Picosecond and subpicosecond pulsed laser deposition of Pb thin films

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F. Gontad

2013-09-01

Full Text Available Pb thin films were deposited on Nb substrates by means of pulsed laser deposition (PLD with UV radiation (248 nm, in two different ablation regimes: picosecond (5 ps and subpicosecond (0.5 ps. Granular films with grain size on the micron scale have been obtained, with no evidence of large droplet formation. All films presented a polycrystalline character with preferential orientation along the (111 crystalline planes. A maximum quantum efficiency (QE of 7.3×10^{-5} (at 266 nm and 7 ns pulse duration was measured, after laser cleaning, demonstrating good photoemission performance for Pb thin films deposited by ultrashort PLD. Moreover, Pb thin film photocathodes have maintained their QE for days, providing excellent chemical stability and durability. These results suggest that Pb thin films deposited on Nb by ultrashort PLD are a noteworthy alternative for the fabrication of photocathodes for superconductive radio-frequency electron guns. Finally, a comparison with the characteristics of Pb films prepared by ns PLD is illustrated and discussed.

Epitaxial growth of metallic buffer layer structure and c-axis oriented Pb(Mn1/3,Nb2/3)O3-Pb(Zr,Ti)O3 thin film on Si for high performance piezoelectric micromachined ultrasonic transducer

Science.gov (United States)

Thao, Pham Ngoc; Yoshida, Shinya; Tanaka, Shuji

2017-12-01

This paper reports on the development of a metallic buffer layer structure, (100) SrRuO3 (SRO)/(100) Pt/(100) Ir/(100) yttria-stabilized zirconia (YSZ) layers for the epitaxial growth of a c-axis oriented Pb(Mn1/3,Nb2/3)O3-Pb(Zr,Ti)O3 (PMnN-PZT) thin film on a (100) Si wafer for piezoelectric micro-electro mechanical systems (MEMS) application. The stacking layers were epitaxially grown on a Si substrate under the optimal deposition condition. A crack-free PMnN-PZT epitaxial thin films was obtained at a thickness up to at least 1.7 µm, which is enough for MEMS applications. The unimorph MEMS cantilevers based on the PMnN-PZT thin film were fabricated and characterized. As a result, the PMnN-PZT thin film exhibited -10 to -12 C/m2 as a piezoelectric coefficient e 31,f and ˜250 as a dielectric constants ɛr. The resultant FOM for piezoelectric micromachined ultrasonic transducer (pMUT) is higher than those of general PZT and AlN thin films. This structure has a potential to provide high-performance pMUTs.

Fatigue-resistant epitaxial Pb(Zr,Ti)O3 capacitors on Pt electrode with ultra-thin SrTiO3 template layers

International Nuclear Information System (INIS)

Takahara, Seiichi; Morimoto, Akiharu; Kawae, Takeshi; Kumeda, Minoru; Yamada, Satoru; Ohtsubo, Shigeru; Yonezawa, Yasuto

2008-01-01

Lead zirconate-titanate Pb(Zr,Ti)O 3 (PZT) capacitors with Pt bottom electrodes were prepared on MgO substrates by pulsed laser deposition (PLD) technique employing SrTiO 3 (STO) template layer. Perovskite PZT thin films are prepared via stoichiometric target using the ultra-thin STO template layers while it is quite difficult to obtain the perovskite PZT on Pt electrode via stoichiometric target in PLD process. The PZT capacitor prepared with the STO template layer showed good hysteresis and leakage current characteristics, and it showed an excellent fatigue resistance. The ultra-thin STO template layers were characterized by angle-resolved X-ray photoelectron spectroscopy measurement. The effect of the STO template layer is discussed based on the viewpoint of the perovskite nucleation and diffusion of Pb and O atoms

Investigation on thermal evaporated CH3NH3PbI3 thin films

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Youzhen Li

2015-09-01

Full Text Available CH3NH3I, PbI2 and CH3NH3PbI3 films were fabricated by evaporation and characterized with X-ray Photoelectron Spectroscopy (XPS and X-ray diffraction (XRD. The XPS results indicate that the PbI2 and CH3NH3PbI3 films are more uniform and stable than the CH3NH3I film. The atomic ratio of the CH3NH3I, PbI2 and CH3NH3PbI3 films are C:N:I=1.00:1.01:0.70, Pb:I= 1.00:1.91 and C: N: Pb: I = 1.29:1.07:1.00:2.94, respectively. The atomic ratio of CH3NH3PbI3 is very close to that of the ideal perovskite. Small angle x-ray diffraction results demonstrate that the as evaporated CH3NH3PbI3 film is crystalline. The valence band maximum (VBM and work function (WF of the CH3NH3PbI3 film are about 0.85eV and 4.86eV, respectively.

Structural characterization of PbTi03, Sm0.6Nd0.4NiO3 and NdMnO3 multifunctional Perovskite thin films

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Rapenne L.

2012-06-01

Full Text Available Different multifunctional (PbTiO3, Sm0.6Nd0.4NiO3, NdMnO3 thin films were grown by metalorganic chemical vapor deposition (MOCVD technique on SrTiO3 and LaAlO3 substrates. TEM and X-ray diffraction measurements reveal that almost single crystalline thin films can be epitaxially grown on the top of substrates. The relationship between the crystallographic orientation of the films and those of the substrates were determined by reciprocal space mapping and TEM analyses. PbTi03 thin films appear to be under tensile or compressive strain according to the different mismatch of their cell parameter with those of the substrate. Relaxation mechanism as a function of the film thickness arises from coexistence of different type of domains and size and strain effect are analyzed. SmNiO3 thin films present diffuse scattering strikes and are less well organized when compared to PbTi03 thin films. Different domains are observed as well as an additional parasitic phase close to NiO. Its regular distribution can be associated to reduced transport properties. Preliminary observations on NdMnO3 thin films show that an amorphous phase is obtained during MOCVD that can be transformed in a single crystalline film by annealing. The films are under tensile or compressive strain according to the different mismatch of their cell parameter with those of the substrate. Magnetic properties are investigated.

Optical properties of PbS thin films

Energy Technology Data Exchange (ETDEWEB)

Akhmedov, O. R., E-mail: orucahmedov@mail.ru; Guseinaliyev, M. G. [National Academy of Azerbaijan, Nakhichevan Branch (Azerbaijan); Abdullaev, N. A.; Abdullaev, N. M.; Babaev, S. S.; Kasumov, N. A. [National Academy of Sciences of Azerbaijan, Abdullaev Institute of Physics (Azerbaijan)

2016-01-15

The complex dielectric function of PbS thin films is studied by spectroscopic ellipsometry in the spectral range from 0.74 to 6.45 eV at a temperature of 293 K. The critical energies are determined to be E{sub 1} = 3.53 eV and E{sub 2} = 4.57 eV. For both energy regions, the best fit is attained at the critical point 2D (m = 0). In addition, the Raman spectra and the optical-absorption spectra of PbS thin films are studied. From the dependence of the quantity (αhν){sup 2} on the photon energy hν, the band gap is established at E{sub g} = 0.37 eV.

Antisolvent-assisted powder engineering for controlled growth of hybrid CH3NH3PbI3 perovskite thin films

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Yong Chan Choi

2017-02-01

Full Text Available We develop antisolvent-assisted powder engineering for the controlled growth of hybrid inorganic-organic CH3NH3PbI3 (MAPbI3 perovskite thin films. The powders, which are used as the precursors for solution processing, are synthesized by pouring a MAPbI3 precursor solution into various antisolvents, such as dichloromethane, chloroform, diethyl ether, and toluene. Two types of powders having different colors are obtained, depending on the antisolvent used. The choice of the antisolvent used for synthesizing the powders strongly influences not only the phases of the powders but also the morphology and structure of the thin films subsequently fabricated by solution processing. This, in turn, affects the photovoltaic performance.

Synthesis and characterization of a-site doped LaTiO3 nano perovskites

International Nuclear Information System (INIS)

Bradha, M.; Ashok, Anuradha

2013-01-01

Nano-sized lanthanum titanate perovskites (La (1-x) A x TiO 3 ) (A= Ba, Sr, Ca) were prepared by sol-gel method and calcined at 800℃. The synthesised perovskites were characterized by Thermogravimetry/ Differential thermal analysis (TGA/DTA), X-ray diffraction (XRD) and High Resolution Transmission Electron Microscopy (HRTEM) etc. LaTiO 3 is a perovskite having prominent interest for a variety of applications such as dielectric, insulators, charge-transport properties etc. It is a defect perovskite, with transport properties varying from insulating to metallic based on oxygen stoichiometry. In a quest to observe the effect of the nano size on its properties, lanthanum titanate (LaTiO 3 ) nano perovskites with different dopants on the A-site were prepared by using sol-gel method. In the present work we discuss the synthesis and structural analysis of (La 0.8 A 0.2 TiO 3 ). Phase purity and structural analysis of the calcined samples were performed by powder X-ray diffraction (XRD, with CuKα radiation). In addition to this, morphology and crystal structure was examined by Transmission Electron Microscopy (TEM) using a JEOL JEM 2100 HRTEM. HRTEM studies indicate that the nano perovskites are of size around 20 nm. Ring pattern in SAED also confirms that the perovskite is polycrystalline/nanocrystalline. More detailed study on high resolution images and crystal structure shed light on the reason for the properties exhibited by this perovskites

Structure-property relations in sputter deposited epitaxial (1-x)Pb(Mg1/3Nb2/3)O3- xPbTiO3 thin films

Science.gov (United States)

Frederick, Joshua C.

Lead-based ferroelectric materials are of significant technological importance for sensing and actuation due to their high piezoelectric performance (i.e., the ability to convert an electrical signal to mechanical displacement, and vice versa). Traditionally, bulk ceramic or single crystals materials have filled these roles; however, emerging technologies stand to benefit by incorporating thin films to achieve miniaturization while maintaining high efficiency and sensitivity. Currently, chemical systems that have been well characterized in bulk form (e.g. Pb(Mg1/3Nb2/3)O3- xPbTiO3, or PMN-xPT) require further study to optimize both the chemistry and structure for deployment in thin film devices. Furthermore, the effect of internal electric fields is more significant at the length scales of thin films, resulting in self biases that require compensation to reveal their intrinsic dielectric response. To this end, the structure-property relations of epitaxial PMN-xPT films sputter deposited on a variety of substrates were investigated. Attention was paid to how the structure (i.e., strain state, crystal structure, domain configuration, and defects) gave rise to the ferroelectric, dielectric, and piezoelectric response. Three-dimensional visualization of the dielectric response as a simultaneous function of electric field and temperature revealed the true phase transition of the films, which was found to correspond to the strain state and defect concentration. A lead-buffered anneal process was implemented to enhance the ferroelectric and dielectric response of the films without altering their stoichiometry. It was discovered that PMN- xPT films could be domain-engineered to exhibit a mixed domain state through chemistry and substrate choice. Such films exhibited a monoclinic distortion similar to that of the bulk compositions near the morphotropic phase boundary. Finally, it was revealed that the piezoelectric response could be greatly enhanced by declamping the film

XPS-and-DFT analyses of the Pb 4f — Zn 3s and Pb 5d — O 2s overlapped ambiguity contributions to the final electronic structure of bulk and thin-film Pb-modulated zincite

Energy Technology Data Exchange (ETDEWEB)

Zatsepin, D.A. [M.N. Miheev Institute of Metal Physics of Ural Branch of Russian Academy of Sciences, 620990 Yekaterinburg (Russian Federation); Institute of Physics and Technology, Ural Federal University, 620002 Yekaterinburg (Russian Federation); Boukhvalov, D.W., E-mail: danil@hanyang.ac.kr [Department of Chemistry, Hanyang University, 17 Haengdang-dong, Seongdong-gu, Seoul 133-791 (Korea, Republic of); Theoretical Physics and Applied Mathematics Department, Ural Federal University,Mira Street 19, 620002 Yekaterinburg (Russian Federation); Gavrilov, N.V. [Institute of Electrophysics, Russian Academy of Sciences, Ural Branch, 620990 Yekaterinburg (Russian Federation); Kurmaev, E.Z. [M.N. Miheev Institute of Metal Physics of Ural Branch of Russian Academy of Sciences, 620990 Yekaterinburg (Russian Federation); Institute of Physics and Technology, Ural Federal University, 620002 Yekaterinburg (Russian Federation); Zatsepin, A.F. [Institute of Physics and Technology, Ural Federal University, 620002 Yekaterinburg (Russian Federation); Cui, L. [Shenzhen Graduate School, Harbin Institute of Technology, Shenzhen 518055 (China); Shur, V. Ya.; Esin, A.A. [Institute of Natural Sciences, Ural Federal University, 51 Lenin Ave, 620000 Yekaterinburg (Russian Federation)

2017-05-31

Highlights: • Two modes of ZnO:Pb in the bulk and surface morphologies were established: the high- and low-interaction. • It was shown the ambiguity contribution of Pb 4f − Zn 3s and Pb 5d − O 2s states into final electronic structure. • The main type of defects is PbO-like with some PbO{sub 2}-like contributions. • An applied wurzite-like structural model well agrees with experimental data obtained for zincite. - Abstract: The electronic structures of zincite Pb-modulated bulk and thin-films were studied via X-ray photoelectron spectroscopy (XPS) and density functional theory (DFT) techniques. Both XPS data and DFT-calculations allowed the derivation of two different Pb-embedding scenarios into the ZnO-hosts. These included the high-interaction mode of Pb-impurity with initial zinc-oxygen host-lattice for the bulk morphology, accompanied with low Pb-metal losses; and the low-interaction mode for thin-films, where there was intake of Pb-impurities into the hollows of the surface. Despite dissimilar mechanisms of Pb-impurity accumulation and distribution in the bulk and thin-films zincite host-matrices, the strong Pb 4f — Zn 3s and Pb 5d — O 2s overlapped ambiguity contribution to the appropriate core-level structure and valence bands was established by XPS analysis and reproduced with the help of DFT-calculations. It was shown that the microscopic structure of the embedded lead-impurity played a crucial role in the Pb ion-beam stimulated synthesis of secondary lead-oxygen phases via large-area defect fabrication, and the difference among zincite and wurzite polymorphs played almost no role in this case.

Perovskite oxynitride LaTiOxNy thin films: Dielectric characterization in low and high frequencies

International Nuclear Information System (INIS)

Lu, Y.; Ziani, A.; Le Paven-Thivet, C.; Benzerga, R.; Le Gendre, L.; Fasquelle, D.; Kassem, H.

2011-01-01

Lanthanum titanium oxynitride (LaTiO x N y ) thin films are studied with respect to their dielectric properties in low and high frequencies. Thin films are deposited by radio frequency magnetron sputtering on different substrates. Effects of nitrogen content and crystalline quality on dielectric properties are investigated. In low-frequency range, textured LaTiO x N y thin films deposited on conductive single crystal Nb–STO show a dielectric constant ε′ ≈ 140 with low losses tanδ = 0.012 at 100 kHz. For the LaTiO x N y polycrystalline films deposited on conductive silicon substrates with platinum (Pt/Ti/SiO 2 /Si), the tunability reached up to 57% for a weak electric field of 50 kV/cm. In high-frequency range, epitaxial LaTiO x N y films deposited on MgO substrate present a high dielectric constant with low losses (ε′ ≈ 170, tanδ = 0.011, 12 GHz).

Pb(Zr,TiO3 (PZT Thin Film Sensors for Fully-Integrated, Passive Telemetric Transponders

Directory of Open Access Journals (Sweden)

Richard X. FU

2011-04-01

Full Text Available The great potential of taking advantages of PZT in a single chip to achieve inexpensive, fully-integrated, passive telemetric transponders has been shown in this paper. The processes for the sputter deposition of Pb(Zr,TiO3 (PZT thin films from two different composite targets on both Si and c-plane sapphire substrates have been demonstrated. PZT thin films have been deposited by sputter technique. PZT films were deposited onto substrates (Si [(100 Cz wafer] and c-plane sapphire (0001//Ti//Pt followed by sputter-deposited Pt top electrodes. X-ray diffraction results showed that both sputtered PZT films were textured along the [110] direction. The degree of preference for the [110] direction was greater on sapphire substrate where the intensity of that peak is seen to be larger compared to the intensity one Si substrate. TEM data revealed that both sputtered PZT films were polycrystalline in nature. Selected area diffraction (SAD pattern showed that the degree of disorientation between the crystallites was smaller on sapphire substrate compared to on Si substrate, which confirmed the results from the XRD. The remnant polarization Pr on sapphire substrate was larger than on Si’s. The leakage current for the 11 % Pb target sputtered film was much less than 22 % Pb target sputtered film. The breakdown voltage on sapphire substrate was the best. However, for the 11 % Pb target sputtered film’s breakdown voltage was much higher than 22 % Pb target sputtered film.

Preparation of Pb(Zr, Ti)O3 Thin Films by Plasma-Assisted Sputtering

Science.gov (United States)

Hioki, Tsuyoshi; Akiyama, Masahiko; Ueda, Tomomasa; Onozuka, Yutaka; Suzuki, Kouji

1999-09-01

A novel plasma-assisted RF magnetron sputtering system with an immersed coil antenna between a target and a substrate was applied for preparing Pb(Zr, Ti)O3 (PZT) thin films. The antenna enabled the generation of inductively coupled plasma (ICP) independently of the target RF source. The plasma assisted by the antenna resulted in the changes of ion fluxes and these energy distributions irradiating to the substrate. The crystalline phase of the deposited PZT thin films was occupied by the perovskite phase depending on the antenna power. In addition, a high deposition rate, modified uniformity of film thickness, and a dense film structure with large columnar grains were obtained as a result of effects of the assisted plasma. The application of the plasma-assisted sputtering method may enable the preparation of PZT thin films that haveexcellent properties.

Tuning structure in epitaxial Pb(Mg{sub 1/3}Nb{sub 2/3})O{sub 3}–PbTiO{sub 3} thin films by using miscut substrates

Energy Technology Data Exchange (ETDEWEB)

Mietschke, M., E-mail: m.mietschke@ifw-dresden.de [IFW Dresden, P.O. Box 270116, D-01171 Dresden (Germany); Dresden University of Technology, Faculty of Mechanical Science and Engineering, D-01062 Dresden (Germany); Oswald, S.; Fähler, S. [IFW Dresden, P.O. Box 270116, D-01171 Dresden (Germany); Schultz, L. [IFW Dresden, P.O. Box 270116, D-01171 Dresden (Germany); Dresden University of Technology, Faculty of Mechanical Science and Engineering, D-01062 Dresden (Germany); Hühne, R. [IFW Dresden, P.O. Box 270116, D-01171 Dresden (Germany)

2015-08-31

Pb(Mg{sub 1/3}Nb{sub 2/3})O{sub 3}–PbTiO{sub 3} (PMN–PT) is one of the most promising ferroelectric material for actuator, dielectric and electrocaloric applications. However, oriented and phase pure thin films are essential to use the outstanding properties of these compounds. In this work it is demonstrated that the use of miscut substrates influences the growth mechanism leading to a significantly broader deposition window to achieve the required film quality. Therefore, epitaxial 0.68Pb(Mg{sub 1/3}Nb{sub 2/3})O{sub 3}–0.32PbTiO{sub 3} films were grown by pulsed laser deposition on (001)-oriented single crystalline SrTiO{sub 3} (STO) substrates with a miscut angle between 0 and 15° towards the [100] direction using a conducting La{sub 0.7}Sr{sub 0.3}CoO{sub 3} buffer layer. The influence of the vicinal angle on the PMN–PT structure was studied by high resolution X-ray diffraction, X-ray photoelectron spectroscopy and transmission electron microscopy. A nearly pure perovskite phase growth with a cube-on-cube epitaxial relationship was obtained on all miscut STO substrates, whereas a significant volume fraction of the pyrochlore phase was present on the standard substrate. Reciprocal space measurements revealed a peak split of the perovskite reflections indicating structural variants of PMN–PT with different c/a ratios. An additional tilting of the PMN–PT planes with respect to the buffer layer was observed on some samples, which might be explained with the incorporation of dislocations according to the Nagai model. Polarization loops were measured in a temperature range between room temperature and 150 °C showing a sharp drop of the remanent polarization above 65 °C on vicinal substrates. - Highlights: • Epitaxial growth of pure perovskite Pb (Mg{sub 1}/{sub 3}Nb{sub 2}/{sub 3})O{sub 3}–PbTiO{sub 3} on miscut SrTiO{sub 3}. • Significant broadening of the deposition window for pyrochlore-free films. • Dependence of the structural parameters

A microfluidic approach to water-rock interactions using thin rock sections: Pb and U sorption onto thin shale and granite sections

Energy Technology Data Exchange (ETDEWEB)

Oh, Youn Soo [Institute of Mine Reclamation Technology, Mine Reclamation Corp., 2 Segye-ro, Wonju-si, Gangwon-do, 26464 (Korea, Republic of); Jo, Ho Young, E-mail: hyjo@korea.ac.kr [Department of Earth and Environmental Sciences, Korea University, Anam-dong, Seongbuk-gu, Seoul, 02841 (Korea, Republic of); Ryu, Ji-Hun; Kim, Geon-Young [Korea Atomic Energy Research Institute, 1045 Daedeokdaero, Yuseong-gu, Daejeon, 34057 (Korea, Republic of)

2017-02-15

Highlights: • Microfluidic tests was used to investigate water-rock (mineral) interactions. • Pb and U sorption onto thin shale and granite sections was evaluated. • Pb removal by thin shale section is related primarily to Fe-containing minerals. • A slightly larger amount of U was removed onto the thin granite section with Fe-containing minerals. - Abstract: The feasibility of using microfluidic tests to investigate water-rock (mineral) interactions in fractures regarding sorption onto thin rock sections (i.e., shale and granite) of lead (Pb) and uranium (U) was evaluated using a synthetic PbCl{sub 2} solution and uranium-containing natural groundwater as fluids. Effluent composition and element distribution on the thin rock sections before and after microfluidic testing were analyzed. Most Pb removal (9.8 mg/cm{sup 2}) occurred within 3.5 h (140 PVF), which was 74% of the total Pb removal (13.2 mg/cm{sup 2}) at the end of testing (14.5 h, 560 PVF). Element composition on the thin shale sections determined by μ-XRF analysis indicated that Pb removal was related primarily to Fe-containing minerals (e.g., pyrite). Two thin granite sections (biotite rich, Bt-R and biotite poor, Bt-P) exhibited no marked difference in uranium removal capacity, but a slightly higher amount of uranium was removed onto the thin Bt-R section (266 μg/cm{sup 2}) than the thin Bt-P section (240 μg/cm{sup 2}) within 120 h (4800 PVF). However, uranium could not be detected by micro X-ray fluorescence (μ-XRF) analysis, likely due to the detection limit. These results suggest that microfluidic testing on thin rock sections enables quantitative evaluation of rock (mineral)-water interactions at the micro-fracture or pore scale.

Enhanced polarization and dielectric properties of Pb(Zr1-xTix)O3 thin films

Science.gov (United States)

Ortega, N.; Kumar, Ashok; Katiyar, R. S.

2008-10-01

We report the fabrication of PbZr0.57Ti0.43O3 (PZT) thin films with preferential growth along (111) and random crystalline orientation on the platinized silicon substrates using pulsed laser deposition technique. X-ray diffraction patterns and surface morphology indicate increase in grain size and nucleation, which support better perovskite matrix with increase in annealing temperature. We observed large dielectric constant (˜4000) and enhanced remanent polarization 70 μC/cm2 at room temperature attributed to grain growth and intermetallic Pt-Pb transient phase. Frequency dependent polarization showed minor reduction in polarization above 10 kHz frequencies. Normalized fatigue characteristic of PZT thin films showed minimal 25% degradation in remanent polarization after 109 cycles, which may be useful for memory devices. ac conductivity spectra illustrated that anomaly near the phase transition temperature with activation energy (Ea˜0.60-0.75 eV) supports the intrinsic nature of ferroelectric phase transition.

Misfit strain dependence of ferroelectric and piezoelectric properties of clamped (001) epitaxial Pb(Zr0.52,Ti0.48)O3 thin films

Science.gov (United States)

Nguyen, Minh D.; Dekkers, Matthijn; Houwman, Evert; Steenwelle, Ruud; Wan, Xin; Roelofs, Andreas; Schmitz-Kempen, Thorsten; Rijnders, Guus

2011-12-01

A study on the effects of the residual strain in Pb(Zr0.52Ti0.48)O3 (PZT) thin films on the ferroelectric and piezoelectric properties is presented. Epitaxial (001)-oriented PZT thin film capacitors are sandwiched between SrRuO3 electrodes. The thin film stacks are grown on different substrate-buffer-layer combinations by pulsed laser deposition. Compressive or tensile strain caused by the difference in thermal expansion of the PZT film and substrate influences the ferroelectric and piezoelectric properties. All the PZT stacks show ferroelectric and piezoelectric behavior that is consistent with the theoretical model for strained thin films in the ferroelectric r-phase. We conclude that clamped (001) oriented Pb(Zr0.52Ti0.48)O3 thin films strained by the substrate always show rotation of the polarization vector.

Highly polarized single-c-domain single-crystal Pb(Mn,Nb)O(3)-PZT thin films.

Science.gov (United States)

Wasa, Kiyotaka; Adachi, Hideaki; Nishida, Ken; Yamamoto, Takashi; Matsushima, Tomoaki; Kanno, Isaku; Kotera, Hidetoshi

2012-01-01

In-plane unstrained single-c-domain/single-crystal thin films of PZT-based ternary ferroelectric perovskite, ξPb(Mn,Nb)O3-(1 - ξ)PZT, were grown on SrRuO(3)/Pt/MgO substrates using magnetron sputtering followed by quenching. The sputtered unstrained thin films exhibit unique ferroelectric properties: high coercive field, Ec > 180 kV/cm, large remanent polarization, P(r) = 100 μC/cm(2), small relative dielectric constants, ε* = 100 to 150, high Curie temperature, Tc = ~600 °C, and bulk-like large transverse piezoelectric constants, e31,f = -12.0 C/m(2) for PZT(48/52) at ξ = 0.06. The unstrained thin films are an ideal structure to extract the bulk ferroelectric properties. Their micro-structures and ferroelectric properties are discussed in relation to the potential applications for piezoelectric MEMS. © 2012 IEEE

Ab initio calculations of PbTiO{sub 3}/SrTiO{sub 3} (001) heterostructures

Energy Technology Data Exchange (ETDEWEB)

Eglitis, R.I.; Piskunov, S.; Zhukovskii, Yu.F. [Institute of Solid State Physics, University of Latvia, 8 Kengaraga Str., 1063 Riga (Latvia)

2016-12-15

We performed ab initio calculations for the PbTiO{sub 3}/SrTiO{sub 3} (001) heterostructures. For both PbO and TiO{sub 2}-terminations of the PbTiO{sub 3} (001) thin film, augmented on the SrTiO{sub 3} (001) substrate, the magnitudes of atomic relaxations Δz increases as a function of the number of augmented monolayers. For both terminations of the augmented PbTiO{sub 3} (001) nanothin film, all upper, third and fifth monolayers are displaced inwards (Δz is negative), whereas all second, fourth and sixth monolayers are displaced outwards (Δz is positive). The B3PW calculated PbTiO{sub 3}/SrTiO{sub 3} (001) heterostructure band gaps, independently from the number of augmented layers, are always smaller than the PbTiO{sub 3} and SrTiO{sub 3} bulk band gaps. For both PbO and TiO{sub 2}-terminated PbTiO{sub 3}/SrTiO{sub 3}(001) heterostructures, their band gaps are reduced due to the increased number of PbTiO{sub 3} (001) monolayers. The band gaps of PbO-terminated augmented PbTiO{sub 3} (001) films are always larger than those for TiO{sub 2}-terminated PbTiO{sub 3} (001) thin films. The only exception is the case of 7-layer PbO-terminated and 8-layer TiO{sub 2}-terminated augmented PbTiO{sub 3} (001) thin films, where their band gaps both are equal to 2.99 eV. For each monolayer of the SrTiO{sub 3} (001) substrate, charge magnitudes always are more than several times larger, than for each monolayer in the augmented PbTiO{sub 3} (001) thin film. (copyright 2016 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

One-step synthesis of PbSe-ZnSe composite thin film

Directory of Open Access Journals (Sweden)

Abe Seishi

2011-01-01

Full Text Available Abstract This study investigates the preparation of PbSe-ZnSe composite thin films by simultaneous hot-wall deposition (HWD from multiple resources. The XRD result reveals that the solubility limit of Pb in ZnSe is quite narrow, less than 1 mol%, with obvious phase-separation in the composite thin films. A nanoscale elemental mapping of the film containing 5 mol% PbSe indicates that isolated PbSe nanocrystals are dispersed in the ZnSe matrix. The optical absorption edge of the composite thin films shifts toward the low-photon-energy region as the PbSe content increases. The use of a phase-separating PbSe-ZnSe system and HWD techniques enables simple production of the composite package.

Synthesis and photocatalytic properties of visible light responsive La/TiO2-graphene composites

International Nuclear Information System (INIS)

Khalid, N.R.; Ahmed, E.; Hong Zhanglian; Ahmad, M.

2012-01-01

Highlights: ► Synthesis of La/TiO 2 -graphene composites by two-step hydrothermal method. ► Efficient charge separation due to La doping and graphene incorporation. ► Enhanced photocatalytic activity of composite catalyst for MB degradation under visible-light. - Abstract: La/TiO 2 -graphene composites used as photocatalyst were prepared by two-step hydrothermal method. The as-prepared composites were characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS), UV-visible diffuse reflectance spectroscopy (DRS) and photoluminescence spectroscopy (PL). The results of optical properties of La/TiO 2 -graphene composites exhibit extended light absorption in visible-light region and possess better charge separation capability as compared to pure TiO 2 . The photocatalytic activity measurement demonstrate that La/TiO 2 -graphene composites exhibited an enhanced photocatalytic activity for methylene blue (MB) degradation under visible-light irradiation compared to pure TiO 2 , which was attributed to greater adsorptivity of dyes, extended light absorption and increased charge separation efficiency due to excellent electrical properties of graphene and the large surface contact between graphene and La/TiO 2 nanoparticles.

Influence of PbCl2 content in PbI2 solution of DMF on the absorption, crystal phase, morphology of lead halide thin films and photovoltaic performance in planar perovskite solar cells

International Nuclear Information System (INIS)

Wang, Mao; Shi, Chengwu; Zhang, Jincheng; Wu, Ni; Ying, Chao

2015-01-01

In this paper, the influence of PbCl 2 content in PbI 2 solution of DMF on the absorption, crystal phase and morphology of lead halide thin films was systematically investigated and the photovoltaic performance of the corresponding planar perovskite solar cells was evaluated. The result revealed that the various thickness lead halide thin film with the small sheet-like, porous morphology and low crystallinity can be produced by adding PbCl 2 powder into PbI 2 solution of DMF as a precursor solution. The planar perovskite solar cell based on the 300-nm-thick CH 3 NH 3 PbI 3−x Cl x thin film by the precursor solution with the mixture of 0.80 M PbI 2 and 0.20 M PbCl 2 exhibited the optimum photoelectric conversion efficiency of 10.12% along with an open-circuit voltage of 0.93 V, a short-circuit photocurrent density of 15.70 mA cm −2 and a fill factor of 0.69. - Graphical abstract: The figure showed the surface and cross-sectional SEM images of lead halide thin films using the precursor solutions: (a) 0.80 M PbI 2 , (b) 0.80 M PbI 2 +0.20 M PbCl 2 , (c) 0.80 M PbI 2 +0.40 M PbCl 2 , and (d) 0.80 M PbI 2 +0.60 M PbCl 2 . With the increase of the PbCl 2 content in precursor solution, the size of the lead halide nanosheet decreased and the corresponding thin films gradually turned to be porous with low crystallinity. - Highlights: • Influence of PbCl 2 content on absorption, crystal phase and morphology of thin film. • Influence of perovskite film thickness on photovoltaic performance of solar cell. • Lead halide thin film with small sheet-like, porous morphology and low crystallinity. • Planar solar cell with 300 nm-thick perovskite thin film achieved PCE of 10.12%.

Degradation and Mineralization of Benzohydroxamic Acid by Synthesized Mesoporous La/TiO2

Directory of Open Access Journals (Sweden)

Xianping Luo

2016-10-01

Full Text Available Rare earth element La-doped TiO2 (La/TiO2 was synthesized by the sol-gel method. Benzohydroxamic acid was used as the objective pollutant to investigate the photocatalytic activity of La/TiO2. The physicochemical properties of the prepared materials were characterized by X-ray diffraction, X-ray photoelectron spectroscopy, UV-vis diffuse reflectance spectroscopy, specific surface area and porosity, scanning electron microscopy and transmission electron microscopy. As a result, the doping of La could inhibit the crystal growth of TiO2, increase its specific surface area and expand its response to visible light, thus improving its photocatalytic activity. La/TiO2 with the doping ratio of 0.75% calcined at 500 °C, showing the highest photocatalytic activity to degrade benzohydroxamic acid under the irradiation of 300 W mercury lamp. About 94.1% of benzohydroxamic acid with the original concentration at 30 mg·L−1 was removed after 120 min in a solution of pH 4.4 with an La/TiO2 amount of 0.5 g·L−1. Furthermore, 88.5% of the total organic carbon was eliminated after 120 min irradiation. In addition, after four recycling runs, La/TiO2 still kept high photocatalytic activity on the photodegradation of benzohydroxamic acid. The interfacial charge transfer processes were also hypothesized.

Optical monitoring of CH3NH3PbI3 thin films upon atmospheric exposure

International Nuclear Information System (INIS)

Ghimire, Kiran; Zhao, Dewei; Cimaroli, Alex; Ke, Weijun; Yan, Yanfa; Podraza, Nikolas J

2016-01-01

CH 3 NH 3 PbI 3 perovskite films of interest for photovoltaic (PV) devices have been prepared by (i) vapor deposition and (ii) solution processing. Complex dielectric function ( ε   =   ε 1   +  i ε 2 ) spectra and structural parameters of the films have been extracted using near infrared to ultraviolet spectroscopic ellipsometry. In situ real time spectroscopic ellipsometry (RTSE) over a 48 h period has been performed on vapor deposited CH 3 NH 3 PbI 3 after the deposition in normal atmospheric laboratory ambient conditions. Analysis of RTSE data for vapor deposited CH 3 NH 3 PbI 3 film prepared under un-optimized conditions identifies phase segregated PbI 2 and CH 3 NH 3 I at the substrate/film interface and unreacted PbI 2 and CH 3 NH 3 I on the film surface. This analysis also provides the time dependence of the effective thicknesses of perovskite film, unreacted components, and phase segregated layers to track CH 3 NH 3 PbI 3 decomposition. (paper)

Growth of Pb(Ti,Zr)O 3 thin films by metal-organic molecular beam epitaxy

Science.gov (United States)

Avrutin, V.; Liu, H. Y.; Izyumskaya, N.; Xiao, B.; Özgür, Ü.; Morkoç, H.

2009-02-01

Single-crystal Pb(Zr xTi 1-x)O 3 thin films have been grown on (0 0 1) SrTiO 3 and SrTiO 3:Nb substrates by molecular beam epitaxy using metal-organic source of Zr and two different sources of reactive oxygen—RF plasma and hydrogen-peroxide sources. The same growth modes and comparable structural properties were observed for the films grown with both oxygen sources, while the plasma source allowed higher growth rates. The films with x up to 0.4 were single phase, while attempts to increase x beyond gave rise to the ZrO 2 second phase. The effects of growth conditions on growth modes, Zr incorporation, and phase composition of the Pb(Zr xTi 1-x)O 3 films are discussed. Electrical and ferroelectric properties of the Pb(Zr xTi 1-x)O 3 films of ~100 nm in thickness grown on SrTiO 3:Nb were studied using current-voltage, capacitance-voltage, and polarization-field measurements. The single-phase films show low leakage currents and large breakdown fields, while the values of remanent polarization are low (around 5 μC/cm 2). It was found that, at high sweep fields, the contribution of the leakage current to the apparent values of remanent polarization can be large, even for the films with large electrical resistivity (˜10 8-10 9 Ω cm at an electric filed of 1 MV/cm). The measured dielectric constant ranges from 410 to 260 for Pb(Zr 0.33Ti 0.67)O 3 and from 313 to 213 for Pb(Zr 0.2Ti 0.8)O 3 in the frequency range from 100 to 1 MHz.

Piezoelectric properties of PbTiO(3) thin films characterized with piezoresponse force and high resolution transmission electron microscopy

NARCIS (Netherlands)

Morelli, A.; Venkatesan, Sriram; Kooi, B. J.; Palasantzas, G.; De Hosson, J. Th. M.

2009-01-01

In this paper we investigate the piezoelectric properties of PbTiO(3) thin films grown by pulsed laser deposition with piezoresponse force microscopy and transmission electron microscopy. The as-grown films exhibit an upward polarization, inhomogeneous distribution of piezoelectric characteristics

CH3NH3PbI3 based solar cell: Modified by antisolvent treatment

Science.gov (United States)

Nandi, Pronoy; Giri, Chandan; Bansode, Umesh; Topwal, D.

2017-05-01

Solar cells based on new class of organic inorganic hybrid perovskite CH3NH3PbI3 were prepared by Ethyl acetate (EA); antisolvent treatment for the first time. This treatment results in new morphology for CH3NH3PbI3 thin film. FESEM image shows microrod type structures of CH3NH3PbI3 after EA antisolvent treatment. Energy band diagram was constructed using photoluminescence and photoemission studies. A better power conversion efficiency was achieved in EA treated film compare to without EA treated film.

Transformation of Sintered CsPbBr3 Nanocrystals to Cubic CsPbI3 and Gradient CsPbBrxI3-x through Halide Exchange.

Science.gov (United States)

Hoffman, Jacob B; Schleper, A Lennart; Kamat, Prashant V

2016-07-13

All-inorganic cesium lead halide (CsPbX3, X = Br(-), I(-)) perovskites could potentially provide comparable photovoltaic performance with enhanced stability compared to organic-inorganic lead halide species. However, small-bandgap cubic CsPbI3 has been difficult to study due to challenges forming CsPbI3 in the cubic phase. Here, a low-temperature procedure to form cubic CsPbI3 has been developed through a halide exchange reaction using films of sintered CsPbBr3 nanocrystals. The reaction was found to be strongly dependent upon temperature, featuring an Arrhenius relationship. Additionally, film thickness played a significant role in determining internal film structure at intermediate reaction times. Thin films (50 nm) showed only a small distribution of CsPbBrxI3-x species, while thicker films (350 nm) exhibited much broader distributions. Furthermore, internal film structure was ordered, featuring a compositional gradient within film. Transient absorption spectroscopy showed the influence of halide exchange on the excited state of the material. In thicker films, charge carriers were rapidly transferred to iodide-rich regions near the film surface within the first several picoseconds after excitation. This ultrafast vectorial charge-transfer process illustrates the potential of utilizing compositional gradients to direct charge flow in perovskite-based photovoltaics.

Thermoelectric prospects of chemically deposited PbSe and SnSe thin films

Science.gov (United States)

Nair, P. K.; Martínez, Ana Karen; Rosa García Angelmo, Ana; Barrios Salgado, Enue; Nair, M. T. S.

2018-03-01

Thin films of PbSe of 400-600 nm in thickness, were obtained via chemical deposition from a solution containing lead nitrate, thiourea and selenosufate. SnSe thin films of 90-180 nm in thickness, were also obtained by chemical deposition from a solution containing selenosulfate. Optical and electrical properties of these thin films were significantly altered by heating them in selenium vapor at 300 °C. Thin film PbSe has a bandgap (Eg) of 1.17 eV (direct gap, forbidden transitions), which decreases to 0.77 eV when it has been heated. Its electrical conductivity (σ) is p-type: 0.18 Ω-1 cm-1 (as-prepared), and 6.4 Ω-1 cm-1 when heated. Thin film SnSe is of orthorhombic crystalline structure which remains stable when heated at 300 °C, but its Eg increases from 1.12 eV (indirect) in as-prepared film to 1.5 eV (direct, forbidden transitions) upon heating. Its electrical conductivity is p-type, which increases from 0.3 Ω-1 cm-1 (as-prepared) to 1 Ω-1 cm-1 when heated (without Se-vapor). When SnSe film is heated at 300 °C in the presence of Se-vapor, they transform to SnSe2, with Eg of 1.5 eV (direct, forbidden) with n-type electrical conductivity, 11 Ω-1 cm-1. The Seebeck coefficient for the PbSe films is: +0.55 mV K-1 (as prepared) and +0.275 mV K-1 (heated); for SnSe films it is: +0.3 mV K-1 (as prepared) and +0.20 mV K-1 (heated); and for SnSe2 film, - 0.35 mV K-1. A five-element PbSe-SnSe2-PbSe-SnSe2-PbSe thermoelectric device demonstrated 50 mV for a temperature difference ΔT = 20 °C (2.5 mV K-1). For SnSe-SnSe2-SnSe-SnSe2-SnSe device, the value is 15 mV for ΔT = 20 °C (0.75 mV K-1). Prospect of these thin films in thermoelectric devices of hybrid materials, in which the coatings may be applied on distinct substrate and geometries is attractive.

