anisotropic fashion (i.e., quantitative anisotropy, QA for fibers crossing 11 brain areas known to be significantly affected following mTBI. Specifically, we investigated how 6 weeks of daily morning blue light exposure therapy (compared to an amber-light placebo condition impacted changes in white matter diffusion in individuals with mTBI. We observed a significant impact of the blue light treatment (relative to the placebo on the amount of water diffusion (QA for multiple brain areas, including the corpus callosum, anterior corona radiata, and thalamus. Moreover, many of these changes were associated with improvements in sleep latency and delayed memory. These findings suggest that blue wavelength light exposure may serve as one of the potential non-pharmacological treatments for facilitating structural and functional recovery following mTBI; they also support the use of QA as a reliable neuro-biomarker for mTBI therapies.

  19. Controlled light emission from white organic light-emitting devices with a single blue-emitting host and multiple fluorescent dopants

    International Nuclear Information System (INIS)

    Chin, Byung Doo; Kim, Jai Kyeong; Park, O Ok

    2007-01-01

    In this work, we fabricated white organic light-emitting devices (WOLEDs) containing a layered light-emitting region composed of a single blue-emitting host and different fluorescent dopant materials. The effects of varying the dye-doping ratio and emitting layer thickness on the efficiency, lifetime, spectral voltage-dependence and white balance were investigated for devices with a blue/orange stacked layer structure. Addition of a blue host layer doped with a green-emitting dopant, to give a blue/green/orange emitter, resulted in a broadband white spectrum without the need for a charge-blocking interlayer. The composition of blue, green and orange dopants in the host and the thickness of each emitting layer were optimized, resulting in a device efficiency of 9-11 cd A -1 even at a high brightness of 10 000 cd m -2 (achieved at a bias voltage of less than 9 V) with an emission spectrum suitable for lighting applications

  20. Stable angular emission spectra in white organic light-emitting diodes using graphene/PEDOT:PSS composite electrode.

    Science.gov (United States)

    Cho, Hyunsu; Lee, Hyunkoo; Lee, Jonghee; Sung, Woo Jin; Kwon, Byoung-Hwa; Joo, Chul-Woong; Shin, Jin-Wook; Han, Jun-Han; Moon, Jaehyun; Lee, Jeong-Ik; Cho, Seungmin; Cho, Nam Sung

    2017-05-01

    In this work, we suggest a graphene/ poly (3,4-ethylenedioxythiophene) polystyrene sulfonate (PEDOT:PSS) composite as a transparent electrode for stabilizing white emission of organic light-emitting diodes (OLEDs). Graphene/PEDOT:PSS composite electrodes have increased reflectance when compared to graphene itself, but their reflectance is still lower than that of ITO itself. Changes in the reflectance of the composite electrode have the advantage of suppressing the angular spectral distortion of white emission OLEDs and achieving an efficiency of 16.6% for white OLEDs, comparable to that achieved by graphene-only electrodes. By controlling the OLED structure to compensate for the two-beam interference effect, the CIE color coordinate change (Δxy) of OLEDs based on graphene/PEDOT:PSS composite electrodes is 0.018, less than that based on graphene-only electrode, i.e.,0.027.

  1. Color improvement of white-light through Mn-enhancing yellow-green emission of SrSi2O2N2:Eu phosphor for white light emitting diodes

    International Nuclear Information System (INIS)

    Fei Qinni; Liu Yanhua; Gu Tiecheng; Wang Dajian

    2011-01-01

    Photoluminescence (PL) enhancement of SrSi 2 O 2 N 2 :Eu and the resultant color improvement of white-light were investigated via co-doping Mn with Eu. We observed that a unique absorption of host lattice of SrSi 2 O 2 N 2 and its visible band emission peaked at around ∼550 nm for SrSi 2 O 2 N 2 :Mn 2+ in the wavelength range of 450-600 nm. This highly eye-sensitive ∼550 nm-peaked band emission of SrSi 2 O 2 N 2 doped with Mn 2+ happens to overlap the 535 nm-peaked band emission of SrSi 2 O 2 N 2 doped with Eu 2+ , resulting in an intensified photoluminescence in a maximum by 355%. By combining this as-prepared Mn intensified SrSi 2 O 2 N 2 :Eu phosphor with blue InGaN chip, the quality of white-light was improved to 93.3% for color rendering index and 3584 K for correlated color temperature. - Research highlights: Photoluminescence enhancement and resultant color improvement of SrSi 2 O 2 N 2 : Eu can be adjusted via co-doping Mn with Eu. The band emission peaked at ∼550 for Mn2+ overlaps that at ∼535 nm for Eu 2+ . A white-light with 93.3% for CRI and 3584 K for CCT is achieved.

  2. THE HEIGHT OF A WHITE-LIGHT FLARE AND ITS HARD X-RAY SOURCES

    Energy Technology Data Exchange (ETDEWEB)

    Martinez Oliveros, Juan-Carlos; Hudson, Hugh S.; Hurford, Gordon J.; Krucker, Saem; Lin, R. P. [Space Sciences Laboratory, UC Berkeley, Berkeley, CA 94720 (United States); Lindsey, Charles [North West Research Associates, CORA Division, Boulder, CO (United States); Couvidat, Sebastien; Schou, Jesper [W. W. Hansen Experimental Physics Laboratory, Stanford University, Stanford, CA (United States); Thompson, W. T. [Adnet Systems, Inc., NASA Goddard Space Flight Center, code 671, Greenbelt, MD (United States)

    2012-07-10

    We describe observations of a white-light (WL) flare (SOL2011-02-24T07:35:00, M3.5) close to the limb of the Sun, from which we obtain estimates of the heights of the optical continuum sources and those of the associated hard X-ray (HXR) sources. For this purpose, we use HXR images from the Reuven Ramaty High Energy Spectroscopic Imager and optical images at 6173 A from the Solar Dynamics Observatory. We find that the centroids of the impulsive-phase emissions in WL and HXRs (30-80 keV) match closely in central distance (angular displacement from Sun center), within uncertainties of order 0.''2. This directly implies a common source height for these radiations, strengthening the connection between visible flare continuum formation and the accelerated electrons. We also estimate the absolute heights of these emissions as vertical distances from Sun center. Such a direct estimation has not been done previously, to our knowledge. Using a simultaneous 195 Angstrom-Sign image from the Solar-Terrestrial RElations Observatory spacecraft to identify the heliographic coordinates of the flare footpoints, we determine mean heights above the photosphere (as normally defined; {tau} = 1 at 5000 A) of 305 {+-} 170 km and 195 {+-} 70 km, respectively, for the centroids of the HXR and WL footpoint sources of the flare. These heights are unexpectedly low in the atmosphere, and are consistent with the expected locations of {tau} = 1 for the 6173 Angstrom-Sign and the {approx}40 keV photons observed, respectively.

  3. Increases in light and intermittent smoking among Asian Americans and non-Hispanic Whites.

    Science.gov (United States)

    Blanco, Lyzette; Nydegger, Liesl A; Sakuma, Kari-Lyn K; Tong, Elisa K; White, Martha M; Trinidad, Dennis R

    2014-06-01

    Asian Americans are the fastest growing immigrant group in the United States and are more likely to be light and intermittent smokers (LITS) compared with non-Hispanic Whites (NHWs). LITS experience adverse health effects related to smoking. Previous research has aggregated Asian American ethnic groups, masking important differences between groups. We sought to compare LITS rates among Asian American subgroups before and after the 1998 Master Settlement Agreement (MSA) with NHWs in California utilizing data from the California Tobacco Surveys (CTS). We combined 1990, 1992, and 1996 CTS (pre-MSA) and the 1999, 2002, 2005, and 2008 CTS (post-MSA) to examine changes in LITS (Filipino, Japanese, and Korean ethnic groups were compared with NHWs. Pre-MSA logistic regression models adjusted for age, gender, education level, language spoken at home, and use of other tobacco products found that Chinese (odds ratio [OR] = 3.38, 95% confidence interval [CI] = 2.19, 5.21), Filipinos (OR = 3.55, 95% CI = 2.73, 4.63), Japanese (OR = 1.99, 95% CI = 1.22, 3.27), and Koreans (OR = 3.22, 95% CI = 2.06, 5.03) were significantly more likely to be LITS compared with NHWs. Post-MSA, all Asian American subgroups experienced an increase in LITS (11.7%-37.8%); however, only Chinese (OR = 2.19, 95% CI = 1.16, 4.13) and Filipinos (OR = 3.33, 95% CI = 2.26, 4.91) remained significantly more likely to be LITS compared with NHWs. Our results highlight the need for tobacco control efforts that address the growing group of LITS among Asian Americans and NHWs.

  4. The Height of a White-Light Flare and its Hard X-Ray Sources

    Science.gov (United States)

    Oliveros, Juan-Carlos Martinez; Hudson, Hugh S.; Hurford, Gordon J.; Kriucker, Saem; Lin, R. P.; Lindsey, Charles; Couvidat, Sebastien; Schou, Jesper; Thompson, W. T.

    2012-01-01

    We describe observations of a white-light (WL) flare (SOL2011-02-24T07:35:00, M3.5) close to the limb of the Sun, from which we obtain estimates of the heights of the optical continuum sources and those of the associated hard X-ray (HXR) sources. For this purpose, we use HXR images from the Reuven Ramaty High Energy Spectroscopic Imager and optical images at 6173 Ang. from the Solar Dynamics Observatory.We find that the centroids of the impulsive-phase emissions in WL and HXRs (30 -80 keV) match closely in central distance (angular displacement from Sun center), within uncertainties of order 0".2. This directly implies a common source height for these radiations, strengthening the connection between visible flare continuum formation and the accelerated electrons. We also estimate the absolute heights of these emissions as vertical distances from Sun center. Such a direct estimation has not been done previously, to our knowledge. Using a simultaneous 195 Ang. image from the Solar-Terrestrial RElations Observatory spacecraft to identify the heliographic coordinates of the flare footpoints, we determine mean heights above the photosphere (as normally defined; tau = 1 at 5000 Ang.) of 305 +/- 170 km and 195 +/- 70 km, respectively, for the centroids of the HXR and WL footpoint sources of the flare. These heights are unexpectedly low in the atmosphere, and are consistent with the expected locations of tau = 1 for the 6173 Ang and the approx 40 keV photons observed, respectively.

  5. Development and Utilization of Host Materials for White Phosphorescent Organic Light-Emitting Diodes

    Energy Technology Data Exchange (ETDEWEB)

    Tang, Ching; Chen, Shaw

    2013-05-31

    Our project was primarily focused on the MYPP 2015 goal for white phosphorescent organic devices (PhOLEDs or phosphorescent organic light-emitting diodes) for solid-state lighting with long lifetimes and high efficiencies. Our central activity was to synthesize and evaluate a new class of host materials for blue phosphors in the PhOLEDs, known to be a weak link in the device operating lifetime. The work was a collaborative effort between three groups, one primarily responsible for chemical design and characterization (Chen), one primarily responsible for device development (Tang) and one primarily responsible for mechanistic studies and degradation analysis (Rothberg). The host materials were designed with a novel architecture that chemically links groups with good ability to move electrons with those having good ability to move “holes” (positive charges), the main premise being that we could suppress the instability associated with physical separation and crystallization of the electron conducting and hole conducting materials that might cause the devices to fail. We found that these materials do prevent crystallization and that this will increase device lifetimes but that efficiencies were reduced substantially due to interactions between the materials creating new low energy “charge transfer” states that are non-luminescent. Therefore, while our proposed strategy could in principle improve device lifetimes, we were unable to find a materials combination where the efficiency was not substantially compromised. In the course of our project, we made several important contributions that are peripherally related to the main project goal. First, we were able to prepare the proposed new family of materials and develop synthetic routes to make them efficiently. These types of materials that can transport both electrons and holes may yet have important roles to play in organic device technology. Second we developed an important new method for controlling the

  6. Highly efficient and stable white organic light emitting diode base on double recombination zones of phosphorescent blue/orange emitters.

    Science.gov (United States)

    Lee, Seok Jae; Koo, Ja Ryong; Lim, Dong Hwan; Park, Hye Rim; Kim, Young Kwan; Ha, Yunkyoung

    2011-08-01

    We demonstrated efficient and stable white phosphorescent organic light-emitting diodes (OLEDs) with double-emitting layers (D-EMLs), which were comprised of two emissive layers with a hole transport-type host of N,N'-dicarbazolyl-3,5-benzene (mCP) and a electron transport-type host of 2,2',2"-(1,3,5-benzenetryl)tris(1-phenyl)-1H-benzimidazol (TPBi) with blue/orange emitters, respectively. We fabricated two type white devices with single emitting layer (S-EML) and D-EML of orange emitter, maintaining double recombination zone of blue emitter. In addition, the device architecture was developed to confine excitons inside the D-EMLs and to manage triplet excitons by controlling the charge injection. As a result, light-emitting performances of white OLED with D-EMLs were improved and showed the steady CIE coordinates compared to that with S-EML of orange emitter, which demonstrated the maximum luminous efficiency and external quantum efficiency were 21.38 cd/A and 11.09%. It also showed the stable white emission with CIE(x,y) coordinates from (x = 0.36, y = 0.37) at 6 V to (x = 0.33, y = 0.38) at 12 V.

  7. Color point tuning for (Sr,Ca,Ba)Si2O2N2:Eu2+ for white light LEDs

    NARCIS (Netherlands)

    Bachmann, V.M.; Ronda, R.C.; Meijerink, A.; Oeckler, O.; Schnick, W.

    2009-01-01

    Color point tuning is an important challenge for improving white light LEDs. In this paper, the possibilities of color tuning with the efficient LED phosphor Sr1-x-y-zCaxBaySi2O2N2:Euz 2+ (0 e x, y e 1; 0.005 e z e 0.16) are investigated. The emission color can be tuned in two ways: by changing Eu2+

  8. Characterization and analysis of sub-micron surface roughness of injection moulded microfluidic systems using White Light Interferometry

    DEFF Research Database (Denmark)

    Tosello, Guido; Marinello, Francesco; Hansen, Hans Nørgaard

    2009-01-01

    Surface topography is of great importance in polymer micro fluidics, therefore the replication capability of the process and the surface quality of the tool has to be suitably optimized. In this paper, optical profilometry (white light interferometry, WLI) is implemented for topographical...... characterization of polymer surfaces. In particular the study considers replication performance of injection moulding applied for the realization of microfluidic systems for blood analysis. Parts were produced by means of a series of statistically designed injection moulding experiments. Three process parameters...

  9. High-efficiency orange and tandem white organic light-emitting diodes using phosphorescent dyes with horizontally oriented emitting dipoles.

    Science.gov (United States)

    Lee, Sunghun; Shin, Hyun; Kim, Jang-Joo

    2014-09-03

    Tandem white organic light-emitting diodes (WOLEDs) using horizontally oriented phosphorescent dyes in an exciplex-forming co-host are presented, along with an orange OLED. A high external quantum efficiency of 32% is achieved for the orange OLED at 1000 cd m(-2) and the tandem WOLEDs exhibit a high maximum EQE of 54.3% (PE of 63 lm W(-1)). © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  10. Conidioma production of the white root rot fungus [Rosellinia] in axenic culture under near-ultraviolet light radiation

    International Nuclear Information System (INIS)

    Nakamura, H.; Ikeda, K.; Arakawa, M.; Matsumoto, N.

    2002-01-01

    Conidiomata of the white root rot fungus were produced in axenic culture under near-ultraviolet light radiation. Pieces of sterilized Japanese pear twigs were placed on 7-day-old oatmeal agar culture in plates. The plates were further incubated for 5 days and then illuminated by near-ultraviolet light. Synnemata developed on the twigs within 5 weeks in 19 of 20 isolates tested, and conidia were observed in 12 of the 19 isolates. The synnemata and conidia produced were morphologically identical to those of Dematophora necatrix

  11. White electroluminescence from ZnO nanorods/p-GaN heterojunction light-emitting diodes under reverse bias

    International Nuclear Information System (INIS)

    Zhang, Lichun; Li, Qingshan; Qu, Chong; Zhang, Zhongjun; Huang, Ruizhi; Zhao, Fengzhou

    2013-01-01

    Heterojunction light-emitting diodes (LEDs) based on arrays of ZnO nanorods were fabricated on p-GaN films by the hydrothermal method. Without any phosphors, white-light electroluminescence (EL) from ZnO nanorods/p-GaN heterojunction LEDs operated at reverse breakdown bias was observed. The EL spectra are composed of an ultraviolet (UV) emission centered at 382 nm, a blue light located at 431 nm and a broadband yellow–green light at around 547 nm, which originated from band-edge emission in ZnO, the Mg acceptor levels in p-GaN and the deep-level states near the ZnO/GaN interface, respectively. The chromaticity coordinates of EL spectrum are very close to the (0.333, 0.333) of standard white light. The origin of these emissions has been discussed and the tunneling effect in the interface is probably the mechanism to explain EL emission. (paper)

  12. White top-emitting organic light-emitting diodes using one-emissive layer of the DCJTB doped DPVBi layer

    Energy Technology Data Exchange (ETDEWEB)

    Kim, M.S.; Jeong, C.H.; Lim, J.T. [Department of Advanced Materials Science and Engineering, Sungkyunkwan University, Suwon, Gyonggi-Do, 440-746 (Korea, Republic of); Yeom, G.Y. [Department of Advanced Materials Science and Engineering, Sungkyunkwan University, Suwon, Gyonggi-Do, 440-746 (Korea, Republic of); The National Program for Tera-level Devices, Hawolgok-dong, Sungbuk-gu, Seoul, 136-791 (Korea, Republic of)], E-mail: gyyeom@skku.edu

    2008-04-01

    White top-emitting organic light-emitting diodes (TEOLEDs) composed of one doped emissive layer which emits two-wavelength light though the radiative recombination were fabricated. As the emissive layer, 4,4-bis(2,2-diphenylethen-1-yl)biphenyl (DPVBi) was used as the host material and 4-(dicyanomethylene)-2-tert-butyl-6-(1,1,7,7-tetramethyljulolidyl-9-enyl) -4H-pyran (DCJTB) was added as the dopant material. By optimizing the DCJTB concentration (1.2%) and the thickness of the DPVBi layer (30 nm), the intensity ratio of the two wavelengths could be adjusted for balanced white light emission. By using the device composed of glass/Ag (100 nm)/ITO (90 nm)/2-TNATA (60 nm)/NPB (15 nm)/DPVBi:DCJTB (1.2%, 30 nm)/Alq{sub 3} (20 nm)/Li (1.0 nm)/Al (2.0 nm)/Ag (20 nm)/ITO (63 nm)/SiO{sub 2} (42 nm), the Commission Internationale d'Eclairage (CIE) chromaticity coordinate of (0.32, 0.34) close to the ideal white color CIE coordinate could be obtained at 100 cd/m{sup 2}.

  13. 4-(dicyanomethylene)-2-methyl-6-(p-dimethylaminostyryl)-4H-pyran (DCM)-doping density dependence of luminescence spectra and white emission in polymer light-emitting diodes

    Energy Technology Data Exchange (ETDEWEB)

    Inoue, Akinori; Hosokawa, Takeshi; Haishi, Motoki; Ohtani, Naoki [Department of Electronics, Doshisha University, Tatara-Miyakodani, Kyotanabe-shi, Kyoto (Japan)

    2009-01-15

    We fabricated white polymer light-emitting diodes (PLEDs), in which the active region is doped with a low-weight molecule. The host polymer material is Poly(9,9-didodecyl-fluorenyl-2,7-yleneethylnylene) (PFO), while the guest luminescent low-weight-molecule is 4-(dicyanomethylene)-2-methyl-6-(p-dimethylaminostyryl)-4H-pyran (DCM). The photoluminescence (PL) and electroluminescence (EL) spectra strongly depend on DCM-doping-density. However, the most suitable DCM-doping-densities for white emissions in PL and EL are slightly different. This discrepancy is caused by the difference in excitation efficiencies. The photo-excitation system for PL measurement is better than the current injection for generating carriers efficiently. Thus, the realization of the white EL signal requires the larger DCM-doping-density than that of the white PL signal. (copyright 2009 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)

  14. A method for the rapid generation of nonsequential light-response curves of chlorophyll fluorescence.

    Science.gov (United States)

    Serôdio, João; Ezequiel, João; Frommlet, Jörg; Laviale, Martin; Lavaud, Johann

    2013-11-01

    Light-response curves (LCs) of chlorophyll fluorescence are widely used in plant physiology. Most commonly, LCs are generated sequentially, exposing the same sample to a sequence of distinct actinic light intensities. These measurements are not independent, as the response to each new light level is affected by the light exposure history experienced during previous steps of the LC, an issue particularly relevant in the case of the popular rapid light curves. In this work, we demonstrate the proof of concept of a new method for the rapid generation of LCs from nonsequential, temporally independent fluorescence measurements. The method is based on the combined use of sample illumination with digitally controlled, spatially separated beams of actinic light and a fluorescence imaging system. It allows the generation of a whole LC, including a large number of actinic light steps and adequate replication, within the time required for a single measurement (and therefore named "single-pulse light curve"). This method is illustrated for the generation of LCs of photosystem II quantum yield, relative electron transport rate, and nonphotochemical quenching on intact plant leaves exhibiting distinct light responses. This approach makes it also possible to easily characterize the integrated dynamic light response of a sample by combining the measurement of LCs (actinic light intensity is varied while measuring time is fixed) with induction/relaxation kinetics (actinic light intensity is fixed and the response is followed over time), describing both how the response to light varies with time and how the response kinetics varies with light intensity.