Effects of thermal treatment conditions on the phase formation and the morphological changes of sol-gel derived 0.67Pb(Mg1/3Nb2/3)O3-0.33PbTiO3 thin films

International Nuclear Information System (INIS)

Yang, Sun A; Han, Jin Kyu; Choi, Yong Chan; Bu, Sang Don

2011-01-01

We report the synthesis of Pb(Mg 1/3 Nb 2/3 )O 3 -PbTiO 3 (PMN-PT) thin films and the effects of thermal conditions on their surface morphologies and phase formation behaviors. The PMN-PT thin films were prepared by spin-coating PMN-PT sol-gel solutions on Pt/Ti/SiO 2 /Si substrates and subsequent thermal treatments including pyrolysis, annealing, and additional pre-annealing. We found that the surface morphologies and the formation of the perovskite phase were strongly affected by the final annealing temperature. The grain size of perovskite phase and the amount of the perovskite phase increased as the annealing temperature was increased from 550 to 800 .deg. C. We also found that the voids started to form on the surface of the film at an annealing temperature of 650 .deg. C and that their areas increased with increasing in annealing temperature. The void formation was found to depend on the time period of pyrolysis and on the pre-annealing process between pyrolysis and final annealing. Dense PMN-PT films with relatively high amounts of the perovskite phase were obtained when additional pre-annealing at 750 .deg. C for 5 min was performed.

Pulsed laser deposited Pb(Zr,Ti)O3 thin films with excellent piezoelectric and mechanical properties

NARCIS (Netherlands)

Nazeer, H.; Nguyen, Duc Minh; Rijnders, Augustinus J.H.M.; Woldering, L.A.; Abelmann, Leon; Elwenspoek, Michael Curt

We present for the first time the combined measured piezoelectric and mechanical properties of epitaxial, (110) oriented Pb(ZrxTi1-x) (PZT) thin films grown on microfabricated silicon cantilevers using pulsed laser deposition (PLD, x=0.4, 0.52, 0.6 and 0.8). The grown PZT thin films develop a strong

Epitaxial Pb(Mg1/3Nb2/3)O3 thin films synthesized by metal-organic chemical vapor deposition

International Nuclear Information System (INIS)

Bai, G. R.; Streiffer, S. K.; Baumann, P. K.; Auciello, O.; Ghosh, K.; Stemmer, S.; Munkholm, A.; Thompson, Carol; Rao, R. A.; Eom, C. B.

2000-01-01

Metal-organic chemical vapor deposition was used to prepare Pb(Mg 1/3 Nb 2/3 )O 3 (PMN) thin films on (001) SrTiO 3 and SrRuO 3 /SrTiO 3 substrates, using solid Mg β-diketonate as the Mg precursor. Parameters including the precursor ratio in the vapor phase, growth temperature, growth rate, and reaction pressure in the reactor chamber were varied in order to determine suitable growth conditions for producing phase-pure, epitaxial PMN films. A cube-on-cube orientation relationship between the thin film and the SrTiO 3 substrate was found, with a (001) rocking curve width of 0.1 degree sign , and in-plane rocking-curve width of 0.8 degree sign . The root-mean-square surface roughness of a 200-nm-thick film on SrTiO 3 was 2 to 3 nm as measured by scanning probe microscopy. The zero-bias dielectric constant and loss measured at room temperature and 10 kHz for a 200-nm-thick film on SrRuO 3 /SrTiO 3 were approximately 1100 and 2%, respectively. The remnant polarization for this film was 16 μC/cm 2 . (c) 2000 American Institute of Physics

Scanning tunneling spectroscopy of Pb thin films

Energy Technology Data Exchange (ETDEWEB)

Becker, Michael

2010-12-13

The present thesis deals with the electronic structure, work function and single-atom contact conductance of Pb thin films, investigated with a low-temperature scanning tunneling microscope. The electronic structure of Pb(111) thin films on Ag(111) surfaces is investigated using scanning tunneling spectroscopy (STS). Quantum size effects, in particular, quantum well states (QWSs), play a crucial role in the electronic and physical properties of these films. Quantitative analysis of the spectra yields the QWS energies as a function of film thickness, the Pb bulk-band dispersion in {gamma}-L direction, scattering phase shifts at the Pb/Ag interface and vacuum barrier as well as the lifetime broadening at anti {gamma}. The work function {phi} is an important property of surfaces, which influences catalytic reactivity and charge injection at interfaces. It controls the availability of charge carriers in front of a surface. Modifying {phi} has been achieved by deposition of metals and molecules. For investigating {phi} at the atomic scale, scanning tunneling microscopy (STM) has become a widely used technique. STM measures an apparent barrier height {phi}{sub a}, which is commonly related to the sample work function {phi}{sub s} by: {phi}{sub a}=({phi}{sub s}+{phi}{sub t}- vertical stroke eV vertical stroke)/2, with {phi}{sub t} the work function of the tunneling tip, V the applied tunneling bias voltage, and -e the electron charge. Hence, the effect of the finite voltage in STM on {phi}{sub a} is assumed to be linear and the comparison of {phi}{sub a} measured at different surface sites is assumed to yield quantitative information about work function differences. Here, the dependence of {phi}{sub a} on the Pb film thickness and applied bias voltage V is investigated. {phi}{sub a} is found to vary significantly with V. This bias dependence leads to drastic changes and even inversion of contrast in spatial maps of {phi}{sub a}, which are related to the QWSs in the Pb

Epitaxial Pb(Zr,Ti)O3 thin films for a MEMS application

International Nuclear Information System (INIS)

Nguyen, Minh D; Vu, Hung N; Blank, Dave H A; Rijnders, Guus

2011-01-01

This research presents the deposition and device fabrication of epitaxial Pb(Zr,Ti)O 3 (PZT) thin films for applications in microelectromechanical systems (MEMS). A piezoelectric micro-membrane is described as an example. Using the pulsed laser deposition (PLD) technique and the MEMS microfabrication process, the piezo-membranes with diameters ranging from 200 to 500 μm were obtained. The displacement of piezo-membranes increased from 5.1 to 17.5 nm V −1 with a piezoelectric-membrane diameter in the range of 200–500 μm. Furthermore, the effect of PZT film-thickness on the mechanical properties has been investigated. By using the conductive-oxide SrRuO 3 (SRO) layers as the electrodes, the degradation of both ferroelectric and piezoelectric properties is prevented up to 10 10 switching cycles

Compliant ferroelastic domains in epitaxial Pb(Zr,Ti)O{sub 3} thin films

Energy Technology Data Exchange (ETDEWEB)

Feigl, L.; McGilly, L. J.; Sandu, C. S.; Setter, N. [Ceramics Laboratory, EPFL - Swiss Federal Institute of Technology, Lausanne CH-1015 (Switzerland)

2014-04-28

Ordered patterns of highly compliant ferroelastic domains have been created by use of tensile strained epitaxial Pb(Zr,Ti)O{sub 3} thin films, of very low defect density, grown on DyScO{sub 3} substrates. The effect of 180° switching on well-ordered a/c 90° domain patterns is investigated by a combination of transmission electron microscopy, piezoelectric force microscopy, and X-ray diffraction. It is shown that ferroelastic a-domains, having an in-plane polarization, can be created and completely removed on a local level by an out-of-plane electric field. The modifications of the ferroelastic domain pattern can be controlled by varying the parameters used during switching with a piezoresponse force microscope to produce the desired arrangement.

Fatigue mechanism verified using photovoltaic properties of Pb(Zr0.52Ti0.48)O3 thin films

Science.gov (United States)

Wu, Ming; Li, Wei; Li, Junning; Wang, Shaolan; Li, Yaqi; Peng, Biaolin; Huang, Haitao; Lou, Xiaojie

2017-03-01

The photovoltaic effect and its evolution during electrical fatigue in Pb(Zr0.52Ti0.48)O3 (PZT) thin films have been investigated. It is found that the photovoltaic effect of the as-grown PZT thin film is highly affected by the asymmetric Schottky barriers, which can be tuned by applying an external electric field. During fatigue processes, both open-circuit voltage (Voc) and short-circuit current (Jsc) decrease considerably with the increase of the number of electrical cycles. This phenomenon could be ascribed to the degradation of the interfacial layer between the thin film and the electrode induced by highly energetic charge carriers injected from the electrode during bipolar cycling. Our work sheds light on the physical mechanism of both ferroelectric photovoltaics and polarization fatigue in thin-film ferroelectrics.

Polarization fatigue resistance of Ca-doped Pb(Zr0.52Ti0.48)O3 thin films prepared by the sol-gel method

International Nuclear Information System (INIS)

Wei, T.; Wang, Y.; Zhu, C.; Dong, X.W.; Xia, Y.D.; Zhu, J.S.; Liu, J.-M.

2008-01-01

The ferroelectric and polarization fatigue characteristics of Pb 1-x Ca x (Zr 0.52 Ti 0.48 )O 3 (PCZT) thin films prepared using the sol-gel method were studied. The Ca-doping slightly suppresses the ferroelectricity of Pb(Zr 0.52 Ti 0.48 )O 3 (PZT) because of the quantum paraelectric behavior of CaTiO 3 . Compared with PZT thin films, the PCZT (x=0.2) thin films show enhanced fatigue resistance at room temperature, further emphasized by the almost fatigue-free behavior at 100 K. The temperature-dependent dc-conductivity suggests a decrease of the oxygen vacancy density by almost 20 times and a slightly declined activation energy U for oxygen vacancies, upon increasing of the Ca-doping content from 0.0 to 0.2. It is argued that the improved fatigue endurance is ascribed to the decreasing density of oxygen vacancies due to the Ca-doping, although the lowered activation energy of oxygen vacancies is unfavorable. (orig.)

Structure and electrical properties of Pb(ZrxTi1-x)O3 deposited on textured Pt thin films

International Nuclear Information System (INIS)

Hong, Jongin; Song, Han Wook; Lee, Hee Chul; Lee, Won Jong; No, Kwangsoo

2001-01-01

The texturing of the bottom electrode plays a key role in the structure and electrical properties of Pb(Zr,Ti)O 3 (PZT) thin films. We fabricated Pt bottom electrodes having a different thickness on MgO single crystals at 600 o C by rf magnetron sputtering. As the thickness of platinum (Pt) thin film increased, the preferred orientation of Pt thin film changed from (200) to (111). PZT thin films were fabricated at 450 o C by electron cyclotron resonance-plasma enhanced metal organic chemical vapor deposition on the textured Pt thin films. The texturing of the bottom electrode caused drastic changes in the C--V characteristics, P--E characteristics, and fatigue characteristics of metal/ferroelectric material/metal (MFM) capacitors. The difference of the electrical properties between the PZT thin films having different texturing was discussed in terms-of the x--y alignment and the interface between electrode and PZT in MFM capacitors. copyright 2001 American Institute of Physics

Piezoelectric characterization of Pb(Zr,Ti)O3 thin films deposited on metal foil substrates by dip coating

Science.gov (United States)

Hida, Hirotaka; Hamamura, Tomohiro; Nishi, Takahito; Tan, Goon; Umegaki, Toshihito; Kanno, Isaku

2017-10-01

We fabricated the piezoelectric bimorphs composed of Pb(Zr,Ti)O3 (PZT) thin films on metal foil substrates. To efficiently inexpensively manufacture piezoelectric bimorphs with high flexibility, 1.2-µm-thick PZT thin films were directly deposited on both surfaces of 10- and 20-µm-thick bare stainless-steel (SS) foil substrates by dip coating with a sol-gel solution. We confirmed that the PZT thin films deposited on the SS foil substrates at 500 °C or above have polycrystalline perovskite structures and the measured relative dielectric constant and dielectric loss were 323-420 and 0.12-0.17, respectively. The PZT bimorphs were demonstrated by comparing the displacements of the cantilever specimens driven by single- and double-side PZT thin films on the SS foil substrates under the same applied voltage. We characterized the piezoelectric properties of the PZT bimorphs and the calculated their piezoelectric coefficient |e 31,f| to be 0.3-0.7 C/m2.

The effect of dual complexing agents of lactic and citric acids on the formation of sol-gel derived Ag–PbTiO3 percolative thin film

International Nuclear Information System (INIS)

Su, Yanbo; Hu, Tao; Tang, Liwen; Weng, Wenjian; Han, Gaorong; Ma, Ning; Du, Piyi

2014-01-01

Controlling the formation of conductive particles to be nano-scale is important for achieving percolation effect in metal dispersed thin film composite to contribute extraordinary dielectric properties required for miniaturization of electronic devices. In this paper, lactic acid (LA) and citric acid (CA) were used as dual complexing agents to prepare a typical Ag nanoparticle dispersed PbTiO 3 (PTO) composite thin film by using a sol-gel method. The phase structure of the thin film and the coordination effect between complexing agent and metallic ions were investigated. It revealed that LA coordinated with Ti 4+ and Pb 2+ and CA coordinated with Ag + . Lead was fixed inside the gel network by LA and restricted to evaporate during heat treatment thus the pyrochlore phase was prevented from forming in the thin film. Ag + was coordinated by CA and the diffusion and thus aggregation of silver during gelation and annealing process were weakened. Silver nanoparticles dispersed in the PTO matrix formed with dual complexing agents of LA and CA introduced during the preparation process. The composite thin film of perfect perovskite phase with silver nanoparticles embedded was obtained at the molar ratio of LA/lead = 0.5 and CA/lead = 0.5. The dielectric constant of the thin film with silver nanoparticles is 5 times higher than that without silver nanoparticles. - Highlights: • Ag nanoparticle–PbTiO 3 percolative film with high dielectric property is prepared. • Evaporation of lead was prevented by coordinating Pb with lactic acid agent. • Dual complexing agents contribute block and pinning effects to form Ag nanoparticles

Piezoelectric coefficients of multilayer Pb(Zr,Ti)O{sub 3} thin films

Energy Technology Data Exchange (ETDEWEB)

Muensit, S. [Prince of Songkla University, Department of Physics, Songkhla (Thailand); NANOTEC Center of Excellence at Prince of Songkhla University, Songkhla (Thailand); Sukwisut, P.; Khaenamkeaw, P. [Prince of Songkla University, Department of Physics, Songkhla (Thailand); Lang, S.B. [Ben-Gurion University of the Negev, Department of Chemical Engineering, Beer Sheva (Israel)

2008-08-15

Sol-gel techniques were used to prepare thin films of Pb(Zr{sub x},Ti{sub 1-x})O{sub 3} (PZT) with three different Zr/Ti ratios and a graded PZT film with three different compositional layers. A Michelson interferometer was used to measure the thickness strains due to an applied ac electric field. Effective d{sub 33} piezoelectric strain coefficients were computed from the experimental data. Interfacial pinning caused these coefficients to differ from the true ones. They were corrected for the pinning using both an analytical model and finite-element analysis. The corrected coefficients of the PZT(52/48) sample were in excellent agreement with values of bulk materials. The coefficients of the multilayer sample were very low, probably due to insufficient poling or domain switching. (orig.)

Effect of Pb content and solution concentration of Pb{sub x}TiO{sub 3} seed layer on (100)-texture and ferroelectric/dielectric behavior of PZT (52/48) thin films

Energy Technology Data Exchange (ETDEWEB)

Zhong, Jian; Batra, Vaishali; Han, Hui; Kotru, Sushma, E-mail: skotru@eng.ua.edu [Department of Electrical and Computer Engineering, The University of Alabama, Tuscaloosa, Alabama 35487 (United States); Pandey, Raghvendar K. [Ingram School of Engineering, Texas State University, San Marcos, Texas 78666 (United States)

2015-09-15

The effect of Pb content and solution concentration of lead titanate (Pb{sub x}TiO{sub 3}) seed layer on the texture and electric properties of Pb{sub 1.1}(Zr{sub 0.52},Ti{sub 0.48})O{sub 3} (PZT) thin films was investigated. A variety of seed layers (y Pb{sub x}TiO{sub 3}) with varying solution concentration (y = 0.02, 0.05, 0.1, and 0.2 M) and Pb content (x = 1.0, 1.05, 1.1, and 1.2) was deposited on Pt/TiO{sub 2}/SiO{sub 2}/Si substrates using chemical-solution deposition method. PZT films were then deposited on these seed layers using the same process. X-ray diffraction (XRD) and X-ray photoelectron spectroscopy investigations of the seed layers confirm change in crystal structure with variation in the solution properties. XRD studies of PZT films deposited on seed layers demonstrate that the seed layer helps in enhancing (100)-texture and suppressing (111)-texture. It was observed that PZT films prepared on seed layers with lower solution concentrations results in highly (100)-textured films, which further helps to improve the electric properties. The polarization and dielectric constant of the PZT films were seen to increase while the coercive field decreased with increase in (100)-texture. Irrespective of the seed layer solution concentration, higher Pb content in the seed layer deteriorates the PZT film properties. Ninety-five percent to ninety-six percent (100)-texture was obtained from thin PZT films deposited on seed layers of 0.02 M solution concentration with 1.05 and 1.10 Pb contents, which is higher than the values reported for thick PZT films. Optimization of both Pb content and solution concentration of the seed layer is a promising route to achieve highly (100)-textured PZT films with improved electric properties.

Preparation and switching kinetics of Pb(Zr, Ti)O3 thin films deposited by reactive sputtering

International Nuclear Information System (INIS)

Hase, Takashi; Shiosaki, Tadashi

1991-01-01

Ferroelectric Pb(Zr, Ti)O 3 [PZT] thin films have been prepared on Pt/Ti/SiO 2 /Si and Pt/SiO 2 /Si substrates using the reactive sputtering method with a metal composite target. The (111)-oriented PZT (80/20) thin films with a perovskite structure have been obtained at a substrate temperature of 595degC on highly (111)-oriented Pt films formed on SiO 2 /Si substrates. When an 8 V pulse sequence was applied to a 265 nm-thick film with an electrode area of 50 x 50 μm 2 , the switching time and the switched charge density measured were 20 ns and 10 μC/cm 2 , respectively. The switching time was strongly dependent on the electrode area. (author)

Exploring Polaronic, Excitonic Structures and Luminescence in Cs4PbBr6/CsPbBr3.

Science.gov (United States)

Kang, Byungkyun; Biswas, Koushik

2018-02-15

Among the important family of halide perovskites, one particular case of all-inorganic, 0-D Cs 4 PbBr 6 and 3-D CsPbBr 3 -based nanostructures and thin films is witnessing intense activity due to ultrafast luminescence with high quantum yield. To understand their emissive behavior, we use hybrid density functional calculations to first compare the ground-state electronic structure of the two prospective compounds. The dispersive band edges of CsPbBr 3 do not support self-trapped carriers, which agrees with reports of weak exciton binding energy and high photocurrent. The larger gap 0-D material Cs 4 PbBr 6 , however, reveals polaronic and excitonic features. We show that those lattice-coupled carriers are likely responsible for observed ultraviolet emission around ∼375 nm, reported in bulk Cs 4 PbBr 6 and Cs 4 PbBr 6 /CsPbBr 3 composites. Ionization potential calculations and estimates of type-I band alignment support the notion of quantum confinement leading to fast, green emission from CsPbBr 3 nanostructures embedded in Cs 4 PbBr 6 .

Effect of elastic compliances and higher order Landau coefficients on the phase diagram of single domain epitaxial Pb(Zr,TiO3 (PZT thin films

Directory of Open Access Journals (Sweden)

M. Mtebwa

2014-12-01

Full Text Available We report the qualitative study of the influence of both elastic compliances and higher order terms of Landau free energy potential on the phase diagram of Pb(Zr0.5Ti0.5O3 thin films by using a single domain Landau theory. Although the impact of elastic compliances and higher order terms of the Landau free energy potential on the phase diagram of ferroelectric thin films are known, the sensitivity of the phase diagram of PZT thin film on these parameters have not been reported. It is demonstrated that, while values of elastic compliances affect the positions of the phase boundaries including phase transition temperature of the cubic phase; higher order terms can potentially introduce an a1a2-phase previously predicted in PbTiO3 phase diagram.

Characterization of Pb(Zr, Ti)O3 thin films fabricated by plasma enhanced chemical vapor deposition on Ir-based electrodes

International Nuclear Information System (INIS)

Lee, Hee-Chul; Lee, Won-Jong

2002-01-01

Structural and electrical characteristics of Pb(Zr, Ti)O 3 (PZT) ferroelectric thin films deposited on various Ir-based electrodes (Ir, IrO 2 , and Pt/IrO 2 ) using electron cyclotron resonance plasma enhanced chemical vapor deposition were investigated. On the Ir electrode, stoichiometric PZT films with pure perovskite phase could be obtained over a very wide range of processing conditions. However, PZT films prepared on the IrO 2 electrode contain a large amount of PbO x phases and exhibited high Pb-excess composition. The deposition characteristics were dependent on the behavior of PbO molecules on the electrode surface. The PZT thin film capacitors prepared on the Ir bottom electrode showed different electrical properties depending on top electrode materials. The PZT capacitors with Ir, IrO 2 , and Pt top electrodes showed good leakage current characteristics, whereas those with the Ru top electrode showed a very high leakage current density. The PZT capacitor exhibited the best fatigue endurance with an IrO 2 top electrode. An Ir top electrode provided better fatigue endurance than a Pt top electrode. The PZT capacitor with an Ir-based electrode is thought to be attractive for the application to ferroelectric random access memory devices because of its wide processing window for a high-quality ferroelectric film and good polarization, fatigue, and leakage current characteristics

Deposition of Cu-doped PbS thin films with low resistivity using DC sputtering

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Hariyadi Soetedjo

2018-03-01

Full Text Available Investigation of the electrical resistivity of Cu-doped PbS thin films has been carried out. The films were prepared using a DC sputtering technique. The doping was achieved by introducing the Cu dopant plate material directly on the surface of the PbS sputtering target plate. SEM-EDX data shows the Cu concentration in the PbS film to be proportional to the Cu plate diameter. The XRD pattern indicates the film is in crystalline cubic form. The Hall effect measurement shows that Cu doping yields an increase in the carrier concentration to 3.55 × 1019 cm−3 and a significant decrease in electrical resistivity. The lowest resistivity obtained was 0.13 Ωcm for a Cu concentration of 18.5%. Preferential orientation of (1 1 1 and (2 0 0 occurs during deposition. Keywords: Thin films, Lead sulfide, Sputtering, Resistivity, Semiconductor, Infrared

Voltage-controlled ferroelastic switching in Pb(Zr.sub.0.2./sub.Ti.sub.0.8./sub.)O.sub.3./sub. thin films

Czech Academy of Sciences Publication Activity Database

Khan, A.I.; Martí, Xavier; Serrao, C.; Ramesh, R.; Salahuddin, S.

2015-01-01

Roč. 15, č. 4 (2015), s. 2229-2234 ISSN 1530-6984 Institutional support: RVO:68378271 Keywords : nanodomains * ferroelastic switching * ferroelectricity * Pb(Zr 0.2 Ti 0.8 )O 3 * thin film Subject RIV: BE - Theoretical Physics Impact factor: 13.779, year: 2015

Enhanced energy storage and pyroelectric properties of highly (100)-oriented (Pb1-x-yLaxCay)Ti1-x/4O3 thin films derived at low temperature

Science.gov (United States)

Zhu, Hanfei; Ma, Hongfang; Zhao, Yuyao

2018-05-01

Highly (100)-oriented (Pb1-x-yLaxCay)Ti1-x/4O3 (x = 0.15, y = 0.05; x = 0.1, y = 0.1; x = 0.05, y = 0.15) thin films were deposited on Pt/Ti/SiO2/Si substrates at a low temperature of 450 °C via a sol-gel route. It was found that all the (Pb1-x-yLaxCay)Ti1-x/4O3 thin films could be completely crystallized and the content of La/Ca showed a significant effect on the electrical properties of films. Among the three films, the (Pb1-x-yLaxCay)Ti1-x/4O3 (x = 0.1, y = 0.1) thin film exhibited the enhanced overall electrical properties, such as a low dielectric loss (tan ⁡ δ energy density (Wre ∼ 15 J/cm3), as well as a large pyroelectric coefficient (p ∼ 190 μC/m2K) and figure of merit (Fd‧∼ 77 μC /m2K). The findings suggest that the fabricated thin films with a good (100) orientation can be an attractive candidate for applications in Si-based energy storage and pyroelectric devices.

Dual-Phase CsPbBr3 -CsPb2 Br5 Perovskite Thin Films via Vapor Deposition for High-Performance Rigid and Flexible Photodetectors.

Science.gov (United States)

Tong, Guoqing; Li, Huan; Li, Danting; Zhu, Zhifeng; Xu, Enze; Li, Guopeng; Yu, Linwei; Xu, Jun; Jiang, Yang

2018-02-01

Inorganic perovskites with special semiconducting properties and structures have attracted great attention and are regarded as next generation candidates for optoelectronic devices. Herein, using a physical vapor deposition process with a controlled excess of PbBr 2 , dual-phase all-inorganic perovskite composite CsPbBr 3 -CsPb 2 Br 5 thin films are prepared as light-harvesting layers and incorporated in a photodetector (PD). The PD has a high responsivity and detectivity of 0.375 A W -1 and 10 11 Jones, respectively, and a fast response time (from 10% to 90% of the maximum photocurrent) of ≈280 µs/640 µs. The device also shows an excellent stability in air for more than 65 d without encapsulation. Tetragonal CsPb 2 Br 5 provides satisfactory passivation to reduce the recombination of the charge carriers, and with its lower free energy, it enhances the stability of the inorganic perovskite devices. Remarkably, the same inorganic perovskite photodetector is also highly flexible and exhibits an exceptional bending performance (>1000 cycles). These results highlight the great potential of dual-phase inorganic perovskite films in the development of optoelectronic devices, especially for flexible device applications. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Self-positioned thin Pb-alloy base electrode Josephson junction

International Nuclear Information System (INIS)

Kuroda, K.; Sato, K.

1986-01-01

A self-positioned thin (SPOT) Pb-alloy base electrode Josephson junction is developed. In this junction, a 50-nm thick Pb-alloy base electrode is restricted within the junction region on an Nb underlayer using a self-alignment technique. The grain size reduction and the base electrode area restriction greatly improve thermal cycling stability, where the thermal cycling tests of 4000 proposed junctions (5 x 5 μm 2 ) showed no failures after 4000 cycles. In addition, the elimination of insulator layer stress on the Pb-alloy base electrode rectifies the problem of size effect on current density. The Nb underlayers also serve to isolate the Pb-alloy base electrodes from the resistors

Nano-embossing technology on ferroelectric thin film Pb(Zr0.3,Ti0.7O3 for multi-bit storage application

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Lu Qian

2011-01-01

Full Text Available Abstract In this work, we apply nano-embossing technique to form a stagger structure in ferroelectric lead zirconate titanate [Pb(Zr0.3, Ti0.7O3 (PZT] films and investigate the ferroelectric and electrical characterizations of the embossed and un-embossed regions, respectively, of the same films by using piezoresponse force microscopy (PFM and Radiant Technologies Precision Material Analyzer. Attributed to the different layer thickness of the patterned ferroelectric thin film, two distinctive coercive voltages have been obtained, thereby, allowing for a single ferroelectric memory cell to contain more than one bit of data.

Preparation and switching kinetics of Pb(Zr, Ti)O sub 3 thin films deposited by reactive sputtering

Energy Technology Data Exchange (ETDEWEB)

Hase, Takashi; Shiosaki, Tadashi [Kyoto Univ. (Japan). Faculty of Engineering

1991-09-01

Ferroelectric Pb(Zr, Ti)O{sub 3} (PZT) thin films have been prepared on Pt/Ti/SiO{sub 2}/Si and Pt/SiO{sub 2}/Si substrates using the reactive sputtering method with a metal composite target. The (111)-oriented PZT (80/20) thin films with a perovskite structure have been obtained at a substrate temperature of 595degC on highly (111)-oriented Pt films formed on SiO{sub 2}/Si substrates. When an 8 V pulse sequence was applied to a 265 nm-thick film with an electrode area of 50 x 50 {mu}m{sup 2}, the switching time and the switched charge density measured were 20 ns and 10 {mu}C/cm{sup 2}, respectively. The switching time was strongly dependent on the electrode area. (author).

Direct observation of fatigue in epitaxially grown Pb(Zr,Ti)O3 thin films using second harmonic piezoresponse force microscopy

Science.gov (United States)

Murari, Nishit M.; Hong, Seungbum; Lee, Ho Nyung; Katiyar, Ram. S.

2011-08-01

Here, we present a direct observation of fatigue phenomena in epitaxially grown Pb(Zr0.2Ti0.8)O3 (PZT) thin films using second harmonic piezoresponse force microscopy (SH-PFM). We observed strong correlation between the SH-PFM amplitude and phase signals with the remnant piezoresponse at different switching cycles. The SH-PFM results indicate that the average fraction of switchable domains decreases globally and the phase delays of polarization switching differ locally. In addition, we found that the fatigue developed uniformly over the whole area without developing region-by-region suppression of switchable polarization as in polycrystalline PZT thin films.

Ferroelectric properties of sandwich structured (Bi, La)4T3O12/Pb(Zr, Ti)O3/ (Bi, La)4Ti3O12 thin films on Pt/Ti/SiO2/Si substrates

International Nuclear Information System (INIS)

Bao Dinghua; Wakiya, Naoki; Shinozaki, Kazuo; Mizutani, Nobuyasu

2002-01-01

Sandwich structured (Bi, La) 4 Ti 3 O 12 /Pb(Zr, Ti)O 3 /(Bi, La) 4 Ti 3 O 12 thin films were fabricated on Pt/Ti/SiO 2 /Si substrates, with the intention of simultaneously utilizing the advantages of both (Bi, La) 4 Ti 3 O 12 (BLT) and Pb(Zr, Ti)O 3 (PZT) thin films such as non-fatigue behaviours of BLT and good ferroelectric properties of PZT. Both BLT and PZT layers were prepared by a chemical solution deposition technique. The experiments demonstrated that the sandwich structure showed fatigue-free characteristics at least up to 10 10 switching bipolar pulse cycles under 8 V and excellent retention properties. The sandwich structured thin films also exhibited well-defined hysteresis loops with a remanent polarization (2P r ) of 8.8 μC cm -2 and a coercive field (E c ) of 47 kV cm -1 . The room-temperature dielectric constant and dissipation factor were 210 and 0.031, respectively, at a frequency of 100 kHz. These results suggest that this sandwich structure is a promising material combination for ferroelectric memory applications. (author)

Characterization of Pb(Zr, Ti)O sub 3 thin films prepared by metal-organic chemical-vapor deposition using a solid delivery system

CERN Document Server

Shin, J C; Hwang, C S; Kim, H J; Lee, J M

1999-01-01

Pb(Zr, Ti)O sub 3 (PZT) thin films were deposited on Pt/SiO sub 2 /Si substrates by metal-organic chemical-vapor deposition technique using a solid delivery system to improve the reproducibility of the deposition. The self-regulation mechanism, controlling the Pb-content of the film, was observed to work above a substrate temperature of 620 .deg. C. Even with the self-regulation mechanism, PZT films having low leakage current were obtained only when the molar mixing ratio of the input precursors was 1<Pb/(Zr+Ti)<1.4. The leakage current mechanism of the Pt/PZT/Pt capacitor was Schottky emission with a barrier height of 1.36 eV.

Structural characterization of chemically deposited PbS thin films

International Nuclear Information System (INIS)

Fernandez-Lima, F.A.; Gonzalez-Alfaro, Y.; Larramendi, E.M.; Fonseca Filho, H.D.; Maia da Costa, M.E.H.; Freire, F.L.; Prioli, R.; Avillez, R.R. de; Silveira, E.F. da; Calzadilla, O.; Melo, O. de; Pedrero, E.; Hernandez, E.

2007-01-01

Polycrystalline thin films of lead sulfide (PbS) grown using substrate colloidal coating chemical bath depositions were characterized by RBS, XPS, AFM and GIXRD techniques. The films were grown on glass substrates previously coated with PbS colloidal particles in a polyvinyl alcohol solution. The PbS films obtained with the inclusion of the polymer showed non-oxygen-containing organic contamination. All samples maintained the Pb:S 1:1 stoichiometry throughout the film. The amount of effective nucleation centers and the mean grain size have being controlled by the substrate colloidal coating. The analysis of the polycrystalline PbS films showed that a preferable (1 0 0) lattice plane orientation parallel to the substrate surface can be obtained using a substrate colloidal coating chemical bath deposition, and the orientation increases when a layer of colloid is initially dried on the substrate

Molecular beam epitaxy of three-dimensional Dirac material Sr3PbO

Science.gov (United States)

Samal, D.; Nakamura, H.; Takagi, H.

2016-07-01

A series of anti-perovskites including Sr3PbO are recently predicted to be a three-dimensional Dirac material with a small mass gap, which may be a topological crystalline insulator. Here, we report the epitaxial growth of Sr3PbO thin films on LaAlO3 using molecular beam epitaxy. X-ray diffraction indicates (001) growth of Sr3PbO, where [110] of Sr3PbO matches [100] of LaAlO3. Measurements of the Sr3PbO films with parylene/Al capping layers reveal a metallic conduction with p-type carrier density of ˜1020 cm-3. The successful growth of high quality Sr3PbO film is an important step for the exploration of its unique topological properties.

Reversible pyroelectric and photogalvanic current in epitaxial Pb(Zr0.52Ti0.48)O3 thin films

Science.gov (United States)

Lee, J.; Esayan, S.; Prohaska, J.; Safari, A.

1994-01-01

The pyroelectric and photogalvanic effects have been studied in epitaxial Pb(Zr0.52Ti0.48)O3 (PZT) thin films. Photoinduced currents, which were completely reversible by electrical voltage, were observed. The photoinduced currents exhibited transient and steady state components. The transient component, in turn, consisted of two components with fast (<1 s) and slow (˜hours) relaxation times. The mechanisms of the photoinduced currents in PZT films and their possible applications in nondestructive readout ferroelectric memory are discussed.

Study of structural and optical properties of PbS thin films

Science.gov (United States)

Homraruen, T.; Sudswasd, Y.; Sorod, R.; Kayunkid, N.; Yindeesuk, W.

2018-03-01

This research aimed to synthesize lead sulfide (PbS) thin films on glass slides using the successive ion layer absorption and reaction (SILAR) method. We studied the optical properties and structure of PbS thin films by changing the number of dipping cycles and the concentration of precursor solution. The results of this experiment show that different conditions have a considerable influence on the thickness and absorbance of the films. When the number of dipping cycles and the concentration of the solution are increased, film thickness and absorbance tend to become higher. The xrays diffraction pattern showed all the diffraction peaks which confirmed the face center cubic and the structure of PbS had identified. Grain size computation was used to confirm how much these conditions could be affected.

Piezoelectric evaluation of ion beam etched Pb(Zr,Ti)O3 thin films by piezoresponse force microscopy

International Nuclear Information System (INIS)

Legrand, C.; Da Costa, A.; Desfeux, R.; Soyer, C.; Remiens, D.

2007-01-01

The evolution of piezoelectric properties of Pb(Zr,Ti)O 3 (PZT) thin films after ion beam etching have been investigated at the nanoscale level by piezoelectric force microscopy. A comparison of the piezoelectric properties on etched and unetched films is realized. Piezoelectric contrasts imaging evidences a modification of the domain architecture at the film surface. Local piezoelectric hysteresis loops measurements on grains indicate that the coercive voltage for switching is much higher for the etched films (2.3 V) compared to the unetched ones (1.0 V) while the average piezoelectric activity is slightly lower. The results are explained in terms of grain-damaging during etching and domain-wall pinning

Synthesis and Characterization of Pb(Zr., Ti.)O-Pb(Nb/, Zn/)O Thin Film Cantilevers for Energy Harvesting Applications

KAUST Repository

Fuentes-Fernandez, E. M. A.

2012-01-18

A complete analysis of the morphology, crystallographic orientation, and resulting electrical properties of Pb(Zr0.53,Ti0.47) Pb(Nb1/3, Zn2/3)O3 (PZT-PZN) thin films, as well as the electrical behavior when integrated in a cantilever for energy harvesting applications, is presented. The PZT-PZN films were deposited using sol-gel methods. We report that using 20% excess Pb, a nucleation layer of PbTiO3 (PT), and a fast ramp rate provides large grains, as well as denser films. The PZT-PZN is deposited on a stack of TiO2/PECVD SiO2/Si3N4/thermal SiO2/Poly-Si/Si. This stack is designed to allow wet-etching the poly-Si layer to release the cantilever structures. It was also found that the introduction of the poly-Si layer results in larger grains in the PZT-PZN film. PZT-PZN films with a dielectric constant of 3200 and maximum polarization of 30 μC/cm2 were obtained. The fabricated cantilever devices produced ~300–400 mV peak-to-peak depending on the cantilever design. Experimental results are compared with simulations.

Ferroelectric properties of BaTiO3/PbZr0.2Ti.08O3 bilayer thin film

Science.gov (United States)

Salev, Pavel; Yang, Chun; Grigoriev, Alexei

2014-03-01

The thin film ferroelectric BaTiO3/PbZr0.2Ti0.8O3 bilayer was epitaxially grown on SrRuO3/SrTiO3 substrate by RF sputtering. Electrical measurements of polarization switching revealed two different switching regimes - a small ferroelectric hysteresis loop at low applied voltage and a larger loop at a high voltage. The measured dielectric permittivity corresponds to weak electrostatic coupling between two layers according to Landau-Ginsburg-Devonshire theory. This weak coupling may allow for independent polarization states to exist in individual layers. This can lead to stable head-to-head and tail-to-tail polarization domain configurations, which would explain the two switching regimes observed in electrical measurements. The compensation of polarization gradient across the interface can be explained by the enhancement of interface charge carrier density due to strong bending of electron energy bands. This work was supported by NSF award DMR-1057159.

Local hysteresis and grain size effect in Pb(Mg1/3Nb2/3)O3- PbTiO3 thin films

Science.gov (United States)

Shvartsman, V. V.; Emelyanov, A. Yu.; Kholkin, A. L.; Safari, A.

2002-07-01

The local piezoelectric properties of relaxor ferroelectric films of solid solutions 0.9Pb(Mg1/3Nb2/3)O3- 0.1PbTiO3 were investigated by scanning force microscopy (SFM) in a piezoelectric contact mode. The piezoelectric hysteresis loops were acquired in the interior of grains of different sizes. A clear correlation between the values of the effective piezoelectric coefficients, deff, and the size of the respective grains is observed. Small grains exhibit slim piezoelectric hysteresis loops with low remanent deff, whereas relatively strong piezoelectric activity is characteristic of larger grains. Part of the grains (approx20-25%) is strongly polarized without application of a dc field. The nature of both phenomena is discussed in terms of the internal bias field and grain size effects on the dynamics of nanopolar clusters.

The effects of inorganic surface treatments on photogenerated carrier mobility and lifetime in PbSe quantum dot thin films

Energy Technology Data Exchange (ETDEWEB)

Goodwin, E.D.; Straus, Daniel B. [Department of Chemistry, University of Pennsylvania, Philadelphia, PA 19104 (United States); Gaulding, E. Ashley [Department of Materials Science and Engineering, University of Pennsylvania, Philadelphia, PA 19104 (United States); Murray, Christopher B. [Department of Chemistry, University of Pennsylvania, Philadelphia, PA 19104 (United States); Department of Materials Science and Engineering, University of Pennsylvania, Philadelphia, PA 19104 (United States); Kagan, Cherie R., E-mail: kagan@seas.upenn.edu [Department of Chemistry, University of Pennsylvania, Philadelphia, PA 19104 (United States); Department of Materials Science and Engineering, University of Pennsylvania, Philadelphia, PA 19104 (United States); Department of Electrical and Systems Engineering, University of Pennsylvania, Philadelphia, PA 19104 (United States)

2016-06-01

Highlights: • Na{sub 2}Se and PbCl{sub 2} treatments modified the surface chemistry of PbSe quantum dots. • Excess Se (Pb) p-doped (n-doped) PbSe quantum dot thin films. • Carrier mobility and lifetime were studied using time-resolved microwave conductivity. • Mobility increased as the Fermi level approached the band edges. - Abstract: We used flash-photolysis, time-resolved microwave conductivity (TRMC) to probe the carrier mobility and lifetime in PbSe quantum dot (QD) thin films treated with solutions of the metal salts of Na{sub 2}Se and PbCl{sub 2}. The metal salt treatments tuned the Pb:Se stoichiometry and swept the Fermi energy throughout the QD thin film bandgap. A stoichiometric imbalance favoring excess Se heavily p-doped the QD thin film, shifted the Fermi energy toward the valence band, and yielded the highest TRMC mobility and lifetime. Introducing Pb first compensated the p-doping and shifted the Fermi level through mid-gap, decreasing the TRMC mobility. Further Pb addition created an excess of Pb, n-doped the QD thin film, moved the Fermi level to near the conduction band, and again increased the TRMC mobility. The increase in TRMC mobility as the Fermi energy was shifted toward the band edges by non-stoichiometry is consistent with the QD thin film density of states.