  15. Selecting the optimal synthesis parameters of InP/CdxZn1-xSe quantum dots for a hybrid remote phosphor white LED for general lighting applications.

    Science.gov (United States)

    Ryckaert, Jana; Correia, António; Tessier, Mickael D; Dupont, Dorian; Hens, Zeger; Hanselaer, Peter; Meuret, Youri

    2017-11-27

    Quantum dots can be used in white LEDs for lighting applications to fill the spectral gaps in the combined emission spectrum of the blue pumping LED and a broad band phosphor, in order to improve the source color rendering properties. Because quantum dots are low scattering materials, their use can also reduce the amount of backscattered light which can increase the overall efficiency of the white LED. The absorption spectrum and narrow emission spectrum of quantum dots can be easily tuned by altering their synthesis parameters. Due to the re-absorption events between the different luminescent materials and the light interaction with the LED package, determining the optimal quantum dot properties is a highly non-trivial task. In this paper we propose a methodology to select the optimal quantum dot to be combined with a broad band phosphor in order to realize a white LED with optimal luminous efficacy and CRI. The methodology is based on accurate and efficient simulations using the extended adding-doubling approach that take into account all the optical interactions. The method is elaborated for the specific case of a hybrid, remote phosphor white LED with YAG:Ce phosphor in combination with InP/CdxZn 1-x Se type quantum dots. The absorption and emission spectrum of the quantum dots are generated in function of three synthesis parameters (core size, shell size and cadmium fraction) by a semi-empirical 'quantum dot model' to include the continuous tunability of these spectra. The sufficiently fast simulations allow to scan the full parameter space consisting of these synthesis parameters and luminescent material concentrations in terms of CRI and efficacy. A conclusive visualization of the final performance allows to make a well-considered trade-off between these performance parameters. For the hybrid white remote phosphor LED with YAG:Ce and InP/CdxZn 1-x Se quantum dots a CRI Ra = 90 (with R9>50) and an overall efficacy of 110 lm/W is found.

  16. The Classical Pathways of Occipital Lobe Epileptic Propagation Revised in the Light of White Matter Dissection.

    Science.gov (United States)

    Latini, Francesco; Hjortberg, Mats; Aldskogius, Håkan; Ryttlefors, Mats

    2015-01-01

    The clinical evidences of variable epileptic propagation in occipital lobe epilepsy (OLE) have been demonstrated by several studies. However the exact localization of the epileptic focus sometimes represents a problem because of the rapid propagation to frontal, parietal, or temporal regions. Each white matter pathway close to the supposed initial focus can lead the propagation towards a specific direction, explaining the variable semiology of these rare epilepsy syndromes. Some new insights in occipital white matter anatomy are herein described by means of white matter dissection and compared to the classical epileptic patterns, mostly based on the central position of the primary visual cortex. The dissections showed a complex white matter architecture composed by vertical and longitudinal bundles, which are closely interconnected and segregated and are able to support specific high order functions with parallel bidirectional propagation of the electric signal. The same sublobar lesions may hyperactivate different white matter bundles reemphasizing the importance of the ictal semiology as a specific clinical demonstration of the subcortical networks recruited. Merging semiology, white matter anatomy, and electrophysiology may lead us to a better understanding of these complex syndromes and tailored therapeutic options based on individual white matter connectivity.

  17. The Classical Pathways of Occipital Lobe Epileptic Propagation Revised in the Light of White Matter Dissection

    Science.gov (United States)

    Latini, Francesco; Hjortberg, Mats; Aldskogius, Håkan; Ryttlefors, Mats

    2015-01-01

    The clinical evidences of variable epileptic propagation in occipital lobe epilepsy (OLE) have been demonstrated by several studies. However the exact localization of the epileptic focus sometimes represents a problem because of the rapid propagation to frontal, parietal, or temporal regions. Each white matter pathway close to the supposed initial focus can lead the propagation towards a specific direction, explaining the variable semiology of these rare epilepsy syndromes. Some new insights in occipital white matter anatomy are herein described by means of white matter dissection and compared to the classical epileptic patterns, mostly based on the central position of the primary visual cortex. The dissections showed a complex white matter architecture composed by vertical and longitudinal bundles, which are closely interconnected and segregated and are able to support specific high order functions with parallel bidirectional propagation of the electric signal. The same sublobar lesions may hyperactivate different white matter bundles reemphasizing the importance of the ictal semiology as a specific clinical demonstration of the subcortical networks recruited. Merging semiology, white matter anatomy, and electrophysiology may lead us to a better understanding of these complex syndromes and tailored therapeutic options based on individual white matter connectivity. PMID:26063964

  18. A novel single-phase white phosphor NaBaBO{sub 3}:Dy{sup 3+},K{sup +} for near-UV white light-emitting diodes

    Energy Technology Data Exchange (ETDEWEB)

    Zheng, Jianghui; Cheng, Qijin; Wu, Jieyang; Cui, Xin; Chen, Rong; Chen, Wenzhi [School of Energy Research, Xiamen University, Xiamen 361005 (China); Chen, Chao, E-mail: cchen@xmu.edu.cn [School of Energy Research, Xiamen University, Xiamen 361005 (China); School of Physics and Mechanical & Electrical Engineering, Xiamen University, Xiamen, 361005 (China)

    2016-01-15

    Highlights: • A white phosphor NaBaBO{sub 3}:Dy{sup 3+},K{sup +} with CIE coordinate (0.301, 0.308) was synthesized. • The optimum doping concentration of Dy{sup 3+} ions was found. • The effect and mechanism of K{sup +} ion as a charge compensator were discussed. • Temperature-dependent PL property of NaBaBO{sub 3}:Dy{sup 3+},K{sup +} was studied. • PL decay and quantum efficiency behaviors of the samples were investigated. - Abstract: A novel Dy{sup 3+}-doped NaBaBO{sub 3} white-emitting phosphor has been prepared by high temperature solid-state reaction method. The phase structure and luminescence properties of NaBaBO{sub 3}:Dy{sup 3+},K{sup +} samples were investigated. Photoluminescence results show that the as-prepared samples could be effectively excited by near-ultraviolet (NUV) light and generate white light emission due to the {sup 4}F{sub 9/2} → {sup 6}H{sub 15/2} (blue) transition and {sup 4}F{sub 9/2} → {sup 6}H{sub 13/2} (yellow) transition of Dy{sup 3+} ions, respectively. The optimum doping concentration of Dy{sup 3+} ions in the NaBaBO{sub 3} host was determined to be 5.0 mol% and the CIE chromaticity of the sample was determined to be (0.301, 0.308). Moreover, the mechanism of K{sup +} ion as a charge compensator on the improvement of photoluminescence property and the effect of temperature on the photoluminescence property of NaBaBO{sub 3}:Dy{sup 3+},K{sup +} were investigated. Furthermore, photoluminescence decay and quantum efficiency behaviors of NaBaBO{sub 3}:Dy{sup 3+},K{sup +} were also studied. The present work demonstrates that the NaBaBO{sub 3}:Dy{sup 3+},K{sup +} phosphor is a potential candidate for NUV white light emitting diodes.

  19. Microwave-assisted aqueous synthesis of transition metal ions doped ZnSe/ZnS core/shell quantum dots with tunable white-light emission

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, Jie [Laboratory of Advanced Materials, Fudan University, Shanghai 200438 (China); Chen, Qiuhang; Zhang, Wanlu; Mei, Shiliang; He, Liangjie; Zhu, Jiatao [Engineering Research Center of Advanced Lighting Technology, Ministry of Education, Institute for Electric Light Sources, Fudan University, Shanghai 200433 (China); Chen, Guoping [School of Information Science and Technology, Fudan University, Shanghai 200433 (China); Guo, Ruiqian, E-mail: rqguo@fudan.edu.cn [Engineering Research Center of Advanced Lighting Technology, Ministry of Education, Institute for Electric Light Sources, Fudan University, Shanghai 200433 (China)

    2015-10-01

    Highlights: • ZnSe-based QDs were formed via a microwave-assisted aqueous approach. • The stabilizer, ZnS coats and UV irradiation played a role in the PL enhancement. • Tunable white-light-emitting Mn:ZnSe QDs and Cu,Mn:ZnSe/ZnS QDs were synthesized. • The formation mechanism of Cu,Mn:ZnSe QDs was clarified. • The corresponding CIE color coordinates of different PL spectra were obtained. - Abstract: Synthesis of bright white-light emitting Mn and Cu co-doped ZnSe/ZnS core/shell quantum dots (QDs) (Cu,Mn:ZnSe/ZnS) was reported. Water-soluble ZnSe-based QDs with Mn and Cu doping were prepared using a versatile hot-injection method in aqueous solution with a microwave-assisted approach. Influence of the Se/S ratio, stabilizer, refluxing time and the concentration of Cu/Mn dopant ions on the particle size and photoluminescence (PL) were investigated. The as-prepared QDs in the different stages of growth were characterized by X-ray powder diffractometer (XRD), high-resolution transmission electron microscopy (HRTEM), UV–visible (UV–vis) spectrophotometer, and fluorescence spectrophotometer. It is found that these ZnSe-based QDs synthesized under mild conditions exhibit emission in the range of 390–585 nm. The PL quantum yield (QY) of the as-prepared water-soluble ZnSe QDs can be up to 24.3% after the UV-irradiation treatment. The band-gap emission of ZnSe is effectively restrained through Mn and Cu doping. The refluxing time influences the doping of not only Mn, but also Cu, which leads to the best refluxing time of Mn:ZnSe and the red-shift of the emission of Cu:ZnSe d-dots. Co-doping induced white-light emission (WLE) from Cu,Mn:ZnSe/ZnS core/shell QDs were obtained, which can offer the opportunity for future-generation white-light emitting diodes (LEDs)

  20. Single-phased CaAl2Si2O8:Tm3+, Dy3+ white-light phosphors under ultraviolet excitation

    International Nuclear Information System (INIS)

    Yang, Penghui; Yu, Xue; Xu, Xuhui; Jiang, Tingming; Yu, Hongling; Zhou, Dacheng; Yang, Zhengwen; Song, Zhiguo; Qiu, Jianbei

    2013-01-01

    A novel white-light-emitting phosphor CaAl 2 Si 2 O 8 :Tm, Dy was synthesized in ambient atmosphere by solid-state reaction. The energy transfer from Tm 3+ to Dy 3+ ions via a dipole–quadrupole reaction was observed and investigated. Upon UV excitation, white light emission was achieved by integrating a blue emission band located at 455 nm and an orange one located at 574 nm attributed to Tm 3+ and Dy 3+ ions, respectively. In addition, the energy-transfer efficiency and critical distance were calculated. Results suggested that the phosphor might be promising as a single-phased white-light-emitting phosphor for UV white-light LED. - Graphical abstract: The results indicate the existence of energy transfer from Tm 3+ to Dy 3+ . By tuning the concentration of Dy 3+ , single-phased white light can be realized. - Highlights: ► Energy transfer from Tm 3+ to Dy 3+ was investigated. ► Color tunable from blue to white can be achieved. ► White light can be realized in CaAl 2 Si 2 O 8 :Tm 3+ , Dy 3+ phosphor

  1. White-light phosphorescence emission from a single molecule: application to OLED.

    Science.gov (United States)

    Bolink, Henk J; De Angelis, Filippo; Baranoff, Etienne; Klein, Cédric; Fantacci, Simona; Coronado, Eugenio; Sessolo, Michele; Kalyanasundaram, K; Grätzel, Michael; Nazeeruddin, Md K

    2009-08-21

    A simple mononuclear cyclometallated iridium(iii) complex exhibits white photo- and electro- luminescence in the wavelength range from 440 to 800 nm, which originates from a single emitting excited state of mixed character.

  2. White-light phosphorescence emission from a single molecule: application to OLED

    OpenAIRE

    Bolink, Henk; De Angelis, Filippo; Baranoff, Etienne; Klein, Cedric; Fantacci, Simona; Coronado Miralles, Eugenio; Sessolo, Michele; Kalyanasundaram, K.; Grätzel, Michael; Nazeeruddin, Md. K.

    1999-01-01

    A simple mononuclear cyclometallated iridium(III) complex exhibits white photo- and electro- luminescence in the wavelength range from 440 to 800 nm, which originates from a single emitting excited state of mixed character. Bolink Henk, ; Coronado Miralles, Eugenio,

  3. Solar flare impulsivity and its relationship with white-light flares and with CMEs

    Science.gov (United States)

    Watanabe, K.; Masuda, S.

    2017-12-01

    There are many types of classification in solar flares. One of them is a classification by flare duration in soft X-rays; so-called impulsive flare and long duration event (LDE). Typically, the duration of an impulsive flare is shorter than 1 hour, and that of an LDE is longer than 1 hour. These two types of flare show different characteristics. In soft X-rays, impulsive flares usually have a compact loop structure. On the other hand, LDEs show a large-scale loop, sometimes a large arcade structure. In hard X-rays (HXRs), the difference appears clear, too. The former shows a strong and short-time (10 minutes) emissions and show a large coronal source. These facts suggest that HXR observation becomes one of a good indicator to classify solar flares, especially for the study on the particle acceleration and the related phenomena. However, HXR data do not always exist due to the satellite orbit and the small sensitivity of HXR instruments. So, in this study, based on the concept of the Neupert effect (Neupert, 1968), we use soft X-ray derivative data as the proxy of HXR. From this data, we define impulsivity (IP) for each flare. Then we investigate solar flares using this new index. First we apply IP index to white-light flare (WLF) research. We investigate how WL enhancement depends on IP, then it is found that WLF tend to have large IP values. So the flare impulsivity (IP) is one of the important factors if WL enhancement appears or not in a solar flare. Next we investigate how CME itself and/or its physical parameters depend on IP index. It has been believed that most of CMEs are associated with LDEs, but we found that there is only a weak correlation between the existence of CME and IP index. Finally, we also search for the relationship between WLF and CME as a function of IP and discuss the physical condition of WLF.

  4. Trivalent europium-doped strontium molybdate red phosphors in white light-emitting diodes: Synthesis, photophysical properties and theoretical calculations

    International Nuclear Information System (INIS)

    Yang, W.-Q.; Liu, H.-G.; Liu, G.-K.; Lin, Y.; Gao, M.; Zhao, X.-Y.; Zheng, W.-C.; Chen, Y.; Xu, J.; Li, L.-Z.

    2012-01-01

    Eu 3+ -doped strontium molybdate red phosphors (Sr 1−x MoO 4 :Eu x (x = 0.01–0.2)) for white light-emitting diodes (LED) were synthesized by the solid-state reaction method. The fluorescent intensities of the as-prepared phosphors were remarkably improved. The excitation and emission spectra demonstrate that these phosphors can be effectively excited by the near-UV light (395 nm) and blue light (466 nm). Their emitted red light peaks are located at 613 nm, and the highest quantum yield value (η) of the as-grown red phosphor, which is 95.85%, is much higher than that of commercial red phosphor (77.53%). These red phosphors plus commercial yellow powers (1:10) were successfully packaged with the GaN-based blue chips on a piranha frame by epoxy resins. The encapsulated white LED lamps show high performance of the CIE chromaticity coordinates and color temperatures. Moreover, to explain the fluorescent spectra of these phosphors, a complete 3003 × 3003 energy matrix was successfully built by an effective operator Hamiltonian including free ion and crystal field interactions. For the first time, the fluorescent spectra for Eu 3+ ion at the tetragonal (S 4 ) Sr 2+ site of SrMoO 4 crystal were calculated from a complete diagonalization (of energy matrix) method. The fitting values are close to the experimental results.

  5. Tunable white light emission from hafnium oxide films co-doped with trivalent terbium and europium ions deposited by Pyrosol technique

    Energy Technology Data Exchange (ETDEWEB)

    Guzman-Olguin, J.C.; Montes, E.; Guzman-Mendoza, J. [Centro de Investigacion en Ciencia Aplicada y Tecnologia Avanzada del Instituto Politecnico Nacional, Unidad Legaria (Mexico); Baez-Rodriguez, A.; Zamora-Peredo, L. [Centro de Investigacion en Micro y Nanotecnologia, Universidad Veracruzana, Boca del Rio, Ver (Mexico); Garcia-Hipolito, M.; Alvarez-Fregoso, O. [Instituto de Investigaciones en Materiales, Universidad Nacional Autonoma de Mexico, Circuito Exterior, Ciudad Universitaria, Coyoacan (Mexico); Martinez-Merlin, I.; Falcony, C. [Centro de Investigacion y de Estudios Avanzados del Instituto Politecnico Nacional (Mexico)

    2017-10-15

    In this paper, the photo and cathodoluminescent properties of HfO{sub 2} films optically activated with different atomic concentrations of Tb{sup 3+} and Eu{sup 3+} ions, deposited by the Pyrosol technique, are reported. These films were deposited at temperatures from 400 to 600 C, using chlorides as raw materials. The surface morphologies of all deposited films were rough and dense. X-ray diffraction analysis showed that the films deposited at 600 C were polycrystalline exhibiting the HfO{sub 2} monoclinic phase. The tuning by the means of the excitation wavelength generates photoluminescence spectra, for co-doped films, in several emissions from blue to yellow (including white light) due to the characteristic electronic transitions of Tb{sup 3+} (green), Eu{sup 3+}(red) ions and the violet-blue emission associated to the host lattice (HfO{sub 2}). According to the chromaticity diagram, the best white light is reached for the sample S2 excited with 382 nm (x = 0.3343, y = 0.3406). The cathodoluminescence emission spectra for co-doped films showed emissions from green to red (including yellow, orange and other intermediate emissions). The averaged quantum efficiency values of the sample labeled as S2 resulted between 47 and 78% depending on the excitation wavelength. In addition, XPS, TEM, SEM and decay times were performed to characterize these films. (copyright 2017 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

  6. Microstructural analysis of human white matter architecture using Polarized Light Imaging (PLI: Views from neuroanatomy

    Directory of Open Access Journals (Sweden)

    Hubertus eAxer

    2011-11-01

    Full Text Available To date, there are several methods for mapping connectivity, ranging from the macroscopic to molecular scales. However, it is difficult to integrate this multiply-scaled data into one concept. Polarized light imaging (PLI is a method to quantify fiber orientation in gross histological brain sections based on the birefringent properties of the myelin sheaths. The method is capable of imaging fiber orientation of larger-scale architectural patterns with higher detail than diffusion MRI of the human brain. PLI analyses light transmission through a gross histological section of a human brain under rotation of a polarization filter combination. Estimates of the angle of fiber direction and the angle of fiber inclination are automatically calculated at every point of the imaged section. Multiple sections can be assembled into a 3D volume. We describe the principles of PLI and present several studies of fiber anatomy in the human brain: 6 brainstems were serially sectioned, imaged with PLI, and 3D reconstructed. Pyramidal tract and lemniscus medialis were segmented in the PLI datasets. PLI data from the internal capsule was related to results from confocal laser scanning microscopy, which is a method of smaller scale fiber anatomy. PLI fiber architecture of the extreme capsule was compared to macroscopical dissection, which represents a method of larger scale anatomy. The microstructure of the anterior human cingulum bundle was analyzed in serial sections of 6 human brains. PLI can generate highly-resolved 3D datsets of fiber orientation of the human brain and has, therefore, a high comparability to diffusion MR. To get additional information regarding axon structure and density, PLI can also be combined with classical histological stains. It brings the directional aspects of diffusion MRI into the range of histology and may represent a promising tool to close the gap between larger scale diffusion orientation and microstructural histological analysis

  7. The performance of quantum dots-based white light-emitting diodes

    Science.gov (United States)