Using Low Temperature Photoluminescence Spectroscopy to Investigate CH3NH3PbI3 Hybrid Perovskite Degradation

Directory of Open Access Journals (Sweden)

Khaoula Jemli

2016-07-01

Full Text Available Investigating the stability and evaluating the quality of the CH3NH3PbI3 perovskite structures is quite critical both to the design and fabrication of high-performance perovskite devices and to fundamental studies of the photophysics of the excitons. In particular, it is known that, under ambient conditions, CH3NH3PbI3 degrades producing some PbI2. We show here that low temperature Photoluminescence (PL spectroscopy is a powerful tool to detect PbI2 traces in hybrid perovskite layers and single crystals. Because PL spectroscopy is a signal detection method on a black background, small PbI2 traces can be detected, when other methods currently used at room temperature fail. Our study highlights the extremely high stability of the single crystals compared to the thin layers and defects and grain boundaries are thought to play an important role in the degradation mechanism.

Epitaxial growth and structural characterization of Pb(Fe1/2Nb1/2)O3 thin films

International Nuclear Information System (INIS)

Peng, W.; Lemee, N.; Holc, J.; Kosec, M.; Blinc, R.; Karkut, M.G.

2009-01-01

We have grown lead iron niobate thin films with composition Pb(Fe 1/2 Nb 1/2 )O 3 (PFN) on (0 0 1) SrTiO 3 substrates by pulsed laser deposition. The influence of the deposition conditions on the phase purity was studied. Due to similar thermodynamic stability spaces, a pyrochlore phase often coexists with the PFN perovskite phase. By optimizing the kinetic parameters, we succeeded in identifying a deposition window which resulted in epitaxial perovskite-phase PFN thin films with no identifiable trace of impurity phases appearing in the X-ray diffractograms. PFN films having thicknesses between 20 and 200 nm were smooth and epitaxially oriented with the substrate and as demonstrated by RHEED streaks which were aligned with the substrate axes. X-ray diffraction showed that the films were completely c-axis oriented and of excellent crystalline quality with low mosaicity (X-ray rocking curve FWHM≤0.09 deg.). The surface roughness of thin films was also investigated by atomic force microscopy. The root-mean-square roughness varies between 0.9 nm for 50-nm-thick films to 16 nm for 100-nm-thick films. We also observe a correlation between grain size, surface roughness and film thickness.

Evaluating the residual stress in PbTiO3 thin films prepared by a polymeric chemical method

International Nuclear Information System (INIS)

Valim, D; Filho, A G Souza; Freire, P T C; Filho, J Mendes; Guarany, C A; Reis, R N; Araujo, E B

2004-01-01

We report a study of residual stress in PbTiO 3 (PT) thin films prepared on Si substrates by a polymeric chemical method. The E(1TO) frequency was used to evaluate the residual stress through an empirical equation available for bulk PT. We find that the residual stress in PT films increases as the film thickness decreases and conclude that it originates essentially from the contributions of extrinsic and intrinsic factors. Polarized Raman experiments showed that the PT films prepared by a polymeric chemical method are somewhat a-domain (polar axis c parallel to the substrate) oriented

Effect of the Ultrasonic Substrate Vibration on Nucleation and Crystallization of PbI2 Crystals and Thin Films

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Fatemeh Zabihi

2018-01-01

Full Text Available Preparation of defect-free and well-controlled solution-processed crystalline thin films is highly desirable for emerging technologies, such as perovskite solar cells. In this work, using PbI2 as a model solution with a vast variety of applications, we demonstrate that the excitation of a liquid thin film by imposed ultrasonic vibration on the film substrate significantly affects the nucleation and crystallization kinetics of PbI2 and the morphology of the resulting solid thin film. It is found that by applying ultrasonic vibration to PbI2 solution spun onto an ITO substrate with a moderate power and excitation duration (5 W and 1 min for the 40 kHz transducer used in this study, the nucleation rate increases and the crystals transform from 2D or planar to epitaxial 3D columnar structures, resulting in the suppression of crystallization dewetting. The effects of various induced physical phenomena as a result of the excitation by ultrasonic vibration are discussed, including microstreaming and micromixing, increased heat transfer and local temperature, a change in the thermodynamic state of the solution, and a decrease in the supersaturation point. It is shown that the ultrasonic-assisted solution deposition of the PbI2 thin films is controllable and reproducible, a process which is low-cost and in line with the large-scale fabrication of such solution-processed thin films.

Influence of the Grain Size on the Properties of CH3NH3PbI3 Thin Films.

Science.gov (United States)

Shargaieva, Oleksandra; Lang, Felix; Rappich, Jörg; Dittrich, Thomas; Klaus, Manuela; Meixner, Matthias; Genzel, Christoph; Nickel, Norbert H

2017-11-08

Hybrid perovskites have already shown a huge success as an absorber in solar cells, resulting in the skyrocketing rise in the power conversion efficiency to more than η = 22%. Recently, it has been established that the crystal quality is one of the most important parameters to obtain devices with high efficiencies. However, the influence of the crystal quality on the material properties is not fully understood. Here, the influence of the morphology on electronic properties of CH 3 NH 3 PbI 3 thin films is investigated. Postannealing was used to vary the average grain size continuously from ≈150 to ≈1000 nm. Secondary grain growth is thermally activated with an activation energy of E a = 0.16 eV. The increase in the grain size leads to an enhancement of the photoluminescence, indicating an improvement in the material quality. According to surface photovoltage measurements, the charge-carrier transport length exhibits a linear increase with increasing grain size. The charge-carrier diffusion length is limited by grain boundaries. Moreover, an improved morphology leads to a drastic increase in power conversion efficiency of the devices.

Role of dual-laser ablation in controlling the Pb depletion in epitaxial growth of Pb(Zr0.52Ti0.48)O3 thin films with enhanced surface quality and ferroelectric properties

Science.gov (United States)

Mukherjee, Devajyoti; Hyde, Robert; Mukherjee, Pritish; Srikanth, Hariharan; Witanachchi, Sarath

2012-03-01

Pb depletion in Pb(Zr0.52Ti0.48)O3 (PZT) thin films has remained as a major setback in the growth of defect-free PZT thin films by pulsed laser ablation techniques. At low excimer (KrF) laser fluences, the high volatility of Pb in PZT leads to non-congruent target ablation and, consequently, non-stoichiometric films, whereas, at high laser fluences, the inherent ejection of molten droplets from the target leads to particulate laden films, which is undesirable in heterostructure growth. To overcome these issues, a dual-laser ablation (PLDDL) process that combines an excimer (KrF) laser and CO2 laser pulses was used to grow epitaxial PZT films on SrTiO3 (100) and MgO (100) substrates. Intensified-charge-coupled-detector (ICCD) images and optical emission spectroscopy of the laser-ablated plumes in PLDDL revealed a broader angular expansion and enhanced excitation of the ablated species as compared to those for single-laser ablation (PLDSL). This led to the growth of particulate-free PZT films with higher Pb content, better crystallinity, and lower surface roughness as compared to those deposited using PLDSL. For FE measurements, PZT capacitors were fabricated in situ using the latticed-matched metallic oxide, La0.7Sr0.3MnO3, as the top and bottom electrodes. PZT films deposited using PLDDL exhibited enhanced polarization for all driving voltages as compared to those deposited using PLDSL. A highest remanent polarization (Pr) of ˜91 μC/cm2 and low coercive field of ˜40 kV/cm was recorded at 9 V driving voltage. Fatigue characterization revealed that PZT films deposited using PLDDL showed unchanging polarization, even after 109 switching cycles.

The energy level alignment at the CH_3NH_3PbI_3/pentacene interface

International Nuclear Information System (INIS)

Ji, Gengwu; Zhao, Bin; Song, Fei; Zheng, Guanhaojie; Zhang, Xiaonan; Shen, Kongchao; Yang, Yingguo; Chen, Shi; Gao, Xingyu

2017-01-01

Highlights: • The Energy Level Alignment at the CH_3NH_3PbI_3/Pentacene Interface was resolved experimentally. • The downward band bending and the dipole found at the pentacene side would favorably drive holes away from the interface into pentacene. • A ∼0.7 eV offset between pentacene HOMO and CH_3NH_3PbI_3 VBM would be in favor of hole transfer whereas a ∼1.35 eV offset between pentacene LUMO and CH_3NH_3PbI_3 CBM should efficiently block the unwanted electron transfer from perovskite to pentacene. • Pentacene could be a viable hole transfer material candidate on perovskite to be explored in perovskite devices. - Abstract: Pentacene thin film on CH_3NH_3PbI_3 was studied by in-situ X-ray photoelectron spectroscopy and ultraviolet photoelectron spectroscopy to determine their interfacial energy level alignment. A 0.2 eV downward band bending together with a 0.1 eV interfacial dipole was found at the pentacene side, whereas there was no band bending found at the CH_3NH_3PbI_3 side. The offset between CH_3NH_3PbI_3 Valance Band Maximum (VBM) and pentacene Highest Occupied Molecular Orbital (HOMO) and that between CH_3NH_3PbI_3 Conduction Band Minimum (CBM) and pentacene Lowest Unoccupied Molecular Orbital (LUMO) was determined to be 0.7 and 1.35 eV, respectively. The band alignment at this interface is favor of efficient hole transfer, which suggests pentacene as a viable HTL candidate to be explored in perovskite solar cells.

General working principles of CH3NH3PbX3 perovskite solar cells.

Science.gov (United States)

Gonzalez-Pedro, Victoria; Juarez-Perez, Emilio J; Arsyad, Waode-Sukmawati; Barea, Eva M; Fabregat-Santiago, Francisco; Mora-Sero, Ivan; Bisquert, Juan

2014-02-12

Organometal halide perovskite-based solar cells have recently realized large conversion efficiency over 15% showing great promise for a new large scale cost-competitive photovoltaic technology. Using impedance spectroscopy measurements we are able to separate the physical parameters of carrier transport and recombination in working devices of the two principal morphologies and compositions of perovskite solar cells, viz. compact thin films of CH3NH3PbI(3-x)Clx and CH3NH3PbI3 infiltrated on nanostructured TiO2. The results show nearly identical spectral characteristics indicating a unique photovoltaic operating mechanism that provides long diffusion lengths (1 μm). Carrier conductivity in both devices is closely matched, so that the most significant differences in performance are attributed to recombination rates. These results highlight the central role of the CH3NH3PbX3 semiconductor absorber in carrier collection and provide a new tool for improved optimization of perovskite solar cells. We report for the first time a measurement of the diffusion length in a nanostructured perovskite solar cell.

TEM and TED investigation of Ag/PbTe thin film bilayers.

Science.gov (United States)

Mandrino, Đorđe; Marinković, V.

Morphology and phase structure of Ag/PbTe thin film bilayers were investigated. This system was of particular interest because of interfacial reaction observed previously in an analogous Ag/SnTe system. Reaction products due to the interdiffusion of Ag with the substrate were determined as well as their orientations. They were discussed in view of the reaction products' structural relations to the PbTe.

Engineering Nanoscale Multiferroic Composites for Memory Applications with Atomic Layer Deposition of Pb(ZrxTi1-x)O3 Thin Films

Science.gov (United States)

Chien, Diana

This work focuses on the development of atomic layer deposition (ALD) for lead zirconate titanate, Pb(ZrxTi1-x)O 3 (PZT). Leveraging the surface-reaction controlled process based on alternating self-limiting surface reactions, PZT can be synthesized not only with elemental precision to realize the desired composition (Zr/Ti = 52/48) but also with outstanding conformality. The latter enables the integration of PZT with a ferromagnetic phase to realize multiferroism (MF) and magnetoelectric (ME) effect. Since PZT is one of the best known ferroelectric and piezoelectric materials due the large displacements of the Pb ions at the morphotropic phase boundary, PZT based MF composites could lead to stronger ME coupling through strain coupling at the interface. Specifically, ALD PZT thin films were synthesized by using beta-diketonate metalorganic precursors Pb(TMHD)2, Zr(TMHD)4, and Ti(O.i-Pr) 2(TMHD)2 and H2O. The number of local cycles and global cycles were regulated to achieve the desired stoichiometry and thickness, respectively. ALD of PZT was studied to obtain (100) textured PZT on Pt (111) oriented platinized silicon substrates. In order to attain a highly oriented PZT thin film, a (100) textured PbTiO3 seed layer was required because PZT orientation is governed by nucleation. MF nanocomposites were engineered using ALD PZT thin films to achieve controlled complex nanoscale structures, enabling porosity to be studied as a new additional parameter for nanocomposite architectures to enhance ME effect. Specifically, 3--6 nm-thick ALD PZT thin films were deposited to uniformly coat the walls of mesoporous cobalt ferrite (CFO) template. The PZT/CFO nanocomposites were electrically poled ex-situ and the change in magnetic moment was measured. The inverse magnetoelectric coupling coefficient, a, was determined to be 85.6 Oe-cm/mV. The in-plane results show no significant change in magnetization (1--4%) as a function of electric field, which was expected due to the effect

Structural, optical and electrical characterization of Ag doped lead chalcogenide (PbSe) thin films

Energy Technology Data Exchange (ETDEWEB)

Al-Ghamdi, A.A., E-mail: aghamdi90@hotmail.com [Department of Physics, Faculty of Science, King Abdulaziz University, Jeddah (Saudi Arabia); Al-Heniti, S. [Department of Physics, Faculty of Science, King Abdulaziz University, Jeddah (Saudi Arabia); Khan, Shamshad A. [Department of Physics, St. Andrew' s College, Gorakhpur, UP (India)

2013-03-15

Research and development efforts are currently underway to fabricate a variety of solid state devices. A good deal of information regarding the synthesis, structural, optical and electrical properties of Ag doped lead chalcogenides have been revealed. The bulk polycrystalline (PbSe){sub 100-x}Ag{sub x} ternary chalcogenides are prepared by diffusion technique. The XRD patterns recorded for the (PbSe){sub 100-x}Ag{sub x} thin films prepared by vacuum deposition technique, show that these films are polycrystalline in nature. The optical measurements reveal that the (PbSe){sub 100-x}Ag{sub x} thin films possess direct band gap and the band gap energy decreases with an increase of Ag concentration. The extinction coefficient (k) and refractive index (n) are found to be changing by increasing Ag concentration in PbSe. These results are interpreted in terms of the change in concentration of localized states due to the shift in Fermi level. The dc conductivities of (PbSe){sub 100-x}Ag{sub x} thin films are measured in temperature range 303-403 K. It is observed that the dc conductivity increases at all the temperatures with an increase of Ag content in PbSe system. The experimental data suggests that the conduction is due to thermally assisted tunneling of the charge carriers in the localized states near the band edges. The activation energy and optical band gap are found to decrease with increasing Ag concentration in lead chalcogenide and there are good agreements between these two values. - Highlights: Black-Right-Pointing-Pointer (PbSe){sub 100-x}Ag{sub x} thin films has been investigated. Black-Right-Pointing-Pointer Polycrystalline nature has been verified by X-ray diffraction. Black-Right-Pointing-Pointer Optical absorption data showed the rules of direct transitions predominate. Black-Right-Pointing-Pointer Dc conductivity increases with an increase of Ag content in PbSe system. Black-Right-Pointing-Pointer Increase of Ag concentration causes a decrease in E{sub g

Upconversion photoluminescence of epitaxial Yb{sup 3+}/Er{sup 3+} codoped ferroelectric Pb(Zr,Ti)O{sub 3} films on silicon substrates

Energy Technology Data Exchange (ETDEWEB)

Zhang, Yang, E-mail: zhangy_acd@hotmail.com [IFW Dresden, P.O. Box 270116, D-01171 Dresden (Germany); Kämpfe, Thomas [Institut für Angewandte Physik, TU Dresden, 01062 Dresden (Germany); Bai, Gongxun [Department of Applied Physics, The Hong Kong Polytechnic University, Hong Kong (China); Mietschke, Michael; Yuan, Feifei; Zopf, Michael [IFW Dresden, P.O. Box 270116, D-01171 Dresden (Germany); Abel, Stefan [IBM Research GmbH, Saümerstrasse 4, 8803 Rüschlikon (Switzerland); Eng, Lukas M. [Institut für Angewandte Physik, TU Dresden, 01062 Dresden (Germany); Hühne, Ruben [IFW Dresden, P.O. Box 270116, D-01171 Dresden (Germany); Fompeyrine, Jean [IBM Research GmbH, Saümerstrasse 4, 8803 Rüschlikon (Switzerland); Ding, Fei, E-mail: f.ding@ifw-dresden.de [IFW Dresden, P.O. Box 270116, D-01171 Dresden (Germany); Schmidt, Oliver G. [IFW Dresden, P.O. Box 270116, D-01171 Dresden (Germany); Material Systems for Nanoelectronics, Chemnitz University of Technology, Reichenhainer strasse 70, 09107 Chemnitz (Germany)

2016-05-31

Thin films of Yb{sup 3+}/Er{sup 3+} codoped Pb(Zr,Ti)O{sub 3} (PZT:Yb/Er) have been epitaxially grown on the SrTiO{sub 3} buffered Si wafer by pulsed laser deposition. Strong upconversion photoluminescence was observed in the PZT:Yb/Er thin film. Using piezoresponse force microscopy, polar domains in the PZT:Yb/Er film can be reversibly switched with a phase change of 180°. Ferroelectric hysteresis loop shape with a well-saturated response was observed. The epitaxially grown lanthanide-doped PZT on silicon opens up a promising route to the integration of luminescent functional oxides on the silicon platform. - Highlights: • Epitaxial growth of Yb{sup 3+}/Er{sup 3+} codoped Pb(Zr,Ti)O{sub 3} films on SrTiO{sub 3} buffered silicon • Upconversion emissions were obtained from the lanthanide ion doped thin films. • Saturated ferroelectric hysteresis loops were observed. • Polar domains were switched by PFM with a phase change of 180°.

Comparison of effective transverse piezoelectric coefficients e31,f of Pb(Zr,Ti)O3 thin films between direct and converse piezoelectric effects

Science.gov (United States)

Tsujiura, Yuichi; Kawabe, Saneyuki; Kurokawa, Fumiya; Hida, Hirotaka; Kanno, Isaku

2015-10-01

We evaluated the effective transverse piezoelectric coefficients (e31,f) of Pb(Zr,Ti)O3 (PZT) thin films from both the direct and converse piezoelectric effects of unimorph cantilevers. (001) preferentially oriented polycrystalline PZT thin films and (001)/(100) epitaxial PZT thin films were deposited on (111)Pt/Ti/Si and (001)Pt/MgO substrates, respectively, by rf-magnetron sputtering, and their piezoelectric responses owing to intrinsic and extrinsic effects were examined. The direct and converse |e31,f| values of the polycrystalline PZT thin films were calculated as 6.4 and 11.5-15.0 C/m2, respectively, whereas those of the epitaxial PZT thin films were calculated as 3.4 and 4.6-4.8 C/m2, respectively. The large |e31,f| of the converse piezoelectric property of the polycrystalline PZT thin films is attributed to extrinsic piezoelectric effects. Furthermore, the polycrystalline PZT thin films show a clear nonlinear piezoelectric contribution, which is the same as the Rayleigh-like behavior reported in bulk PZT. In contrast, the epitaxial PZT thin films on the MgO substrate show a piezoelectric response owing to the intrinsic and linear extrinsic effects, and no nonlinear contribution was observed.

Deposition of Cu-doped PbS thin films with low resistivity using DC sputtering

Science.gov (United States)

Soetedjo, Hariyadi; Siswanto, Bambang; Aziz, Ihwanul; Sudjatmoko

2018-03-01

Investigation of the electrical resistivity of Cu-doped PbS thin films has been carried out. The films were prepared using a DC sputtering technique. The doping was achieved by introducing the Cu dopant plate material directly on the surface of the PbS sputtering target plate. SEM-EDX data shows the Cu concentration in the PbS film to be proportional to the Cu plate diameter. The XRD pattern indicates the film is in crystalline cubic form. The Hall effect measurement shows that Cu doping yields an increase in the carrier concentration to 3.55 × 1019 cm-3 and a significant decrease in electrical resistivity. The lowest resistivity obtained was 0.13 Ωcm for a Cu concentration of 18.5%. Preferential orientation of (1 1 1) and (2 0 0) occurs during deposition.

Optical properties of Pb2 -based aggregated phases in CsBr Thin film and single crystal matrices

Science.gov (United States)

Nikl, M.; Nitsch, K.; Mihokova, E.; Polak, K.; Fabeni, P.; Pazzi, G. P.; Gurioli, M.; Phani, R.; Santucci, S.; Scacco, A.; Somma, F.

Emission characteristics of CsPbBr3 and Cs4PbBr6 aggregates in CsBr bulk and thin film matrices are reported. The emission of the former aggregated phase is peaking about 520-560 nm. It shows small Stokes shift (50 meV) related to narrow free exciton emission line of sub-nanosecond decay times. Quantum size effect was evidenced for the aggregates of 6-7 nm in diameter. The Cs4PbBr6 aggregates show emission peak at 375 nm and overall emission characteristics are similar to those of KBr: Pb, which is explained by very close local arrangement of emission centres-(PbBr6)4- octahedra-in both structures.

Crystallization behavior and domain structure in textured Pb(Zr0.52Ti0.48)O3 thin films by different annealing processes

International Nuclear Information System (INIS)

Huang, W.; Jiang, S.W.; Li, Y.R.; Zhu, J.; Zhang, Y.; Wei, X.H.; Zeng, H.Z.

2006-01-01

Amorphous Pb(Zr 0.52 Ti 0.48 )O 3 (PZT) thin films were prepared on the Pt/Ti/SiO 2 /Si substrates by radio-frequency magnetron sputtering at room temperature. After rapid thermal annealing (RTA) and conventional furnace annealing (CFA) at different temperatures, the films were transformed into polycrystalline PZT thin films with (111) and (100) orientation, respectively. The phase formation and ferroelectric domains correlated with different orientation were systematically investigated by X-ray diffraction and piezoresponse force microscopy. The results showed that the perovskite PZT crystal with [111] orientation hetero-nucleated preferentially on top of the PtPb intermetallic phase at the PZT/Pt interface during RTA process. It is of interest to find that the domain self-organized into a structure with rounded shape at the early stage of crystallization. While the nucleation of the films treated by CFA dominantly homo-nucleated, thus the (100) orientation grains with minimum surface energy were easy to grow. The texture effects on ferroelectric properties of PZT films were also discussed in relation to the domain structure

Nanocrystalline CsPbBr3 thin films: a grain boundary opto-electronic study

Science.gov (United States)

Conte, G.; Somma, F.; Nikl, M.

2005-01-01

CsPbBr3 thin films with nanocrystalline morphology were studied by using optoelectronic techniques to infer the grain boundary region in respect of the crystallite's interior performance. Co-evaporation of puri-fied powders or crushed Bridgman single crystals were used to deposit materials and compare recombina-tion mechanism and dielectric relaxation processes within them. Nanosecond photoconduction decay was observed on both materials as well as activated hopping transport. An asymmetric Debye-like peak was evaluated from impedance spectroscopy with a FWHM value, which remains constant for 1.25 +/- 0.02 deca-des, addressing the presence of a tight conductivity relaxation times distribution. The evaluated activation energy, equal to 0.72 +/- 0.05 eV, similar to that estimated by DC measurements, is well smaller then that expected for an intrinsic material with exciton absorption at 2.36 eV. A simple model based on Voigt's elements was used to model the electronic characteristics of these nanostructured materials, to discuss observed results and define the role played by grain boundaries.

Enhanced piezoelectric properties of (110)-oriented PbZr1−xTixO3 epitaxial thin films on silicon substrates at shifted morphotropic phase boundary

NARCIS (Netherlands)

Wan, X.; Houwman, Evert Pieter; Steenwelle, Ruud Johannes Antonius; van Schaijk, R.; Nguyen, Duc Minh; Dekkers, Jan M.; Rijnders, Augustinus J.H.M.

2014-01-01

Piezoelectrical, ferroelectrical, and structural properties of epitaxial pseudocubic (110)pc oriented 500 nm thick PbZr1−xTixO3 thin films, prepared by pulsed laser deposition on (001) silicon substrates, were measured as a function of composition. The dependence of the measurement data on the Ti

Investigation of optical and electrical properties of Pb(Zr1-xTix)O3 thin films on different substrates

International Nuclear Information System (INIS)

Kafadaryan, Eugenia; Aghamalyan, Natella; Nikogosyan, Sergey

2006-01-01

Pb(Zr 1-x Ti x )O 3 (PZT) polycrystalline thin films were prepared by sol-gel and pulsed laser deposition techniques on Pt/Ti/SiO 2 /Si (Pt) and SrRuO 3 /LaAlO 3 (SRO/LAO) substrates. Infrared reflectivity spectroscopy with oblique (45deg) light incidence revealed both the 3LO (688cm -1 ) phonon lineshape asymmetry decrease with increasing in thickness and the thinner, disordered boundary layer at the SRO/PZT interface independently of the film preparation method. The fatigue properties of PZT films were studied for various crystallographic orientations. It was observed that in the 52/48 PZT/SRO/LAO film, when the field is applied along the (001) direction, excellent fatigue resistance is obtained. (author)

Molecular Self-Assembly Fabrication and Carrier Dynamics of Stable and Efficient CH3 NH3 Pb(1-x) Snx I3 Perovskite Solar Cells.

Science.gov (United States)

Fan, Jiandong; Liu, Chong; Li, Hongliang; Zhang, Cuiling; Li, Wenzhe; Mai, Yaohua

2017-10-09

The Sn-based perovskite solar cells (PSCs) provide the possibility of swapping the Pb element toward developing toxic-free PSCs. Here, we innovatively employed a molecular self-assembly approach to obtain a series CH 3 NH 3 Pb (1-x) Sn x I 3 (0≤x≤1) perovskite thin films with full coverage. The optimized planar CH 3 NH 3 Pb 0.75 Sn 0.25 I 3 PSC with inverted structure was consequently realized with a maximum power conversion efficiency (PCE) over 14 %, which displayed a stabilized power output (SPO) over 12 % within 200 s at 0.6 V forward bias. Afterward, we investigated the factors that limited the efficiency improvement of hybrid Sn-Pb PSCs, and analyzed the possible reason of the hysteresis effect occurred even in the inverted structure cell. Particularly, the oxidation of hybrid Sn-Pb perovskite thin film was demonstrated to be the main reason that limited its further efficiency improvement. The imbalance of charge transport was intensified, which was associated with the increased hole defect-state density and decreased electron defect-state density after Sn was introduced. This study helps tackle the intractable issue regarding the toxic Pb in perovskite devices and is a step forward toward realizing lead-free PSCs with high stability and efficiency. © 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

Tuning metal-insulator behavior in LaTiO3/SrTiO3 heterostructures integrated directly on Si(100) through control of atomic layer thickness

Science.gov (United States)

Ahmadi-Majlan, Kamyar; Chen, Tongjie; Lim, Zheng Hui; Conlin, Patrick; Hensley, Ricky; Chrysler, Matthew; Su, Dong; Chen, Hanghui; Kumah, Divine P.; Ngai, Joseph H.

2018-05-01

We present electrical and structural characterization of epitaxial LaTiO3/SrTiO3 heterostructures integrated directly on Si(100). By reducing the thicknesses of the heterostructures, an enhancement in carrier-carrier scattering is observed in the Fermi liquid behavior, followed by a metal to insulator transition in the electrical transport. The insulating behavior is described by activated transport, and its onset occurs near an occupation of 1 electron per Ti site within the SrTiO3, providing evidence for a Mott driven transition. We also discuss the role that structure and gradients in strain could play in enhancing the carrier density. The manipulation of Mott metal-insulator behavior in oxides grown directly on Si opens the pathway to harnessing strongly correlated phenomena in device technologies.

Deposition and characteristics of PbS thin films by an in-situ solution chemical reaction process

Energy Technology Data Exchange (ETDEWEB)

Ji, Junna; Ji, Huiming; Wang, Jian; Zheng, Xuerong; Lai, Junyun; Liu, Weiyan; Li, Tongfei [School of Materials Science and Engineering, Key Laboratory for Advanced Ceramics and Machining Technology of Ministry of Education, Tianjin University, Tianjin 300072 (China); Ma, Yuanliang; Li, Haiqin; Zhao, Suqin [College of Physics and Electronic Information Engineering, Qinghai University for Nationalities, Xining 810007 (China); Jin, Zhengguo, E-mail: zhgjin@tju.edu.cn [School of Materials Science and Engineering, Key Laboratory for Advanced Ceramics and Machining Technology of Ministry of Education, Tianjin University, Tianjin 300072 (China)

2015-09-01

Preferential oriented and uniform PbS thin films were deposited by a room temperature in-situ solution chemical reaction process, in which the lead nitrate as precursor in a form of thin solid films from lead precursor solution was used to react with ammonium sulfide ethanol solution. Influence of 1-butanol addition in the lead precursor solution, Pb:S molar ratios in the separate cationic and anionic solutions, deposition cycle numbers and annealing treatment in Ar atmosphere on structure, morphology, chemical composition and optical absorption properties of the deposited PbS films were investigated based on X-ray diffraction, field emission scanning electron microscopy, energy dispersive spectrometer, atomic force microscopy, selected area electron diffraction, UV–vis, near infrared ray and fourier transform infrared spectroscopy measurements. The results showed that the deposited PbS thin films had a cubic structure and highly preferred orientation along with the plane (100). The deposition rate of single-layer was stable, about 30 nm in thickness per deposition cycle. - Highlights: • Time-efficiency synthetic method for the preparation of lead sulfide (PbS) films • Effect of 1-butanol addition into cationic precursor solution is discussed. • Growth rate of the PbS films is stable at about 30 nm per cycle.

Observation of lower defect density in CH{sub 3}NH{sub 3}Pb(I,Cl){sub 3} solar cells by admittance spectroscopy

Energy Technology Data Exchange (ETDEWEB)

Jiang, Minlin; Lan, Fei; Tao, Quan; Li, Guangyong, E-mail: gaod@pitt.edu, E-mail: gul6@pitt.edu [Department of Electrical and Computer Engineering, University of Pittsburgh, Pittsburgh, Pennsylvania 15260 (United States); Zhao, Bingxin [Department of Chemical and Petroleum Engineering, University of Pittsburgh, Pittsburgh, Pennsylvania 15260 (United States); Key Laboratory of Advanced Functional Materials, College of Materials Science and Engineering, Beijing University of Technology, Beijing 100124 (China); Wu, Jiamin; Gao, Di, E-mail: gaod@pitt.edu, E-mail: gul6@pitt.edu [Department of Chemical and Petroleum Engineering, University of Pittsburgh, Pittsburgh, Pennsylvania 15260 (United States)

2016-06-13

The introduction of Cl into CH{sub 3}NH{sub 3}PbI{sub 3} precursors is reported to enhance the performance of CH{sub 3}NH{sub 3}PbI{sub 3} solar cell, which is attributed to the significantly increased diffusion lengths of carriers in CH{sub 3}NH{sub 3}Pb(I,Cl){sub 3} solar cell. It has been assumed but never experimentally approved that the defect density in CH{sub 3}NH{sub 3}Pb(I,Cl){sub 3} solar cell should be reduced according to the higher carrier lifetime observed from photoluminescence (PL) measurement. We have fabricated CH{sub 3}NH{sub 3}Pb(I,Cl){sub 3} solar cell by adding a small amount of Cl source into CH{sub 3}NH{sub 3}PbI{sub 3} precursor. The performance of CH{sub 3}NH{sub 3}Pb(I,Cl){sub 3} solar cell is significantly improved from 15.39% to 18.60%. Results from scanning electron microscopy and X-ray diffraction indicate that the morphologies and crystal structures of CH{sub 3}NH{sub 3}PbI{sub 3} and CH{sub 3}NH{sub 3}Pb(I,Cl){sub 3} thin films remain unchanged. Open circuit voltage decay and admittance spectroscopy characterization jointly approve that Cl plays an extremely important role in suppressing the formation of defects in perovskite solar cells.

Rietveld refinement of the crystal structure of perovskite solar cells using CH3NH3PbI3 and other compounds

Science.gov (United States)

Ando, Yuji; Ohishi, Yuya; Suzuki, Kohei; Suzuki, Atsushi; Oku, Takeo

2018-01-01

The crystal structures of perovskite thin films including CH3NH3PbI3, CH3NH3Pb1-xSbxI3, and CH3NH3PbI3-yCly in the solar cell configuration were studied by using Rietveld refinement. For the CH3NH3PbI3 and CH3NH3Pb1-xSbxI3 samples, satisfactory agreement with the measured profiles was obtained with a weighted profile R-factor (Rwp) of as low as 3%. It was shown that the site occupancy of methylammonium (MA) was decreased in the antimonized cell due to the compensation effect of an increased positive charge brought about by replacing Pb2+ with Sb3+. Photovoltaic measurements showed that the power conversion efficiency was enhanced by adding a small amount of Sb to the CH3NH3PbI3 cell, but it was monotonically decreased as the mole fraction of Sb exceeded 0.03. This variation of the conversion efficiency was considered as a result of suppressed crystallization of PbI2 and carrier recombination via MA vacancies in the antimonized cells. In the case of CH3NH3PbI2.88Cl0.12 sample, the agreement with the measured profile with an Rwp of as high as 7% suggested the co-existence of cubic and tetragonal phases in the chlorinated cell.

Electric Properties of Pb(Sb1/2Nb1/2)O3 PbTiO3 PbZrO3 Ceramics

Science.gov (United States)

Kawamura, Yasushi; Ohuchi, Hiromu

1994-09-01

Solid-solution ceramics of ternary system xPb(Sb1/2Nb1/2)O3 yPbTiO3 zPbZrO3 were prepared by the solid-state reaction of powder materials. Ceramic, electric, dielectric and piezoelectric properties and crystal structures of the system were studied. Sintering of the system xPb(Sb1/2Nb1/2)O3 yPbTiO3 zPbZrO3 is much easier than that of each end composition, and well-sintered high-density ceramics were obtained for the compositions near the morphotropic transformation. Piezoelectric ceramics with high relative dielectric constants, high radial coupling coefficient and low resonant resistance were obtained for the composition near the morphotropic transformation. The composition Pb(Sb1/2Nb1/2)0.075Ti0.45Zr0.475O3 showed the highest dielectric constant (ɛr=1690), and the composition Pb(Sb1/2Nb1/2)0.05Ti0.45Zr0.5O3 showed the highest radial coupling coefficient (kp=64%).

Configuration and local elastic interaction of ferroelectric domains and misfit dislocation in PbTiO3/SrTiO3 epitaxial thin films

Directory of Open Access Journals (Sweden)

Takanori Kiguchi, Kenta Aoyagi, Yoshitaka Ehara, Hiroshi Funakubo, Tomoaki Yamada, Noritaka Usami and Toyohiko J Konno

2011-01-01

Full Text Available We have studied the strain field around the 90° domains and misfit dislocations in PbTiO3/SrTiO3 (001 epitaxial thin films, at the nanoscale, using the geometric phase analysis (GPA combined with high-resolution transmission electron microscopy (HRTEM and high-angle annular dark field––scanning transmission electron microscopy (HAADF-STEM. The films typically contain a combination of a/c-mixed domains and misfit dislocations. The PbTiO3 layer was composed from the two types of the a-domain (90° domain: a typical a/c-mixed domain configuration where a-domains are 20–30 nm wide and nano sized domains with a width of about 3 nm. In the latter case, the nano sized a-domain does not contact the film/substrate interface; it remains far from the interface and stems from the misfit dislocation. Strain maps obtained from the GPA of HRTEM images show the elastic interaction between the a-domain and the dislocations. The normal strain field and lattice rotation match each other between them. Strain maps reveal that the a-domain nucleation takes place at the misfit dislocation. The lattice rotation around the misfit dislocation triggers the nucleation of the a-domain; the normal strains around the misfit dislocation relax the residual strain in a-domain; then, the a-domain growth takes place, accompanying the introduction of the additional dislocation perpendicular to the misfit dislocation and the dissociation of the dislocations into two pairs of partial dislocations with an APB, which is the bottom boundary of the a-domain. The novel mechanism of the nucleation and growth of 90° domain in PbTiO3/SrTiO3 epitaxial system has been proposed based on above the results.

Interfacial Charge-Carrier Trapping in CH3NH3PbI3-Based Heterolayered Structures Revealed by Time-Resolved Photoluminescence Spectroscopy.

Science.gov (United States)

Yamada, Yasuhiro; Yamada, Takumi; Shimazaki, Ai; Wakamiya, Atsushi; Kanemitsu, Yoshihiko

2016-06-02

The fast-decaying component of photoluminescence (PL) under very weak pulse photoexcitation is dominated by the rapid relaxation of the photoexcited carriers into a small number of carrier-trapping defect states. Here, we report the subnanosecond decay of the PL under excitation weaker than 1 nJ/cm(2) both in CH3NH3PbI3-based heterostructures and bare thin films. The trap-site density at the interface was evaluated on the basis of the fluence-dependent PL decay profiles. It was found that high-density defects determining the PL decay dynamics are formed near the interface between CH3NH3PbI3 and the hole-transporting Spiro-OMeTAD but not at the CH3NH3PbI3/TiO2 interface and the interior regions of CH3NH3PbI3 films. This finding can aid the fabrication of high-quality heterointerfaces, which are required improving the photoconversion efficiency of perovskite-based solar cells.

Effect of band-aligned double absorber layers on photovoltaic characteristics of chemical bath deposited PbS/CdS thin film solar cells.

Science.gov (United States)

Ho Yeon, Deuk; Chandra Mohanty, Bhaskar; Lee, Seung Min; Soo Cho, Yong

2015-09-23

Here we report the highest energy conversion efficiency and good stability of PbS thin film-based depleted heterojunction solar cells, not involving PbS quantum dots. The PbS thin films were grown by the low cost chemical bath deposition (CBD) process at relatively low temperatures. Compared to the quantum dot solar cells which require critical and multistep complex procedures for surface passivation, the present approach, leveraging the facile modulation of the optoelectronic properties of the PbS films by the CBD process, offers a simpler route for optimization of PbS-based solar cells. Through an architectural modification, wherein two band-aligned junctions are stacked without any intervening layers, an enhancement of conversion efficiency by as much as 30% from 3.10 to 4.03% facilitated by absorption of a wider range of solar spectrum has been obtained. As an added advantage of the low band gap PbS stacked over a wide gap PbS, the devices show stability over a period of 10 days.

Preparation of nanostructured PbS thin films as sensing element for NO{sub 2} gas

Energy Technology Data Exchange (ETDEWEB)

Kaci, S., E-mail: k_samira05@yahoo.fr [Centre de Recherche en Technologie des Semi-conducteurs pour l’Energétique (CRTSE) Division Couches Minces et Interfaces, 02 Bd Frantz Fanon, B.P. 140, 7 Merveilles, 16038 Algiers (Algeria); Keffous, A.; Hakoum, S. [Centre de Recherche en Technologie des Semi-conducteurs pour l’Energétique (CRTSE) Division Couches Minces et Interfaces, 02 Bd Frantz Fanon, B.P. 140, 7 Merveilles, 16038 Algiers (Algeria); Trari, M. [Université des Sciences et Technologies Houari Boumediene (USTHB), Laboratoire de Stockage et de Valorisation des Eneriges Renouvelables, Faculté de Chimie, BP 32, EL Alia, 16111 Bab Ezzouar, Algiers (Algeria); Mansri, O.; Menari, H. [Centre de Recherche en Technologie des Semi-conducteurs pour l’Energétique (CRTSE) Division Couches Minces et Interfaces, 02 Bd Frantz Fanon, B.P. 140, 7 Merveilles, 16038 Algiers (Algeria)

2014-06-01

In this work, we demonstrate that semiconducting films of A{sub IV}B{sub VI} compounds, in particular, of nanostructured lead sulfide (PbS) which prepared by chemical bath deposition (CBD), can be used as a sensing element for nitrogen dioxide (NO{sub 2}) gas. The CBD method is versatile, simple in implementation and gives homogeneous semiconductor structures. We have prepared PbS nanocrystalline thin film at different reaction baths and temperatures. In the course of deposition, variable amounts of additives, such as organic substances among them, were introduced into the baths. The energy dispersive analysis (EDX) confirms the chemical composition of PbS films. A current–voltage (I–V) characterization of Pd/nc-PbS/a-SiC:H pSi(100)/Al Schottky diode structures were studied in the presence of NO{sub 2} gas. The gas sensing behavior showed that the synthesized PbS nanocrystalline thin films were influenced by NO{sub 2} gas at room temperature. The results can be used for developing an experimental sensing element based on chemically deposited nanostructured PbS films which can be applicable in gas sensors.

Synthesis and characterization of Ba_0_._5Pb_0_._5TiO_3 perovskite - type thin films deposited by spin coating at low temperatures

International Nuclear Information System (INIS)

Wermuth, T.B.; Wiederkehr, N.A.; Alves, A.K.; Bergmann, C.P.