    Chen, Kuan-Lin; Chung, Shu-Ru

    2017-08-01

    Recently, the investigation of quantum dots (QDs) as a color converter for white light-emitting diodes (WLEDs) application has attracted a great deal of attention. Because the narrow emission wavelength of QDs can be controlled by their particle sizes and compositions, which is facilitated to improve the color gamut of display as well as color rendering index (CRI) and the correlated color temperature (CCT) of WLEDs. In a typical commercially available LCD display, the color gamut is approximately to 75 % which is defined by the National Television System Committee (NTSC). In order to enhance NTSC, the full width at half-maximum (FWHM) of color converter should be less than 30 nm. Therefore, the QDs are the best choice for display application due to the FWHM of QDs is meet the demand of display application. In this study, the hot injection method with one-pot process is used to synthesis of colloidal ternary ZnCdSe green (G-) and red-emission (R-) QDs with a narrow emission wavelength around 537 and 610 nm. By controlling the complex reagents-stearic acid (SA) and lauric acid (LA), high performance of G- and R-QDs can be prepared. The quantum yields (QYs), particle sizes and FWHM for G- and R-QDs are 70, 30 %, 3.2 +/- 0.5, 4.1 +/- 0.5 nm and 25, 26 nm, respectively. In order to explore the performance of QDs-based WLEDs, mixing ratios effect between G-QD and R-QD are studied and the WLED is packed as conformal-type. Different ratios of R-QD and G-QD (1:10, 1:20 and 1:30) are mixed and fill up the 3020 SMD blue-InGaN LED, and named as LED-10, LED-20 and LED-30. After that, UV curable gel is deposited on the top of QD layer to form WLED and named as LED-10*, LED-20* and LED-30*. The results show that the Commission International d'Eclairage (CIE) chromaticity coordinates, color rendering index (CRI), luminous efficacy of LED-10*, LED-20* and LED-30* are (0.27, 0.21), 53, 1.9 lm/W, (0.29, 0.30), 72, 3.3 lm/W and (0.25, 0.34), 45, 6.8 lm/W, respectively. We can find

  8. Subcutaneous white adipocytes express a light sensitive signaling pathway mediated via a melanopsin/TRPC channel axis.

    Science.gov (United States)

    Ondrusova, Katarina; Fatehi, Mohammad; Barr, Amy; Czarnecka, Zofia; Long, Wentong; Suzuki, Kunimasa; Campbell, Scott; Philippaert, Koenraad; Hubert, Matthew; Tredget, Edward; Kwan, Peter; Touret, Nicolas; Wabitsch, Martin; Lee, Kevin Y; Light, Peter E

    2017-11-27

    Subcutaneous white adipose tissue (scWAT) is the major fat depot in humans and is a central player in regulating whole body metabolism. Skin exposure to UV wavelengths from sunlight is required for Vitamin D synthesis and pigmentation, although it is plausible that longer visible wavelengths that penetrate the skin may regulate scWAT function. In this regard, we discovered a novel blue light-sensitive current in human scWAT that is mediated by melanopsin coupled to transient receptor potential canonical cation channels. This pathway is activated at physiological intensities of light that penetrate the skin on a sunny day. Daily exposure of differentiated adipocytes to blue light resulted in decreased lipid droplet size, increased basal lipolytic rate and alterations in adiponectin and leptin secretion. Our results suggest that scWAT function may be directly under the influence of ambient sunlight exposure and may have important implications for our current understanding of adipocyte biology. (150 words).

  9. Transparent organic light-emitting diodes with balanced white emission by minimizing waveguide and surface plasmonic loss.

    Science.gov (United States)

    Zhang, Yi-Bo; Ou, Qing-Dong; Li, Yan-Qing; Chen, Jing-De; Zhao, Xin-Dong; Wei, Jian; Xie, Zhong-Zhi; Tang, Jian-Xin

    2017-07-10

    It is challenging in realizing high-performance transparent organic light-emitting diodes (OLEDs) with symmetrical light emission to both sides. Herein, an efficient transparent OLED with highly balanced white emission to both sides is demonstrated by integrating quasi-periodic nanostructures into the organic emitter and the metal-dielectric composite top electrode, which can simultaneously suppressing waveguide and surface plasmonic loss. The power efficiency and external quantum efficiency are raised to 83.5 lm W -1 and 38.8%, respectively, along with a bi-directional luminance ratio of 1.26. The proposed scheme provides a facile route for extending application scope of transparent OLEDs for future transparent displays and lightings.

  10. Al/WO{sub 3}/Au as the interconnecting layer for efficient tandem white organic light-emitting diodes

    Energy Technology Data Exchange (ETDEWEB)

    Zhang Hongmei; Dai Yanfeng; Ma Dongge [State Key Laboratory of Polymer Physics and Chemistry, Changchun Institute of Applied Chemistry, Chinese Academy of Sciences, Graduate School of Chinese Academy of Sciences, Changchun 130022 (China)], E-mail: mdg1014@ciac.jl.cn

    2008-05-21

    White light emission from tandem organic light-emitting diodes consisting of blue and red light units separated by a transparent interconnecting layer of Al/WO{sub 3}/Au has been realized. The devices have a structure of indium-tin-oxide (ITO)/molybdenum oxide (MoO{sub 3}) (8 nm)/N, N'-di(naphthalene-1-yl)-N, N'-diphenyl-benzidine (NPB)(100 nm)/p-bis(p-N,N-diphenyl-aminostyryl)benzene) (DSA-ph):2-methyl-9,10-di(2-naphthyl) anthracene (MADN)(40 nm)/tris(8-hydroxylquinoline) aluminium (Alq{sub 3}) (10 nm)/LiF(1 nm)/Al(2 nm)/WO{sub 3}(3 nm)/Au(16 nm)/MoO{sub 3}(5 nm)/NPB(60 nm)/Alq{sub 3}: 4-(dicyanomethylene)-2-t-butyl-6-(1,1,7,7- tetramethyljulolidyl-9-enyl)-4H-pyran (DCJTB)(30 nm)/Alq{sub 3}(30 nm)/LiF(1 nm)/Al(150 nm). It can be seen that a stable white light emission, including 461 and 491 nm peaks from DSA-ph and 620 nm peak from DCJTB, with Commission International De L'Eclairage chromaticity coordinates from (0.35, 0.33) at 8 V to (0.37, 0.30) at 12 V was obtained. The current efficiency and brightness of the white devices are basically equal to the sum of the blue unit and red unit devices. The maximum brightness reached 20 700 cd m{sup -2} at a bias of 23 V, and the maximum current efficiency was 9.1 cd A{sup -1} at a current density of 0.41 mA cm{sup -2}. (fast track communication)

  11. Highly Efficient White Organic Light-Emitting Diodes with Ultrathin Emissive Layers and a Spacer-Free Structure

    Science.gov (United States)

    Wu, Shengfan; Li, Sihua; Sun, Qi; Huang, Chenchao; Fung, Man-Keung

    2016-05-01

    Ultrathin emissive layers (UEMLs) of phosphorescent materials with a layer thickness of less than 0.3 nm were introduced for high-efficiency organic light-emitting diodes (OLEDs). All the UEMLs for white OLEDs can be prepared without the use of interlayers or spacers. Compared with devices fabricated with interlayers inserted in-between the UEMLs, our spacer-free structure not only significantly improves device efficiency, but also simplifies the fabrication process, thus it has a great potential in lowering the cost of OLED panels. In addition, its spacer-free structure decreases the number of interfaces which often introduce unnecessary energy barriers in these devices. In the present work, UEMLs of red, green and blue-emitting phosphorescent materials and yellow and blue phosphorescent emitters are utilized for the demonstration of spacer-free white OLEDs. Upon optimization of the device structure, we demonstrated spacer-free and simple-structured white-emitting OLEDs with a good device performance. The current and power efficiencies of our white-emitting devices are as high as 56.0 cd/A and 55.5 lm/W, respectively. These efficiencies are the highest ever reported for OLEDs fabricated with the UEML approach.

  12. Generation of an incident focused light pulse in FDTD.

    Science.gov (United States)

    Capoğlu, Ilker R; Taflove, Allen; Backman, Vadim

    2008-11-10

    A straightforward procedure is described for accurately creating an incident focused light pulse in the 3-D finite-difference time-domain (FDTD) electromagnetic simulation of the image space of an aplanatic converging lens. In this procedure, the focused light pulse is approximated by a finite sum of plane waves, and each plane wave is introduced into the FDTD simulation grid using the total-field/scattered-field (TF/SF) approach. The accuracy of our results is demonstrated by comparison with exact theoretical formulas.

  13. Electron-transporting layer doped with cesium azide for high-performance phosphorescent and tandem white organic light-emitting devices

    International Nuclear Information System (INIS)

    Yu, Yaoyao; Chen, Xingming; Jin, Yu; Wu, Zhijun; Yu, Ye; Lin, Wenyan; Yang, Huishan

    2017-01-01

    Cesium azide was employed as an effective n-dopant in the electron-transporting layer (ETL) of organic light-emitting devices (OLEDs) owing to its low deposition temperature and high ambient stability. By doping cesium azide onto 4,7-diphenyl-1,10-phenanthroline, a green phosphorescent OLED having best efficiencies of 66.25 cd A −1 , 81.22 lm W −1 and 18.82% was realized. Moreover, the efficiency roll-off from 1000 cd m −2 to 10 000 cd m −2 is only 12.9%, which is comparable with or even lower than that of devices utilizing the co-host system. Physical mechanisms for the improvement of device performance were studied in depth by analyzing the current density–voltage ( J – V ) characteristics of the electron-only devices. In particular, by comparing the J – V characteristics of the electron-only devices instead of applying the complicated ultraviolet photoelectron spectrometer measurements, we deduced the decrease in barrier height for electron injection at the ETL/cathode contact. Finally, an efficient tandem white OLED utilizing the n-doped layer in the charge generation unit (CGU) was constructed. As far as we know, this is the first report on the application of this CGU for fabricating tandem white OLEDs. The emissions of the tandem device are all in the warm white region from 1213 cd m −2 to 10870 cd m −2 , as is beneficial to the lighting application. (paper)

  14. Highly Efficient White Organic Light Emitting Diodes Using New Blue Fluorescence Emitter.

    Science.gov (United States)

    Kim, Seungho; Kim, Beomjin; Lee, Jaehyun; Yu, Young-Jun; Park, Jongwook

    2015-07-01

    Two different emitting compounds, 1-[1,1';3',1"]Terphenyl-5'-yl-6-(10-[1,1';3',1"]terpheny-5'-yl- anthracen-9-yl)-pyrene (TP-AP-TP) and Poly-phenylene vinylene derivative (PDY 132) were used to white OLED device. By incorporating adjacent blue and yellow emitting layers in a multi-layered structure, highly efficient white emission has been attained. The device was fabricated with a hybrid configuration structure: ITO/PEDOT (40 nm)/PDY-132 (8-50 nm)/ NPB (10 nm)/TP-AP-TP (30 nm)/Alq3 (20 nm)/LiF (1 nm)/Al (200 nm). After fixing TP-AP-TP thickness of 30 nm by evaporation, PDY-132 thickness varied with 8, 15, 35, and 50 nm by spin coating in device. The luminance efficiency of the white devices at 10 mA/cm2 were 2.93 cd/A-6.55 cd/A. One of white devices showed 6.55 cd/A and white color of (0.290, 0.331).

  15. Prevention of the appearance of light-struck taste in white wine = Prevenzione della comparsa del gusto di luce nel vino bianco

    OpenAIRE

    Fracassetti, D.; Gabrielli, M.; Encinas, J.; Manara, M.; Pellegrino, L.; Tirelli, A.

    2016-01-01

    The light-struck taste is a defect of bottled white wine due to the light exposure and involving the riboflavin (RF), as a photosensitizer, and methionine. The reaction pathways lead to the formation of volatile sulfur compounds, methanethiol and dimethyldisulphide, conferring cabbage-like aromas. The development of this defect is limited at low RF concentrations. In this study, the yeast-mediated release of RF, RF degradation kinetics in model solution and white wine, and RF removal by using...

  16. Schrodinger cat state generation using a slow light

    International Nuclear Information System (INIS)

    Ham, B. S.; Kim, M. S.

    2003-01-01

    We show a practical application of giant Kerr nonlinearity to quantum information processing based on superposition of two distinct macroscopic states- Schrodinger cat state. The giant Kerr nonlinearity can be achieved by using electromagnetically induced transparency, in which light propagation should be slowed down so that a pi-phase shift can be easily obtained owing to increased interaction time.

  17. Caregiving Practice Patterns of Asian, Hispanic, and Non-Hispanic White American Family Caregivers of Older Adults Across Generations.

    Science.gov (United States)

    Miyawaki, Christina E

    2016-03-01

    This study is a cross-sectional investigation of caregiving practice patterns among Asian, Hispanic and non-Hispanic White American family caregivers of older adults across three immigrant generations. The 2009 California Health Interview Survey (CHIS) dataset was used, and 591 Asian, 989 Hispanic and 6537 non-Hispanic White American caregivers of older adults were selected. First, descriptive analyses of caregivers' characteristics, caregiving situations and practice patterns were examined by racial/ethnic groups and immigrant generations. Practice patterns measured were respite care use, hours and length of caregiving. Three hypotheses on caregiving patterns based on assimilation theory were tested and analyzed using logistic regression and generalized linear models by racial/ethnic groups and generations. Caregiving patterns of non-Hispanic White caregivers supported all three hypotheses regarding respite care use, caregiving hours and caregiving duration, showing less caregiving involvement in later generations. However, Asian and Hispanic counterparts showed mixed results. Third generation Asian and Hispanic caregivers used respite care the least and spent the most caregiving hours per week and had the longest caregiving duration compared to earlier generations. These caregiving patterns revealed underlying cultural values related to filial responsibility, even among later generations of caregivers of color. Findings suggest the importance of considering the cultural values of each racial/ethnic group regardless of generation when working with racially and ethnically diverse populations of family caregivers of older adults.

  18. White Light Emitting MZr4(PO4)6:Dy3+ (M = Ca, Sr, Ba) Phosphors for WLEDs.

    Science.gov (United States)

    Nair, Govind B; Dhoble, S J

    2017-03-01

    A series of MZr 4 (PO 4 ) 6 :Dy 3+ (M = Ca, Sr, Ba) phosphors were prepared by the solid state diffusion method. Confirmation of the phase formation and morphological studies were performed by X-ray powder diffraction (XRD) measurements and scanning electron microscopy, respectively. Photoluminescence (PL) properties of these phosphors were thoroughly analyzed and the characteristic emissions of Dy 3+ ions were found to arise from them at an excitation wavelength of 351 nm. The PL emission spectra of the three phosphors were analyzed and compared. The CIE chromaticity coordinates assured that the phosphors produced cool white-light emission and hence, they are potential candidates for UV excited white-LEDs (WLEDs). Graphical Abstract ᅟ.

  19. White emission from nano-structured top-emitting organic light-emitting diodes based on a blue emitting layer

    International Nuclear Information System (INIS)

    Hyun, Woo Jin; Park, Jung Jin; Park, O Ok; Im, Sang Hyuk; Chin, Byung Doo

    2013-01-01

    We demonstrated that white emission can be obtained from nano-structured top-emitting organic light-emitting diodes (TEOLEDs) based on a blue emitting layer (EML). The nano-structured TEOLEDs were fabricated on nano-patterned substrates, in which both optical micro-cavity and scattering effects occur simultaneously. Due to the combination of these two effects, the electroluminescence spectra of the nano-structured device with a blue EML exhibited not only blue but also yellow colours, which corresponded to the intrinsic emission of the EML and the resonant emission of the micro-cavity effect. Consequently, it was possible to produce white emission from nano-structured TEOLEDs without employing a multimode micro-cavity. The intrinsic emission wavelength can be varied by altering the dopant used for the EML. Furthermore, the emissive characteristics turned out to be strongly dependent on the nano-pattern sizes of the nano-structured devices. (paper)

  20. Effects of electron blocking and hole trapping of the red guest emitter materials on hybrid white organic light emitting diodes

    International Nuclear Information System (INIS)

    Hong, Lin-Ann; Vu, Hoang-Tuan; Juang, Fuh-Shyang; Lai, Yun-Jr; Yeh, Pei-Hsun; Tsai, Yu-Sheng

    2013-01-01

    Hybrid white organic light emitting diodes (HWOLEDs) with fluorescence and phosphorescence hybrid structures are studied in this work. HWOLEDs were fabricated with blue/red emitting layers: fluorescent host material doped with sky blue material, and bipolar phosphorescent host emitting material doped with red dopant material. An electron blocking layer is applied that provides hole red guest emitter hole trapping effects, increases the charge carrier injection quantity into the emitting layers and controls the recombination zone (RZ) that helps balance the device color. Spacer layers were also inserted to expand the RZ, increase efficiency and reduce energy quenching along with roll-off effects. The resulting high efficiency warm white OLED device has the lower highest occupied molecule orbital level red guest material, current efficiency of 15.9 cd/A at current density of 20 mA/cm 2 , and Commission Internationale de L'Eclairage coordinates of (0.34, 0.39)

  1. Phosphorescence white organic light-emitting diodes with single emitting layer based on isoquinolinefluorene-carbazole containing host.

    Science.gov (United States)

    Koo, Ja Ryong; Lee, Seok Jae; Hyung, Gun Woo; Kim, Bo Young; Shin, Hyun Su; Lee, Kum Hee; Yoon, Seung Soo; Kim, Woo Young; Kim, Young Kwan

    2013-03-01

    We have demonstrated a stable phosphorescent white organic light-emitting diodes (WOLEDs) using an orange emitter, Bis(5-benzoyl-2-(4-fluorophenyl)pyridinato-C,N) iridium(III)acetylacetonate [(Bz4Fppy)2Ir(III)acac] doped into a newly synthesized blue host material, 2-(carbazol-9-yl)-7-(isoquinolin-1-yl)-9,9-diethylfluorene (CzFliq). When 1 wt.% (Bz4Fppy)2Ir(III)acac was doped into emitting layer, it was realized an improved EL performance and a pure white color in the OLED. The optimum WOLED showed maximum values as a luminous efficiency of 10.14 cd/A, a power efficiency of 10.24 Im/W, a peak external quantum efficiency 4.07%, and Commission Internationale de L'Eclairage coordinates of (0.34, 0.39) at 8 V.

  2. Effects of electron blocking and hole trapping of the red guest emitter materials on hybrid white organic light emitting diodes

    Energy Technology Data Exchange (ETDEWEB)

    Hong, Lin-Ann; Vu, Hoang-Tuan [National Formosa University, Institute of Electro-Optical and Materials Science, Huwei, Yunlin County, Taiwan (China); Juang, Fuh-Shyang, E-mail: fsjuang@seed.net.tw [National Formosa University, Institute of Electro-Optical and Materials Science, Huwei, Yunlin County, Taiwan (China); Lai, Yun-Jr [National Formosa University, Institute of Electro-Optical and Materials Science, Huwei, Yunlin County, Taiwan (China); Yeh, Pei-Hsun [Raystar Optronics, Inc., 5F No. 25, Keya Rd. Daya Township, Taichung County, Taiwan (China); Tsai, Yu-Sheng [National Formosa University, Institute of Electro-Optical and Materials Science, Huwei, Yunlin County, Taiwan (China)

    2013-10-01

    Hybrid white organic light emitting diodes (HWOLEDs) with fluorescence and phosphorescence hybrid structures are studied in this work. HWOLEDs were fabricated with blue/red emitting layers: fluorescent host material doped with sky blue material, and bipolar phosphorescent host emitting material doped with red dopant material. An electron blocking layer is applied that provides hole red guest emitter hole trapping effects, increases the charge carrier injection quantity into the emitting layers and controls the recombination zone (RZ) that helps balance the device color. Spacer layers were also inserted to expand the RZ, increase efficiency and reduce energy quenching along with roll-off effects. The resulting high efficiency warm white OLED device has the lower highest occupied molecule orbital level red guest material, current efficiency of 15.9 cd/A at current density of 20 mA/cm{sup 2}, and Commission Internationale de L'Eclairage coordinates of (0.34, 0.39)

  3. Electrochemical characterization of Si in tetra-methyl ammonium hydroxide (TMAH) and TMAH:Triton-X-100 solutions under white light effects

    Science.gov (United States)

    Conway, Elizabeth M.; Cunnane, Vincent J.

    2002-03-01

    An experimental study of the electrochemical characteristics of the silicon/tetra-methyl ammonium hydroxide (TMAH) junction under dark and white light conditions are investigated for both n- and p-type Si. The presence of Triton-X-100 (TX100) in the TMAH solution under white light conditions is also studied. Cyclic voltammetry (CV) and ex situ atomic force microscopy (AFM) are employed to study the white light effects on the etching characteristics of silicon in TMAH and TMAH:TX100. It was found that the passivation peak potential shifted significantly for both n- and p-type Si under white light conditions. The positions of the flatband potential for n- and p-type Si were predicted by CV under illumination. Finally, etch rate studies and preliminary surface roughness measurements were performed on p(100) Si in TMAH under both dark and white light conditions. These latter studies concluded that a reduction in the vertical surface roughness occurred in the presence of white light.