2014-01-01

In this paper we present a non-aqueous sol-gel route for the obtention of solid compounds and thin films of oxide type- perovskite ABO_3, such as Ba_0_._5 Pb_0_._5 TiO_3, synthesized by sol - gel route with subsequent heat treatment. The solid compounds were characterized by X-ray diffraction (XRD) techniques and thermal analysis (TGA / DTA). The thin film was obtained by using spin-coating techniques at low temperatures onto commercial substrates of polymethylmethacrylate (PMMA) and characterized by contact angle, atomic force microscopy (AFM) and scanning electron microscopy (SEM). The results show that the films present microstructures and roughness directly related to annealing temperatures, characterized by the formation of crystalline nanostructures with surface regularity and transparency. (author)

The energy level alignment at the CH{sub 3}NH{sub 3}PbI{sub 3}/pentacene interface

Energy Technology Data Exchange (ETDEWEB)

Ji, Gengwu [Shanghai Synchrotron Radiation Facility, Shanghai Institute of Applied Physics, Chinese Academy of Sciences, Shanghai 201204 (China); University of Chinese Academy of Science, Beijing 100049 (China); Zhao, Bin; Song, Fei [Shanghai Synchrotron Radiation Facility, Shanghai Institute of Applied Physics, Chinese Academy of Sciences, Shanghai 201204 (China); Zheng, Guanhaojie; Zhang, Xiaonan [Shanghai Synchrotron Radiation Facility, Shanghai Institute of Applied Physics, Chinese Academy of Sciences, Shanghai 201204 (China); University of Chinese Academy of Science, Beijing 100049 (China); Shen, Kongchao [Department of Physics, Zhejiang University, Hangzhou 310027 (China); Yang, Yingguo [Shanghai Synchrotron Radiation Facility, Shanghai Institute of Applied Physics, Chinese Academy of Sciences, Shanghai 201204 (China); Chen, Shi, E-mail: ChenShi@ntu.edu.sg [Division of Physics and Applied Physics, School of Physical and Mathematical Sciences, Nanyang Technological University, 21 Nanyang Link, Singapore 637371 (Singapore); Gao, Xingyu, E-mail: gaoxingyu@sinap.ac.cn [Shanghai Synchrotron Radiation Facility, Shanghai Institute of Applied Physics, Chinese Academy of Sciences, Shanghai 201204 (China)

2017-01-30

Highlights: • The Energy Level Alignment at the CH{sub 3}NH{sub 3}PbI{sub 3}/Pentacene Interface was resolved experimentally. • The downward band bending and the dipole found at the pentacene side would favorably drive holes away from the interface into pentacene. • A ∼0.7 eV offset between pentacene HOMO and CH{sub 3}NH{sub 3}PbI{sub 3} VBM would be in favor of hole transfer whereas a ∼1.35 eV offset between pentacene LUMO and CH{sub 3}NH{sub 3}PbI{sub 3} CBM should efficiently block the unwanted electron transfer from perovskite to pentacene. • Pentacene could be a viable hole transfer material candidate on perovskite to be explored in perovskite devices. - Abstract: Pentacene thin film on CH{sub 3}NH{sub 3}PbI{sub 3} was studied by in-situ X-ray photoelectron spectroscopy and ultraviolet photoelectron spectroscopy to determine their interfacial energy level alignment. A 0.2 eV downward band bending together with a 0.1 eV interfacial dipole was found at the pentacene side, whereas there was no band bending found at the CH{sub 3}NH{sub 3}PbI{sub 3} side. The offset between CH{sub 3}NH{sub 3}PbI{sub 3} Valance Band Maximum (VBM) and pentacene Highest Occupied Molecular Orbital (HOMO) and that between CH{sub 3}NH{sub 3}PbI{sub 3} Conduction Band Minimum (CBM) and pentacene Lowest Unoccupied Molecular Orbital (LUMO) was determined to be 0.7 and 1.35 eV, respectively. The band alignment at this interface is favor of efficient hole transfer, which suggests pentacene as a viable HTL candidate to be explored in perovskite solar cells.

Spin-coating deposition of PbS and CdS thin films for solar cell application

Energy Technology Data Exchange (ETDEWEB)

Patel, Jayesh; Mighri, Frej [Laval University, CREPEC, Department of Chemical Engineering, Quebec, QC (Canada); Ajji, Abdellah [Ecole Polytechnique, CREPEC, Chemical Engineering Department, Montreal, QC (Canada); Tiwari, Devendra; Chaudhuri, Tapas K. [Charotar University of Science and Technology (CHARUSAT), Dr. K.C. Patel Research and Development Centre, Anand District, Gujarat (India)

2014-12-15

In this work, we describe a simple spin-coating deposition technique for lead sulphide (PbS) and cadmium sulphide (CdS) films from a methanolic metal-thiourea complex. The characterization of the films by X-ray diffraction and X-ray photoelectron spectroscopy techniques revealed that pure cubic phase PbS and CdS layers were formed via this method. As shown by atomic force microscopy and scanning electron microscopy results, both films were homogeneous and presented a smooth surface. Optical properties showed that the energy band gap of PbS and CdS films were around 1.65 and 2.5 eV, respectively. The PbS film is p-type in nature with an electrical conductivity of around 0.8 S/cm. The hole concentration and mobility were 2.35 x 10{sup 18} cm{sup -3} and 2.16 x 10{sup -3} cm{sup 2}/V/s, respectively, as determined from Hall measurement. Both films were used to develop a thin film solar cell device of graphite/PbS/CdS/ITO/glass. Device characterization showed the power conversion efficiency of around 0.24 %. The corresponding open circuit voltage, short circuit current and fill factor were 0.570 V, 1.32 mA/cm{sup 2} and 0.32, respectively. (orig.)

Research Update: Enhanced energy storage density and energy efficiency of epitaxial Pb0.9La0.1(Zr0.52Ti0.48O3 relaxor-ferroelectric thin-films deposited on silicon by pulsed laser deposition

Directory of Open Access Journals (Sweden)

Minh D. Nguyen

2016-08-01

Full Text Available Pb0.9La0.1(Zr0.52Ti0.48O3 (PLZT relaxor-ferroelectric thin films were grown on SrRuO3/SrTiO3/Si substrates by pulsed laser deposition. A large recoverable storage density (Ureco of 13.7 J/cm3 together with a high energy efficiency (η of 88.2% under an applied electric field of 1000 kV/cm and at 1 kHz frequency was obtained in 300-nm-thick epitaxial PLZT thin films. These high values are due to the slim and asymmetric hysteresis loop when compared to the values in the reference undoped epitaxial lead zirconate titanate Pb(Zr0.52Ti0.48O3 ferroelectric thin films (Ureco = 9.2 J/cm3 and η = 56.4% which have a high remanent polarization and a small shift in the hysteresis loop, under the same electric field.

Unraveling current hysteresis effects in regular-type C60-CH3NH3PbI3 heterojunction solar cells.

Science.gov (United States)

Chen, Lung-Chien; Lin, Yu-Shiang; Tang, Po-Wen; Tai, Chao-Yi; Tseng, Zong-Liang; Lin, Ja-Hon; Chen, Sheng-Hui; Kuo, Hao-Chung

2017-11-23

Comprehensive studies were carried out to understand the origin of the current hysteresis effects in highly efficient C 60 -CH 3 NH 3 PbI 3 (MAPbI 3 ) heterojunction solar cells, using atomic-force microscopy, transmittance spectra, photoluminescence spectra, X-ray diffraction patterns and a femtosecond time-resolved pump-probe technique. The power conversion efficiency (PCE) of C 60 -MAPbI 3 solar cells can be increased to 18.23% by eliminating the point (lattice) defects in the MAPbI 3 thin film which is fabricated by using the one-step spin-coating method with toluene washing treatment. The experimental results show that the point defects and surface defects of the MAPbI 3 thin films can be minimized by varying the dropping time of the washing solvent. The point defects (surface defects) can be reduced with an (a) increase (decrease) in the dropping time, resulting in an optimized dropping time for obtaining the defect-minimized MAPbI 3 thin film deposited on top of the C 60 thin film. Consequently, the formation of the defect-minimized MAPbI 3 thin film allows for high-efficiency MAPbI 3 solar cells.

Nanosecond Characterization of Regional Domain Imprint from Fast Domain Switching Currents in Pb(Zr,Ti)O_3 Thin Films

International Nuclear Information System (INIS)

Jun Jiang; An-Quan Jiang

2016-01-01

The traditional imprint characterization of ferroelectric thin films estimates imprint time dependence of the mean coercive voltage of all domains from a polarization-voltage hysteresis loop, which shows a semilogarithmic time dependence above an initial imprint time of τ_0 > 1 μs at room temperature. Below τ_0, the imprint effect is believed to be weak. In consideration of region-by-region domain reversal under a rising pulsed voltage with ordered coercive voltages increasing from zero up to the maximum applied voltage during capacitor charging time, we can estimate the imprinted coercive voltage of each domain from domain switching current transient separately with imprint time as short as 20 ns. In disagreement with the previous observations, all imprinted coercive voltages for the domains in Pt/Pb(Zr_0_._4Ti_0_._6)O_3/Pt thin-film capacitors show step-like increases at two characteristic times of 300 ns and 0.27s. The imprint effect is surprisingly strong enough even at shortened time down to 20 ns without any evidence of weakening. (paper)

A digital output piezoelectric accelerometer using a Pb(Zr, Ti)O3 thin film array electrically connected in series

International Nuclear Information System (INIS)

Kobayashi, T; Okada, H; Maeda, R; Itoh, T; Masuda, T

2010-01-01

A digital output piezoelectric accelerometer is proposed to realize an ultra-low power consumption wireless sensor node. The accelerometer has patterned piezoelectric thin films (piezoelectric plates) electrically connected in series accompanied by CMOS switches at the end of some of the piezoelectric plates. The connected piezoelectric plates amplify the output voltage without the use of amplifiers. The CMOS switches turn on when the output voltage of the piezoelectric plates is higher than the CMOS threshold voltage. The piezoelectric accelerometer converts the acceleration into a number of on-state CMOS switches, which can be called the digital output. The proposed digital output piezoelectric accelerometer, using Pb(Zr, Ti)O 3 (PZT) thin films as the piezoelectric material, was fabricated through a microelectromechanical system (MEMS) microfabrication process. The output voltage was found to be amplified by the number of connected piezoelectric plates. The DC output voltage obtained by using an AC to DC conversion circuit is proportional to the number of connections. The results show the potential for realizing the proposed digital output piezoelectric accelerometer

Preferential Creation of Polar Translational Boundaries by Interface Engineering in Antiferroelectric PbZrO3 Thin Films

OpenAIRE

Wei XK; Vaideeswaran K; Sandu CS; Jia CL; Setter N

2015-01-01

Polar translational boundaries (PTBs) are preferentially created in antiferroelectric PbZrO3 films through interfacial engineering. Probe corrected scanning transmission electron microscopy studies reveal that RIII 1 and RI 1 type PTBs are favorably created in PbZrO3/BaZrO3/SrTiO3 and PbZrO3/SrTiO3 films respectively. The relationship between interfacial strain and the internal strain of boundaries is the driving force for the selective formation of PTBs.

Combined effect of preferential orientation and Zr/Ti atomic ratio on electrical properties of Pb(ZrxTi1-x)O3 thin films

International Nuclear Information System (INIS)

Gong Wen; Li Jingfeng; Chu Xiangcheng; Gui Zhilun; Li Longtu

2004-01-01

Lead zirconate titanate [Pb(Zr x Ti 1-x )O 3 , PZT] thin films with various compositions, whose Zr/Ti ratio were varied as 40/60, 48/52, 47/53, and 60/40, were deposited on Pt(111)/Ti/SiO 2 /Si substrates by sol-gel method. A seeding layer was introduced between the PZT layer and the bottom electrode to control the texture of overlaid PZT thin films. A single perovskite PZT thin film with absolute (100) texture was obtained, when lead oxide was used as the seeding crystal, whereas titanium dioxide resulted in highly [111]-oriented PZT films. The dielectric and ferroelectric properties of PZT films with different preferential orientations were evaluated systemically as a function of composition. The maximums of relative dielectric constant were obtained in the morphotropic phase boundary region for both (100)- and (111)-textured PZT films. The ferroelectric properties also greatly depend on films' texture and composition. The intrinsic and extrinsic contributions to dielectric and ferroelectric properties were discussed

Morphology and stress study of nanostructured porous silicon as a substrate for PbTe thin films growth by electrochemical process

Directory of Open Access Journals (Sweden)

Claudia Renata Borges Miranda

2004-12-01

Full Text Available Porous silicon layers (PSL were produced by stain etching from a HF:HNO3 500:1 mixture with etching time varying in the range of 1 up to 10 min. The samples have presented nanometric porosity as a function of etching time, characteristic of heavily doped p type silicon. The residual stress and the correlation length of the layers were obtained through the analysis of the micro-Raman spectra using a phonon confinement model including a term to account for the amorphous phase. The residual compressive stress tends to increase as expected due to the contribution of smaller crystallites to be more representative as the etching time increases. PbTe thin films were electrodeposited on PSL from aqueous alkaline solutions of Pb(CH3COO2, disodium salt of ethylendiaminetetraacetic acid (EDTA and TeO2 by galvanostatic and potentiostatic method. It was also obtained nanostructured PbTe thin films with polycrystalline morphology evidenced by X-ray Diffraction (XRD spectra. Scanning Electron Microscopy (SEM analysis has demonstrated good films reproducibility with an average grain size of 100 nm.

Facile synthesis of CsPbBr3/PbSe composite clusters.

Science.gov (United States)

Nguyen, Thang Phan; Ozturk, Abdullah; Park, Jongee; Sohn, Woonbae; Lee, Tae Hyung; Jang, Ho Won; Kim, Soo Young

2018-01-01

In this work, CsPbBr 3 and PbSe nanocomposites were synthesized to protect perovskite material from self-enlargement during reaction. UV absorption and photoluminescence (PL) spectra indicate that the addition of Se into CsPbBr 3 quantum dots modified the electronic structure of CsPbBr 3 , increasing the band gap from 2.38 to 2.48 eV as the Cs:Se ratio increased to 1:3. Thus, the emission color of CsPbBr 3 perovskite quantum dots was modified from green to blue by increasing the Se ratio in composites. According to X-ray diffraction patterns, the structure of CsPbBr 3 quantum dots changed from cubic to orthorhombic due to the introduction of PbSe at the surface. Transmission electron microscopy and X-ray photoemission spectroscopy confirmed that the atomic distribution in CsPbBr 3 /PbSe composite clusters is uniform and the composite materials were well formed. The PL intensity of a CsPbBr 3 /PbSe sample with a 1:1 Cs:Se ratio maintained 50% of its initial intensity after keeping the sample for 81 h in air, while the PL intensity of CsPbBr 3 reduced to 20% of its initial intensity. Therefore, it is considered that low amounts of Se could improve the stability of CsPbBr 3 quantum dots.

Magnetically tunable dielectric, impedance and magnetoelectric response in MnFe{sub 2}O{sub 4}/(Pb{sub 1−x}Sr{sub x})TiO{sub 3} composites thin films

Energy Technology Data Exchange (ETDEWEB)

Bala, Kanchan, E-mail: bala.kanchan1987@gmail.com [Department of Physics, Himachal Pradesh University, Shimla 171005 (India); Kotnala, R.K. [CSIR, National Physical Laboratory, Dr. K.S. Krishnan Road, New Delhi 110012 (India); Negi, N.S., E-mail: nsn_phy_hpu@yahoo.com [Department of Physics, Himachal Pradesh University, Shimla 171005 (India)

2017-02-15

We have synthesized piezomagnetic–piezoelectric composites thin films MnFe{sub 2}O{sub 4}/(Pb{sub 1−x}Sr{sub x})TiO{sub 3}, where x=0.1, 0.2, and 0.3, using the metalorganic deposition (MOD) reaction method. The structural and microstructural analysis using the X-ray diffraction (XRD), AFM, and SEM reveals the presence of homogenous growth of both pervoskite and spinel phases in the composite films. Our results show that all the composites films exhibit good multiferroic as well as considerable magnetoelectric coupling. The impedance (Z′ and Z″) and electrical modulus (M′ and M″) Nyquist plots show distinct electrical responses with the magnetic field. Our analyses suggest that this electrical response arises due to the coexistence of the high resistive phase and the comparatively conductive phase in the MFO/PST composite films. The maximum magnetoelectric coefficient (α) is found to be 4.29 V Oe{sup −1} cm{sup −1} and 2.82 V Oe{sup −1} cm{sup −1} for compositions x=0.1 and 0.2. These values are substantially larger than those reported for bilayer composites thin films in literature and make them interesting for room temperature device applications. - Highlights: • Influence of Sr doping on multiferroic and magnetoelectric properties composites thin films of MnFe{sub 2}O{sub 4} and (Pb, Sr)TiO{sub 3}. • Dielectric constant and dielectric loss with application of magnetic field. • Magnetically tunable AC electrical properties. • Magnetoelectric coupling in MnFe{sub 2}O{sub 4}/(Pb, Sr)TiO{sub 3} composite films by passive method.

Optimization of synthesis conditions of PbS thin films grown by chemical bath deposition using response surface methodology

Energy Technology Data Exchange (ETDEWEB)

Yücel, Ersin, E-mail: dr.ersinyucel@gmail.com [Department of Physics, Faculty of Arts and Sciences, Mustafa Kemal University, 31034 Hatay (Turkey); Yücel, Yasin; Beleli, Buse [Department of Chemistry, Faculty of Arts and Sciences, Mustafa Kemal University, 31034 Hatay (Turkey)

2015-09-05

Highlights: • For the first time, RSM and CCD used for optimization of PbS thin film. • Tri-sodium citrate, deposition time and temperature were independent variables. • PbS thin film band gap value was 2.20 eV under the optimum conditions. • Quality of the film was improved after chemometrics optimization. - Abstract: In this study, PbS thin films were synthesized by chemical bath deposition (CBD) under different deposition parameters. Response surface methodology (RSM) was used to optimize synthesis parameters including amount of tri-sodium citrate (0.2–0.8 mL), deposition time (14–34 h) and deposition temperature (26.6–43.4 °C) for deposition of the films. 5-level-3-factor central composite design (CCD) was employed to evaluate effects of the deposition parameters on the response (optical band gap of the films). The significant level of both the main effects and the interaction are investigated by analysis of variance (ANOVA). The film structures were characterized by X-ray diffractometer (XRD). Morphological properties of the films were studied with a scanning electron microscopy (SEM). The optical properties of the films were investigated using a UV–visible spectrophotometer. The optimum amount of tri-sodium citrate, deposition time and deposition temperature were found to be 0.7 mL, 18.07 h and 30 °C respectively. Under these conditions, the experimental band gap of PbS was 2.20 eV, which is quite good correlation with value (1.98 eV) predicted by the model.

Optimization of synthesis conditions of PbS thin films grown by chemical bath deposition using response surface methodology

International Nuclear Information System (INIS)

Yücel, Ersin; Yücel, Yasin; Beleli, Buse

2015-01-01

Highlights: • For the first time, RSM and CCD used for optimization of PbS thin film. • Tri-sodium citrate, deposition time and temperature were independent variables. • PbS thin film band gap value was 2.20 eV under the optimum conditions. • Quality of the film was improved after chemometrics optimization. - Abstract: In this study, PbS thin films were synthesized by chemical bath deposition (CBD) under different deposition parameters. Response surface methodology (RSM) was used to optimize synthesis parameters including amount of tri-sodium citrate (0.2–0.8 mL), deposition time (14–34 h) and deposition temperature (26.6–43.4 °C) for deposition of the films. 5-level-3-factor central composite design (CCD) was employed to evaluate effects of the deposition parameters on the response (optical band gap of the films). The significant level of both the main effects and the interaction are investigated by analysis of variance (ANOVA). The film structures were characterized by X-ray diffractometer (XRD). Morphological properties of the films were studied with a scanning electron microscopy (SEM). The optical properties of the films were investigated using a UV–visible spectrophotometer. The optimum amount of tri-sodium citrate, deposition time and deposition temperature were found to be 0.7 mL, 18.07 h and 30 °C respectively. Under these conditions, the experimental band gap of PbS was 2.20 eV, which is quite good correlation with value (1.98 eV) predicted by the model

Investigations of the physical and chemical properties of solid solutions Pb/Mnsub(1/2), Nbsub(1/2)/O3 - PbTiO3 - PbZrO3

International Nuclear Information System (INIS)

Szadkowska, A.; Majewska-Pilchowska, K.

1981-01-01

The preparation of the PMTZ materials on the basis of solid solutions Pb/Mnsub(1/2)/O 3 - PbTiO 3 - PbZrO 3 has been described. The X-ray analysis of the examined materials has been made, and porosity and grain size have been determined. Dielectric constant and mechanical quality factor as a function of PbZrO 3 content have been determined. The obtained results indicate that solid solutions Pb/Mnsub(1/2), Nbsub(1/2)/O 3 - PbTiO 3 - PbZrO 3 are useful piezoelectric materials. (author)

Sulfide precursor concentration and lead source effect on PbS thin films properties

Energy Technology Data Exchange (ETDEWEB)

Beddek, L.; Messaoudi, M.; Attaf, N. [Laboratoire Couche Minces et Interfaces, Université frères Mentouri Constantine, 25000, Constantine (Algeria); Aida, M.S., E-mail: aida_salah2@yahoo.fr [Laboratoire Couche Minces et Interfaces, Université frères Mentouri Constantine, 25000, Constantine (Algeria); Bougdira, J. [Université de Lorraine, Institut Jean Lamour UMR 7198, Vandoeuvre 54506 (France)

2016-05-05

Lead sulfide (PbS) thin films were synthesized using chemical bath deposition (CBD). Bath solutions are formed of various concentrations of thiourea, sulfide source, ranged from 0.6 to 1.2 M and two different salts as Pb source (lead acetate and lead nitrate). From the growth mechanism, we inferred that PbS is formed through the ion by ion process when using acetate lead source, while, using nitrate source yields to films growth through the complex-decomposition process. Due to the difference in the involved growth process, lead acetate produces films with larger crystallite size (from 4 to 16 nm), smooth and dense films. However, lead nitrate produces rough films with smaller crystallite size (from 1 to 4 nm). Increasing the thiourea concentration results in crystallinity improvement when using lead acetate and, oppositely, in crystallinity degradation when using lead nitrate. Due to the quantum effect caused by the small crystallite sizes, the films optical gap is varied from 0.5 to 0.9 eV. - Highlights: • PbS thin films were synthesized by chemical bath deposition. • Ion by ion is the growth process when using the acetate lead source. • Deposition process is by complex-decomposition when using nitrate source. • Lead acetate yields to dense films with larger crystallite size. • Lead nitrate produces rough films with smaller crystallite size.

Sulfide precursor concentration and lead source effect on PbS thin films properties

International Nuclear Information System (INIS)

Beddek, L.; Messaoudi, M.; Attaf, N.; Aida, M.S.; Bougdira, J.

2016-01-01

Lead sulfide (PbS) thin films were synthesized using chemical bath deposition (CBD). Bath solutions are formed of various concentrations of thiourea, sulfide source, ranged from 0.6 to 1.2 M and two different salts as Pb source (lead acetate and lead nitrate). From the growth mechanism, we inferred that PbS is formed through the ion by ion process when using acetate lead source, while, using nitrate source yields to films growth through the complex-decomposition process. Due to the difference in the involved growth process, lead acetate produces films with larger crystallite size (from 4 to 16 nm), smooth and dense films. However, lead nitrate produces rough films with smaller crystallite size (from 1 to 4 nm). Increasing the thiourea concentration results in crystallinity improvement when using lead acetate and, oppositely, in crystallinity degradation when using lead nitrate. Due to the quantum effect caused by the small crystallite sizes, the films optical gap is varied from 0.5 to 0.9 eV. - Highlights: • PbS thin films were synthesized by chemical bath deposition. • Ion by ion is the growth process when using the acetate lead source. • Deposition process is by complex-decomposition when using nitrate source. • Lead acetate yields to dense films with larger crystallite size. • Lead nitrate produces rough films with smaller crystallite size.

Ferroelectric properties of bilayer structured Pb(Zr0.52Ti0.48)O3/SrBi2Ta2O9 (PZT/SBT) thin films on Pt/TiO2/SiO2/Si substrates

International Nuclear Information System (INIS)

Zhang Wenqi; Li Aidong; Shao Qiyue; Xia Yidong; Wu Di; Liu Zhiguo; Ming Naiben

2008-01-01

Pb(Zr 0.52 Ti 0.48 )O 3 (PZT) thin films with large remanent polarization and SrBi 2 Ta 2 O 9 (SBT) thin films with excellent fatigue-resisting characteristic have been widely studied for non-volatile random access memories, respectively. To combine these two advantages , bilayered Pb(Zr 0.52 Ti 0.48 )O 3 /SrBi 2 Ta 2 O 9 (PZT/SBT) thin films were fabricated on Pt/TiO 2 /SiO 2 /Si substrates by chemical solution deposition method. X-ray diffraction patterns revealed that the diffraction peaks of PZT/SBT thin films were completely composed of PZT and SBT, and no other secondary phase was observed. The electrical properties of the bilayered structure PZT/SBT films have been investigated in comparison with pure PZT and SBT films. PZT/SBT bilayered thin films showed larger remanent polarization (2P r ) of 18.37 μC/cm 2 than pure SBT and less polarization fatigue up to 1 x 10 9 switching cycles than pure PZT. These results indicated that this bilayered structure of PZT/SBT is a promising material combination for ferroelectric memory applications

Growth and characteristics of PbS/polyvinyl alcohol nanocomposites for flexible high dielectric thin film applications

International Nuclear Information System (INIS)

Hmar, J.J.L.; Majumder, T.; Mondal, S.P.

2016-01-01

PbS/polyvinyl alcohol (PbS/PVA) nanocomposites have been grown by a chemical bath deposition process at various growth temperatures (60–100 °C). Transmission electron microscopy (TEM) study revealed the formation of PbS nanoparticles of diameter 6–20 nm encapsulated in PVA matrix. Optical band gap of the nanocomposite films have been found to decrease (1.45 eV–0.67 eV) with increase in growth temperature from 60 °C to 100 °C. The impedance measurements have been carried out by depositing the PbS/PVA films on indium tin oxide (ITO) coated flexible polyethylene terephthalate (PET) substrates. The room temperature dielectric permittivity and ac conductivity measurements have been carried out for ITO/PbS/PVA/Al devices deposited at various growth temperatures. The nanocomposite films demonstrate superior dielectric permittivity compare to pure PVA polymer. The flexibility studies of ITO/PbS/PVA/Al devices have been performed at different bending angles. - Highlights: • PbS nanoparticles of diameter 6–20 nm were grown in polyvinyl (PVA) matrix. • Optical band gap of nanocomposite films was varied from 1.45–0.67 eV. • The nanocomposite thin films demonstrated superior dielectric permittivity. • Flexibility study of thin film devices was performed at various bending angles.

Low temperature formation of ferroelectric PbTiO3 films by laser ablation with 2nd laser irradiation; Reiki hikari laser heiyo laser ablation ho ni yoru kyoyudentai PbTiO3 usumaku no teion keisei

Energy Technology Data Exchange (ETDEWEB)

Tabata, H.; Kawai, T. [Osaka University, Osaka (Japan)

1997-08-20

The unique advantage of the pulsed laser deposition is its ability to produce highly oriented stoichiometric films at a low substrate temperature. Ferroelectric PbTiO3 thin films have been formed using 2nd laser assisted laser ablaion technique at low temperature, i.e., 350degC, on Sr7iO3 single-crystal substrates and Pt/MgO electrodes. The second laser irradiation at the substrate surface is quite effective for crystallization of the films at low substrate temperature below 400degC. The suitable energy density (fluence) of the irradiation laser is in the range of 30-100 mJ/cm{sup 2}. X-ray diffraction patterns of PbTiO3 thin films show c-axis orientation, with a rocking angle of 1.0 - 0.5deg. These films exhibit ferroelectric hysteresis loop. The dielectric constant and remanent polalyzation of the PbTiO3 films are in the range of 120-150 and 60-80 {mu}C/cm{sup 2}, respectively. 31 refs., 10 figs., 1 tab.

Photosensitive thin-film In/p-Pb{sub x}Sn{sub 1-x}S Schottky barriers: Fabrication and properties

Energy Technology Data Exchange (ETDEWEB)

Gremenok, V. F., E-mail: gremenok@ifttp.bas-net.by [Scientific-Practical Center of the National Academy of Sciences of Belarus State Scientific and Production Association (Belarus); Rud' , V. Yu., E-mail: rudvas.spb@gmail.com [St. Petersburg State Polytechnic University (Russian Federation); Rud' , Yu. V. [Russian Academy of Sciences, Ioffe Physical Technical Institute (Russian Federation); Bashkirov, S. A.; Ivanov, V. A. [Scientific-Practical Center of the National Academy of Sciences of Belarus State Scientific and Production Association (Belarus)

2011-08-15

Thin Pb{sub x}Sn{sub 1-x}S films are obtained by the 'hot-wall' method at substrate temperatures of 210-330 Degree-Sign C. The microstructure, composition, morphology, and electrical characteristics of films are investigated. On the basis of the obtained films, photosensitive In/p-Pb{sub x}Sn{sub 1-x}S Schottky barriers are fabricated for the first time. The photosensivity spectra of these structures are investigated, and the character of interband transitions and the band-gap values are determined from them. The conclusion is drawn that Pb{sub x}Sn{sub 1-x}S thin polycrystalline films may be used in solar-energy converters.

Influence of gold nanoparticles on the 805 nm gain in Tm3+/Yb3+ codoped PbO-GeO2 pedestal waveguides

Science.gov (United States)

de Assumpção, T. A. A.; Camilo, M. E.; Alayo, M. I.; da Silva, D. M.; Kassab, L. R. P.

2017-10-01

The production and characterization of pedestal waveguides based on PbO-GeO2 amorphous thin films codoped with Tm3+/Yb3+, with and without gold nanoparticles (NPs), are reported. Pedestal structure was obtained by conventional photolithography and plasma etching. Tm3+/Yb3+ codoped PGO amorphous thin film was obtained by RF Magnetron Sputtering deposition and used as core layer in the pedestal optical waveguide. The minimum propagation losses in the waveguide were 3.6 dB/cm at 1068 nm. The internal gain at 805 nm was enhanced and increased to 8.67 dB due to the presence of gold NPs. These results demonstrate for the first time that Tm3+/Yb3+ codoped PbO-GeO2 waveguides are promising for first telecom window and integrated photonics, especially for applications on fiber network at short distances.

Structural and magnetic properties of La0.7Sr0.3MnO3 ferromagnetic thin film grown on PMN-PT by sol–gel method

Directory of Open Access Journals (Sweden)

Jing Zhang

2017-08-01

Full Text Available We report the preparation of epitaxial La0.7Sr0.3MnO3 thin films grown on (001-oriented 0.72Pb(Mg1∕3Nb2∕3O3-0.28PbTiO3 substrates by the sol–gel technique. The phase structure, magnetic properties and magnetoresistance of the samples are investigated by using high solution X-ray diffraction, atomic force microscopy, physical property measurement system, respectively. The La0.7Sr0.3MnO3 thin films display a well-defined hysteresis loop and typical ferromagnetism behavior at lower temperature. High magnetoresistance at 5T of 42% appears at 227K for La0.7Sr0.3MnO3 thin film.

Anelastic deformation of Pb(Zr,Ti)O3 thin films by non-180 deg. ferroelectric domain wall movements during nanoindentation

International Nuclear Information System (INIS)

Alguero, M.; Bushby, A.J.; Reece, M.J.; Seifert, A.

2002-01-01

Lead zirconate titanate Pb(Zr,Ti)O 3 ferroelectric thin films show significant anelastic deformation when indented with spherical tipped indenters. Experiments on films with different Zr/Ti ratio and a mixed , preferred crystallographic orientation have shown that there is a good agreement between the anelastic deformation and the maximum strain achievable by non-180 deg. domain wall movement. An expected increase of the indentation stiffness of the films also accompanies the anelastic deformation because of the single crystal elastic anisotropy. All these observations seem to indicate that non-180 deg. ferroelectric domain wall movements occur under indentation stresses and cause anelasticity. Stresses for maximum anelastic deformation are compared with those for recently reported stress-induced depolarization

Enhanced Piezoelectric Response in HybridPerovskite via Interfacing with Ferroelectric Pb(Zr,Ti)O3

Science.gov (United States)

Song, Jingfeng; Xiao, Zhiyong; Chen, Bo; Prockish, Spencer; Chen, Xuegang; Wang, Dong; Huang, Jinsong; Hong, Xia

In this work, we have carried out a comprehensive study of the piezoelectric properties of polycrystalline hybrid perovskite CH3NH3PbI3 (MAPbI3) thin films on two types of substrates. We spin coated 20-100 nm MAPbI3 thin films on gold and ferroelectric Pb(Zr,Ti)O3 (PZT), and characterized their piezoelectric coefficient d33 using piezoresponse force microscopy (PFM). The MAPbI3 thin films on gold showed a d33 of 0.4 pm/V. The epitaxial PZT films ( 50 nm) were deposited on (La,Sr)MnO3/SrTiO3 substrates, with polarization uniformly oriented in the up direction. For MAPbI3 films on PZT, there are regions showing clear PFM phase response, suggesting that MAPbI3 is polar with out-of-plane polarization. The PFM amplitude image of MAPbI3 indicated the existence of both constructive and destructive piezoresponse with that of PZT. The extracted d33is4 pm/V, 10-fold higher than that on gold. The enhanced piezoresponse is attributed to the dipole-dipole interaction between MAPbI3 and PZT. Our study points to an effective route to engineer the piezoelectric properties MAPbI3 for applications such as mechanical actuators and energy harvesting.

Study of Exciton Hopping Transport in PbS Colloidal Quantum Dot Thin Films Using Frequency- and Temperature-Scanned Photocarrier Radiometry

Science.gov (United States)

Hu, Lilei; Mandelis, Andreas; Melnikov, Alexander; Lan, Xinzheng; Hoogland, Sjoerd; Sargent, Edward H.

2017-01-01

Solution-processed colloidal quantum dots (CQDs) are promising materials for realizing low-cost, large-area, and flexible photovoltaic devices. The study of charge carrier transport in quantum dot solids is essential for understanding energy conversion mechanisms. Recently, solution-processed two-layer oleic-acid-capped PbS CQD solar cells with one layer treated with tetrabutylammonium iodide (TBAI) serving as the main light-absorbing layer and the other treated with 1,2-ethanedithiol (EDT) acting as an electron-blocking/hole-extraction layer were reported. These solar cells demonstrated a significant improvement in power conversion efficiency of 8.55% and long-term air stability. Coupled with photocarrier radiometry measurements, this work used a new trap-state mediated exciton hopping transport model, specifically for CQD thin films, to unveil and quantify exciton transport mechanisms through the extraction of hopping transport parameters including exciton lifetimes, hopping diffusivity, exciton detrapping time, and trap-state density. It is shown that PbS-TBAI has higher trap-state density than PbS-EDT that results in higher PbS-EDT exciton lifetimes. Hopping diffusivities of both CQD thin film types show similar temperature dependence, particularly higher temperatures yield higher hopping diffusivity. The higher diffusivity of PbS-TBAI compared with PbS-EDT indicates that PbS-TBAI is a much better photovoltaic material than PbS-EDT. Furthermore, PCR temperature spectra and deep-level photothermal spectroscopy provided additional insights to CQD surface trap states: PbS-TBAI thin films exhibit a single dominant trap level, while PbS-EDT films with lower trap-state densities show multiple trap levels.

Interfacial electronic structures revealed at the rubrene/CH3NH3PbI3 interface.

Science.gov (United States)

Ji, Gengwu; Zheng, Guanhaojie; Zhao, Bin; Song, Fei; Zhang, Xiaonan; Shen, Kongchao; Yang, Yingguo; Xiong, Yimin; Gao, Xingyu; Cao, Liang; Qi, Dong-Chen

2017-03-01

The electronic structures of rubrene films deposited on CH 3 NH 3 PbI 3 perovskite have been investigated using in situ ultraviolet photoelectron spectroscopy (UPS) and X-ray photoelectron spectroscopy (XPS). It was found that rubrene molecules interacted weakly with the perovskite substrate. Due to charge redistribution at their interface, a downward 'band bending'-like energy shift of ∼0.3 eV and an upward band bending of ∼0.1 eV were identified at the upper rubrene side and the CH 3 NH 3 PbI 3 substrate side, respectively. After the energy level alignment was established at the rubrene/CH 3 NH 3 PbI 3 interface, its highest occupied molecular orbital (HOMO)-valence band maximum (VBM) offset was found to be as low as ∼0.1 eV favoring the hole extraction with its lowest unoccupied molecular orbital (LUMO)-conduction band minimum (CBM) offset as large as ∼1.4 eV effectively blocking the undesired electron transfer from perovskite to rubrene. As a demonstration, simple inverted planar solar cell devices incorporating rubrene and rubrene/poly(3,4-ethylenedioxythiophene):poly(styrenesulfonate) (PEDOT:PSS) hole transport layers (HTLs) were fabricated in this work and yielded a champion power conversion efficiency of 8.76% and 13.52%, respectively. Thus, the present work suggests that a rubrene thin film could serve as a promising hole transport layer for efficient perovskite-based solar cells.

Carrier injection and recombination processes in perovskite CH3NH3PbI3 solar cells studied by electroluminescence spectroscopy

Science.gov (United States)

Handa, Taketo; Okano, Makoto; Tex, David M.; Shimazaki, Ai; Aharen, Tomoko; Wakamiya, Atsushi; Kanemitsu, Yoshihiko

2016-02-01

Organic-inorganic hybrid perovskite materials, CH3NH3PbX3 (X = I and Br), are considered as promising candidates for emerging thin-film photovoltaics. For practical implementation, the degradation mechanism and the carrier dynamics during operation have to be clarified. We investigated the degradation mechanism and the carrier injection and recombination processes in perovskite CH3NH3PbI3 solar cells using photoluminescence (PL) and electroluminescence (EL) imaging spectroscopies. By applying forward bias-voltage, an inhomogeneous distribution of the EL intensity was clearly observed from the CH3NH3PbI3 solar cells. By comparing the PL- and EL-images, we revealed that the spatial inhomogeneity of the EL intensity is a result of the inhomogeneous luminescence efficiency in the perovskite layer. An application of bias-voltage for several tens of minutes in air caused a decrease in the EL intensity and the conversion efficiency of the perovskite solar cells. The degradation mechanism of perovskite solar cells under bias-voltage in air is discussed.

Nano-crystalline Ag–PbTe thermoelectric thin films by a multi-target PLD system

Energy Technology Data Exchange (ETDEWEB)

Cappelli, E., E-mail: emilia.cappelli@ism.cnr.it [CNR-ISM, Montelibretti, Via Salaria Km 29.3, P.O.B. 10, 00016 Rome (Italy); Bellucci, A. [CNR-ISM, Montelibretti, Via Salaria Km 29.3, P.O.B. 10, 00016 Rome (Italy); Dip. Fisica, Un. Roma Sapienza, Piazzale Aldo Moro 2, 00185 Rome (Italy); Medici, L. [CNR-IMAA, Tito Scalo, 85050 Potenza (Italy); Mezzi, A.; Kaciulis, S. [CNR-ISMN, Montelibretti, Via Salaria Km 29.3, P.O.B. 10, 00016 Rome (Italy); Fumagalli, F.; Di Fonzo, F. [Center Nano Science Technology @Polimi, I.I.T., Via Pascoli 70/3, 20133 Milano (Italy); Trucchi, D.M. [CNR-ISM, Montelibretti, Via Salaria Km 29.3, P.O.B. 10, 00016 Rome (Italy)

2015-05-01

Highlights: • Thermoelectric PbTe thin films, with increasing Ag percentage, were deposited by PLD. • Almost stoichiometric PbTe (Ag doped) films were grown, as verified by XPS analysis. • GI-XRD established the formation of cubic PbTe, with nano-metric structure (∼35 nm). • Surface resistivity shows an increase in conductivity, with increasing Ag doping. • From Seebeck values and XPS depth analysis, 10% Ag seems to be the solubility limit. - Abstract: It has been evaluated the ability of ArF pulsed laser ablation to grow nano-crystalline thin films of high temperature PbTe thermoelectric material, and to obtain a uniform and controlled Ag blending, through the entire thickness of the film, using a multi-target system in vacuum. The substrate used was a mirror polished technical alumina slab. The increasing atomic percentage of Ag effect on physical–chemical and electronic properties was evaluated in the range 300–575 K. The stoichiometry and the distribution of the Ag component, over the whole thickness of the samples deposited, have been studied by XPS (X-ray photoelectron spectroscopy) and corresponding depth profiles. The crystallographic structure of the film was analyzed by grazing incidence X-ray diffraction (GI-XRD) system. Scherrer analysis for crystallite size shows the presence of nano-structures, of the order of 30–35 nm. Electrical resistivity of the samples, studied by the four point probe method, as a function of increasing Ag content, shows a typical semi-conductor behavior. From conductivity values, carrier concentration and Seebeck parameter determination, the power factor of deposited films was calculated. Both XPS, Hall mobility and Seebeck analysis seem to indicate a limit value to the Ag solubility of the order of 5%, for thin films of ∼200 nm thickness, deposited at 350 °C. These data resulted to be comparable to theoretical evaluation for thin films but order of magnitude lower than the corresponding bulk materials.