  4. A novel orange emissive phosphor SrWO4:Sm3+ for white light-emitting diodes

    International Nuclear Information System (INIS)

    Ju Zhenghua; Wei Ruiping; Ma Jingxin; Pang Chaoran; Liu Weisheng

    2010-01-01

    Research highlights: → A novel orange emissive phosphor SrWO 4 :Sm 3+ was firstly reported. → The optics properties of Sm 3+ -doped SrWO 4 phosphor were successfully discussed. → The temperature-dependent luminescence indicates the phosphor exhibits a small thermal-quenching property. → The phosphor is a potential candidate as orange-emitting component for white LED. - Abstract: A novel orange emissive phosphor, Sm 3+ -doped SrWO 4 , was synthesized by high temperature solid-state reaction in air atmosphere. The excitation spectra show that the phosphors can be efficiently excited by ultraviolet and near-ultraviolet light, the optimized concentration is 4 mol%. Three emission peaks locate at 562, 596 and 642 nm, corresponding to CIE chromaticity coordinates of (x = 0.54, y = 0.46), which indicates the orange light emitting. The decay curves are well fitted with triple-exponential decay models. The quantum yield of the Sr 0.96 Sm 0.04 WO 4 phosphor is about 70.65% under excitation of 377 nm. Furthermore, the temperature-dependent luminescence indicates the phosphor exhibits a small thermal-quenching property. So the phosphor is able to be applied to UV-LED chip-based white light-emitting diodes.

  5. Application of exciplex in the fabrication of white organic light emitting devices with mixed fluorescent and phosphorescent layers

    Energy Technology Data Exchange (ETDEWEB)

    Yang, Dan; Duan, Yahui; Yang, Yongqiang [State Key Laboratory on Integrated Optoelectronics, College of Electronic Science & Engineering, Jilin University, Changchun 130012 (China); Hu, Nan [State Key Laboratory on Integrated Optoelectronics, College of Electronic Science & Engineering, Jilin University, Changchun 130012 (China); Changchun University of Science and Technology, Changchun 130012 (China); Wang, Xiao [State Key Laboratory on Integrated Optoelectronics, College of Electronic Science & Engineering, Jilin University, Changchun 130012 (China); Sun, Fengbo [State Key Laboratory on Integrated Optoelectronics, College of Electronic Science & Engineering, Jilin University, Changchun 130012 (China); Changchun University of Science and Technology, Changchun 130012 (China); Duan, Yu, E-mail: duanyu@jlu.edu.cn [State Key Laboratory on Integrated Optoelectronics, College of Electronic Science & Engineering, Jilin University, Changchun 130012 (China)

    2015-10-15

    In this study, a highly efficient fluorescent/phosphorescent white organic light-emitting device (WOLED) was fabricated using exciplex light emission. The hole-transport material 4,4',4''-tris(N-carbazolyl)triphenylamine (TCTA), and electron-transport material, 4,7-diphenyl-1,10-phenanthroline (Bphen), were mixed to afford a blue-emitting exciplex. The WOLED was fabricated with a yellow phosphorescent dye, Ir(III) bis(4-phenylthieno [3,2-c] pyridinato-N,C{sup 2'}) acetylacetonate (PO-01), combined with the exciplex. In this structure, the energy can be efficiently transferred from the blend layer to the yellow phosphorescent dye, thus improving the efficiency of the utilization of the triplet exciton. The maximum power efficiency of the WOLED reached a value 9.03 lm/W with an external quantum efficiency of 4.3%. The Commission Internationale de I'Eclairage (CIE) color coordinates (x,y) of the device were from (0.39, 0.45) to (0.27, 0.31), with a voltage range of 4–9 V. - Highlights: • An exciplex/phosphorescence hybrid white OLED was fabricated for the first time with blue/orange complementary emitters. • By using exciplex as the blue emitter, non-radiative triplet-states on the exciplex can be harvested for light-emission by transferring them to low triplet-state phosphors.

  6. Application of exciplex in the fabrication of white organic light emitting devices with mixed fluorescent and phosphorescent layers

    International Nuclear Information System (INIS)

    Yang, Dan; Duan, Yahui; Yang, Yongqiang; Hu, Nan; Wang, Xiao; Sun, Fengbo; Duan, Yu

    2015-01-01

    In this study, a highly efficient fluorescent/phosphorescent white organic light-emitting device (WOLED) was fabricated using exciplex light emission. The hole-transport material 4,4',4''-tris(N-carbazolyl)triphenylamine (TCTA), and electron-transport material, 4,7-diphenyl-1,10-phenanthroline (Bphen), were mixed to afford a blue-emitting exciplex. The WOLED was fabricated with a yellow phosphorescent dye, Ir(III) bis(4-phenylthieno [3,2-c] pyridinato-N,C 2' ) acetylacetonate (PO-01), combined with the exciplex. In this structure, the energy can be efficiently transferred from the blend layer to the yellow phosphorescent dye, thus improving the efficiency of the utilization of the triplet exciton. The maximum power efficiency of the WOLED reached a value 9.03 lm/W with an external quantum efficiency of 4.3%. The Commission Internationale de I'Eclairage (CIE) color coordinates (x,y) of the device were from (0.39, 0.45) to (0.27, 0.31), with a voltage range of 4–9 V. - Highlights: • An exciplex/phosphorescence hybrid white OLED was fabricated for the first time with blue/orange complementary emitters. • By using exciplex as the blue emitter, non-radiative triplet-states on the exciplex can be harvested for light-emission by transferring them to low triplet-state phosphors

  7. Efficient Color-Stable Inverted White Organic Light-Emitting Diodes with Outcoupling-Enhanced ZnO Layer.

    Science.gov (United States)

    Zhao, Xin-Dong; Li, Yan-Qing; Xiang, Heng-Yang; Zhang, Yi-Bo; Chen, Jing-De; Xu, Lu-Hai; Tang, Jian-Xin

    2017-01-25

    Inverted organic light-emitting diode (OLED) has attracted extensive attention due to the demand in active-matrix OLED display panels as its geometry enables the direct connection with n-channel transistor backplane on the substrate. One key challenge of high-performance inverted OLED is an efficient electron-injection layer with superior electrical and optical properties to match the indium tin oxide cathode on substrate. We here propose a synergistic electron-injection architecture using surface modification of ZnO layer to simultaneously promote electron injection into organic emitter and enhance out-coupling of waveguided light. An efficient inverted white OLED is realized by introducing the nanoimprinted aperiodic nanostructure of ZnO for broadband and angle-independent light out-coupling and inserting an n-type doped interlayer for energy level tuning and injection barrier lowering. As a result, the optimized inverted white OLEDs have an external quantum efficiency of 42.4% and a power efficiency of 85.4 lm W 1- , which are accompanied by the superiority of angular color stability over the visible wavelength range. Our results may inspire a promising approach to fabricate high-efficiency inverted OLEDs for large-scale display panels.

  8. Colours in black and white: the depiction of lightness and brightness in achromatic engravings before the invention of photography.

    Science.gov (United States)

    Zavagno, Daniele; Massironi, Manfredo

    2006-01-01

    What is it like to see the world in black and white? In the pioneer days of cinema, when movies displayed grey worlds, was it true that no 'colours' were actually seen? Did every object seen in those projections appear grey in the same way? The answer is obviously no--people in those glorious days were seeing a world full of light, shadows, and objects in which colours were expressed in terms of lightness. But the marvels of grey worlds have not always been so richly displayed. Before the invention of photography, the depiction of scenes in black-and-white had to face some technical and perceptual challenges. We have studied the technical and perceptual constraints that XV-XVIII century engravers had to face in order to translate actual colours into shades of grey. An indeterminacy principle is considered, according to which artists had to prefer the representation of some object or scene features over others (for example brightness over lightness). The reasons for this lay between the kind of grey scale technically available and the kind of information used in the construction of 3-D scenes. With the invention of photography, photomechanical reproductions, and new printing solutions, artists had at their disposal a continuous grey scale that greatly reduces the constraints of the indeterminacy principle.

  9. Hydrogen generator from light hydrocarbons for stationary applications

    International Nuclear Information System (INIS)

    Cipiti, F.; Recupero, Vincenzo; Pino, L.; Vita, A.; Lagana, M.

    2006-01-01

    The present article describes the activities carried out in the CNR institute, particularly the development, realization and testing of one unit of hydrogen generation to integrate with fuel-cells for residential applications [it

  10. On the efficient warm white-light emission from nano-sized Y{sub 2}O{sub 3}

    Energy Technology Data Exchange (ETDEWEB)

    Cesaria, M., E-mail: maura.cesaria@le.infn.it [Department of Mathematics and Physics “E. De Giorgi”, University of Salento, Lecce (Italy); Collins, J. [Wheaton College, Norton, MA (United States); Di Bartolo, B. [Department of Physics, Boston College, Chestnut Hill, MA (United States)

    2016-01-15

    We consider the reported emission of white light (WL) in the spectral range from 400 to beyond 900 nm induced by monochromatic infrared light (803.5 and 975 nm) continuous wave excitation of nominally un-doped yttrium oxide (Y{sub 2}O{sub 3}) nano-powders. Based on the experimental evidence, such an emission feature is a nano-scale phenomenon, resembles very closely the emission from an incandescent lamp (mimicking the sunlight, i.e., the most comfortable light to human eyes) and exhibits very high efficiency (864 lum/W) and nearly theoretical (i.e., 99) color rendering index. At the fundamental level, the origin of this phenomenon is still unexplained. In this paper we address the fundamental questions raised by the reported occurrence of WL emission from Y{sub 2}O{sub 3} nanopowders and attempt an interpretation at a more fundamental level. In particular we focus on the multiphoton-absorption and nonexponential decay patterns of the reported WL emission as starting points to formulate models and interpretations of the experimental occurrences still lacking in the literature. Our discussion invokes the electronic dispersion of Y{sub 2}O{sub 3} and nanoscale effects, which is supported by the experimental evidence according to which the observed warm WL emission is a nanoscale phenomenon with properties that only can be explained by nanoscale physics. - Highlights: • Emission of white light from 400 to beyond 900 nm induced by infrared light of un-doped Y{sub 2}O{sub 3} nano-powders. • The emission feature resembles very closely the emission from an incandescent lamp. • The observed emission properties only can be explained by nanoscale physics.

  11. Using Nonuniform Fiber to Generate Slow Light via SBS

    Directory of Open Access Journals (Sweden)

    Wenhai Li

    2008-01-01

    Full Text Available The data pulse delay based on slow light induced by stimulated Brillouin scattering (SBS in a nonuniform dispersion decreasing fiber (DDF is demonstrated experimentally, and the distortions of data pulses at different beat frequencies are studied. We found that a delay exceeding a pulse width can be achieved at particular beat frequency, and the DDF has larger delay versus gain slope coefficient with much better output pulse quality than single-mode fiber.

  12. Characterization of surface modifications by white light interferometry: applications in ion sputtering, laser ablation, and tribology experiments.

    Science.gov (United States)

    Baryshev, Sergey V; Erck, Robert A; Moore, Jerry F; Zinovev, Alexander V; Tripa, C Emil; Veryovkin, Igor V

    2013-02-27

    In materials science and engineering it is often necessary to obtain quantitative measurements of surface topography with micrometer lateral resolution. From the measured surface, 3D topographic maps can be subsequently analyzed using a variety of software packages to extract the information that is needed. In this article we describe how white light interferometry, and optical profilometry (OP) in general, combined with generic surface analysis software, can be used for materials science and engineering tasks. In this article, a number of applications of white light interferometry for investigation of surface modifications in mass spectrometry, and wear phenomena in tribology and lubrication are demonstrated. We characterize the products of the interaction of semiconductors and metals with energetic ions (sputtering), and laser irradiation (ablation), as well as ex situ measurements of wear of tribological test specimens. Specifically, we will discuss: i. Aspects of traditional ion sputtering-based mass spectrometry such as sputtering rates/yields measurements on Si and Cu and subsequent time-to-depth conversion. ii. Results of quantitative characterization of the interaction of femtosecond laser irradiation with a semiconductor surface. These results are important for applications such as ablation mass spectrometry, where the quantities of evaporated material can be studied and controlled via pulse duration and energy per pulse. Thus, by determining the crater geometry one can define depth and lateral resolution versus experimental setup conditions. iii. Measurements of surface roughness parameters in two dimensions, and quantitative measurements of the surface wear that occur as a result of friction and wear tests. Some inherent drawbacks, possible artifacts, and uncertainty assessments of the white light interferometry approach will be discussed and explained.

  13. Anthocyanin biosynthesis is differentially regulated by light in the skin and flesh of white-fleshed and teinturier grape berries.

    Science.gov (United States)

    Guan, Le; Dai, Zhanwu; Wu, Ben-Hong; Wu, Jing; Merlin, Isabelle; Hilbert, Ghislaine; Renaud, Christel; Gomès, Eric; Edwards, Everard; Li, Shao-Hua; Delrot, Serge

    2016-01-01

    Light exclusion reduces the concentration and modifies the composition of grape anthocyanins, by altering the expression of genes involved in anthocyanin biosynthesis and transport, in a cultivar- and tissue-specific manner. Unlike most grapes, teinturier grapes accumulate anthocyanins both in skin and flesh. However, the concentration and composition of anthocyanins in both tissues differ, providing a valuable system to study tissue-specific regulation of anthocyanin synthesis. Furthermore, little is known about the mechanisms controlling the sensitivity of anthocyanin accumulation to light. Here, light was excluded from Gamay (white-fleshed) and Gamay Fréaux (teinturier mutant) berries throughout berry development. Under light-exposed conditions, the skin of Gamay Fréaux accumulated the highest level of anthocyanins, followed by the skin of Gamay, while the pulp of Gamay Fréaux had much lower anthocyanins than the skins. Network analysis revealed the same order on the number of significant correlations among metabolites and transcripts in the three colored tissues, indicating a higher connectivity that reflects a higher efficiency of the anthocyanin pathway. Compared to light conditions, light exclusion reduced the total amount of anthocyanins, most severely in the skin of Gamay and to a lesser extent in the flesh and skin of Gamay Fréaux. Coordinated decrease in the transcript abundance of structural, regulatory and transporter genes by light exclusion correlated with the reduced anthocyanin concentration in a cultivar- and tissue-specific manner. Moreover, light exclusion increased the ratio of dihydroxylated to trihydroxylated anthocyanins, in parallel with F3'H and F3'5'H transcript amounts. Sugars and ABA only play a limited role in the control of anthocyanin synthesis in the berries, in contrast with what has been described in cell suspensions. This study provides novel insights into the regulation of anthocyanin in wild type and teinturier cultivars.

  14. White light emission and effect of annealing on the Ho3+–Yb3+ codoped BaCa2Al8O15 phosphor

    International Nuclear Information System (INIS)

    Kumari, Astha; Rai, Vineet Kumar

    2015-01-01

    Graphical abstract: The upconversion emission spectra of the Ho 3+ /Yb 3+ doped/codoped BaCa 2 Al 8 O 15 phosphors with different doping concentrations of Ho 3+ /Yb 3+ ions along with UC emission spectrum of the white light emitting phosphor annealed at 800 °C. - Highlights: • BaCa 2 Al 8 O 15 phosphors codoped with Ho 3+ –Yb 3+ have been prepared by combustion method. • Phosphor annealed at 800 °C, illuminate an intense white light upon NIR excitation. • The sample annealed at higher temperatures emits in the pure green region. • The colour emitted persists in the white region even at high pump power density. • Developed phosphor is suitable for making upconverters and WLEDs. - Abstract: The BaCa 2 Al 8 O 15 (BCAO) phosphors codoped with suitable Ho 3+ –Yb 3+ dopant concentration prepared by combustion method illuminate an intense white light upon near infrared diode laser excitation. The structural analysis of the phosphors and the detection of impurity contents have been performed by using the X-Ray Diffraction, FESEM and FTIR analysis. The purity of white light emitted from the sample has been confirmed by the CIE chromaticity diagram. Also, the white light emitted from the sample persists with the variation of pump power density. The phosphors emit upconversion (UC) emission bands in the blue, green and red region (three primary colours required for white light emission) along with one more band in the near infrared region of the electromagnetic spectrum. On annealing the white light emitting sample at higher temperatures, the sample starts to emit green colour and also the intensity of green and red UC emission bands get enhanced largely.

  15. Extreme sensitivity to ultraviolet light in the fungal pathogen causing white-nose syndrome of bats

    Science.gov (United States)

    Jonathan M. Palmer; Kevin P. Drees; Jeffrey T. Foster; Daniel L. Lindner

    2018-01-01

    Bat white-nose syndrome (WNS), caused by the fungal pathogen Pseudogymnoascus destructans, has decimated North American hibernating bats since its emergence in 2006. Here, we utilize comparative genomics to examine the evolutionary history of this pathogen in comparison to six closely related nonpathogenic species....

  16. Unusual near-white electroluminescence of light emitting diodes based on saddle-shaped porphyrins.

    Science.gov (United States)

    Shahroosvand, Hashem; Zakavi, Saeed; Sousaraei, Ahmad; Mohajerani, Ezeddin; Mahmoudi, Malek

    2015-05-14

    In contrast to the red electroluminescence emission frequently observed in porphyrins based OLED devices, the present devices exhibit a nearly white emission with greenish yellow, yellowish green and blue green hues in the case of Fe(II)(TCPPBr6) (TCPPBr6 = β-hexabromo-meso-tetrakis-(4-phenyl carboxyl) porphyrinato), Zn(II)(TPPBr6) and Co(II)(TPPBr6), respectively.

  17. Liquid Phase Epitaxial Growth of Al-doped f-SiC for White Light-Emitting Diodes

    DEFF Research Database (Denmark)

    Tang, Kai; Ma, Xiang; can der Eijk, Casper

    efficiency, better light quality and longer lifespan, compared to the current yellow phosphor based white LEDs.Liquid phase epitaxy technology can yield a high crystalline quality in terms of structural perfection owing to the fact that it is a near equilibrium crystalline growth process. In addition....... The experimental results are presented and discussed. Since operational temperature of LPE growth is much lower than that currently used in physical vapour transport (PVT) process, it is expected to save the energy consumption for SiC crystal growth....

  18. An optical and electrical study of full thermally activated delayed fluorescent white organic light-emitting diodes

    OpenAIRE

    Pereira, Daniel de Sa; dos Santos, Paloma L.; Ward, Jonathan S.; Data, Przemyslaw; Okazaki, Masato; Takeda, Youhei; Minakata, Satoshi; Bryce, Martin R.; Monkman, Andrew P.

    2017-01-01

    We report on the engineering of full thermally activated delayed fluorescence – based white organic light emitting diodes (W-OLEDs) composed of three emitters (2,7-bis(9,9-dimethyl-acridin-10-yl)-9,9-dimethylthioxanthene-S,S-dioxide (DDMA-TXO2), 2,7-bis(phenoxazin-10-yl)-9,9-dimethylthioxanthene-S,S-dioxide (DPO-TXO2) and 3,11-di(10H-phenoxazin-10-yl)dibenzo[a,j]phenazine (POZ-DBPHZ) in two different hosts. By controlling the device design through the study of the emission of DDMA-TXO2 and DP...

  19. Interaction between a dark spot and a two-dimensional nonlinear photonic lattice with fully incoherent white light

    International Nuclear Information System (INIS)

    Liu, Zhaohong; Liu, Simin; Guo, Ru; Song, Tao; Zhu, Nan

    2007-01-01

    We study experimentally the interaction of a dark spot with a nonlinear photonic lattice with fully incoherent white light emitted from an incandescent bulb in the self-defocussing photovoltaic media when the dark spot is aimed at different positions of lattices with different lattice spacing. In this case a host of novel phenomena is demonstrated, including dark spot induced lattice dislocation-deformation, the annihilation of the dark spot and so on. Results demonstrate that the interaction between incoherent dark spot and photonic lattice is always attraction and the large-spacing photonic lattice is analogous to the continuous medium

  20. Teager-Kaiser Energy and Higher-Order Operators in White-Light Interference Microscopy for Surface Shape Measurement

    Directory of Open Access Journals (Sweden)

    Abdel-Ouahab Boudraa

    2005-10-01

    Full Text Available In white-light interference microscopy, measurement of surface shape generally requires peak extraction of the fringe function envelope. In this paper the Teager-Kaiser energy and higher-order energy operators are proposed for efficient extraction of the fringe envelope. These energy operators are compared in terms of precision, robustness to noise, and subsampling. Flexible energy operators, depending on order and lag parameters, can be obtained. Results show that smoothing and interpolation of envelope approximation using spline model performs better than Gaussian-based approach.