Far-infrared properties of sol-gel derived PbZr0.52Ti0.48O3 thin films on Pt-coated substrates

International Nuclear Information System (INIS)

Kafadaryan, E A; Hovsepyan, R K; Khachaturova, A A; Aghamalyan, N R; Shirinyan, G O; Manukyan, A L; Vardanyan, R S; Hayrapetyan, A G; Grigoryan, S G; Vardanyan, E S

2003-01-01

Polycrystalline tetragonal PbZr 0.52 Ti 0.48 O 3 (PZT) thin films have been deposited on the nickel and (111) platinum coated (110) sapphire substrates by the sol-gel method. Optical properties of the PZT thin films were studied using far-infrared reflectivity spectroscopy in the 200-10 000 cm -1 frequency range at 300 K. The frequency dependence of the optical characteristics (σ, ε, -Im ε -1 ) of the films were calculated by the Kramers-Kronig transformation of the reflectivity spectra and analysed by the Drude-Lorentz model. The frequency dependence of the optical conductivity, σ(ω), of the PZT films deposited on platinum coated sapphire is well described by the free-carrier term and an overdamped mid-infrared component. Sapphire/Pt/PZT structures reveal semiconductor properties (effective carrier concentration N/m* is up to 10 20 cm -3 , plasma minimum is located near 3000 cm -1 ). This effect can be related to the favourable influence of the platinum electrode on the charge carrier density at Pt/PZT contact and formation of the interfacial conductive layer

A study on dependence of the structural, optical and electrical properties of cadmium lead sulphide thin films on Cd/Pb ratio

Energy Technology Data Exchange (ETDEWEB)

Nair, Sinitha B., E-mail: sinithanair@gmail.com, E-mail: anithakklm@gmail.com; Abraham, Anitha, E-mail: sinithanair@gmail.com, E-mail: anithakklm@gmail.com; Philip, Rachel Reena, E-mail: reenatara@rediffmail.com [Thin film research Lab, U.C. College, Aluva, Kerala (India); Pradeep, B., E-mail: bp@cusat.ac.in [Solid State Physics Laboratory, Cochin University of science and Technology, Cochin (India); Shripathi, T., E-mail: shri@csr.res.in, E-mail: vganesancsr@gmail.com; Ganesan, V., E-mail: shri@csr.res.in, E-mail: vganesancsr@gmail.com [UGC-DAE CSR, Khandwa Road, Indore, 452001, Madhya Pradesh (India)

2014-10-15

Cadmium Lead Sulphide thin films with systematic variation in Cd/Pb ratio are prepared at 333K by CBD, adjusting the reagent-molarity, deposition time and pH. XRD exhibits crystalline-amorphous transition as Cd% exceeds Pb%. AFM shows agglomeration of crystallites of size ∼50±5 nm. EDAX assess the composition whereas XPS ascertains the ternary formation, with binding energies of Pb4f{sub 7/2} and 4f{sub 5/2}, Cd3d{sub 5/2} and 3d{sub 3/2} and S2p at 137.03, 141.606, 404.667, 412.133 and 160.218 eV respectively. The optical absorption spectra reveal the variance in the direct allowed band gaps, from 1.57eV to 2.42 eV as Cd/Pb ratio increases from 0.2 to 2.7, suggesting possibility of band gap engineering in the n-type films.

Facile synthesis of CsPbBr3/PbSe composite clusters

OpenAIRE

Nguyen, Thang Phan; Ozturk, Abdullah; Park, Jongee; Sohn, Woonbae; Lee, Tae Hyung; Jang, Ho Won; Kim, Soo Young

2017-01-01

Abstract In this work, CsPbBr3 and PbSe nanocomposites were synthesized to protect perovskite material from self-enlargement during reaction. UV absorption and photoluminescence (PL) spectra indicate that the addition of Se into CsPbBr3 quantum dots modified the electronic structure of CsPbBr3, increasing the band gap from 2.38 to 2.48 eV as the Cs:Se ratio increased to 1:3. Thus, the emission color of CsPbBr3 perovskite quantum dots was modified from green to blue by increasing the Se ratio ...

Piezoelectric properties and temperature stability of Mn-doped Pb(Mg1/3Nb2/3)-PbZrO3-PbTiO3 textured ceramics

OpenAIRE

Yan, Yongke; Cho, Kyung-Hoon; Priya, Shashank

2012-01-01

In this letter, we report the electromechanical properties of textured 0.4Pb(Mg1/3Nb2/3) O-3-0.25PbZrO(3)-0.35PbTiO(3) (PMN-PZT) composition which has relatively high rhombohedral to tetragonal (R-T) transition temperature (TR-T of 160 degrees C) and Curie temperature (T-C of 234 degrees C) and explore the effect of Mn-doping on this composition. It was found that MnO2-doped textured PMN-PZT ceramics with 5 vol.% BaTiO3 template (T-5BT) exhibited inferior temperature stability. The coupling f...

High-Pressure-Induced Comminution and Recrystallization of CH3 NH3 PbBr3 Nanocrystals as Large Thin Nanoplates.

Science.gov (United States)

Yin, Tingting; Fang, Yanan; Chong, Wee Kiang; Ming, Koh Teck; Jiang, Shaojie; Li, Xianglin; Kuo, Jer-Lai; Fang, Jiye; Sum, Tze Chien; White, Timothy J; Yan, Jiaxu; Shen, Ze Xiang

2018-01-01

High pressure (HP) can drive the direct sintering of nanoparticle assemblies for Ag/Au, CdSe/PbS nanocrystals (NCs). Instead of direct sintering for the conventional nanocrystals, this study experimentally observes for the first time high-pressure-induced comminution and recrystallization of organic-inorganic hybrid perovskite nanocrystals into highly luminescent nanoplates with a shorter carrier lifetime. Such novel pressure response is attributed to the unique structural nature of hybrid perovskites under high pressure: during the drastic cubic-orthorhombic structural transformation at ≈2 GPa, (301) the crystal plane fully occupied by organic molecules possesses a higher surface energy, triggering the comminution of nanocrystals into nanoslices along such crystal plane. Beyond bulk perovskites, in which pressure-induced modifications on crystal structures and functional properties will disappear after pressure release, the pressure-formed variants, i.e., large (≈100 nm) and thin (perovskite nanoplates, are retained and these exhibit simultaneous photoluminescence emission enhancing (a 15-fold enhancement in the photoluminescence) and carrier lifetime shortening (from ≈18.3 ± 0.8 to ≈7.6 ± 0.5 ns) after releasing of pressure from 11 GPa. This pressure-induced comminution of hybrid perovskite NCs and a subsequent amorphization-recrystallization treatment offer the possibilities of engineering the advanced hybrid perovskites with specific properties. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Photoinduced changes in the fatigue behavior of SrBi2Ta2O9 and Pb(Zr,Ti)O3 thin films

International Nuclear Information System (INIS)

Dimos, D.; Al-Shareef, H.N.; Warren, W.L.; Tuttle, B.A.

1996-01-01

It is shown that SrBi 2 Ta 2 O 9 (SBT) thin films can be made to exhibit significant polarization fatigue by electric-field cycling under broad-band, optical illumination. Photoinduced fatigue is also observed for Pb(Zr,Ti)O 3 (PZT) thin-film capacitors with (La,Sr)CoO 3 (LSCO) electrodes. These results demonstrate that both the Pt/SBT/Pt and the LSCO/PZT/LSCO systems are susceptible to fatigue effects, which are attributed primarily to pinning of domain walls due to charge trapping. Capacitors that have been fatigued under illumination can be fully rejuvinated by applying a dc saturating bias with light or by electric-field cycling without light, which indicates an intrinsic, field-assisted recovery mechanism. We suggest that fatigue is essentially a competition between domain wall pinning and unpinning and that domain pinning is not necessarily absent in these nominally fatigue-free systems, but rather these systems are ones in which unpinning occurs at least as rapidly as any pinning. In both cases, the extent of photoinduced fatigue decreases with increased cycling voltage, indicating the relative importance of field-assisted unpinning. Finally, the observation of photoinduced fatigue implies that increased injection rates, potentially due to oxygen vacancy accumulation, may account for the electrode dependence on fatigue in PZT thin films

Electrode contacts on ferroelectric Pb(Zr x Ti1−x )O3 and SrBi2Ta2O9 thin films and their influence on fatigue properties

OpenAIRE

Lee, J. J.; Thio, C. L.; Desu, Seshu B.

1995-01-01

The degradation (fatigue) of dielectric properties of ferroelectric Pb(ZrxTi1-x)O-3 (PZT) and SrBi2Ta2O9 thin films during cycling was investigated. PZT and SrBi2Ta2O9 thin films were fabricated by metalorganic decomposition and pulsed laser deposition, respectively. Samples with electrodes of platinum (Pt) and ruthenium oxide (RuO2) were studied. The interfacial capacitance (if any) at the Pt/PZT, RuO2/PZT, and Pt/SrBi2Ta2O9 interfaces was determined from the thickness dependence of low-fiel...

Piezoelectric response and electrical properties of Pb(Zr1-xTix)O3 thin films: The role of imprint and composition

Science.gov (United States)

Cornelius, T. W.; Mocuta, C.; Escoubas, S.; Merabet, A.; Texier, M.; Lima, E. C.; Araujo, E. B.; Kholkin, A. L.; Thomas, O.

2017-10-01

The compositional dependence of the piezoelectric properties of self-polarized PbZr1-xTixO3 (PZT) thin films deposited on Pt/TiO2/SiO2/Si substrates (x = 0.47, 0.49 and 0.50) was investigated by in situ synchrotron X-ray diffraction and electrical measurements. The latter evidenced an imprint effect in the studied PZT films, which is pronounced for films with the composition of x = 0.50 and tends to disappear for x = 0.47. These findings were confirmed by in situ X-ray diffraction along the crystalline [100] and [110] directions of the films with different compositions revealing asymmetric butterfly loops of the piezoelectric strain as a function of the electric field; the asymmetry is more pronounced for the PZT film with a composition of x = 0.50, thus indicating a higher built-in electric field. The enhancement of the dielectric permittivity and the effective piezoelectric coefficient at compositions around the morphotropic phase boundary were interpreted in terms of the polarization rotation mechanism and the monoclinic phase in the studied PZT thin films.

Polarization retention loss in PbTiO3 ferroelectric films due to leakage currents

NARCIS (Netherlands)

Morelli, A.; Venkatesan, Sriram; Palasantzas, G.; Kooi, B. J.; De Hosson, J. Th. M.

2007-01-01

The relationship between retention loss in single crystal PbTiO3 ferroelectric thin films and leakage currents is demonstrated by piezoresponse and conductive atomic force microscopy measurements. It was found that the polarization reversal in the absence of an electric field followed a stretched

Chemically synthesized PbS Nano particulate thin films for a rapid NO2 gas sensor

Directory of Open Access Journals (Sweden)

Burungale Vishal V.

2016-03-01

Full Text Available Rapid NO2 gas sensor has been developed based on PbS nanoparticulate thin films synthesized by Successive Ionic Layer Adsorption and Reaction (SILAR method at different precursor concentrations. The structural and morphological properties were investigated by means of X-ray diffraction and field emission scanning electron microscope. NO2 gas sensing properties of PbS thin films deposited at different concentrations were tested. PbS film with 0.25 M precursor concentration showed the highest sensitivity. In order to optimize the operating temperature, the sensitivity of the sensor to 50 ppm NO2 gas was measured at different operating temperatures, from 50 to 200 °C. The gas sensitivity increased with an increase in operating temperature and achieved the maximum value at 150 °C, followed by a decrease in sensitivity with further increase of the operating temperature. The sensitivity was about 35 % for 50 ppm NO2 at 150 °C with rapid response time of 6 s. T90 and T10 recovery time was 97 s at this gas concentration.

Decoration of PbS nanoparticles on Al-doped ZnO nanorod array thin film with hydrogen treatment as a photoelectrode for solar water splitting

Energy Technology Data Exchange (ETDEWEB)

Hsu, Chih-Hsiung; Chen, Chao-Hong [Department of Chemical Engineering and Research Center for Energy Technology and Strategy, National Cheng Kung University, Tainan 701, Taiwan, ROC (China); Chen, Dong-Hwang, E-mail: chendh@mail.ncku.edu.tw [Department of Chemical Engineering and Research Center for Energy Technology and Strategy, National Cheng Kung University, Tainan 701, Taiwan, ROC (China)

2013-03-25

Highlights: ► AZO nanorod array thin film is used as a photoanode for solar water splitting. ► Hydrogen treatment and sensitization by PbS nanoparticles enhance photocurrent. ► A novel ITO/FTO-free composite photoelectrode is developed. ► The pre-fabrication and use of an extra TCO thin film substrate is unnecessary. -- Abstract: Al-doped ZnO (AZO) nanorod arrays thin film with hydrogen treatment is directly used as a photoelectrode for solar water splitting without an extra transparent conducting oxide (TCO) thin film because it possesses the functions of TCO thin film and photoactive 1-dimensional nanostructured semiconductor simultaneously. To enhance the absorption in the visible region, PbS nanoparticles decorated the AZO nanorods via successive ionic layer adsorption and reaction route. The PbS nanoparticles have a face-centered cubic structure and their decoration does not destroy the 1-dimensional morphology of AZO nanorod arrays. With increasing the cycle number of PbS nanoparticles decoration, the grain size and loading of PbS nanoparticles become larger gradually which leads to lower energy bandgap and stronger absorption. A maximum photocurrent density of 1.65 mW cm{sup −2} is obtained when the cycle number is 20, which is much higher than those without PbS nanoparticles sensitization or hydrogen treatment. This demonstrates that the AZO nanorod array thin film with hydrogen treatment can be directly used as a photoelectrode without an extra TCO thin film. Because the use of expensive metals can be avoided and the pre-fabrication of TCO thin film substrate is necessary no more, the fabrication of such a composite photoelectrode becomes simple and low-cost. So, it has great potentials in solar water splitting after sensitization by quantum dots capable of visible light absorption.

Absence of morphotropic phase boundary effects in BiFeO3-PbTiO3 thin films grown via a chemical multilayer deposition method

Science.gov (United States)

Gupta, Shashaank; Bhattacharjee, Shuvrajyoti; Pandey, Dhananjai; Bansal, Vipul; Bhargava, Suresh K.; Peng, Ju Lin; Garg, Ashish

2011-07-01

We report an unusual behavior observed in (BiFeO3)1- x -(PbTiO3) x (BF- xPT) thin films prepared using a multilayer chemical solution deposition method. Films of different compositions were grown by depositing several bilayers of BF and PT precursors of varying BF and PT layer thicknesses followed by heat treatment in air. X-ray diffraction showed that samples of all compositions show mixing of two compounds resulting in a single-phase mixture, also confirmed by transmission electron microscopy. In contrast to bulk compositions, samples show a monoclinic (MA-type) structure suggesting disappearance of the morphotropic phase boundary (MPB) at x=0.30 as observed in the bulk. This is accompanied by the lack of any enhancement of the remanent polarization at the MPB, as shown by the ferroelectric measurements. Magnetic measurements showed an increase in the magnetization of the samples with increasing BF content. Significant magnetization in the samples indicates melting of spin spirals in the BF- xPT films, arising from a random distribution of iron atoms. Absence of Fe2+ ions was corroborated by X-ray photoelectron spectroscopy measurements. The results illustrate that thin film processing methodology significantly changes the structural evolution, in contrast to predictions from the equilibrium phase diagram, besides modifying the functional characteristics of the BP- xPT system dramatically.

Preparation and Characterization of PbO-SrO-Na2O-Nb2O5-SiO2 Glass Ceramics Thin Film for High-Energy Storage Application

Science.gov (United States)

Tan, Feihu; Zhang, Qingmeng; Zhao, Hongbin; Wei, Feng; Du, Jun

2018-03-01

PbO-SrO-Na2O-Nb2O5-SiO2 (PSNNS) glass ceramic thin films were prepared by pulsed laser deposition technology on heavily doped silicon substrates. The influence of annealing temperatures on microstructures, dielectric properties and energy storage performances of the as-prepared films were investigated in detail. X-ray diffraction studies indicate that Pb2Nb2O7 crystallizes at 800°C and disappears at 900°C, while NaNbO3 and PbNb2O6 are formed at the higher temperature of 900°C. The dielectric properties of the glass ceramics thin films have a strong dependence on the phase assemblages that are developed during heat treatment. The maximum dielectric constant value of 171 was obtained for the film annealed at 800°C, owing to the high electric breakdown field strength, The energy storage densities of the PSNNS films annealed at 800°C were as large as 36.9 J/cm3, These results suggest that PSNNS thin films are promising for energy storage applications.

Chemical Bath Deposition of PbS:Hg2+ Nanocrystalline Thin Films

Directory of Open Access Journals (Sweden)

R. Palomino-Merino

2013-01-01

Full Text Available Nanocrystalline PbS thin films were prepared by Chemical Bath Deposition (CBD at 40 ± 2°C onto glass substrates and their structural and optical properties modified by in-situ doping with Hg. The morphological changes of the layers were analyzed using SEM and the X-rays spectra showing growth on the zinc blende (ZB face. The grain size determined by using X-rays spectra for undoped samples was found to be ~36 nm, whereas with the doped sample was 32–20 nm. Optical absorption spectra were used to calculate the Eg, showing a shift in the range 1.4–2.4 eV. Raman spectroscopy exhibited an absorption band ~135 cm−1 displaying only a PbS ZB structure.

Topological crystalline insulator PbxSn1-xTe thin films on SrTiO3 (001 with tunable Fermi levels

Directory of Open Access Journals (Sweden)

Hua Guo

2014-05-01

Full Text Available In this letter, we report a systematic study of topological crystalline insulator PbxSn1-xTe (0 < x < 1 thin films grown by molecular beam epitaxy on SrTiO3(001. Two domains of PbxSn1-xTe thin films with intersecting angle of α ≈ 45° were confirmed by reflection high energy diffraction, scanning tunneling microscopy, and angle-resolved photoemission spectroscopy (ARPES. ARPES study of PbxSn1-xTe thin films demonstrated that the Fermi level of PbTe could be tuned by altering the temperature of substrate whereas SnTe cannot. An M-shaped valance band structure was observed only in SnTe but PbTe is in a topological trivial state with a large gap. In addition, co-evaporation of SnTe and PbTe results in an equivalent variation of Pb concentration as well as the Fermi level of PbxSn1-xTe thin films.

Three-State Ferroelastic Switching and Large Electromechanical Responses in PbTiO ₃ Thin Films

Energy Technology Data Exchange (ETDEWEB)

Damodaran, Anoop R. [Univ. of California, Berkeley, CA (United States); Pandya, Shishir [Univ. of California, Berkeley, CA (United States); Agar, Josh C. [Univ. of California, Berkeley, CA (United States); Cao, Ye [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Vasudevan, Rama K. [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Xu, Ruijuan [Univ. of California, Berkeley, CA (United States); Saremi, Sahar [Univ. of California, Berkeley, CA (United States); Li, Qian [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Kim, Jieun [Univ. of California, Berkeley, CA (United States); McCarter, Margaret R. [Univ. of California, Berkeley, CA (United States); Dedon, Liv R. [Univ. of California, Berkeley, CA (United States); Angsten, Tom [Univ. of California, Berkeley, CA (United States); Balke, Nina [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Jesse, Stephen [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Asta, Mark [Univ. of California, Berkeley, CA (United States); Kalinin, Sergei V. [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Martin, Lane W. [Univ. of California, Berkeley, CA (United States); Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States)

2017-07-31

Leveraging competition between energetically degenerate states to achieve large field-driven responses is a hallmark of functional materials, but routes to such competition are limited. Here, a new route to such effects involving domain-structure competition is demonstrated, which arises from straininduced spontaneous partitioning of PbTiO₃ thin films into nearly energetically degenerate, hierarchical domain architectures of coexisting c/a and a₁/a₂ domain structures. Using band-excitation piezoresponse force microscopy, this study manipulates and acoustically detects a facile interconversion of different ferroelastic variants via a two-step, three-state ferroelastic switching process (out-of-plane polarized c+ → in-plane polarized a → out-of-plane polarized c- state), which is concomitant with large nonvolatile electromechanical strains (≈1.25%) and tunability of the local piezoresponse and elastic modulus (>23%). It is further demonstrated that deterministic, nonvolatile writing/erasure of large-area patterns of this electromechanical response is possible, thus showing a new pathway to improved function and properties.

Sequential Introduction of Cations Deriving Large-Grain Csx FA1-x PbI3 Thin Film for Planar Hybrid Solar Cells: Insight into Phase-Segregation and Thermal-Healing Behavior.

Science.gov (United States)

Huang, Jiahao; Xu, Pan; Liu, Jian; You, Xiao-Zeng

2017-03-01

Composition engineering of perovskite materials has been demonstrated to be important for high-performance solar cells. Recently, the energy favorable hybridization of formamidinium (FA) and cesium (Cs) in three dimension lead halide perovskites has been attracting increasing attention due to its potential benefit on durability. Herein, we reported a simple and effective method to produce phase-pure CsxFA1-xPbI3 thin film via sequential introduction of cations, in which the FA cation was introduced by interdiffusion annealing in the presence of N-methylimidazole (NMI). NMI was employed as an additive to slow down the crystallization and thus drive the formation of CsxFA1-xPbI3 with micrometer grain size, which probably facilitate the charge dissociation and transportation in photovoltaic devices. More importantly, composition dependent phase-segregation has been revealed and investigated for the first time during the phase-pure mixed-cation perovskites CsxFA1-xPbI3. The present findings demonstrated that suppressing phase-segregation of mixed-cation perovskites by meticulous composition engineering is significant for further development of efficient photovoltaics. It also suggested that phase-pure Cs0.15FA0.85PbI3 may be a promising candidate with superior phase-durability, which performed an efficiency over 16% in planar perovskite solar cells. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

PbS Thin Films for Photovoltaic Applications Obtained by Non-Traditional Chemical Bath Deposition

Directory of Open Access Journals (Sweden)

Pérez-García Claudia Elena

2015-01-01

Full Text Available To optimize cost-efficiency relation for thin film solar cells, we explore the recently developed versions of chemical deposition of semiconductor films, together with classic CBD (Chemical Bath Deposition: SILAR (Successive Ionic Layer Adsorption and Reaction and PCBD (Photo Chemical Bath Deposition, all of them ammonia-free and ecologically friendly. The films of CdS and PbS were made, and experimental solar cells with CdS window layer and PbS absorber elaborated. We found that band gap of PbS films can be monitored by deposition process due to porosity-induced quantum confinement which depends on the parameters of the process. We expect that the techniques employed can be successfully used for production of optoelectronic devices.

Highly c-axis-oriented monocrystalline Pb(Zr, Ti)O₃ thin films on si wafer prepared by fast cooling immediately after sputter deposition.

Science.gov (United States)

Yoshida, Shinya; Hanzawa, Hiroaki; Wasa, Kiyotaka; Esashi, Masayoshi; Tanaka, Shuji

2014-09-01

We successfully developed sputter deposition technology to obtain a highly c-axis-oriented monocrystalline Pb(Zr, Ti)O3 (PZT) thin film on a Si wafer by fast cooling (~-180°C/min) of the substrate after deposition. The c-axis orientation ratio of a fast-cooled film was about 90%, whereas that of a slow-cooled (~-40°C/min) film was only 10%. The c-axis-oriented monocrystalline Pb(Zr0.5, Ti0.5)O3 films showed reasonably large piezoelectric coefficients, e(31,f) = ~-11 C/m(2), with remarkably small dielectric constants, ϵ(r) = ~220. As a result, an excellent figure of merit (FOM) was obtained for piezoelectric microelectromechanical systems (MEMS) such as a piezoelectric gyroscope. This c-axis orientation technology on Si will extend industrial applications of PZT-based thin films and contribute further to the development of piezoelectric MEMS.

Room-temperature synthesis of pure perovskite-related Cs4PbBr6 nanocrystals and their ligand-mediated evolution into highly luminescent CsPbBr3 nanosheets

Science.gov (United States)

Yang, Liu; Li, Dongmei; Wang, Cong; Yao, Wei; Wang, Hao; Huang, Kaixiang

2017-07-01

Currently, all-inorganic cesium lead-halide perovskite nanocrystals have attracted enormous attentions owing to their excellent optical performances. While great efforts have been devoted to CsPbBr3 nanocrystals, the perovskite-related Cs4PbBr6 nanocrystals, which were newly reported, still remained poorly understood. Here, we reported a novel room-temperature reaction strategy to synthesize pure perovskite-related Cs4PbBr6 nanocrystals. Size of the products could be adjusted through altering the amount of ligands, simply. A mixture of two good solvents with different polarity was innovatively used as precursor solvent, being one key to the high-yield Cs4PbBr6 nanocrystals synthesis. Other two keys were Cs+ precursor concentration and surface ligands. Ingenious experiments were designed to reveal the underlying reaction mechanism. No excitonic emission was observed from the prepared Cs4PbBr6 nanocrystals in our work. We considered the green emission which was observed in other reports originated from the avoidless transformation of Cs4PbBr6 into CsPbBr3 nanocrystals. Indeed, the new-prepared Cs4PbBr6 nanocrystals could transform into CsPbBr3 nanosheets with surface ligands mediated. The new-transformed two-dimensional CsPbBr3 nanosheets could evolve into large-size nanosheets. The influences of surface ligand density on the fluorescent intensity and stability of transformed CsPbBr3 nanosheets were also explained. Notably, the photoluminescence quantum yield of the as-transformed CsPbBr3 nanosheets could reach as high as 61.6% in the form of thin film. The fast large-scale synthesis of Cs4PbBr6 nanocrystals and their ligand-mediated transformation into high-fluorescent CsPbBr3 nanosheets will be beneficial to the future optoelectronic applications. Our work provides new approaches to understand the structural evolution and light-emitting principle of perovskite nanocrystals. [Figure not available: see fulltext.

Synthesis and Characterization of Pb(Zr𝟎.𝟓𝟑, Ti𝟎.𝟒𝟕)O𝟑-Pb(Nb𝟏/𝟑, Zn𝟐/𝟑)O𝟑 Thin Film Cantilevers for Energy Harvesting Applications

KAUST Repository

Fuentes-Fernandez, E. M. A.; Debray-Mechtaly, W.; Quevedo-Lopez, M. A.; Gnade, B.; Leon-Salguero, E.; Shah, P.; Alshareef, Husam N.

2012-01-01

A complete analysis of the morphology, crystallographic orientation, and resulting electrical properties of Pb(Zr0.53,Ti0.47) Pb(Nb1/3, Zn2/3)O3 (PZT-PZN) thin films, as well as the electrical behavior when integrated in a cantilever for energy harvesting applications, is presented. The PZT-PZN films were deposited using sol-gel methods. We report that using 20% excess Pb, a nucleation layer of PbTiO3 (PT), and a fast ramp rate provides large grains, as well as denser films. The PZT-PZN is deposited on a stack of TiO2/PECVD SiO2/Si3N4/thermal SiO2/Poly-Si/Si. This stack is designed to allow wet-etching the poly-Si layer to release the cantilever structures. It was also found that the introduction of the poly-Si layer results in larger grains in the PZT-PZN film. PZT-PZN films with a dielectric constant of 3200 and maximum polarization of 30 μC/cm2 were obtained. The fabricated cantilever devices produced ~300–400 mV peak-to-peak depending on the cantilever design. Experimental results are compared with simulations.

Soft electronic structure modulation of surface (thin-film) and bulk (ceramics) morphologies of TiO{sub 2}-host by Pb-implantation: XPS-and-DFT characterization

Energy Technology Data Exchange (ETDEWEB)

Zatsepin, D.A. [M.N. Miheev Institute of Metal Physics of Ural Branch of Russian Academy of Sciences, 620990 Yekaterinburg (Russian Federation); Institute of Physics and Technology, Ural Federal University, 620002 Yekaterinburg (Russian Federation); Boukhvalov, D.W., E-mail: danil@hanyang.ac.kr [Department of Chemistry, Hanyang University, 17 Haengdang-dong, Seongdong-gu, Seoul 133-791 (Korea, Republic of); Theoretical Physics and Applied Mathematics Department, Ural Federal University, Mira Street 19, 620002 Yekaterinburg (Russian Federation); Gavrilov, N.V. [Institute of Electrophysics, Russian Academy of Sciences, Ural Branch, 620990 Yekaterinburg (Russian Federation); Zatsepin, A.F. [Institute of Physics and Technology, Ural Federal University, 620002 Yekaterinburg (Russian Federation); Shur, V.Ya.; Esin, A.A. [Institute of Natural Sciences, Ural Federal University, 51 Lenin Ave, 620000 Yekaterinburg (Russian Federation); Kim, S.S. [School of Materials Science and Engineering, Inha University, Incheon 402-751 (Korea, Republic of); Kurmaev, E.Z. [M.N. Miheev Institute of Metal Physics of Ural Branch of Russian Academy of Sciences, 620990 Yekaterinburg (Russian Federation); Institute of Physics and Technology, Ural Federal University, 620002 Yekaterinburg (Russian Federation)

2017-04-01

Highlights: • Experiment and theory demonstrate significant difference between patterns of Pb-ion implantation in TiO{sub 2}. • In bulk TiO{sub 2} Pb-impurities leads formation of PbO phase. • On the surface of TiO{sub 2}:Pb occur formation of PbxOy configurations. • In both bulk and surface TiO{sub 2}:Pb occur decreasing of the bandgap by shift of valence band about 1 eV up. - Abstract: The results of combined experimental and theoretical study of substitutional and clustering effects in the structure of Pb-doped TiO{sub 2}-hosts (bulk ceramics and thin-film morphologies) are presented. Pb-doping of the bulk and thin-film titanium dioxide was made with the help of pulsed ion-implantation without posterior tempering (Electronic Structure Modulation Mode). The X-ray photoelectron spectroscopy (XPS) qualification of core-levels and valence bands and Density-Functional Theory (DFT) calculations were employed in order to study the yielded electronic structure of Pb-ion modulated TiO{sub 2} host-matrices. The combined XPS-and-DFT analysis has agreed definitely with the scenario of the implantation stimulated appearance of PbO-like structures in the bulk morphology of TiO{sub 2}:Pb, whereas in thin-film morphology the PbO{sub 2}-like structure becomes dominating, essentially contributing weak O/Pb bonding (Pb{sub x}O{sub y} defect clusters). The crucial role of the oxygen hollow-type vacancies for the process of Pb-impurity “insertion” into the structure of bulk TiO{sub 2} was pointed out employing DFT-based theoretical background. Both experiment and theory established clearly the final electronic structure re-arrangement of the bulk and thin-film morphologies of TiO{sub 2} because of the Pb-modulated deformation and shift of the initial Valence Base-Band Width about 1 eV up.

Photostriction of CH3NH3PbBr3 Perovskite Crystals

KAUST Repository

Wei, Tzu-Chiao

2017-07-17

Organic-inorganic hybrid perovskite materials exhibit a variety of physical properties. Pronounced coupling between phonon, organic cations, and the inorganic framework suggest that these materials exhibit strong light-matter interactions. The photoinduced strain of CH3 NH3 PbBr3 is investigated using high-resolution and contactless in situ Raman spectroscopy. Under illumination, the material exhibits large blue shifts in its Raman spectra that indicate significant structural deformations (i.e., photostriction). From these shifts, the photostrictive coefficient of CH3 NH3 PbBr3 is calculated as 2.08 × 10-8 m2 W-1 at room temperature under visible light illumination. The significant photostriction of CH3 NH3 PbBr3 is attributed to a combination of the photovoltaic effect and translational symmetry loss of the molecular configuration via strong translation-rotation coupling. Unlike CH3 NH3 PbI3 , it is noted that the photostriction of CH3 NH3 PbBr3 is extremely stable, demonstrating no signs of optical decay for at least 30 d. These results suggest the potential of CH3 NH3 PbBr3 for applications in next-generation optical micro-electromechanical devices.

Emulsion Synthesis of Size-Tunable CH3NH3PbBr3 Quantum Dots: An Alternative Route toward Efficient Light-Emitting Diodes.

Science.gov (United States)

Huang, Hailong; Zhao, Fangchao; Liu, Lige; Zhang, Feng; Wu, Xian-gang; Shi, Lijie; Zou, Bingsuo; Pei, Qibing; Zhong, Haizheng

2015-12-30

We report a facile nonaqueous emulsion synthesis of colloidal halide perovskite quantum dots by controlled addition of a demulsifier into an emulsion of precursors. The size of resulting CH3NH3PbBr3 quantum dots can be tuned from 2 to 8 nm by varying the amount of demulsifier. Moreover, this emulsion synthesis also allows the purification of these quantum dots by precipitation from the colloidal solution and obtains solid-state powder which can be redissolved for thin film coating and device fabrication. The photoluminescence quantum yields of the quantum dots is generally in the range of 80-92%, and can be well-preserved after purification (∼80%). Green light-emitting diodes fabricated comprising a spin-cast layer of the colloidal CH3NH3PbBr3 quantum dots exhibited maximum current efficiency of 4.5 cd/A, power efficiency of 3.5 lm/W, and external quantum efficiency of 1.1%. This provides an alternative route toward high efficient solution-processed perovskite-based light-emitting diodes. In addition, the emulsion synthesis is versatile and can be extended for the fabrication of inorganic halide perovskite colloidal CsPbBr3 nanocrystals.

Luminescence of CsPbBr3 films under high-power excitation

OpenAIRE

高橋, 一彰; 斎藤, 忠昭; 近藤, 新一; 浅田, 拡志

2004-01-01

Highly excited photoluminescence of CsPbBr3 has been measured for thin films prepared by crystallization from the amorphous phase into microcrystalline/ polycrystalline states. With the increase of excitation intensity, there occurs jumping of the dominant emission band from a free-exciton band to a new band originating from exciton-exciton inelastic collision. Stimulated emission is observed for the new band at very low threshold excitation intensities of the order of 10kW/cm2.

Photosensitive srtuctures on the basis of Pb1-xMnxTe semimagnetic semiconductors thin films

International Nuclear Information System (INIS)

Mehrabova, M.A.; Kerimova, T.I.; Memishova, R.M.; Nuriyev, I.R.; Ismayilov, T.G.

2010-01-01

Full text : Narrow-band semimagnetic semiconductors (SMS) Pb 1 -xMn x Te are unique materials for infrared optoelectronics. The investigation of Faraday effect in Pb 1 -xMn x Te thin films of SMS is of a special interest. So it can be used at the construction of optic isolators, amplifiers, IR detectors and other equipments. In the given work Pb 1 -xMn x Te thin films (SMS) have been produced, the interband Faraday effect in these semiconductors has been theoretically and experimentally studied. Opportunities of making IR detectors have been studied. Pb 1 -xMn x Te thin films have been grown at BaF 2 substrates by the method of molecular beam condensation. The optimal conditions of producing thin films with high crystallic perfection, electrophysical and optical parameters have been determined. The energy spectrum and wave functions have been theoretically calculated for quantum-sized films of Pb 1 -xMn x Te SMS in the case when the surface of the film is perpendicular to the axis X and the spin-spin exchange interaction occurs between the electrons in the conductivity band (valence band) and the electrons of half-filled d-shells of manganese ions as well as taking into account electron spins and the band nonparabolicity. For the calculation of the spectra and wave functions double-band Kane model has been used. On the basis of the found formulae an analytical equation has been found out for interband Faraday rotation (IFR) depending on the energy of the incident photon, band gap and the film thickness. It has been shown that by the decrease in the band gap the value of the IFR angle increases too. The formula of parabolic approximation has been also obtained. The dependence of IFR angle on photon energy, band gap and the film thickness has been built. It has been specified that the decrease of the film thickness leads to a strong increase of IFR angle. The contribution of nonparabolicity into IFR angle has been established, so taking into consideration the band

Combination of short-length TiO_2 nanorod arrays and compact PbS quantum-dot thin films for efficient solid-state quantum-dot-sensitized solar cells

International Nuclear Information System (INIS)

Zhang, Zhengguo; Shi, Chengwu; Chen, Junjun; Xiao, Guannan; Li, Long

2017-01-01

Graphical abstract: The TiO_2 nanorod array with the length of 600 nm, the diameter of 20 nm, the areal density of 500 μm"−"2 was successfully prepared. The compact PbS quantum-dot thin film was firstly obtained on the TiO_2 nanorod array by spin-coating-assisted successive ionic layer absorption and reaction with using 1,2-ethanedithiol. The photoelectric conversion efficiency (PCE) of the compact PbS quantum-dot thin film sensitized solar cells achieved 4.10% using spiro-OMeTAD as a hole transporting layer, while the PCE of the PbS quantum-dot sensitized solar cells was only 0.54%. - Highlights: • Preparation of TiO_2 nanorod arrays with the length of 600 nm, diameter of 20 nm. • The compact PbS QD thin film and short-length TiO_2 nanorod array were combined. • EDT addition improved PbS nanoparticle coverage and photovoltaic performance. • The compact PbS QD thin film sensitized solar cell achieved the PCE of 4.10%. - Abstract: Considering the balance of the hole diffusion length and the loading quantity of quantum-dots, the rutile TiO_2 nanorod array with the length of 600 nm, the diameter of 20 nm, and the areal density of 500 μm"−"2 is successfully prepared by the hydrothermal method using the aqueous grown solution of 38 mM titanium isopropoxide and 6 M hydrochloric acid at 170 °C for 105 min. The compact PbS quantum-dot thin film on the TiO_2 nanorod array is firstly obtained by the spin-coating-assisted successive ionic layer absorption and reaction with using 1,2-ethanedithiol (EDT). The result reveals that the strong interaction between lead and EDT is very important to control the crystallite size of PbS quantum-dots and obtain the compact PbS quantum-dot thin film on the TiO_2 nanorod array. The all solid-state sensitized solar cell with the combination of the short-length, high-density TiO_2 nanorod array and the compact PbS quantum-dot thin film achieves the photoelectric conversion efficiency of 4.10%, along with an open

Ab initio hybrid DFT calculations of BaTiO{sub 3}, PbTiO{sub 3}, SrZrO{sub 3} and PbZrO{sub 3} (111) surfaces

Energy Technology Data Exchange (ETDEWEB)

Eglitis, Roberts I., E-mail: rieglitis@gmail.com

2015-12-15

Highlights: • Surface energies for AO{sub 3}-term (111) surfaces are larger than for Ti (Zr)-term surfaces. • A increase of Ti−O (Zr−O) bond covalency near the ABO{sub 3} (111) surface relative to the bulk is observed. • The ABO{sub 3} (111) surface energy is larger than the earlier calculated (001) surface energy. • Band gap for PbTiO{sub 3}, SrZrO{sub 3} and PbZrO{sub 3} (111) surfaces becomes smaller, but for BaTiO{sub 3} (111) larger with respect to the bulk . - Abstract: The results of ab initio calculations for polar BaTiO{sub 3}, PbTiO{sub 3}, SrZrO{sub 3} and PbZrO{sub 3} (111) surfaces using the CRYSTAL code are presented. By means of the hybrid B3LYP approach, the surface relaxation has been calculated for two possible B (B = Ti or Zr) or AO{sub 3} (A = Ba, Pb or Sr) BaTiO{sub 3}, PbTiO{sub 3}, SrZrO{sub 3} and PbZrO{sub 3} (111) surface terminations. According to performed B3LYP calculations, all atoms of the first surface layer, for both terminations, relax inwards. The only exception is a small outward relaxation of the PbO{sub 3}-terminated PbTiO{sub 3} (111) surface upper layer Pb atom. B3LYP calculated surface energies for BaO{sub 3}, PbO{sub 3}, SrO{sub 3} and PbO{sub 3}-terminated BaTiO{sub 3}, PbTiO{sub 3}, SrZrO{sub 3} and PbZrO{sub 3} (111) surfaces are considerably larger than the surface energies for Ti (Zr)-terminated (111) surfaces. Performed B3LYP calculations indicate a considerable increase of Ti−O (Zr−O) chemical bond covalency near the BaTiO{sub 3}, PbTiO{sub 3}, SrZrO{sub 3} and PbZrO{sub 3} (111) surface relative to the BaTiO{sub 3}, PbTiO{sub 3}, SrZrO{sub 3} and PbZrO{sub 3} bulk. Calculated band gaps at the Γ-point near the PbTiO{sub 3}, SrZrO{sub 3} and PbZrO{sub 3} (111) surfaces are reduced, but near BaTiO{sub 3} (111) surfaces increased, with respect to the BaTiO{sub 3}, PbTiO{sub 3}, SrZrO{sub 3} and PbZrO{sub 3} bulk band gap at the Γ-point values.

Highly enhanced photocurrent of novel quantum-dot-co-sensitized PbS-Hg/CdS/Cu:ZnO thin films for photoelectrochemical applications

International Nuclear Information System (INIS)

Gohel, Jignasa V.; Jana, A.K.; Singh, Mohit

2017-01-01

A novel quantum-dot-co-sensitized PbS-Hg/CdS/Cu:ZnO thin films synthesized by low-cost process. The properties of ZnO are also enhanced by doping and co-doping. It is also compared with quantum-dot co-sensitization. Optical properties, crystal structure, morphology, and photocurrent are characterized by UV-Vis spectroscopy, XRD, SEM, and solar simulator, respectively. The bandgap is interestingly reduced highly to 2.6 eV for Ag co-doped Cu:ZnO. It is unprecedentedly reduced to 2.1 eV and even 1.97 eV for CdS and PbS-Hg QD-sensitized thin films, respectively. An exceptionally enhanced photocurrent of 17.1 mA/cm"2 is achieved with PbS-Hg-co-sensitized CdS-sensitized Cu:ZnO thin film. This is an excellent achievement, which highly supports the potential of low-cost solar conversion. (orig.)

Highly enhanced photocurrent of novel quantum-dot-co-sensitized PbS-Hg/CdS/Cu:ZnO thin films for photoelectrochemical applications

Energy Technology Data Exchange (ETDEWEB)

Gohel, Jignasa V.; Jana, A.K.; Singh, Mohit [Sardar Vallabhbhai National Institute of Technology, Chemical Engineering Department, Surat, Gujarat (India)

2017-08-15

A novel quantum-dot-co-sensitized PbS-Hg/CdS/Cu:ZnO thin films synthesized by low-cost process. The properties of ZnO are also enhanced by doping and co-doping. It is also compared with quantum-dot co-sensitization. Optical properties, crystal structure, morphology, and photocurrent are characterized by UV-Vis spectroscopy, XRD, SEM, and solar simulator, respectively. The bandgap is interestingly reduced highly to 2.6 eV for Ag co-doped Cu:ZnO. It is unprecedentedly reduced to 2.1 eV and even 1.97 eV for CdS and PbS-Hg QD-sensitized thin films, respectively. An exceptionally enhanced photocurrent of 17.1 mA/cm{sup 2} is achieved with PbS-Hg-co-sensitized CdS-sensitized Cu:ZnO thin film. This is an excellent achievement, which highly supports the potential of low-cost solar conversion. (orig.)

Combination of short-length TiO{sub 2} nanorod arrays and compact PbS quantum-dot thin films for efficient solid-state quantum-dot-sensitized solar cells

Energy Technology Data Exchange (ETDEWEB)

Zhang, Zhengguo [School of Chemistry and Chemical Engineering, Hefei University of Technology, Hefei 230009 (China); School of Chemistry and Chemical Engineering, Beifang University of Nationalities, Yinchuan 750021 (China); Shi, Chengwu, E-mail: shicw506@foxmail.com [School of Chemistry and Chemical Engineering, Hefei University of Technology, Hefei 230009 (China); Chen, Junjun; Xiao, Guannan; Li, Long [School of Chemistry and Chemical Engineering, Hefei University of Technology, Hefei 230009 (China)

2017-07-15

Graphical abstract: The TiO{sub 2} nanorod array with the length of 600 nm, the diameter of 20 nm, the areal density of 500 μm{sup −2} was successfully prepared. The compact PbS quantum-dot thin film was firstly obtained on the TiO{sub 2} nanorod array by spin-coating-assisted successive ionic layer absorption and reaction with using 1,2-ethanedithiol. The photoelectric conversion efficiency (PCE) of the compact PbS quantum-dot thin film sensitized solar cells achieved 4.10% using spiro-OMeTAD as a hole transporting layer, while the PCE of the PbS quantum-dot sensitized solar cells was only 0.54%. - Highlights: • Preparation of TiO{sub 2} nanorod arrays with the length of 600 nm, diameter of 20 nm. • The compact PbS QD thin film and short-length TiO{sub 2} nanorod array were combined. • EDT addition improved PbS nanoparticle coverage and photovoltaic performance. • The compact PbS QD thin film sensitized solar cell achieved the PCE of 4.10%. - Abstract: Considering the balance of the hole diffusion length and the loading quantity of quantum-dots, the rutile TiO{sub 2} nanorod array with the length of 600 nm, the diameter of 20 nm, and the areal density of 500 μm{sup −2} is successfully prepared by the hydrothermal method using the aqueous grown solution of 38 mM titanium isopropoxide and 6 M hydrochloric acid at 170 °C for 105 min. The compact PbS quantum-dot thin film on the TiO{sub 2} nanorod array is firstly obtained by the spin-coating-assisted successive ionic layer absorption and reaction with using 1,2-ethanedithiol (EDT). The result reveals that the strong interaction between lead and EDT is very important to control the crystallite size of PbS quantum-dots and obtain the compact PbS quantum-dot thin film on the TiO{sub 2} nanorod array. The all solid-state sensitized solar cell with the combination of the short-length, high-density TiO{sub 2} nanorod array and the compact PbS quantum-dot thin film achieves the photoelectric conversion

Interface engineering of CsPbBr3/TiO2 heterostructure with enhanced optoelectronic properties for all-inorganic perovskite solar cells

Science.gov (United States)

Qian, Chong-Xin; Deng, Zun-Yi; Yang, Kang; Feng, Jiangshan; Wang, Ming-Zi; Yang, Zhou; Liu, Shengzhong Frank; Feng, Hong-Jian

2018-02-01

Interface engineering has become a vital method in accelerating the development of perovskite solar cells in the past few years. To investigate the effect of different contacted surfaces of a light absorber with an electron transporting layer, TiO2, we synthesize CsPbBr3/TiO2 thin films with two different interfaces (CsBr/TiO2 and PbBr2/TiO2). Both interfacial heterostructures exhibit enhanced visible light absorption, and the CsBr/TiO2 thin film presents higher absorption than the PbBr2/TiO2 interface, which is attributed to the formation of interface states and the decreased interface bandgap. Furthermore, compared with the PbBr2/TiO2 interface, CsBr/TiO2 solar devices present larger output short circuit current and shorter photoluminescence decay time, which indicates that the CsBr contacting layer with TiO2 can better extract and separate the photo-induced carriers. The first-principles calculations confirm that, due to the existence of staggered gap (type II) offset junction and the interface states, the CsBr/TiO2 interface can more effectively separate the photo-induced carriers and thus drive the electron transfer from the CsPbBr3 perovskite layer to the TiO2 layer. These results may be beneficial to exploit the potential application of all-inorganic perovskite CsPbBr3-based solar cells through the interface engineering route.

Damped soft phonons and diffuse scattering in 40%Pb(Mg1/3Nb2/3)O3-60%PbTiO3

International Nuclear Information System (INIS)

Stock, C.; Ellis, D.; Swainson, I. P.; Xu, Guangyong; Hiraka, H.; Shirane, G.; Zhong, Z.; Luo, H.; Zhao, X.; Viehland, D.; Birgeneau, R. J.

2006-01-01

Using neutron elastic and inelastic scattering and high-energy x-ray diffraction, we present a comparison of 40% Pb(Mg 1/3 Nb 2/3 )O 3 -60% PbTiO 3 (PMN-60PT) with pure Pb(Mg 1/3 Nb 2/3 )O 3 (PMN) and PbTiO 3 (PT). We measure the structural properties of PMN-60PT to be identical to pure PT, however, the lattice dynamics are exactly that previously found in relaxors PMN and Pb(Zn 1/3 Nb 2/3 )O 3 (PZN). PMN-60PT displays a well-defined macroscopic structural transition from a cubic to tetragonal unit cell at 550 K. The diffuse scattering is shown to be weak indicating that the structural distortion is long-range in PMN-60PT and short-range polar correlations (polar nanoregions) are not present. Even though polar nanoregions are absent, the soft optic mode is short-lived for wave vectors near the zone center. Therefore PMN-60PT displays the same waterfall effect as prototypical relaxors PMN and PZN. We conclude that it is random fields resulting from the intrinsic chemical disorder which is the reason for the broad transverse optic mode observed in PMN and PMN-60PT near the zone center and not due to the formation of short-ranged polar correlations. Through our comparison of PMN, PMN-60PT, and pure PT, we interpret the dynamic and static properties of the PMN-xPT system in terms of a random field model in which the cubic anisotropy term dominates with increasing doping of PbTiO 3

PHOTOSENSITIVE STRUCTURES ON THE BASIS OF THIN FILMS OF SEMIMAGNETIC SEMICONDUCTORS Pb1-x Mnx Te

International Nuclear Information System (INIS)

Mehrabova, M.A; Nuriyev, I.R; Ismayilov, T.G; Kerimova, T.I; Mamishova, R.M

2011-01-01

Full text: Narrow-band semimagnetic semiconductors (SMS) Pb1-xMnxTe are unique materials for infrared (IR) optoelectronics.The investigation of Faraday effect in Pb1-xMnxTe thin films of SMS is of a special interest. So it can be used at the construction of optic isolators, amplifiers, IR detectors and other equipments.In the given work Pb1-xMnxTe thin films (SMS) have been produced, the interband Faraday effect in these semiconductors has been theoretically and experimentally studied. Opportunities of making IR detectors have been studied. Pb1-xMnxTe (x=0.005 0.06) thin films have been grown at BaF2 substrates by the method of molecular beam condensation. The optimal conditions of producing thin films with high crystallic perfection, electrophysical and optical parameters have been determined [1]. The energy spectrum and wave functions have been theoretically calculated for quantum-sized films of Pb1-xMnxTe SMS in the case when the surface of the film is perpendicular to the axis X and the spin-spin exchange interaction occurs between the electrons in the conductivity band (valence band) and the electrons of half-filled d-shells of manganese ions as well as taking into account electron spins and the band nonparabolicity. For the calculation of the spectra and wave functions double-band Kane model has been used. On the basis of the found formulae an analytical equation has been found out for interband Faraday rotation (IFR) depending on the energy of the incident photon, band gap and the film thickness. It has been shown that by the decrease in the band gap the value of the IFR angle increases too [2]. The formula of parabolic approximation has been also obtained. The dependence of IFR angle on photon energy, band gap and the film thickness has been built. It has been specified that the decrease of the film thickness leads to a strong increase of IFR angle. The contribution of nonparabolicity into IFR angle has been established, so taking into consideration the

Multiferroic magnetoelectric coupling effect of bilayer La1.2Sr1.8Mn2O7/PbZr0.3Ti0.7O3 complex thin film

Science.gov (United States)

Liang, K.; Zhou, P.; Ma, Z. J.; Qi, Y. J.; Mei, Z. H.; Zhang, T. J.

2017-05-01

Magnetoelectric (ME) coupling effect of 2-2-type ferromagnetic/ferroelectric bi-layer multiferroic epitaxial thin film (La1.2Sr1.8Mn2O7/PbZr0.3Ti0.7O3, LSMO/PZT) on SrRuO3 (SRO) substrate is investigated systematically by using Landau-Ginzburg-Devonshire (LGD) thermodynamic theory and modified constitutive equations. The calculating results clarify the detail relationships between ME coupling response and the residual strain, the volume fraction of constituent phases, the interface coupling coefficients, the magnetic field and the temperature. It also shows that improved ME coupling response can be modulated by these parameters. External magnetic fields (H1) induced ME coupling effect could be enhanced around Curie Temperature (Tc) of ferromagnetic phase and ME voltage coefficient (αE31) approaches a maximum at H1 ∼ 4.5 kOe near Tc. The remarkable variations of ME coupling response can be used to provide useful guidelines on the design of multifunctional devices.

Formation of nanodots and enhancement of thermoelectric power induced by ion irradiation in PbTe:Ag composite thin films

Energy Technology Data Exchange (ETDEWEB)

Bala, Manju, E-mail: manjubala474@gmail.com [Inter-University Accelerator Centre, Aruna Asaf Ali Marg, New Delhi 110067 (India); Meena, Ramcharan; Gupta, Srashti; Pannu, Compesh [Inter-University Accelerator Centre, Aruna Asaf Ali Marg, New Delhi 110067 (India); Tripathi, Tripurari S. [Aalto University, Värmemansgränden 2, 02150 Espoo (Finland); Varma, Shikha [Institute of Physics, Bhubaneshwar, Odisha 751005 (India); Tripathi, Surya K. [Department of Physics, Panjab University, Chandigarh 160 014 (India); Asokan, K., E-mail: asokaniuac@gmail.com [Inter-University Accelerator Centre, Aruna Asaf Ali Marg, New Delhi 110067 (India); Avasthi, Devesh K. [Amity University, Noida 201313, Uttar Pradesh (India)

2016-07-15

Present study demonstrates an enhancement in thermoelectric power of 10% Ag doped PbTe (PbTe:Ag) thin films when irradiated with 200 keV Ar ion. X-ray diffraction showed an increase in crystallinity for both PbTe and PbTe:10Ag nano-composite films after Ar ion irradiation due to annealing of defects in the grain boundaries. The preferential sputtering of Pb and Te ions in comparison to Ag ions resulted in the formation of nano-dots. This was further confirmed by X-ray photoelectron spectroscopy (XPS). Such an enhancement in thermoelectric power of irradiated PbTe:10Ag films in comparison to pristine PbTe:10Ag film is attributed to the decrease in charge carrier concentration that takes part in the transport process via restricting the tunneling of carriers through the wider potential barrier formed at the interface of nano-dots.

Modulation of electronic and optical properties in mixed halide perovskites CsPbCl3xBr3(1-x) and CsPbBr3xI3(1-x)

Science.gov (United States)

Zhou, Ziqi; Cui, Yu; Deng, Hui-Xiong; Huang, Le; Wei, Zhongming; Li, Jingbo

2017-03-01

The recent discovery of lead halide perovskites with band gaps in the visible presents important potential in the design of high efficient solar cells. CsPbCl3, CsPbBr3 and CsPbI3 are stable compounds within this new family of semiconductors. By performing the first-principles calculation, we explore the structural, electronic and optical properties of CsPbCl3xBr3(1-x) and CsPbBr3xI3(1-x) with various compositions of halide atoms. Structural stability is demonstrated with halide atoms distributing randomly at the halide atomic sites. CsPbCl3xBr3(1-x) and CsPbBr3xI3(1-x) exhibit the modulation of their band gaps by varying the halide composition. Our results also indicate that CsPbCl3xBr3(1-x) and CsPbBr3xI3(1-x) with different halide compositions are suitable to application to solar cells for the general features are well preserved. Good absorption to lights of different wavelengths has been obtained in these mixed halide perovskites.

Comparative study of effects of Mo and W dopants on the ferroelectric property of Pb(Zr0.3Ti0.7) thin films

International Nuclear Information System (INIS)

Zhang Zhen; Wang Shijie; Lu Li; Shu Chang; Song Wendong; Wu Ping

2008-01-01

Pb(Zr 0.3 Ti 0.7 )O 3 thin films, respectively, doped with 1 mol% W and 1 mol% Mo have been deposited on the LaNiO 3 bottom electrodes using pulse laser deposition. The x-ray diffraction analyses revealed that both dopants induced (1 1 0) orientation of the perovskite structures. Compared with the undoped PZT films, the doped PZT films showed smoother and denser surfaces. The XPS measurements indicated that W possessed a valence state of +6 in the PZTW films, but Mo showed mixed valence states of +4 and +6. The hysteresis loops and fatigue results of the undoped, the W-doped (PZTW) and the Mo-doped PZT (PZTM) films were obtained. While both the two doped films revealed better fatigue behaviour than undoped PZT, the PZTW film had a slow fatigue rate in comparison with the PZTM film, which is consistent with our previous theoretical predictions

New Pb(Mg1/3Nb2/3)O3-Pb(In1/2Nb1/2)O3-PbZrO3-PbTiO3 Quaternary Ceramics: Morphotropic Phase Boundary Design and Electrical Properties.

Science.gov (United States)

Luo, Nengneng; Zhang, Shujun; Li, Qiang; Xu, Chao; Yang, Zhanlue; Yan, Qingfeng; Zhang, Yiling; Shrout, Thomas R

2016-06-22

Four series of Pb(Mg1/3Nb2/3)O3-Pb(In1/2Nb1/2)O3-PbZrO3-PbTiO3 (PMN-PIN-PZ-PT) quaternary ceramics with compositions located at the morphotropic phase boundary (MPB) regions were prepared. The MPBs of the multicomponent system were predicted using a linear combination rule and experimentally confirmed by X-ray powder diffraction and electrical measurement. The positions of MPBs in multicomponent systems were found in linear correlation with the tolerance factor and ionic radii of non-PT end-members. The phase structure, piezoelectric coefficient, electromechanical coupling coefficient, unipolar strains, and dielectric properties of as-prepared ceramics were systematically investigated. The largest d33s were obtained at S36.8, L37.4, M39.6, and N35.8, with the corresponding values of 580, 450, 420, and 530 pC/N, respectively, while the largest kps were found at S34.8, L37.4, M39.6, and N35.8, with the respective values of 0.54, 0.50, 0.47, and 0.53. The largest unipolar strain Smax and high-field piezoelectric strain coefficients d33* were also observed around the respective MPB regions. The rhombohedral-to-tetragonal phase transition temperature Trt increased with increasing PIN and PZ contents. Of particular importance is that high Trt of 140-197 °C was achieved in the M series with PZ and PIN contents being around 0.208 and 0.158, which will broaden the temperature usage range.

The role of cationic precursors in structural, morphological and optical properties of PbS thin films

International Nuclear Information System (INIS)

Preetha, K C; Murali, K V; Ragina, A J; Deepa, K; Dhanya, A C; Remadevi, T L

2013-01-01

Thin films of Lead sulphide (PbS) were grown on soda lime glass substrate by Successive Ionic Layer Adsorption and Reaction (SILAR) method using lead acetate, lead chloride, lead nitrate, and lead sulphate as cationic precursors and thioacetamide as sulphur source. The experiments were carried out at room temperature under normal pressure utilizing aqueous conditions. The structural and morphological aspects of the as prepared samples were investigated by means of XRD and SEM results. The prepared samples were polycrystalline with nanometer-sized grains and identified as galena type cubic structure (FCC). The values of average crystallite size were found to be in the range 22 to 30 nm. The SEM micrographs show variations in morphology. Optical studies revealed that the absorption edges of the films indicated strong blue shifts with respect to bulk sample. In this work, we establish that the cationic precursor sources and in turn the size of the crystallites affects the structural, morphological and optical properties of PbS thin films.

Hybridization of Single Nanocrystals of Cs4PbBr6 and CsPbBr3.

Science.gov (United States)

Weerd, Chris de; Lin, Junhao; Gomez, Leyre; Fujiwara, Yasufumi; Suenaga, Kazutomo; Gregorkiewicz, Tom

2017-09-07

Nanocrystals of all-inorganic cesium lead halide perovskites (CsPbX 3 , X = Cl, Br, I) feature high absorption and efficient narrow-band emission which renders them promising for future generation of photovoltaic and optoelectronic devices. Colloidal ensembles of these nanocrystals can be conveniently prepared by chemical synthesis. However, in the case of CsPbBr 3 , its synthesis can also yield nanocrystals of Cs 4 PbBr 6 and the properties of the two are easily confused. Here, we investigate in detail the optical characteristics of simultaneously synthesized green-emitting CsPbBr 3 and insulating Cs 4 PbBr 6 nanocrystals. We demonstrate that, in this case, the two materials inevitably hybridize, forming nanoparticles with a spherical shape. The actual amount of these Cs 4 PbBr 6 nanocrystals and nanohybrids increases for synthesis at lower temperatures, i.e., the condition typically used for the development of perovskite CsPbBr 3 nanocrystals with smaller sizes. We use state-of-the-art electron energy loss spectroscopy to characterize nanoparticles at the single object level. This method allows distinguishing between optical characteristics of a pure Cs 4 PbBr 6 and CsPbBr 3 nanocrystal and their nanohybrid. In this way, we resolve some of the recent misconceptions concerning possible visible absorption and emission of Cs 4 PbBr 6 . Our method provides detailed structural characterization, and combined with modeling, we conclusively identify the nanospheres as CsPbBr 3 /Cs 4 PbBr 6 hybrids. We show that the two phases are independent of each other's presence and merge symbiotically. Herein, the optical characteristics of the parent materials are preserved, allowing for an increased absorption in the UV due to Cs 4 PbBr 6 , accompanied by the distinctive efficient green emission resulting from CsPbBr 3 .

Photostriction of CH3NH3PbBr3 Perovskite Crystals

KAUST Repository

Wei, Tzu-Chiao; Wang, Hsin-Ping; Li, Ting-You; Lin, Chun-Ho; Hsieh, Ying-Hui; Chu, Ying-Hao; He, Jr-Hau

2017-01-01

.e., photostriction). From these shifts, the photostrictive coefficient of CH3 NH3 PbBr3 is calculated as 2.08 × 10-8 m2 W-1 at room temperature under visible light illumination. The significant photostriction of CH3 NH3 PbBr3 is attributed to a combination

Synthesis, vibrational and optical properties of a new three-layered organic-inorganic perovskite (C4H9NH3)4Pb3I4Br6

International Nuclear Information System (INIS)

Dammak, T.; Elleuch, S.; Bougzhala, H.; Mlayah, A.; Chtourou, R.; Abid, Y.

2009-01-01

An organic-inorganic hybrid perovskite (C 4 H 9 NH 3 ) 4 Pb 3 I 4 Br 6 was synthesized and studied by X-ray diffraction, Raman and infrared spectroscopies, optical transmission and photoluminescence. The title compound, abbreviated (C 4 ) 4 Pb 3 I 4 Br 6 , crystallises in a periodic two-dimensional multilayer structure with P2 1 /a space group. The structure is built up from alternating inorganic and organic layers. Each inorganic layer consists of three sheets of PbX 6 (X=I, Br) octahedra. Raman and infrared spectra of the title compound were recorded in the 100-3500 and 400-4000 cm -1 frequency ranges, respectively. An assignment of the observed vibration modes is reported. Optical transmission measurements, performed on thin films of (C 4 ) 4 Pb 3 I 4 Br 6 , revealed two absorption bands at 474 and 508 nm. Photoluminescence measurements have shown a green emission peak at 519 nm.

Photoelectric characteristics of CH3NH3PbI3/p-Si heterojunction

Science.gov (United States)

Yamei, Wu; Ruixia, Yang; Hanmin, Tian; Shuai, Chen

2016-05-01

Organic-inorganic hybrid perovskite CH3NH3PbI3 film is prepared on p-type silicon substrate using the one-step solution method to form a CH3NH3PbI3/p-Si heterojunction. The film morphology and structure are characterized by atomic force microscopy (AFM) and scanning electron microscopy (SEM). The photoelectric properties of the CH3NH3PbI3/p-Si heterojunction are studied by testing the current-voltage (I-V) with and without illumination and capacitance-voltage (C-V) characteristics. It turns out from the I-V curve without illumination that the CH3NH3PbI3/p-Si heterojunction has a rectifier feature with the rectification ratio over 70 at the bias of ±5 V. Also, there appears a photoelectric conversion phenomenon on this heterojunction with a short circuit current (Isc) of 0.16 μA and an open circuit voltage (Voc) of about 10 mV The high frequency C-V characteristic of the Ag/CH3NH3PbI3/p-Si heterojunction turns out to be similar to that of the metal-insulator-semiconductor (MIS) structure, and a parallel translation of the C-V curve along the forward voltage axis is found. This parallel translation means the existence of defects at the CH3NH3PbI3/p-Si interface and positive fixed charges in the CH3NH3PbI3 layer. The defects at the interface of the CH3NH3PbI3/p-Si heterojunction result in the dramatic decline of the Voc. Besides, the C-V test of CH3NH3PbI3 film shows a non-linear dielectric property and the dielectric value is about 4.64 as calculated. Project supported by the Hebei Province Natural Science Foundation of China (No. F2014202184) and the Tianjin Natural Science Foundation of China (No. 15JCZDJC37800).

Preparation of Pb(Zr0.52Ti0.48)O3 thin films on Pt/RuO2 double electrode by a new sol-gel route

International Nuclear Information System (INIS)

Kim, S.; Choi, Y.; Kim, C.; Oh, Y.

1997-01-01

Pb(Zr 0.52 Ti 0.48 )O 3 (PZT) thin film on Pt/RuO 2 double electrode was successfully prepared by using new alkoxide endash alkanolamine, sol-gel method. It was observed that the use of Pt/RuO 2 double electrode reduced leakage current, resulting in a marked improvement in the leakage characteristics and more reliable capacitors. Typical P-E hysteresis behavior was observed even at low applied voltage of 5 V, manifesting greatly improved remanance and coercivity. Fatigue and breakdown characteristic, measured at 5 V, showed stable behavior and no degradation in polarization was observed up to 10 11 cycles.copyright 1997 Materials Research Society

Optical studies on Zn-doped lead chalcogenide (PbSe){sub 100−x}Zn{sub x} thin films composed of nanoparticles

Energy Technology Data Exchange (ETDEWEB)

Ashraf, Md. Tanweer [Department of Applied Sciences and Humanities, Jamia Millia Islamia (JMI), New Delhi-25 (India); Salah, Numan A. [Center of Nanotechnology, King Abdulaziz University, Jeddah (Saudi Arabia); Rafat, M. [Department of Applied Sciences and Humanities, Jamia Millia Islamia (JMI), New Delhi-25 (India); Zulfequar, M. [Department of Physics, Jamia Millia Islamia, New Delhi-25 (India); Khan, Zishan H., E-mail: zishan_hk@yahoo.co.in [Department of Applied Sciences and Humanities, Jamia Millia Islamia (JMI), New Delhi-25 (India)

2016-08-01

The effect of laser-Irradiation on the optical properties of Zn-doped PbSe thin films composed of nanoparticles has been studied. Scanning electron microscope (SEM) investigations suggest the formation of nanoparticles of average size of 50 nm for all the studied Zn compositions. XRD studies show that the as-prepared thin films are polycrystalline in nature. The formation of nanoparticles of Zn-doped PbSe has been confirmed by indexing the crystal planes as observed in the XRD spectra. The addition of Zn in (PbSe){sub 100−x}Zn{sub x} thin films result in the blue shift in photoluminescence spectra, this blue shift is associated with the narrowing of the band gap. Optical absorption measurements reveal a direct band gap for the present samples, which decreases on increasing the Zn content. The same trend has also been observed for the samples irradiated with laser. Further, the calculated values of Urbach energy are found to increase with the increase in Zn contents for the as-prepared as well as laser-irradiated samples. All the above observations agree well with the results of optical band gap and suggest that the decrease in band gap may be due to increase in band tails, defects and particle size. - Highlights: • Nanoparticles of Zn doped (PbSe){sub 100−x}Zn{sub x} lead chalcogenides have been synthesized. • Effect of laser irradiation on optical properties of (PbSe){sub 100−x}Zn{sub x} has been studied. • A blue shift in PL spectra is obtained on Zn incorporation.

Beam-Mode Piezoelectric Properties of Ternary Pb(In1/2Nb1/2)O3-Pb(Mg1/3Nb2/3)O3-PbTiO3 Single Crystals for Medical Linear Array Applications

Science.gov (United States)

Wang, Wei; Wang, Sheng; Zhang, Yaoyao; Zhao, Xiangyong; Luo, Haosu

2011-11-01

In this work, the dielectric and beam-mode piezoelectric properties of ternary 0.35Pb(In1/2Nb1/2)O3-0.35Pb(Mg1/3Nb2/3)O3-0.30PbTiO3 (PIMNT35/35/30) piezoelectric single crystals were investigated. The Curie temperature ( T C) and rhombohedral-to-tetragonal phase-transition temperature ( T rt) are 187°C and 127°C, about 30°C higher than those of PMNT crystals. The beam-mode coupling coefficient k {33/ w } was found to be 90.3%. Furthermore, 3.5-MHz linear arrays based on PIMNT35/35/30 crystals and Pb(Zr1- x Ti x )O3 ceramic (PZT-5H) were simulated using PiezoCAD software. The results indicate that the sensitivity and -6 dB bandwidth of a PIMNT35/35/30 transducer would be approximately 4 dB and 20% higher, respectively, compared with a traditional PZT transducer.

Enhancement of photocurrent extraction and electron injection in dual-functional CH3NH3PbBr3 perovskite-based optoelectronic devices via interfacial engineering

Science.gov (United States)

Tsai, Chia-Lung; Lu, Yi-Chen; Hsiung Chang, Sheng

2018-07-01

Photocurrent extraction and electron injection in CH3NH3PbBr3 (MAPbBr3) perovskite-based optoelectronic devices are both significantly increased by improving the contact at the PCBM/MAPbBr3 interface with an extended solvent annealing (ESA) process. Photoluminescence quenching and x-ray diffraction experiments show that the ESA not only improves the contact at the PCBM/MAPbBr3 interface but also increases the crystallinity of the MAPbBr3 thin films. The optimized dual-functional PCBM-MAPbBr3 heterojunction based optoelectronic device has a high power conversion efficiency of 4.08% and a bright visible luminescence of 1509 cd m‑2. In addition, the modulation speed of the MAPbBr3 based light-emitting diodes is larger than 14 MHz, which indicates that the defect density in the MAPbBr3 thin film can be effectively reduced by using the ESA process.

Dependence of e31,f on polar axis texture for tetragonal Pb(Zrx,Ti1-x)O3 thin films

Science.gov (United States)

Yeager, Charles B.; Ehara, Yoshitaka; Oshima, Naoya; Funakubo, Hiroshi; Trolier-McKinstry, Susan

2014-09-01

It was shown by Ouyang et al. [Appl. Phys. Lett. 86, 152901 (2005)] that the piezoelectric e31,f coefficient is largest parallel to the spontaneous polarization in tetragonal PbZrxTi1-xO3 (PZT) films. However, the expected piezoelectric data are typically calculated from phenomenological constants derived from data on ceramic PZT. In this work, the dependence of e31,f on c-axis texture fraction, f001, for {001}PZT thin films was measured by growing films with systematically changed f001 using CaF2, MgO, SrTiO3, and Si substrates. An approximately linear increase in e31,f with f001 was observed for compositions up to 43 mol. % Zr, and 100% c-domain properties were extrapolated. It was demonstrated that c-axis PZT films can achieve e31,f exceeding -12 C/m2 for many tetragonal compositions. The energy harvesting figure of merit, e31,f2/ɛr, for c-axis PZT films surpassed 0.8 C2/m4. This is larger than the figure of merit of gradient-free PZT films grown on Si substrates by a factor of four.

CH3NH3Pb1-xMgxI3 perovskites as environmentally friendly photovoltaic materials

Science.gov (United States)

Zhang, Y. D.; Feng, J.

2018-01-01

In an effort to reduce the toxicity of Pb in perovskite solar cells, the band structures, electron and hole effective masses, and electronic and optical properties of the novel perovskites CH3NH3Pb1-xMgxI3 were predicted using density functional theory with the scalar relativistic generalized gradient approximation. The calculation results indicated that the introduction of the Mg component caused the band gaps of the CH3NH3Pb1-xMgxI3 compounds to exceed that of CH3NH3PbI3. The calculated absorption coefficients of the CH3NH3PbI3 and CH3NH3Pb1-xMgxI3 perovskites revealed that substituting 12.5 mol % of the Pb in CH3NH3PbI3 with Mg had little effect on the absorption ability. Surprisingly, it was also found that CH3NH3Pb0.75Mg0.25I3 retained up to 83% of the absorption performance relative to CH3NH3PbI3. This indicates that the amount of toxic Pb used in perovskite solar cells could be reduced by a quarter while retaining over 80% of the light-absorbing ability. In general, these novel CH3NH3Pb1-xMgxI3 (x ≤ 0.25) perovskites represent promising candidates for environmentally friendly light-harvesting materials for use in solar cells.

Transitions between localized and itinerant antiferromagnetism in the Ce(Pb,In) sub 3 and Ce(Pb,Tl) sub 3 systems

Energy Technology Data Exchange (ETDEWEB)

Rahman, S; Timlin, J; Crow, J E; Mihalisin, T; Schlottmann, P [Temple Univ., Philadelphia, PA (United States)

1990-01-01

CePb{sub 3} is an itinerant heavy fermion antiferromagnetic displaying an incommensurate magnetic structure and an extremely small ordered moment. CeIn{sub 3} and CeTl{sub 3}, on the other hand are well-localized, simple antiferromagnets with the full moments expected for crystal field doublet Ce{sup 3+} ion systems. The authors have performed specific heat, sysceptibility and resistivity measurements for both the Ce(Pb,In){sub 3} and Ce(Pb,Tl){sub 3} systems. These systems remain cubic Cu{sub 3}Au structures across the entire series. They display extremely interesting T{sub N} behavior which suggests that a continuous transition from itinerant to localized antiferromagnetic behavior occurs for the Ce(Pb,Tl){sub 3} system. In the Ce (Pb,In){sub 3} system both types of antiferromagnetism are present but they are separated by a concentration range ({approximately}10-40% Pb) over which antiferromagnetism does not exist. The behavior of these systems cannot be accounted for by a Kondo necklace approach that neglects the coherence of a heavy fermion lattice and resulting itinerant antiferromagnetism.

Highly crystalline p-PbS thin films with tunable optical and hole transport parameters by chemical bath deposition

International Nuclear Information System (INIS)

Bai, Rekha; Kumar, Dinesh; Chaudhary, Sujeet; Pandya, Dinesh K.

2017-01-01

Lead sulfide (PbS) thin films, consisting of well faceted (up to 400 nm) cubic-nanocrystals and possessing significantly improved opto-electronic parameters essential for photovoltaic applications, are grown by utilizing chemical bath deposition (CBD) technique with bath concentrations of 10–200 mM. X-ray diffraction (XRD) and Raman studies confirm the highly crystalline and pure phase of PbS. FESEM and HRTEM studies show that all the films possess uniform and compact (111) oriented nanocubic morphology. Bath concentration change provides tunability of nanocube size from 100 to 400 nm and the direct optical band gap from 1.50 to 0.94 eV. The PbS films exhibit p-type semiconducting behavior with hitherto unreported concurrent highest mobility of 29.3 cm"2V"−"1s"−"1 and high carrier concentration of ∼10"1"8 cm"−"3 with the lowest room temperature resistivity of 0.26 Ω–cm. The 25 mM and 10 mM films show significant surface plasmon absorption in 1200–2400 nm range making them suitable as efficient infrared absorbers in excitonic and multi-junction solar cells.

Photovoltaic properties of Cu-doped CH3NH3PbI3 with perovskite structure

Science.gov (United States)

Shirahata, Yasuhiro; Oku, Takeo

2017-01-01

Photovoltaic properties of copper (Cu)-doped perovskite (CH3NH3PbCuxI3+x) photovoltaic devices with different Cu content were investigated. The CH3NH3PbCuxI3+x films were polycrystalline with a tetragonal system, and their lattice constants and crystallite size varied with Cu doping. Compared to conversion efficiencies of non-doped CH3NH3PbI3 photovoltaic device, those of CH3NH3PbCuxI3+x photovoltaic devises increased. The improvement of photovoltaic properties was attributed to partial substitution of Cu at the Pb sites.

The efficiency limit of CH3NH3PbI3 perovskite solar cells

International Nuclear Information System (INIS)

Sha, Wei E. I.; Ren, Xingang; Chen, Luzhou; Choy, Wallace C. H.

2015-01-01

With the consideration of photon recycling effect, the efficiency limit of methylammonium lead iodide (CH 3 NH 3 PbI 3 ) perovskite solar cells is predicted by a detailed balance model. To obtain convincing predictions, both AM 1.5 spectrum of Sun and experimentally measured complex refractive index of perovskite material are employed in the detailed balance model. The roles of light trapping and angular restriction in improving the maximal output power of thin-film perovskite solar cells are also clarified. The efficiency limit of perovskite cells (without the angular restriction) is about 31%, which approaches to Shockley-Queisser limit (33%) achievable by gallium arsenide (GaAs) cells. Moreover, the Shockley-Queisser limit could be reached with a 200 nm-thick perovskite solar cell, through integrating a wavelength-dependent angular-restriction design with a textured light-trapping structure. Additionally, the influence of the trap-assisted nonradiative recombination on the device efficiency is investigated. The work is fundamentally important to high-performance perovskite photovoltaics

Investigation of the structural, optical and dielectric properties of highly (1 0 0)-oriented (Pb{sub 0.60}Ca{sub 0.20}Sr{sub 0.20})TiO{sub 3} thin films on LaNiO{sub 3} bottom electrode

Energy Technology Data Exchange (ETDEWEB)

Pontes, D.S.L. [Laboratorio Interdisciplinar de Eletroquimica e Cerâmica, Department of Chemistry, Universidade Federal de São Carlos, Via Washington Luiz, Km 235, P.O. Box 676, 13565-905 São Carlos, São Paulo (Brazil); Pontes, F.M., E-mail: fenelon@fc.unesp.br [Department of Chemistry, Universidade Estadual Paulista, P.O. Box 473, 17033-360 Bauru, São Paulo (Brazil); Chiquito, A.J. [NanO LaB, Transporte Eletrônico em Nanoestruturas, Department of Physics, Universidade Federal de São Carlos, Via Washington Luiz, Km 235, P.O. Box 676, 13565-905 São Carlos, São Paulo (Brazil); Longo, E. [Laboratorio Interdisciplinar de Eletroquimica e Cerâmica, Department of Chemistry, Universidade Federal de São Carlos, Via Washington Luiz, Km 235, P.O. Box 676, 13565-905 São Carlos, São Paulo (Brazil); Institute of Chemistry, Universidade Estadual Paulista, Araraquara, São Paulo (Brazil)

2014-07-01

Highlights: • Highly (h 0 0) oriented LNO and PCST thin films were grown on LAO(1 0 0) substrate. • PCST/LNO/LAO structure shown classic ferroelectric–paraelectric phase transition. • PCST/LNO/LAO structure shows superior dielectric properties. • PCST/LAO films showed a direct allowed optical transition. - Abstract: Highly (1 0 0)-oriented Pb{sub 0.60}Ca{sub 0.20}Sr{sub 0.20}TiO{sub 3}/LNO/LAO structure was fabricated using a chemical deposition process via spin-coating technique. XRD revealed that both LNO and Pb{sub 0.60}Ca{sub 0.20}Sr{sub 0.20}TiO{sub 3} films grown on LAO(1 0 0) substrate and LNO/LAO(1 0 0) structure were crystallized to be highly (h 0 0)-oriented, respectively. AFM images revealed smooth surfaces, spherical-shaped grains and a crack-free surface with a roughness of about 3–7 nm. The tetragonal perovskite phase was confirmed by Raman spectroscopy for Pb{sub 0.60}Ca{sub 0.20}Sr{sub 0.20}TiO{sub 3}/LNO/LAO and Pb{sub 0.60}Ca{sub 0.20}Sr{sub 0.20}TiO{sub 3}/LAO structures. The optical transmittance of 340 nm thick Pb{sub 0.60}Ca{sub 0.20}Sr{sub 0.20}TiO{sub 3} films on a LAO(1 0 0) substrate exhibited an average transmittance above 80% in the wavelength range of 500–1000 nm and an optical band gap E{sub g} of 3.56 and 2.87 eV for the direct and indirect transition processes, respectively. The Au/Pb{sub 0.60}Ca{sub 0.20}Sr{sub 0.20}TiO{sub 3}/LNO/LAO structure has a hysteresis loop with remnant polarization, P{sub r}, of 12 μC/cm{sup 2}, and a coercive field, E{sub c}, of 46 kV/cm for an electric field at 370 kV/cm along with a dielectric constant over 1200.

Note: High-power piezoelectric transformer fabricated with ternary relaxor ferroelectric Pb(Mg(1/3)Nb(2/3))O3-Pb(In(1/2)Nb(1/2))O3-PbTiO3 single crystal.

Science.gov (United States)

Wang, Qing; Ma, Chuanguo; Wang, Feifei; Liu, Bao; Chen, Jianwei; Luo, Haosu; Wang, Tao; Shi, Wangzhou

2016-03-01

A plate-shaped piezoelectric transformer was designed and fabricated using ternary relaxor ferroelectric single crystal Pb(Mg(1/3)Nb(2/3))O3-Pb(In(1/2)Nb(1/2))O3-PbTiO3. Both the input and output sections utilized the transverse-extensional vibration mode. The frequency and load dependences of the electrical properties for the proposed transformer were systematically studied. Results indicated that under a matching load resistance of 14.9 kΩ, a maximum output power of 2.56 W was obtained with the temperature rise less than 5 °C. The corresponding power density reached up to 50 W/cm(3). This ternary single-crystal transformer had potential applications in compact-size converters requiring high power density.

Optimization of Pb(Zr0.53,Ti0.47)O3 films for micropower generation using integrated cantilevers

KAUST Repository

Fuentes-Fernandez, E. M A; Baldenegro-Pé rez, Leonardo Aurelio; Quevedo-Ló pez, Manuel Angel Quevedo; Gnade, Bruce E.; Hande, Abhiman; Shah, Pradeep; Alshareef, Husam N.

2011-01-01

Lead zirconate titanate, Pb(Zr0.53,Ti0.47)O 3 or PZT, thin films and integrated cantilevers have been fabricated for energy harvesting applications. The PZT films were deposited on PECVD SiO2/Si substrates with a sol-gel derived ZrO2 buffer layer

Nuclear magnetic shielding tensors of 207Pb2+ in Pb(NO3)2

International Nuclear Information System (INIS)

Lutz, O.; Nolle, A.

1980-01-01

The NMR signals of 207 Pb were observed in a single crystal of Pb(NO 3 ) 2 and could be assigned to the four different Pb 2+ sites by the dependence of the linewidths on the orientation. Four different nuclear magnetic shielding tensors with equal principal values but with different characteristic vectors could be determined. The symmetry of the shielding tensors is in agreement with the symmetry at the Pb 2+ sites. It is shown, that intermolecular contributions can not account for the anisotropy of the nuclear magnetic shielding, which is 3 0 / 00 of the isotropic absolute magnetic shielding. (orig.)

Piezoelectric properties and temperature stability of Mn-doped Pb(Mg1/3Nb2/3)-PbZrO3-PbTiO3 textured ceramics

Science.gov (United States)

Yan, Yongke; Cho, Kyung-Hoon; Priya, Shashank

2012-03-01

In this letter, we report the electromechanical properties of textured 0.4Pb(Mg1/3Nb2/3)O3-0.25PbZrO3-0.35PbTiO3 (PMN-PZT) composition which has relatively high rhombohedral to tetragonal (R-T) transition temperature (TR-T of 160 °C) and Curie temperature (TC of 234 °C) and explore the effect of Mn-doping on this composition. It was found that MnO2-doped textured PMN-PZT ceramics with 5 vol. % BaTiO3 template (T-5BT) exhibited inferior temperature stability. The coupling factor (k31) of T-5BT ceramic started to degrade from 75 °C while the random counterpart showed a very stable tendency up to 180 °C. This degradation was associated with the "interface region" formed in the vicinity of BT template. MnO2 doped PMN-PZT ceramics textured with 3 vol. % BT and subsequently poled at 140 °C (T-3BT140) exhibited very stable and high k31 (>0.53) in a wide temperature range from room temperature to 130 °C through reduction in the interface region volume. Further, the T-3BT140 ceramic exhibited excellent hard and soft combinatory piezoelectric properties of d33 = 720 pC/N, k31 = 0.53, Qm = 403, tan δ = 0.3% which are very promising for high power and magnetoelectric applications.

Ultra Uniform Pb0.865La0.09(Zr0.65Ti0.35O3 Thin Films with Tunable Optical Properties Fabricated via Pulsed Laser Deposition

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Shenglin Jiang

2018-03-01

Full Text Available Ferroelectric thin films have been utilized in a wide range of electronic and optical applications, in which their morphologies and properties can be inherently tuned by a qualitative control during growth. In this work, we demonstrate the evolution of the Pb0.865La0.09(Zr0.65Ti0.35O3 (PLZT thin films on MgO (200 with high uniformity and optimized optical property via the controls of the deposition temperatures and oxygen pressures. The perovskite phase can only be obtained at the deposition temperature above 700 °C and oxygen pressure over 50 Pa due to the improved crystallinity. Meanwhile, the surface morphologies gradually become smooth and compact owing to spontaneously increased nucleation sites with the elevated temperatures, and the crystallization of PLZT thin films also sensitively respond to the oxygen vacancies with the variation of oxygen pressures. Correspondingly, the refractive indices gradually develop with variations of the deposition temperatures and oxygen pressures resulted from the various slight loss, and the extinction coefficient for each sample is similarly near to zero due to the relatively smooth morphology. The resulting PLZT thin films exhibit the ferroelectricity, and the dielectric constant sensitively varies as a function of electric filed, which can be potentially applied in the electronic and optical applications.

Photoresponse of CsPbBr3 and Cs4PbBr6 Perovskite Single Crystals.

Science.gov (United States)

Cha, Ji-Hyun; Han, Jae Hoon; Yin, Wenping; Park, Cheolwoo; Park, Yongmin; Ahn, Tae Kyu; Cho, Jeong Ho; Jung, Duk-Young

2017-02-02

High-quality and millimeter-sized perovskite single crystals of CsPbBr 3 and Cs 4 PbBr 6 were prepared in organic solvents and studied for correlation between photocurrent generation and photoluminescence (PL) emission. The CsPbBr 3 crystals, which have a 3D perovskite structure, showed a highly sensitive photoresponse and poor PL signal. In contrast, Cs 4 PbBr 6 crystals, which have a 0D perovskite structure, exhibited more than 1 order of magnitude higher PL intensity than CsPbBr 3 , which generated an ultralow photoresponse under illumination. Their contrasting optoelectrical characteristics were attributed to different exciton binding energies, induced by coordination geometry of the [PbBr 6 ] 4- octahedron sublattices. This work correlated the local structures of lead in the primitive perovskite and its derivatives to PL spectra as well as photoconductivity.

A novel UV-emitting phosphor: LiSr4(BO3)3: Pb2+

International Nuclear Information System (INIS)

Pekgözlü, İlhan

2013-01-01

Pure and Pb 2+ doped LiSr 4 (BO 3 ) 3 materials were prepared by a solution combustion synthesis method. The phase analysis of all synthesized materials were determined using the powder XRD. The synthesized materials were investigated using spectrofluorometer at room temperature. The excitation and emission bands of LiSr 4 (BO 3 ) 3 : Pb 2+ were observed at 284 and 328 nm, respectively. The dependence of the emission intensity on the Pb 2+ concentration for the LiSr 4 (BO 3 ) 3 were studied in detail. It was observed that the concentration quenching of Pb 2+ in LiSr 4 (BO 3 ) 3 is 0.005 mol. The Stokes shifts of LiSr 4 (BO 3 ) 3 : Pb 2+ phosphor was calculated to be 4723 cm –1 . -- Highlights: • A novel UV-emitting phosphor: LiSr 4 (BO 3 ) 3 : Pb 2+ ” synthesized for the first time. • The emission band of LiSr 4 (BO 3 ) 3 : Pb 2+ was observed at 328 nm upon excitation with 284 nm. • LiSr 4 (BO 3 ) 3 : Pb 2+ is a good phosphor for broadband UV application

CH3NH3Pb1−xMgxI3 perovskites as environmentally friendly photovoltaic materials

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Y. D. Zhang

2018-01-01

Full Text Available In an effort to reduce the toxicity of Pb in perovskite solar cells, the band structures, electron and hole effective masses, and electronic and optical properties of the novel perovskites CH3NH3Pb1−xMgxI3 were predicted using density functional theory with the scalar relativistic generalized gradient approximation. The calculation results indicated that the introduction of the Mg component caused the band gaps of the CH3NH3Pb1−xMgxI3 compounds to exceed that of CH3NH3PbI3. The calculated absorption coefficients of the CH3NH3PbI3 and CH3NH3Pb1−xMgxI3 perovskites revealed that substituting 12.5 mol % of the Pb in CH3NH3PbI3 with Mg had little effect on the absorption ability. Surprisingly, it was also found that CH3NH3Pb0.75Mg0.25I3 retained up to 83% of the absorption performance relative to CH3NH3PbI3. This indicates that the amount of toxic Pb used in perovskite solar cells could be reduced by a quarter while retaining over 80% of the light-absorbing ability. In general, these novel CH3NH3Pb1−xMgxI3 (x ≤ 0.25 perovskites represent promising candidates for environmentally friendly light-harvesting materials for use in solar cells.

The off-stoichiometric Bi1.8Pb0.3Sr2Ca2Cu3.3Ox target for thin films

International Nuclear Information System (INIS)

Harabor, A.; Deletter, M.

1996-01-01

X-ray diffraction (XRD), EDAX, AC susceptibility and resistivity measurements has been used as characterization methods for the Bi-2223 monophase target with the starting stoichiometry Bi 1.8 Pb 0.3 Sr 2 Ca 2 Cu 3.3 O x . Pressure parameter is playing an important role in obtaining good superconducting properties for this compound. Critical currents and activation energy has been calculated from susceptibility and magnetoresistivity curves, respectively. The results could be interpreted in terms of TAPS and TAFF models. (orig.)

Prediction on electronic structure of CH3NH3PbI3/Fe3O4 interfaces

Science.gov (United States)

Hou, Xueyao; Wang, Xiaocha; Mi, Wenbo; Du, Zunfeng

2018-01-01

The interfacial electronic structures of CH3NH3PbI3(MAPbI3)/Fe3O4 heterostructures are predicted by density functional theory. Four models (MAI/FeBO, PbI2/FeBO, MAI/FeA and PbI2/FeA) are included. Especially, a half-metal to semiconductor transition of Fe3O4 appears in PbI2/FeA model. A series of electric field is added to PbI2/FeA model, and a direct-indirect bandgap transition of Fe3O4 appears at a 500-kV/cm field. The electric field can control the bandgap of Fe3O4 in PbI2/FeA model by modulating the hybridization. The prediction of spin-related bandgap characteristic in MAPbI3/Fe3O4 is meaningful for further study.

Perovskite Thin Films via Atomic Layer Deposition

KAUST Repository

Sutherland, Brandon R.; Hoogland, Sjoerd; Adachi, Michael M.; Kanjanaboos, Pongsakorn; Wong, Chris T. O.; McDowell, Jeffrey J.; Xu, Jixian; Voznyy, Oleksandr; Ning, Zhijun; Houtepen, Arjan J.; Sargent, Edward H.

2014-01-01

© 2014 Wiley-VCH Verlag GmbH & Co. KGaA. (Graph Presented) A new method to deposit perovskite thin films that benefit from the thickness control and conformality of atomic layer deposition (ALD) is detailed. A seed layer of ALD PbS is place-exchanged with PbI2 and subsequently CH3NH3PbI3 perovskite. These films show promising optical properties, with gain coefficients of 3200 ± 830 cm-1.

Perovskite Thin Films via Atomic Layer Deposition

KAUST Repository

Sutherland, Brandon R.

2014-10-30

© 2014 Wiley-VCH Verlag GmbH & Co. KGaA. (Graph Presented) A new method to deposit perovskite thin films that benefit from the thickness control and conformality of atomic layer deposition (ALD) is detailed. A seed layer of ALD PbS is place-exchanged with PbI2 and subsequently CH3NH3PbI3 perovskite. These films show promising optical properties, with gain coefficients of 3200 ± 830 cm-1.

Realization of PbS thin films by reactive evaporation technique for possible opto-electronic applications

Energy Technology Data Exchange (ETDEWEB)

A, Abhilash, E-mail: abhiltp@cusat.ac.in; Nair, Aparna S.; S, Rajasree; E, Hiba Rahman; Pradeep, B. [Solid State Physics Laboratory, Department of Physics, Cochin University of Science and Technology, Kochi-682022 (India)

2015-06-24

Stoichiometric Lead sulphide (PbS) thin films were successfully prepared on glass substrates by reactive evaporation technique. Elemental evaporation of lead and sulphur taken in different sources onto substrates held at temperature of 400±5K employed in the present study. The structural as well as compositional studies compromises compound formation. Electrical transport properties and optical co-efficient were evaluated from appropriate characterization techniques.

PbBr3 Perovskite Crystals

KAUST Repository

Wei, Tzu-Chiao

2018-01-31

Researchers have recently revealed that hybrid lead halide perovskites exhibit ferroelectricity, which is often associated with other physical characteristics, such as a large nonlinear optical response. In this work, the nonlinear optical properties of single crystal inorganic–organic hybrid perovskite CH3NH3PbBr3 are studied. By exciting the material with a 1044 nm laser, strong two-photon absorption-induced photoluminescence in the green spectral region is observed. Using the transmission open-aperture Z-scan technique, the values of the two-photon absorption coefficient are observed to be 8.5 cm GW−1, which is much higher than that of standard two-photon absorbing materials that are industrially used in nonlinear optical applications, such as lithium niobate (LiNbO3), LiTaO3, KTiOPO4, and KH2PO4. Such a strong two-photon absorption effect in CH3NH3PbBr3 can be used to modulate the spectral and spatial profiles of laser pulses, as well as to reduce noise, and can be used to strongly control the intensity of incident light. In this study, the superior optical limiting, pulse reshaping, and stabilization properties of CH3NH3PbBr3 are demonstrated, opening new applications for perovskites in nonlinear optics.

Influence of grain size on structural and optic properties of PbS thin films produced by SILAR method

International Nuclear Information System (INIS)

Güneri, E.; Göde, F.; Çevik, S.

2015-01-01

In this the paper, we use the successive ion layer adsorption and reaction technique (SILAR) chemical deposition method to fabricate good quality PbS thin films and the effects of grain size on the structural and optical properties of the thin films were determined by varying deposition cases. All of the films obtained in different dipping cycles show cubic rock-salt (NaCl) structure. The preferred orientation changed from the (111) direction to the (200) direction with increasing dipping cycles. Grain size determined from scanning electron microscopy (SEM) increased from 32 nm to 104 nm. Moreover, changing of atomic ratio of the thin films is determined according to the results of energy dispersive X-ray (EDX). The transmission of the thin films was characterized by UV–Vis measurements from 400 nm to 1100 nm. It was determined from the allowed direct graphics that the energy band gaps of the thin films shift from 1.33 eV to 1.92 eV in connection with deposition conditions. The variation in band gap may be attributed to the variation of grain size. Additionally, the refractive index (n), extinction coefficient (k), real (ε 1 ) and imaginary (ε 2 ) dielectric constants varied with increasing immersion cycles. - Highlights: • The effects of grain size on the structural, optical properties of PbS thin films deposited by SILAR were investigated. • The preferred orientation varied from the (111) direction to the (200) direction with changing grain size. • The energy band gaps of the thin films shift from 1.33 eV to 1.92 eV in connection with deposition conditions. • The refractive index, extinction coefficient, real and imaginary dielectric constants varied with increasing dipping cycles

Influence of grain size on structural and optic properties of PbS thin films produced by SILAR method

Energy Technology Data Exchange (ETDEWEB)

Güneri, E., E-mail: emineg7@gmail.com [Department of Primary Education, Erciyes University, Kayseri 38039, Turkey. (Turkey); Göde, F.; Çevik, S. [Department of Physics, Mehmet Akif Ersoy University, Burdur 15030, Turkey. (Turkey)

2015-08-31

In this the paper, we use the successive ion layer adsorption and reaction technique (SILAR) chemical deposition method to fabricate good quality PbS thin films and the effects of grain size on the structural and optical properties of the thin films were determined by varying deposition cases. All of the films obtained in different dipping cycles show cubic rock-salt (NaCl) structure. The preferred orientation changed from the (111) direction to the (200) direction with increasing dipping cycles. Grain size determined from scanning electron microscopy (SEM) increased from 32 nm to 104 nm. Moreover, changing of atomic ratio of the thin films is determined according to the results of energy dispersive X-ray (EDX). The transmission of the thin films was characterized by UV–Vis measurements from 400 nm to 1100 nm. It was determined from the allowed direct graphics that the energy band gaps of the thin films shift from 1.33 eV to 1.92 eV in connection with deposition conditions. The variation in band gap may be attributed to the variation of grain size. Additionally, the refractive index (n), extinction coefficient (k), real (ε{sub 1}) and imaginary (ε{sub 2}) dielectric constants varied with increasing immersion cycles. - Highlights: • The effects of grain size on the structural, optical properties of PbS thin films deposited by SILAR were investigated. • The preferred orientation varied from the (111) direction to the (200) direction with changing grain size. • The energy band gaps of the thin films shift from 1.33 eV to 1.92 eV in connection with deposition conditions. • The refractive index, extinction coefficient, real and imaginary dielectric constants varied with increasing dipping cycles.

Fatigue properties of piezoelectric-electrostrictive Pb(Mg1/3,Nb2/3)O3-PbTiO3 monolithic bilayer composites

Science.gov (United States)

Hall, A.; Akdogan, E. K.; Safari, A.

2006-11-01

The fatigue response of monolithic piezoelectric 0.65Pb(Mg1/3Nb2/3)O3-0.35PbTiO3-electrostrictive 0.90Pb(Mg1/3Nb2/3)O3-0.10PbTiO3 bilayer composites was investigated experimentally. The monomorph bilayers were cosintered at 1150°C, and the polarization hysteresis, relative permittivity, displacement, and cyclic fatigue (107cycles) were measured as a function of piezoelectric-electrostrictive volume fraction (PEVF) ratio. The highest tip displacement of bilayers was found in the 3:1 PEVF monolith, reaching 40μm at 5kV/cm applied field strength. By minimizing the electrostrictive layer thickness, tip displacement substantially increased, while maintaining a lower hysteresis than the purely piezoelectric counterpart. Fatigue measurements indicated a 31% decrease in displacement after 107cycles in 3:1 monoliths, whereas the 1:3 PEVF only showed a 12% decrease under the same conditions. There is a 30% increase in polarization after 107cycles for 1:1 PEVF bilayers, which is attributed to self-poling due to a diffuse transition layer in the vicinity of the interface. It was found that partial 90° domain switching occurred prior to poling because of the residual stresses in the composite, imposed by the electrostrictive layer and the spontaneous strain associated with the cubic-tetragonal transition in the ferroelectric layer. The results indicate that the electrostrictive layer, which is electrically in series with the piezoelectric one, enhances the fatigue resistance of the monolithic bilayer composites in addition to the increase in tip displacement.

Effects of PbO-B2O3 Glass Doping on the Sintering Temperature and Piezoelectric Properties of 0.35Pb (Ni1/3Nb2/3)O3-0.65Pb(Zr0.41Ti0.59)O3 Ceramics

Science.gov (United States)

Yi, Jinqiao; Shen, Meng; Liu, Sisi; Jiang, Shenglin

2015-12-01

0.35Pb(Ni1/3Nb2/3)O3-0.65Pb(Zr0.41Ti0.59)O3 (PNN-PZT) ceramics doped with 0.5PbO-0.5B2O3 glass have been synthesized by the conventional solid-state sintering technique. The effects of 0.5PbO-0.5B2O3 glass on the sintering temperature and piezoelectric properties of PNN-PZT ceramics were studied. The results indicated that the sintering temperature of PNN-PZT was significantly reduced due to the incorporation of 0.5PbO-0.5B2O3 glass dopant. When the content of 0.5PbO-0.5B2O3 glass was 0.5 wt.%, the sintering temperature of PNN-PZT was observed to reduce from above 1200°C to 920°C while the samples maintained high density (7.91 g/cm3), excellent piezoelectric constant ( d 33 = 479 pC/N), large electromechanical coupling coefficient ( K p = 0.55), and relatively low electromechanical quality factor ( Q m = 79). Moreover, large dielectric constant ( ɛ 33 T / ɛ 0 = 2904) and low dielectric loss (tan δ = 0.0166) were obtained in this work.

Strong Nonvolatile Magnon-Driven Magnetoelectric Coupling in Single-Crystal Co /[PbMg1/3Nb2/3O3] 0.71[PbTiO3]0.29 Heterostructures

Science.gov (United States)

Zhou, Cai; Shen, Lvkang; Liu, Ming; Gao, Cunxu; Jia, Chenglong; Jiang, Changjun

2018-01-01

The ability to manipulate the magnetism on interfacing ferromagnetic and ferroelectric materials via electric fields to achieve an emergent multiferroic response has enormous potential for nanoscale devices with novel functionalities. Herein, a strong electric-field control of the magnetism modulation is reported for a single-crystal Co (14 nm )/(001 )Pb (Mg1/3Nb2/3) 0.7Ti0.3O3 (PMN-PT) heterostructure by fabricating an epitaxial Co layer on a PMN-PT substrate. Electric-field-tuned ferromagnetic resonance exhibits a large resonance field shift, with a 120-Oe difference between that under positive and negative remanent polarizations, which demonstrates nonvolatile electric-field control of the magnetism. Further, considering the complexity of the twofold symmetry magnetic anisotropy, the linear change of the fourfold symmetry magnetic anisotropy, relating to the single-crystal cubic magnetocrystal anisotropy of the Co thin film, is resolved and quantified to exert a magnon-driven, strong direct magnetoelectric effect on the Co /PMN -PT interface. These results are promising for future multiferroic devices.

CH3NH3PbI3 and CsPbI3 Supramolecular Clusters in 1D: Do They Evolve with the Same Principle of Cooperative Binding?

Science.gov (United States)

Varadwaj, Arpita; Varadwaj, Pradeep R.; Yamashita, Koichi

Development of novel semiconductor-based photo-catalytic and -voltaic systems is a major area of research in nanoscience and technologies, and engineering. The process can be either direct or indirect in converting the light energy into electricity. Some of the photovoltaics include the organic, dye-sensitized, and halide perovskite solar cells, among others. Methylammonium lead iodide (CH3NH3PbI3) inorganic-organic hybrid perovskite is one among the many highly valued semiconductors reported till date, comparable with the inorganic cesium lead iodide (CsPbI3) perovskite. These are competitive candidates in the solar energy race. Nevertheless, this study was concentrated on the fundamental understanding of the rational designs of the CH3NH3PbI3 and CsPbI3 supramolecular materials using first-principles calculations, emerged though the self-assembly of the respective building blocks. It therefore addresses the question whether the (CH3NH3PbI3)n and (CsPbI3)n (n =1-10) supramolecular clusters are the consequences of additivity, or non-additive cooperative binding? For addressing this question, the supramolecular properties such as the polarizability, the intermolecular charge transfer, and the binding energy, etc., all w.r.t the cluster size n, are exploited. CREST-JST, 7 Gobancho, Chiyoda-ku, Tokyo, Japan 102-0076.

Orientación de láminas delgadas de (Pb, CaTiO3

Directory of Open Access Journals (Sweden)

Mendiola, J.

1999-06-01

Full Text Available Calcium modified PbTiO3 thin films have been prepared on platinized Si, MgO and SrTiO3 substrates. The films were deposited from a sol-gel solution with a concentration of 0.3 M and with a 10% excess of PbO. Two deposits of this solution on the substrates were made by spin-coating, crystallizing each of them by a Rapid Thermal Processing. The resulting films present a single (Pb,CaTiO3 perovskite phase. All the films are textured, but the films deposited on MgO and SrTiO3 show a preferred orientation in the polar direction of the perovskite. As a result of this orientation, pyroelectric coefficients were measured, without any poling, for the films on MgO and SrTiO3. Pyroelectric measurements indicate the application of these films in infrarred sensors.Se han preparado láminas delgadas de PbTiO3 modificado con calcio sobre substratos de Si, MgO y SrTiO3 electrodados con Pt. Las películas se depositaron a partir de una solución sintetizada por sol-gel, con concentración 0.3 M y con un 10 % en exceso de PbO. En cada lámina se hicieron dos depósitos de la solución sobre el substrato mediante la técnica de “spin-coating”, cristalizando cada uno de ellos con un tratamiento térmico rápido. Todas las láminas resultantes presentaban como única fase cristalina la perovskita de (Pb,CaTiO3. Las láminas presentaron una cierta textura, observándose una orientación preferente en la dirección polar en el caso de las películas depositas sobre MgO y SrTiO3. Como resultado de esta orientación, se midieron coeficientes piroeléctricos, sin polarización previa, en las láminas sobre MgO y SrTiO3. Las medidas piroeléctricas de estos materiales evidencian su utilidad en dispositivos para sensores de infrarrojo.

Solid Liquid Interdiffusion Bonding of (Pb, Sn)Te Thermoelectric Modules with Cu Electrodes Using a Thin-Film Sn Interlayer

Science.gov (United States)

Chuang, T. H.; Lin, H. J.; Chuang, C. H.; Yeh, W. T.; Hwang, J. D.; Chu, H. S.

2014-12-01

A (Pb, Sn)Te thermoelectric element plated with a Ni barrier layer and a Ag reaction layer has been joined with a Cu electrode coated with Ag and Sn thin films using a solid-liquid interdiffusion bonding method. This method allows the interfacial reaction between Ag and Sn such that Ag3Sn intermetallic compounds form at low temperature and are stable at high temperature. In this study, the bonding strength was about 6.6 MPa, and the specimens fractured along the interface between the (Pb, Sn)Te thermoelectric element and the Ni barrier layer. Pre-electroplating a film of Sn with a thickness of about 1 μm on the thermoelectric element and pre-heating at 250°C for 3 min ensures the adhesion between the thermoelectric material and the Ni barrier layer. The bonding strength is thus increased to a maximal value of 12.2 MPa, and most of the fractures occur inside the thermoelectric material. During the bonding process, not only the Ag3Sn intermetallics but also Cu6Sn5 forms at the Ag3Sn/Cu interface, which transforms into Cu3Sn with increases in the bonding temperature or bonding time.

Electromechanical behavior of [001]-textured Pb(Mg1/3Nb2/3)O3-PbTiO3 ceramics

Science.gov (United States)

Yan, Yongke; Wang, Yu. U.; Priya, Shashank

2012-05-01

[001]-textured Pb(Mg1/3Nb2/3)O3-PbTiO3 (PMN-PT) ceramics were synthesized by using templated grain growth method. Significantly high [001] texture degree corresponding to 0.98 Lotgering factor was achieved at 1 vol. % BaTiO3 template. Electromechanical properties for [001]-textured PMN-PT ceramics with 1 vol. % BaTiO3 were found to be d33 = 1000 pC/N, d31 = 371 pC/N, ɛr = 2591, and tanδ = ˜0.6%. Elastoelectric composite based modeling results showed that higher volume fraction of template reduces the overall dielectric constant and thus has adverse effect on the piezoelectric response. Clamping effect was modeled by deriving the changes in free energy as a function of applied electric field and microstructural boundary condition.

CH3 NH3 PbI3 and HC(NH2 )2 PbI3 Powders Synthesized from Low-Grade PbI2 : Single Precursor for High-Efficiency Perovskite Solar Cells.

Science.gov (United States)

Zhang, Yong; Kim, Seul-Gi; Lee, Do-Kyoung; Park, Nam-Gyu

2018-05-09

High-efficiency perovskite solar cells are generally fabricated by using highly pure (>99.99 %) PbI 2 mixed with an organic iodide in polar aprotic solvents. However, the use of such an expensive chemical may impede progress toward large-scale industrial applications. Here, we report on the synthesis of perovskite powders by using inexpensive low-grade (99 %) PbI 2 and on the photovoltaic performance of perovskite solar cells prepared from a powder-based single precursor. Pure APbI 3 [A=methylammonium (MA) or formamidinium (FA)] perovskite powders were synthesized by treating low-grade PbI 2 with MAI or FAI in acetonitrile at ambient temperature. The structural phase purity was confirmed by X-ray diffraction. The solar cell with a MAPbI 3 film prepared from the synthesized perovskite powder demonstrated a power conversion efficiency (PCE) of 17.14 %, which is higher than the PCE of MAPbI 3 films prepared by using both MAI and PbI 2 as precursors (PCE=13.09 % for 99 % pure PbI 2 and PCE=16.39 % for 99.9985 % pure PbI 2 ). The synthesized powder showed better absorption and photoluminescence, which were responsible for the better photovoltaic performance. For the FAPbI 3 powder, a solution with a yellow non-perovskite δ-FAPbI 3 powder synthesized at room temperature was found to lead to a black perovskite film, whereas a solution with the black perovskite α-FAPbI 3 powder synthesized at 150 °C was not transformed into a black perovskite film. The α↔δ transition between the powder and film was assumed to correlate with the difference in the iodoplumbates in the powder-dissolved solution. An average PCE of 17.21 % along with a smaller hysteresis [ΔPCE=PCE reverse -PCE forward )=1.53 %] was demonstrated from the perovskite solar cell prepared by using δ-FAPbI 3 powder; this PCE is higher than the average PCE of 17.05 % with a larger hysteresis (ΔPCE=2.71 %) for a device based on a conventional precursor solution dissolving MAI with high

Characteristics of ferroelectric Pb(Zr,Ti)O3 thin films having Pt/PtOx electrode barriers

International Nuclear Information System (INIS)

Lee, Kwangbae; Rhee, Byung Roh; Lee, Chanku

2001-01-01

We have investigated the feasibility of the Pt/PtO x multilayer as an electrode barrier for Pb(Zr,Ti)O 3 (PZT)-based ferroelectric random access memories. PtO x and Pt layers were prepared on polycrystalline-Si/SiO 2 /Si substrates by means of the sputtering method in Ar and O 2 ambience, and the Pb(Zr 0.53 Ti 0.47 )O 3 layer was prepared by the sol-gel method. A capacitor consisting of Pt/PtO x /PZT/PtO x /Pt/PtO x /poly-Si had a remanent polarization of 18 μC/cm 2 and a low coercive field of 32 kV/cm. The polarization fatigue behavior of test capacitors was improved as compared with that of Pt/PZT/Pt, which showed negligible fatigue loss of 15% after 10 11 switching repetitions with a frequency of 1 MHz. Copyright 2001 American Institute of Physics

On the growth of CH3NH3PbI3-xClx single crystal and characterization

Science.gov (United States)

Su, J.; Wang, W. F.; Lei, Y.; Zhang, L.; Xu, L. H.; Wang, D.; Lu, D.; Bai, Y.

2018-05-01

In this paper, CH3NH3PbI3-xClx crystal was grown by solution cooling method with CH3NH3I and PbCl2 as raw materials. Lead compounds and CH3NH3PbI3-xClx crystal with size about 6 mm × 4 mm × 2 mm were obtained. The chemical reactions with different CH3NH3I/PbCl2 ratios were analyzed. XPS shows the content of chlorine in CH3NH3PbI3-xClx is about 0.91%. PXRD, FT-IR, Raman and absorbance spectra were used to study the structure and optical properties of CH3NH3PbI3-xClx by comparing with CH3NH3PbI3 crystal. The CH3NH3PbI3-xClx crystal grown is of tetragonal structure with the lattice constants a = b = 8.8165 Å, c = 12.7920 Å and the bandgap value of 1.57 eV.

Crystal structure and magnetic properties of the Ba3TeCo3P2O14, Pb3TeCo3P2O14, and Pb3TeCo3V2O14 langasites

DEFF Research Database (Denmark)

Krizan, J.W.; de la Cruz, C.; Andersen, Niels Hessel

2013-01-01

We report the structural and magnetic characterizations of Ba3TeCo3P2O14, Pb3TeCo3P2O14, and Pb3TeCo3V2O14, compounds that are based on the mineral dugganite, which is isostructural to langasites. The magnetic part of the structure consists of layers of Co2+ triangles. Nuclear and magnetic...... structures were determined through a co-refinement of synchrotron and neutron powder diffraction data. In contrast to the undistorted P321 langasite structure of Ba3TeCo3P2O14, a complex structural distortion yielding a large supercell is found for both Pb3TeCo3P2O14 and Pb3TeCo3V2O14. Comparison...... of the three compounds studied along with the zinc analog Pb3TeZn3P2O14, also characterized here, suggests that the distortion is driven by Pb2+ lone pairs; as such, the Pb compounds crystallize in a pyroelectric space group, P2. Magnetic susceptibility, magnetization, and heat capacity measurements were...

Local and average structures of 0.7Pb(Mg1/3Nb2/3)O3 - 0.3PbZrO3

International Nuclear Information System (INIS)

Krishna, P.S.R.; Shinde, A.B.; Narasimhan, S.L.; Tiwari, V.S.; Singh, G.

2005-01-01

The local and average structure of 0.7Pb(Mg 1/3 Nb 2/3 )O 3 - 0.3PbZrO 3 (PMN-PZ) was studied by neutron diffraction. The Rietveld refinement was carried out to determine the average, long-range crystallographic structure, while the pair density function (PDF) analysis was used in studying the local atomic structure. The local atomic structure determined by the PDF analysis, was found to be significantly different from the average crystallographic structure determined by the Rietveld analysis. These results show that the conflict between the local structural preference and the average structure is not limited to relax or ferroelectric oxides, but may be widely prevalent in mixed-ion ferroelectrics. (author)

Structural and electrochemical analysis of chemically synthesized microcubic architectured lead selenide thin films

Science.gov (United States)

Bhat, T. S.; Shinde, A. V.; Devan, R. S.; Teli, A. M.; Ma, Y. R.; Kim, J. H.; Patil, P. S.

2018-01-01

The present work deals with the synthesis of lead selenide (PbSe) thin films by simple and cost-effective chemical bath deposition method with variation in deposition time. The structural, morphological, and electrochemical properties of as-deposited thin films were examined using characterization techniques such as X-ray diffraction spectroscopy (XRD), field-emission scanning electron microscopy (FE-SEM), X-ray photoelectron spectroscopy (XPS), cyclic voltammetry (CV), galvanostatic charge-discharge and electrochemical impedance spectroscopy. XRD reveals formation of rock salt phase cubic structured PbSe. FE-SEM images show the formation of microcubic structured morphology. The existence of the PbSe is confirmed from the XPS analysis. On the other hand, CV curves show four reaction peaks corresponding to oxidation [PbSe and Pb(OH)2] and reduction (PbO2 and Pb(OH)2) at the surface of PbSe thin films. The PbSe:2 sample deposited for 80 min. shows maximum specific capacitance of 454 ± 5 F g- 1 obtained at 0.25 mA cm- 2 current density. The maximum energy density of 69 Wh kg- 1 was showed by PbSe:2 electrode with a power density of 1077 W kg- 1. Furthermore, electrochemical impedance studies of PbSe:2 thin film show 80 ± 3% cycling stability even after 500 CV cycles. Such results show the importance of microcubic structured PbSe thin film as an anode in supercapacitor devices.

Photon Reabsorption in Mixed CsPbCl3:CsPbI3 Perovskite Nanocrystal Films for Light-Emitting Diodes

KAUST Repository

Davis, Nathaniel J. L. K.; de la Peñ a, Francisco J.; Tabachnyk, Maxim; Richter, Johannes M.; Lamboll, Robin D.; Booker, Edward P.; Wisnivesky Rocca Rivarola, Florencia; Griffiths, James T.; Ducati, Caterina; Menke, S. Matthew; Deschler, Felix; Greenham, Neil C.

2017-01-01

is significantly reduced. We investigate samples containing mixtures of perovskite nanocrystals with different compositions and study the resulting optical and electrical interactions. We report excitation transfer from CsPbCl3 to CsPbI3 in solution and within a

Ferroelectric BaPbO3/PbZr0.53Ti0.47/BaPbO3 heterostructures

International Nuclear Information System (INIS)

Liang Chunsheng; Wu Jennming; Chang Mingchu

2002-01-01

BaPbO 3 (BPO)/PbZr 0.53 Ti 0.47 (PZT)/BPO heterostructures were fabricated by combining the sol-gel and rf-magnetron sputtering techniques. Experimental results indicate that the BPO bottom electrodes effectively prevent the formation of the rosette structure of PZT, producing smooth surfaces. Additionally, ferroelectric, fatigue, and leakage current properties were markedly improved when both the top and the bottom electrodes were changed from Pt to BPO. These improvements are due to a superior electrode/ferroelectric interface. BPO is better than Pt and other oxide electrodes for use in PZT ferroelectric capacitors due to its remarkably improved properties and quite low growth temperature

Nonlinear dielectric thin films for high-power electric storage with energy density comparable with electrochemical supercapacitors.

Science.gov (United States)

Yao, Kui; Chen, Shuting; Rahimabady, Mojtaba; Mirshekarloo, Meysam Sharifzadeh; Yu, Shuhui; Tay, Francis Eng Hock; Sritharan, Thirumany; Lu, Li

2011-09-01

Although batteries possess high energy storage density, their output power is limited by the slow movement of charge carriers, and thus capacitors are often required to deliver high power output. Dielectric capacitors have high power density with fast discharge rate, but their energy density is typically much lower than electrochemical supercapacitors. Increasing the energy density of dielectric materials is highly desired to extend their applications in many emerging power system applications. In this paper, we review the mechanisms and major characteristics of electric energy storage with electrochemical supercapacitors and dielectric capacitors. Three types of in-house-produced ferroic nonlinear dielectric thin film materials with high energy density are described, including (Pb(0.97)La(0.02))(Zr(0.90)Sn(0.05)Ti(0.05))O(3) (PLZST) antiferroelectric ceramic thin films, Pb(Zn(1/3)Nb(2/3))O(3-)Pb(Mg(1/3)Nb(2/3))O(3-)PbTiO(3) (PZN-PMN-PT) relaxor ferroelectric ceramic thin films, and poly(vinylidene fluoride) (PVDF)-based polymer blend thin films. The results showed that these thin film materials are promising for electric storage with outstandingly high power density and fairly high energy density, comparable with electrochemical supercapacitors.

Pb(Zn1/3Nb2/3O3–PbTiO3 single crystal and device development

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L. C. Lim

2014-01-01

Full Text Available This paper describes recent device developments with relaxor ferroelectric Pb(Zn1/3Nb2/3O3–PbTiO3 (PZN–PT single crystals carried out at Microfine Materials Technologies Pte. Ltd, Singapore. Promising [011]-poled transverse cuts of PZN–PT single crystals and the results on the effect of electric field and axial compressive stress on the rhombohedral-to-orthorhombic (R–O phase transformation behavior of such cuts are presented and discussed. The single crystal devices described include a compact low-frequency broadband power-efficient underwater tonpilz projector, high sensitivity shear accelerometers and acoustic vector sensors (AVS. The unique characteristics offered by these PZN–PT single crystal devices are highlighted, which serve as examples of new-generation piezoelectric devices and systems for a wide range of demanding applications.

Texture control and seeded nucleation of nanosize structures of ferroelectric thin films

Science.gov (United States)

Muralt, Paul

2006-09-01

An overview is given on nucleation phenomena of Pb(Zr ,Ti)O3 (PZT) thin films on Pt(111)-based substrates. Emphasis is given on in situ growth methods, particularly in situ reactive sputtering from three metallic targets. Growth of PZT thin films is discussed from the point of view of the PbOx-TiO2 phase diagram, PbO vapor pressure, and classical nucleation theory. The role of thin TiO2 affinity layers and spots is explained in the frame of this theory. Activation energies for desorption and chemisorption are adapted to comply with the fact that nucleation rates on TiO2 are much larger than the ones on bare Pt(111). The model reproduces well the PbO surface flux from bare Pt(111) to the affinity spots in the case of PbTiO3 nucleation and the reversed tendency in the case of PZT 40/60 nucleation, explaining experimental observations. The critical size of nuclei was calculated to contain 8-10unit cells for PbTiO3/Pt nucleation and 14-17 for PZT/Pt nucleation.

Room temperature chemical synthesis of lead selenide thin films with preferred orientation

Science.gov (United States)

Kale, R. B.; Sartale, S. D.; Ganesan, V.; Lokhande, C. D.; Lin, Yi-Feng; Lu, Shih-Yuan

2006-11-01

Room temperature chemical synthesis of PbSe thin films was carried out from aqueous ammoniacal solution using Pb(CH3COO)2 as Pb2+ and Na2SeSO3 as Se2- ion sources. The films were characterized by a various techniques including, X-ray diffraction (XRD), energy dispersive X-ray analysis (EDAX), scanning electron microscopy (SEM), transmission electron microscopy (TEM), high resolution transmission electron microscopy (HR-TEM), selected area electron diffraction (SAED), Fast Fourier transform (FFT) and UV-vis-NIR techniques. The study revealed that the PbSe thin film consists of preferentially oriented nanocubes with energy band gap of 0.5 eV.

Room temperature chemical synthesis of lead selenide thin films with preferred orientation

International Nuclear Information System (INIS)

Kale, R.B.; Sartale, S.D.; Ganesan, V.; Lokhande, C.D.; Lin, Y.-F.; Lu, S.-Y.

2006-01-01

Room temperature chemical synthesis of PbSe thin films was carried out from aqueous ammoniacal solution using Pb(CH 3 COO) 2 as Pb 2+ and Na 2 SeSO 3 as Se 2- ion sources. The films were characterized by a various techniques including, X-ray diffraction (XRD), energy dispersive X-ray analysis (EDAX), scanning electron microscopy (SEM), transmission electron microscopy (TEM), high resolution transmission electron microscopy (HR-TEM), selected area electron diffraction (SAED), Fast Fourier transform (FFT) and UV-vis-NIR techniques. The study revealed that the PbSe thin film consists of preferentially oriented nanocubes with energy band gap of 0.5 eV

Tunable CsPbBr3/Cs4PbBr6 phase transformation and their optical spectroscopic properties.

Science.gov (United States)

Chen, Xiao; Chen, Daqin; Li, Junni; Fang, Gaoliang; Sheng, Hongchao; Zhong, Jiasong

2018-04-24

As a novel type of promising materials, metal halide perovskites are a rising star in the field of optoelectronics. On this basis, a new frontier of zero-dimensional perovskite-related Cs4PbBr6 with bright green emission and high stability has attracted an enormous amount of attention, even though its photoluminescence still requires to clarification. Herein, the controllable phase transformation between three-dimensional CsPbBr3 and zero-dimensional Cs4PbBr6 is easily achieved in a facile ligand-assisted supersaturated recrystallization synthesis procedure via tuning the amount of surfactants, and their unique optical properties are investigated and compared in detail. Both Cs4PbBr6 and CsPbBr3 produce remarkably intense green luminescence with quantum yields up to 45% and 80%, respectively; however, significantly different emitting behaviors are observed. The fluorescence lifetime of Cs4PbBr6 is much longer than that of CsPbBr3, and photo-blinking is easily detected in the Cs4PbBr6 product, proving that the zero-dimensional Cs4PbBr6 is indeed a highly luminescent perovskite-related material. Additionally, for the first time, tunable emissions over the visible-light spectral region are demonstrated to be achievable via halogen composition modulations in the Cs4PbX6 (X = Cl, Br, I) samples. Our study brings a simple method for the phase control of CsPbBr3/Cs4PbBr6 and demonstrates the intrinsic luminescence nature of the zero-dimensional perovskite-related Cs4PbX6 products.

Fabrication of CH3NH3PbI3/PVP Composite Fibers via Electrospinning and Deposition

Science.gov (United States)

Chao, Li-Min; Tai, Ting-Yu; Chen, Yueh-Ying; Lin, Pei-Ying; Fu, Yaw-Shyan

2015-01-01

In our study, one-dimensional PbI2/polyvinylpyrrolidone (PVP) composition fibers have been prepared by using PbI2 and PVP as precursors dissolved in N,N-dimethylformamide via a electrospinning process. Dipping the fibers into CH3NH3I solution changed its color, indicating the formation of CH3NH3PbI3, to obtain CH3NH3PbI3/PVP composite fibers. The structure, morphology and composition of the all as-prepared fibers were characterized by using X-ray diffraction and scanning electron microscopy. PMID:28793517

Fabrication of CH3NH3PbI3/PVP Composite Fibers via Electrospinning and Deposition

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Li-Min Chao

2015-08-01

Full Text Available In our study, one-dimensional PbI2/polyvinylpyrrolidone (PVP composition fibers have been prepared by using PbI2 and PVP as precursors dissolved in N,N-dimethylformamide via a electrospinning process. Dipping the fibers into CH3NH3I solution changed its color, indicating the formation of CH3NH3PbI3, to obtain CH3NH3PbI3/PVP composite fibers. The structure, morphology and composition of the all as-prepared fibers were characterized by using X-ray diffraction and scanning electron microscopy.

Photon Reabsorption in Mixed CsPbCl3:CsPbI3 Perovskite Nanocrystal Films for Light-Emitting Diodes

KAUST Repository

Davis, Nathaniel J. L. K.

2017-01-24

Cesium lead halide nanocrystals, CsPbX3 (X = Cl, Br, I), exhibit photoluminescence quantum efficiencies approaching 100% without the core–shell structures usually used in conventional semiconductor nanocrystals. These high photoluminescence efficiencies make these crystals ideal candidates for light-emitting diodes (LEDs). However, because of the large surface area to volume ratio, halogen exchange between perovskite nanocrystals of different compositions occurs rapidly, which is one of the limiting factors for white-light applications requiring a mixture of different crystal compositions to achieve a broad emission spectrum. Here, we use mixtures of chloride and iodide CsPbX3 (X = Cl, I) perovskite nanocrystals where anion exchange is significantly reduced. We investigate samples containing mixtures of perovskite nanocrystals with different compositions and study the resulting optical and electrical interactions. We report excitation transfer from CsPbCl3 to CsPbI3 in solution and within a poly(methyl methacrylate) matrix via photon reabsorption, which also occurs in electrically excited crystals in bulk heterojunction LEDs.

Optical evidences for an intermediate phase in relaxor ferroelectric Pb(In1/2Nb1/2O3-Pb(Mg1/3Nb2/3O3-PbTiO3 single crystals

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Xiaolong Zhang

2016-02-01

Full Text Available The mechanism of low-temperature structural transformation and evolution of polar nano-structures in relaxor ferroelectric Pb(In1/2Nb1/2O3-Pb(Mg1/3Nb2/3O3-xPbTiO3 (x = 0.33, 0.35, and 0.42 single crystals have been investigated with the aid of temperature dependent low-wavenumber Raman scattering (LWRS and photoluminescence (PL spectra. The E(TO1 phonon mode reveals the characteristic relaxational polarization fluctuations associated with the reorientation of either polar nano-regions or polar nano-domains. It was found that these mechanisms are not independent and they can be ascribed to the phonon localization. In addition, a short-range monoclinic phase (Mc can be found below 250 K in the tetragonal phase region by LWRS, which is always associated with the morphotropic phase boundary (MPB and excellent electromechanical properties. It is interesting that PL spectra confirm these results. The present work indicates that external field modulation and change of composition can result in the monoclinic phase and co-existence of multi-phase.

Degradation mechanism of CH3NH3PbI3 perovskite materials upon exposure to humid air

International Nuclear Information System (INIS)

Shirayama, Masaki; Kato, Masato; Fujiseki, Takemasa; Hara, Shota; Kadowaki, Hideyuki; Murata, Daisuke; Fujiwara, Hiroyuki; Miyadera, Tetsuhiko; Sugita, Takeshi; Chikamatsu, Masayuki

2016-01-01

Low stability of organic-inorganic perovskite (CH 3 NH 3 PbI 3 ) solar cells in humid air environments is a serious drawback which could limit practical application of this material severely. In this study, from real-time spectroscopic ellipsometry characterization, the degradation mechanism of ultra-smooth CH 3 NH 3 PbI 3 layers prepared by a laser evaporation technique is studied. We present evidence that the CH 3 NH 3 PbI 3 degradation in humid air proceeds by two competing reactions of (i) the PbI 2 formation by the desorption of CH 3 NH 3 I species and (ii) the generation of a CH 3 NH 3 PbI 3 hydrate phase by H 2 O incorporation. In particular, rapid phase change occurs in the near-surface region and the CH 3 NH 3 PbI 3 layer thickness reduces rapidly in the initial 1 h air exposure even at a low relative humidity of 40%. After the prolonged air exposure, the CH 3 NH 3 PbI 3 layer is converted completely to hexagonal platelet PbI 2 /hydrate crystals that have a distinct atomic-scale multilayer structure with a period of 0.65 ± 0.05 nm. We find that conventional x-ray diffraction and optical characterization in the visible region, used commonly in earlier works, are quite insensitive to the surface phase change. Based on results obtained in this work, we discuss the degradation mechanism of CH 3 NH 3 PbI 3 in humid air.

Ferroelectricity-induced resistive switching in Pb(Zr0.52Ti0.48)O3/Pr0.7Ca0.3MnO3/Nb-doped SrTiO3 epitaxial heterostructure

Science.gov (United States)

Md. Sadaf, Sharif; Mostafa Bourim, El; Liu, Xinjun; Hasan Choudhury, Sakeb; Kim, Dong-Wook; Hwang, Hyunsang

2012-03-01

We investigated the effect of a ferroelectric Pb(Zr0.52Ti0.48)O3 (PZT) thin film on the generation of resistive switching in a stacked Pr0.7Ca0.3MnO3 (PCMO)/Nb-doped SrTiO3 (Nb:STO) heterostructure forming a p-n junction. To promote the ferroelectric effect, the thin PZT active layer was deposited on an epitaxially grown p-type PCMO film on a lattice-matched n-type Nb:STO single crystal. It was concluded that the observed resistive switching behavior in the all-perovskite Pt/PZT/PCMO/Nb:STO heterostructure was related to the modulation of PCMO/Nb:STO p-n junction's depletion width, which was caused either by the PZT ferroelectric polarization field effect, the electrochemical drift of oxygen ions under an electric field, or both simultaneously.

Local strain heterogeneity and elastic relaxation dynamics associated with relaxor behavior in the single-crystal perovskite Pb (I n1 /2N b1 /2 ) O3-PbZr O3-Pb (M g1 /3N b2 /3 ) O3-PbTi O3

Science.gov (United States)

He, Wenhui; Carpenter, Michael A.; Lampronti, Giulio I.; Li, Qiang; Yan, Qingfeng

2017-10-01

Recently, Pb (In1/2Nb1/2 ) O3-PbZr O3-Pb (Mg1/3Nb2/3 ) O3-PbTiO3 (PIN-PZ-PMN-PT) relaxor single crystals were demonstrated to possess improved temperature-insensitive properties, which would be desirable for high-power device applications. The relaxor character associated with the development of local random fields (RFs) and a high rhombohedral-tetragonal (R-T) ferroelectric transition temperature (TR-T>120°C) would be critical for the excellent properties. A significant effect of the chemical substitution of In3+ and Zr4+ in PMN-PT to give PIN-PZ-PMN-PT is the development of local strain heterogeneity, which acts to suppress the development of macroscopic shear strains without suppressing the development of local ferroelectric moments and contribute substantially to the RFs in PIN-PZ-PMN-PT. Measurements of elastic and anelastic properties by resonant ultrasound spectroscopy show that PIN-PZ-PMN-PT crystal has a quite different form of elastic anomaly due to Vogel-Fulcher freezing, rather than the a discrete cubic-T transition seen in a single crystal of PMN-28PT. It also has high acoustic loss of the relaxor phase down to TR-T. Analysis of piezoresponse force microscopy phase images at different temperatures provides a quantitative insight into the extent to which the RFs influence the microdomain structure and the short-range order correlation length 〈ξ 〉 .

Preparation of Pb(Zr, Ti)O3 Thin Films on Glass Substrates

Science.gov (United States)

Hioki, Tsuyoshi; Akiyama, Masahiko; Ueda, Tomomasa; Onozuka, Yutaka; Hara, Yujiro; Suzuki, Kouji

2000-09-01

Lead-zirconate-titanate (PZT) thin films were prepared on non-alkaline glass substrates widely used in liquid crystal display (LCD) devices, by plasma-assisted magnetron RF sputtering with an immersed coil. After preparation of the PZT thin film, the glass was available for use in LCD device processing. No mutual diffusion of the elements was recognized between the glass substrate and the bottom electrode. The PZT layer had a dense film structure with rectangular and columnar grains, and only its perovskite phase was crystalline. PZT thin films on a glass substrate had leakage current densities of about 10-8 A/cm2, acceptable hysteresis loop shapes with the remanent polarization (Pr) of 45 μC/cm2 and the coercive field (Ec) of 90 kV/cm. Ferroelectric properties on a glass substrate almost conform with those on a Si-based substrate.

Pb(Zr,Ti)O3-Pb(Mn1/3Nb2/3)O3 piezoelectric thick films by aerosol deposition

International Nuclear Information System (INIS)

Ryu, Jungho; Choi, Jong-Jin; Hahn, Byung-Dong; Yoon, Woon-Ha; Lee, Byoung-Kuk; Choi, Joon Hwan; Park, Dong-Soo

2010-01-01

Piezoelectric thick films of Pb(Zr,Ti)O 3 -Pb(Mn 1/3 Nb 2/3 )O 3 (PZT-PMnN) with Zr:Ti ratios ranging from 0.45:0.55 to 0.60:0.40 were fabricated on a platinized silicon wafer by aerosol deposition (AD). All the films were deposited with a thickness of 10 μm with high density. By adding PMnN to 57:43 PZT, a dielectric constant as low as ∼660 was achieved while the effective piezoelectric constant was over 140 pC/N. PZT-PMnN with a Zr:Ti ratio of 57:43 thus showed a maximum piezoelectric voltage constant (g 33 ) of 23.8 x 10 -3 Vm/N and is a good candidate for high quality thick films for application to high-energy density or high sensitivity, piezoelectric energy harvesters and sensors.

Photoinduced effects of ferroelectric domains in PbZr1-xTixO3 thin films as obtained by using piezoresponse force microscopy

International Nuclear Information System (INIS)

Jang, Y. H.; Kim, C. H.; Hwang, H. J.; Cho, J. H.; Moon, H. B.; Bhang, S. H.

2011-01-01

Piezoresponse force microscopy (PFM) has been used to investigate the photoinduced effect of ferroelectric domains in PbZr 1-x Ti x O 3 (PZT) thin films. In order to perform nondestructive visualization of the high-resolution domain structure, we optimized the imaging condition, such as applying a lower voltage than 1.0 Vpp (peak-to-peak voltage). In this study, domain changes were measured before and after illumination on the surface of PZT films by using an UV light emitting diode (LED) source (λ = 310 nm) with a focusing lens to investigate the influence of the photoinduced carriers on the ferroelectric polarization. In addition, to investigate the photoinduced effects on the domain distribution, we performed histogram of positive and negative domains before and after UV-light illumination. The illumination with UV light resulted in an increase of the positive domain of the out-of-plane mode. Also, a change in the out-of-plane domain distribution was observed before and after UV illumination. The relaxation of photoinduced changes was monitored by repeated scans within a time range of 20 ∼ 60 minutes.

Room temperature chemical synthesis of lead selenide thin films with preferred orientation

Energy Technology Data Exchange (ETDEWEB)

Kale, R.B. [Department of Chemical Engineering, National Tsing-Hua University, Hsin-Chu, Taiwan 30043 (China)]. E-mail: rb_kale@yahoo.co.in; Sartale, S.D. [Hahn Meitner Institute, Glienicker Strasse-100, D-14109 Berlin (Germany); Ganesan, V. [UGC-DAE Consortium for Scientific Research, University Campus, Khandwa Road, Indore 452017 (India); Lokhande, C.D. [Thin Film Physics Laboratory, Department of Physics, Shivaji University, Kolhapur 416004 (India); Lin, Y.-F. [Department of Chemical Engineering, National Tsing-Hua University, Hsin-Chu, Taiwan 30043 (China); Lu, S.-Y. [Department of Chemical Engineering, National Tsing-Hua University, Hsin-Chu, Taiwan 30043 (China)]. E-mail: sylu@mx.nthu.edu.tw

2006-11-15

Room temperature chemical synthesis of PbSe thin films was carried out from aqueous ammoniacal solution using Pb(CH{sub 3}COO){sub 2} as Pb{sup 2+} and Na{sub 2}SeSO{sub 3} as Se{sup 2-} ion sources. The films were characterized by a various techniques including, X-ray diffraction (XRD), energy dispersive X-ray analysis (EDAX), scanning electron microscopy (SEM), transmission electron microscopy (TEM), high resolution transmission electron microscopy (HR-TEM), selected area electron diffraction (SAED), Fast Fourier transform (FFT) and UV-vis-NIR techniques. The study revealed that the PbSe thin film consists of preferentially oriented nanocubes with energy band gap of 0.5 eV.

Growing large columnar grains of CH3NH3PbI3 using the solid-state reaction method enhanced by less-crystallized nanoporous PbI2 films

Science.gov (United States)

Zheng, Huifeng; Wang, Weiqi; Liu, Yangqiao; Sun, Jing

2017-03-01

Compact, pinhole-free and PbI2-free perovskite films, are desirable for high-performance perovskite solar cells (PSCs), especially if large columnar grains are obtained in which the adverse effects of grain boundaries will be minimized. However, the conventional solid-state reaction methods, originated from the two-step method, failed to grow columnar grains of CH3NH3PbI3 in a facile way. Here, we demonstrate a strategy for growing large columnar grains of CH3NH3PbI3, by less-crystallized nanoporous PbI2 (ln-PbI2) film enhanced solid-state reaction method. We demonstrated columnar grains were obtainable only when ln-PbI2 films were applied. Therefore, the replacement of compact PbI2 by ln-PbI2 in the solid-sate reaction, leads to higher power conversion efficiency, better reproducibility, better stability and less hysteresis. Furthermore, by systematically investigating the effects of annealing temperature and duration, we found that an annealing temperature ≥120 °C was also critical for growing columnar grains. With the optimal process, a champion efficiency of 16.4% was obtained and the average efficiency reached 14.2%. Finally, the mechanism of growing columnar grains was investigated, in which a VPb″ -assisted hooping model was proposed. This work reveals the origins of grain growth in the solid-state reaction method, which will contribute to preparing high quality perovskite films with much larger columnar grains.

X-ray diffraction, vibrational and photoluminescence studies of the self-organized quantum well crystal H3N(CH2)6NH3PbBr4

International Nuclear Information System (INIS)

Dammak, T.; Fourati, N.; Boughzala, H.; Mlayah, A.; Abid, Y.

2007-01-01

We have prepared new semiconductor H 3 N(CH 2 ) 6 NH 3 PbBr 4 crystals which are self-assembled organic-inorganic hybrid materials. The grown crystals have been studied by X-ray diffraction, infrared absorption and Raman spectroscopy scattering. We found that the title compound, abbreviated 2C 6 PbBr 4 , crystallizes in a two-dimensional (2D) structure with a P2 1 /a space group. In the inorganic semiconductor sub-lattice, the corner sharing PbBr 6 octahedra form infinite 2D chains. The organic C 6 H 18 N 2 + ions form the insulator barriers between the inorganic semiconductor layers. Such a packing leads to a self-assembled multiple quantum well structure. Raman and infrared spectra of the title compound were recorded in the 50-500 and 400-4000 cm -1 frequency regions, respectively. The assignment of the observed Raman lines was performed by comparison with the homologous compounds. Transmission measurements on thin films of 2C 6 PbBr 4 , obtained by the spin coating method, revealed a strong absorption peak at 380 nm. Luminescence measurements showed an emission line at 402 nm associated with radiative recombinations of excitons confined within the PbBr 6 layers. The electron-hole binding energy is estimated at 180 meV

Etch characteristics of (Pb,Sr)TiO3 thin films using CF4/Ar inductively coupled plasma

International Nuclear Information System (INIS)

Kim, Gwan-Ha; Kim, Kyoung-Tae; Kim, Dong-Pyo; Kim, Chang-Il

2003-01-01

The investigations of the (Pb,Sr)TiO 3 (PST) etching characteristics in CF 4 /Ar plasma were carried out using the inductively coupled plasma system. Experiments showed that an increase of the Ar mixing ratio under constant pressure and input power conditions leads to increasing etch rate of PST, which reaches a maximum of 740 A/min when the Ar is 80% of the gas mixture. To understand the etching mechanism, the surface state of the etched PST samples was investigated using x-ray photoelectron spectroscopy. It was found that Pb and Ti atoms were removed mainly by the ion-assisted etching mechanism. At the same time, Sr forms extremely low volatile fluorides and therefore can be removed only by physical (sputter) etching

Layer-by-layer deposition of nanostructured CsPbBr3 perovskite thin films

Science.gov (United States)

Reshetnikova, A. A.; Matyushkin, L. B.; Andronov, A. A.; Sokolov, V. S.; Aleksandrova, O. A.; Moshnikov, V. A.

2017-11-01

Layer-by-layer deposition of nanostructured perovskites cesium lead halide thin films is described. The method of deposition is based on alternate immersion of the substrate in the precursor solutions or colloidal solution of nanocrystals and methyl acetate/lead nitrate solution using the device for deposition of films by SILAR and dip-coating techniques. An example of obtaining a photosensitive structure based on nanostructures of ZnO nanowires and layers of CsBbBr3 nanocrystals is also shown.

Effect of TEA on characteristics of CdS/PbS thin film solar cells prepared by CBD

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Sattarian H.

2016-09-01

Full Text Available In this study, a solar cell with a glass/ITO/CdS/PbS/Al structure was constructed. Both window (CdS and absorption (PbS layers were deposited by chemical bath deposition (CBD method. The CdS window layer was deposited on ITO-glass. The PbS nanocrystalline thin film was prepared with and without triethanolamine on CdS films at bath temperature of 25 °C. CdS and PbS nanocrystals were identified using XRD and SEM. The cells are photosensitive in a large spectral range (at visible and near infrared regions. The cell with absorbing layer obtained from the bath without TEA has higher efficiency with the following parameters: the open circuit voltage (Voc is 275 mV, short circuit current (Jsc is 12.24 mA/cm2, maximum voltage (Vmax is 165 mV and maximum current (Jmax is 7.11 mA/cm2 with the efficiency η = 1.31 %, fill factor FF is 32 % under the illumination intensity of 90 mW/cm2. The cells have an area of 0.15 cm2.

Effects of Bi(Zn2/3Nb1/3)O3 Modification on the Relaxor Behavior and Piezoelectricity of Pb(Mg1/3Nb2/3)O3-PbTiO3 Ceramics.

Science.gov (United States)

Liu, Zenghui; Wu, Hua; Paterson, Alisa; Ren, Wei; Ye, Zuo-Guang

2017-10-01

Relaxor lead magnesium niobate (PMN)-based materials exhibit complex structures and unusual properties that have been puzzling researchers for decades. In this paper, a new ternary solid solution of Pb(Mg 1/3 Nb 2/3 )O 3 -PbTiO 3 -Bi(Zn 2/3 Nb 1/3 )O 3 (PMN-PT-BZN) is prepared in the form of ceramics, and the effects of the incorporation of BZN into the PMN-PT binary system are investigated. The crystal structure favors a pseudocubic symmetry and the relaxor properties are enhanced as the concentration of BZN increases. The relaxor behavior and the related phase transformations are studied by dielectric spectroscopy. A phase diagram mapping out the characteristic temperatures and various states is established. Interestingly, the piezoelectricity of the PMN-PT ceramics is significantly enhanced by the BZN substitution, with an optimal value of d 33 reaching 826 pC/N for 0.96[0.7Pb(Mg 1/3 Nb 2/3 )O 3 -0.3PbTiO 3 ]-0.04Bi(Zn 2/3 Nb 1/3 )O 3 . This paper provides a better understanding of the relaxor ferroelectric behavior, and unveils a new relaxor-based ternary system as piezoelectric materials potentially useful for electromechanical transducer applications.

Probing interfacial electronic properties of graphene/CH3NH3PbI3 heterojunctions: A theoretical study

Science.gov (United States)

Hu, Jisong; Ji, Gepeng; Ma, Xinguo; He, Hua; Huang, Chuyun

2018-05-01

Interfacial interactions and electronic properties of graphene/CH3NH3PbI3 heterojunctions were investigated by first-principles calculations incorporating semiempirical dispersion-correction scheme to describe van der Waals interactions. Two lattice match configurations between graphene and CH3NH3PbI3(0 0 1) slab were constructed in parallel contact and both of them were verified to form remarkable van der Waals heterojunctions with similar work functions. Our calculated energy band structures show that the Dirac-cone of graphene and the direct band gap of CH3NH3PbI3 are still preserved in the heterojunctions, thus graphene can be a promising candidate either as a capping or supporting layer for encapsulating CH3NH3PbI3 layer. It is identified that the Schottky barrier of graphene/CH3NH3PbI3 heterojunctions can be controlled by the interlayer distance and affected by the stacking pattern of graphene and CH3NH3PbI3. The 3D charge density differences present the build-in internal electric field from graphene to CH3NH3PbI3 after interface equilibrium and thus, a low n-type Schottky barrier is needed for high efficient charge transferring in the interface. The possible mechanism of the band edge modulations in the heterojunctions and corresponding photoinduced charge transfer processes are also described.

Pyroelectric Study on Dipolar Alignment in 0.69Pb(Mg1/3Nb2/3)O3-0.31PbTiO3 Single Crystals

Institute of Scientific and Technical Information of China (English)

ZHAO Liang; SHEN Ming-Rong; CAO Wen-Wu

2012-01-01

Pyroelectric measurements are conducted during zero-Geld heating in [001], [110] and [111] poled 0.69Pb(Mg1/3 Nb2/3)O3-0.31PbTiO3 single crystals. Compared to the room-temperature-poled samples, the crystals poled by using the Rield cooling method show broad but well recognizable pyroelectric current peaks near 190℃, which is much higher than the Curie point (126℃) of the crystal. We propose that this peak of the crystals poled by field-cooling above the Curie point is ascribed to the order-disorder transition of the dipoles in polar nano-regions formed at the Burns temperature.%Pyroelectric measurements are conducted during zero-field heating in [001],[110] and [111] poled 0.69Pb(Mg1/3Nb2/3)O3-0.31PbTiO3 single crystals.Compared to the room-temperature-poled samples,the crystals poled by using the field cooling method show broad but well recognizable pyroelectric current peaks near 190℃,which is much higher than the Curie point (126℃) of the crystal.We propose that this peak of the crystals poled by field-cooling above the Curie point is ascribed to the order-disorder transition of the dipoles in polar nano-regions formed at the Burns temperature.

Mesoscopic CH 3 NH 3 PbI 3 /TiO 2 Heterojunction Solar Cells

KAUST Repository

Etgar, Lioz

2012-10-24

We report for the first time on a hole conductor-free mesoscopic methylammonium lead iodide (CH 3NH 3PbI 3) perovskite/TiO 2 heterojunction solar cell, produced by deposition of perovskite nanoparticles from a solution of CH 3NH 3I and PbI 2 in γ-butyrolactone on a 400 nm thick film of TiO 2 (anatase) nanosheets exposing (001) facets. A gold film was evaporated on top of the CH 3NH 3PbI 3 as a back contact. Importantly, the CH 3NH 3PbI 3 nanoparticles assume here simultaneously the roles of both light harvester and hole conductor, rendering superfluous the use of an additional hole transporting material. The simple mesoscopic CH 3NH 3PbI 3/TiO 2 heterojunction solar cell shows impressive photovoltaic performance, with short-circuit photocurrent J sc= 16.1 mA/cm 2, open-circuit photovoltage V oc = 0.631 V, and a fill factor FF = 0.57, corresponding to a light to electric power conversion efficiency (PCE) of 5.5% under standard AM 1.5 solar light of 1000 W/m 2 intensity. At a lower light intensity of 100W/m 2, a PCE of 7.3% was measured. The advent of such simple solution-processed mesoscopic heterojunction solar cells paves the way to realize low-cost, high-efficiency solar cells. © 2012 American Chemical Society.

Luminescence characteristics of Pb2+ centres in undoped and Ce3+-doped Lu3Al5O12 single-crystalline films and Pb2+→Ce3+ energy transfer processes

International Nuclear Information System (INIS)

Babin, V.; Gorbenko, V.; Makhov, A.; Mares, J.A.; Nikl, M.; Zazubovich, S.; Zorenko, Yu.

2007-01-01

At 4.2-350 K, the steady-state and time-resolved emission and excitation spectra and luminescence decay kinetics were studied under excitation in the 2.5-15 eV energy range for the undoped and Ce 3+ -doped Lu 3 Al 5 O 12 (LuAG) single-crystalline films grown by liquid phase epitaxy method from the PbO-based flux. The spectral bands arising from the single Pb 2+ -based centres were identified. The processes of energy transfer from the host lattice to Pb 2+ and Ce 3+ ions and from Pb 2+ to Ce 3+ ions were investigated. Competition between Pb 2+ and Ce 3+ ions in the processes of energy transfer from the LuAG crystal lattice was evidenced especially in the exciton absorption region. Due to overlap of the 3.61 eV emission band of Pb 2+ centres with the 3.6 eV absorption band of Ce 3+ centres, an effective nonradiative energy transfer from Pb 2+ ions to Ce 3+ ions takes place, resulting in the appearance of slower component in the luminescence decay kinetics of Ce 3+ centres and decrease of the Ce 3+ -related luminescence intensity

Controlling Piezoelectric Responses in Pb(Zr0.52Ti0.48)O3 Films through Deposition Conditions and Nanosheet Buffer Layers on Glass

NARCIS (Netherlands)

Nguyen, Minh D.; Houwman, Evert P.; Yuan, Huiyu; Wylie- Van Eerd, Benjamin; Dekkers, Matthijn; Koster, Gertjan; Ten Elshof, Johan E.; Rijnders, Guus

2017-01-01

Nanosheet Ca2Nb3O10 (CNOns) layers were deposited on ultralow expansion glass substrates by the Langmuir-Blodgett method to obtain preferential (001)-oriented growth of Pb(Zr0.52Ti0.48)O3 (PZT) thin films using pulsed laser deposition (PLD) to enhance the ferroelectric and piezoelectric properties

An impedance spectroscopy investigation of nanocrystalline CsPbBr{sub 3} films

Energy Technology Data Exchange (ETDEWEB)

Vitale, G. [Department of Electronic Engineering and INFM, University of Rome ' Roma Tre' , Via della Vasca Navale 84, 00146 Rome (Italy); Conte, G. [Department of Electronic Engineering and INFM, University of Rome ' Roma Tre' , Via della Vasca Navale 84, 00146 Rome (Italy)]. E-mail: gconte@ele.uniroma3.it; Aloe, P. [Department of Physics and INFM, University of Rome ' Roma Tre' , Via della Vasca Navale 84, 00146 Rome (Italy); Somma, F. [Department of Physics and INFM, University of Rome ' Roma Tre' , Via della Vasca Navale 84, 00146 Rome (Italy)

2005-12-15

Thin films of CsPbBr{sub 3} were prepared by co-evaporation of CsBr and PbBr{sub 2} powders. Deposited materials are constituted by nanometer-sized crystals as evidenced by atomic force microscopy and X ray diffraction. Impedance spectroscopy measurements, aimed to study the dielectric relaxation processes and transport mechanisms at grain boundary and grain interior, reveal a complex response of the material both on the frequency and on the temperature variations. DC current voltage curves are ohmic for applied electric field strength up to 2 x 10{sup 6} V/cm. The DC conductivity Arrhenius plot gives a value of the activation energy equal to 0.85 eV, smaller then that expected for an intrinsic semiconductor. On the other hand, impedance measurements on a wide frequency range and at different temperatures can be reduced to a single master curve addressing hopping transport mechanism and dielectric relaxation processes being active. Finally, a simple model based on multiple Voigt's elements has been used to fit the impedance spectroscopy data and to evaluate relevant material parameters.

Hybridization of Single Nanocrystals of Cs4PbBr6 and CsPbBr3

OpenAIRE

Weerd, Chris de; Lin, Junhao; Gomez, Leyre; Fujiwara, Yasufumi; Suenaga, Kazutomo; Gregorkiewicz, Tom

2017-01-01

Nanocrystals of all-inorganic cesium lead halide perovskites (CsPbX3, X = Cl, Br, I) feature high absorption and efficient narrow-band emission which renders them promising for future generation of photovoltaic and optoelectronic devices. Colloidal ensembles of these nanocrystals can be conveniently prepared by chemical synthesis. However, in the case of CsPbBr3, its synthesis can also yield nanocrystals of Cs4PbBr6 and the properties of the two are easily confused. Here, we investigate in de...

Role of phase composition for electronic states in CH{sub 3}NH{sub 3}PbI{sub 3} prepared from CH{sub 3}NH{sub 3}I/PbCl{sub 2} solution

Energy Technology Data Exchange (ETDEWEB)

Naikaew, Atittaya; Prajongtat, Pongthep [Helmholtz-Center Berlin for Energy and Materials, Institute of Heterogeneous Materials, Hahn-Meitner-Platz 1, D-14109 Berlin (Germany); Department of Materials Science, Faculty of Science, Kasetsart University, Bangkok 10900 (Thailand); Lux-Steiner, Martha Ch.; Dittrich, Thomas, E-mail: dittrich@helmholtz-berlin.de [Helmholtz-Center Berlin for Energy and Materials, Institute of Heterogeneous Materials, Hahn-Meitner-Platz 1, D-14109 Berlin (Germany); Arunchaiya, Marisa [Department of Materials Science, Faculty of Science, Kasetsart University, Bangkok 10900 (Thailand)

2015-06-08

Modulated surface photovoltage (SPV) spectra have been correlated with the phase composition in layers of CH{sub 3}NH{sub 3}PbI{sub 3} (MAPbI{sub 3}) prepared from MAI and PbCl{sub 2} and annealed at 100 °C. Depending on the annealing time, different compositions of MAPbI{sub 3}, MAPbCl{sub 3}, MACl, PbI{sub 2}, and an un-identified phase were found. It has been demonstrated that evaporation of MAI and HI is crucial for the development of electronic states in MAPbI{sub 3} and that only the appearance and evolution of the phase PbI{sub 2} has an influence on electronic states in MAPbI{sub 3}. With ongoing annealing, (i) a transition from p- to n-type doping was observed with the appearance of PbI{sub 2}, (ii) shallow acceptor states were distinguished and disappeared in n-type doped MAPbI{sub 3}, and (iii) a minimum of the SPV response related to deep defect states was found at the transition from p- to n-type doping. The results are discussed with respect to the further development of highly efficient and stable MAPbI{sub 3} absorbers for solar cells.

Nanoscale semiconductor Pb{sub 1-x}Sn{sub x}Se (x = 0.2) thin films synthesized by electrochemical atomic layer deposition

Energy Technology Data Exchange (ETDEWEB)

Lin Shaoxiong; Zhang Xin; Shi Xuezhao; Wei Jinping; Lu Daban; Zhang Yuzhen; Kou Huanhuan [Department of Chemistry, Lanzhou University, Lanzhou 730000 (China); Wang Chunming, E-mail: wangcm@lzu.edu.cn [Department of Chemistry, Lanzhou University, Lanzhou 730000 (China)

2011-04-15

In this paper the fabrication and characterization of IV-VI semiconductor Pb{sub 1-x}Sn{sub x}Se (x = 0.2) thin films on gold substrate by electrochemical atomic layer deposition (EC-ALD) method at room temperature are reported. Cyclic voltammetry (CV) is used to determine approximate deposition potentials for each element. The amperometric I-t technique is used to fabricate the semiconductor alloy. The elements are deposited in the following sequence: (Se/Pb/Se/Pb/Se/Pb/Se/Pb/Se/Sn ...), each period is formed using four ALD cycles of PbSe followed by one cycle of SnSe. Then the deposition manner above is cyclic repeated till a satisfactory film with expected thickness of Pb{sub 1-x}Sn{sub x}Se is obtained. The morphology of the deposit is observed by field emission scanning electron microscopy (FE-SEM). X-ray diffraction (XRD) pattern is used to study its crystalline structure; X-ray photoelectron spectroscopy (XPS) of the deposit indicates an approximate ratio 1.0:0.8:0.2 of Se, Pb and Sn, as the expected stoichiometry for the deposit. Open-circuit potential (OCP) studies indicate a good p-type property, and the good optical activity makes it suitable for fabricating a photoelectric switch.

PbBr3 Perovskite Crystals

KAUST Repository

Wei, Tzu-Chiao; Mokkapati, Sudha; Li, Ting-You; Lin, Chun-Ho; Lin, Gong-Ru; Jagadish, Chennupati; He, Jr-Hau

2018-01-01

, such as lithium niobate (LiNbO3), LiTaO3, KTiOPO4, and KH2PO4. Such a strong two-photon absorption effect in CH3NH3PbBr3 can be used to modulate the spectral and spatial profiles of laser pulses, as well as to reduce noise, and can be used to strongly control

Electronic structure, photoemission spectra, and vacuum-ultraviolet optical spectra of CsPbCl3 and CsPbBr3

Science.gov (United States)

Heidrich, K.; Schäfer, W.; Schreiber, M.; Söchtig, J.; Trendel, G.; Treusch, J.; Grandke, T.; Stolz, H. J.

1981-11-01

Optical spectra of CsPbCl3 and CsPbBr3 have been measured in the range from 2 to 10 eV and have been combined with ultraviolet-photoemission-spectroscopy (UPS)-measurements at 21.1 and 40.8 eV. A quantitative band calculation is presented, which takes into account anion-anion interaction as well as electronic states of the Cs+ ion. The prominent features of earlier band models and measurements are reestablished through our measurements and calculations, namely that the valence band consists of anionic p functions and Pb 6s functions, the lowest conduction band being Pb 6p type, and the lowest gap occuring at the R point of the Brillouin zone. Inclusion of a further (Cs 6s-type) conduction band, however, is necessary to bring the calculated joint density of states into agreement with vacuum-ultraviolet optical spectra. The calculated densities of states of the valence bands are in quantitative agreement with those deduced from our UPS measurements.

Imprint and oxygen deficiency in (Pb,La)(Zr,Ti)O3 thin-film capacitors with La-Sr-Co-O electrodes

International Nuclear Information System (INIS)

Lee, J.; Ramesh, R.; Keramidas, V.G.; Warren, W.L.; Pike, G.E.; Evans, J.T. Jr.

1995-01-01

La-Sr-Co-O/Pb-La-Zr-Ti-O/La-Sr-Co-O thin-film capacitors have been grown in various oxygen ambients by pulsed laser deposition. As the oxygen ambient became more reducing, the capacitors developed more voltage asymmetry in hysteresis loops and a more preferred polarization state directed towards the top electrode. PLZT capacitors cooled in a fully oxidizing atmosphere (i.e., 1 atm oxygen pressure) exhibited nominally symmetric hysteresis loops and also showed little imprint both with and without fully saturating bias fields. We find that ambient oxygen pressure is an important process parameter and the imprint behavior is closely related with ambient oxygen induced effects such as oxygen vacancies, its related defect-dipole complexes and trapping of free charges. The different imprint behavior under negative and positive bias also suggests that the dipolar-defect complexes tend to cause imprint in PLZT capacitors

NMR study of glasses in the PbO-B/sub 2/O/sub 3/-PbF/sub 2/-AlF/sub 3/ system

Energy Technology Data Exchange (ETDEWEB)

Vopilov, V.A.; Bogdanov, V.L.; Buznik, V.M.; Karapetyan, A.K.; Matsulev, A.N.

1986-01-01

The NMR method has been successfully used in the study of the structure of oxide glasses and in lithium glasses. Using steady-state and pulse methods of B-11 and F-19 NMR, the authors have studied borate glasses in the PbO-B/sub 2/O/sub 3/-PbF/sub 2/-AlF/sub 3/ system. Lead fluoride was added to the composition of the experimental glasses. A small amount of PbF2 has a weak effect on the electrical conductivity, and it is only in the specimen with the maximum values of the PbF/sub 2/ concentration that conductivity becomes significant. In glasses of the PbO X B/sub 2/O/sub 3/ X AlF/sub 3/ compositions, there is an exchange of the oxygen and fluoride modifier anions and as a result the F ions are incorporated into the first coordination sphere of the lead cations.

Enhanced magnetoelectric coupling in a composite multiferroic system via interposing a thin film polymer

Science.gov (United States)

Xiao, Zhuyun; Mohanchandra, Kotekar P.; Lo Conte, Roberto; Ty Karaba, C.; Schneider, J. D.; Chavez, Andres; Tiwari, Sidhant; Sohn, Hyunmin; Nowakowski, Mark E.; Scholl, Andreas; Tolbert, Sarah H.; Bokor, Jeffrey; Carman, Gregory P.; Candler, Rob N.

2018-05-01

Enhancing the magnetoelectric coupling in a strain-mediated multiferroic composite structure plays a vital role in controlling magnetism by electric fields. An enhancement of magnetoelastic coupling between ferroelectric single crystal (011)-cut [Pb(Mg1/3Nb2/3)O3](1-x)-[PbTiO3]x (PMN-PT, x≈ 0.30) and ferromagnetic polycrystalline Ni thin film through an interposed benzocyclobutene polymer thin film is reported. A nearly twofold increase in sensitivity of remanent magnetization in the Ni thin film to an applied electric field is observed. This observation suggests a viable method of improving the magnetoelectric response in these composite multiferroic systems.

Electrical tuning of magnetization rotation and microwave properties in FeCoZr/[Pb(Mg1/3Nb2/3)O3]0.68-[PbTiO3]0.32(011) multiferroic heterostructure

International Nuclear Information System (INIS)

Phuoc, Nguyen N; Ong, C K

2015-01-01

The permeability spectra of a multiferroic heterostructure composed of a FeCoZr thin film grown onto a [Pb(Mg 1/3 Nb 2/3 )O 3 ] 0.68 -[PbTiO 3 ] 0.32 (011) (PMN-PT) substrate are characterized as a function of an electrical field applied through the thickness of the substrate. When the sample is in an unpoled state and the applied electrical field is increased from 0 kV cm −1 to 2 kV cm −1 , the resonance frequency remains relatively the same. However, as the electrical field is increased beyond 2 kV cm −1 , the resonance frequency is drastically increased from 2.17 GHz to 3.28 GHz and the peak of the permeability spectra becomes much broader. When the electrical field is further increased from 2 kV cm −1 to 6 kV cm −1 , the resonance frequency is gradually increased and finally reaches 4 GHz. As the electrical field is reduced from 6 kV cm −1 back to 2 kV cm −1 , the resonance frequency is reduced in the same manner, and the peak disappears when the electrical field is reduced to less than 2 kV cm −1 . These behaviors are discussed in terms of the magnetization rotation and magnetic anisotropy dispersion based on the stress distribution of the piezoelectric substrate as a function of the applied electrical field. This argument is consistent with the hysteresis loops measured before and after poling. The result suggests that the electrical tunability of the magnetization rotation in multiferroic heterostructures can be employed to electrically turn on and off the microwave operation of the materials, which is promising for applications. (paper)

Synthesis, crystal structure and properties of a new lead fluoride borate, Pb{sub 3}OBO{sub 3}F

Energy Technology Data Exchange (ETDEWEB)

Zhao, Wenwu [Xinjiang Key Laboratory of Electronic Information Materials and Devices, Xinjiang Technical Institute of Physics and Chemistry, Chinese Academy of Sciences, 40-1 South Beijing Road, Urumqi 830011 (China); Graduate School of the Chinese Academy of Sciences, Beijing 100049 (China); Pan, Shilie, E-mail: slpan@ms.xjb.ac.cn [Xinjiang Key Laboratory of Electronic Information Materials and Devices, Xinjiang Technical Institute of Physics and Chemistry, Chinese Academy of Sciences, 40-1 South Beijing Road, Urumqi 830011 (China); Dong, Xiaoyu [Xinjiang Key Laboratory of Electronic Information Materials and Devices, Xinjiang Technical Institute of Physics and Chemistry, Chinese Academy of Sciences, 40-1 South Beijing Road, Urumqi 830011 (China); Graduate School of the Chinese Academy of Sciences, Beijing 100049 (China); Li, Junjie; Tian, Xuelin; Fan, Xiaoyun [Xinjiang Key Laboratory of Electronic Information Materials and Devices, Xinjiang Technical Institute of Physics and Chemistry, Chinese Academy of Sciences, 40-1 South Beijing Road, Urumqi 830011 (China); Chen, Zhaohui [Xinjiang Key Laboratory of Electronic Information Materials and Devices, Xinjiang Technical Institute of Physics and Chemistry, Chinese Academy of Sciences, 40-1 South Beijing Road, Urumqi 830011 (China); Physical and Chemical Detecting Center, Xinjiang University, Urumqi 830046 (China); Zhang, Fangfang [Xinjiang Key Laboratory of Electronic Information Materials and Devices, Xinjiang Technical Institute of Physics and Chemistry, Chinese Academy of Sciences, 40-1 South Beijing Road, Urumqi 830011 (China)

2012-04-15

Graphical abstract: The structure of Pb{sub 3}OBO{sub 3}F consists of two distortional Pb-centered tetrahedra and BO{sub 3} triangles which are all symmetrical with each other respectively in the gestalt structure to the extent that the Pb{sub 3}OBO{sub 3}F compound crystallizes in the symmetrical space group. Highlights: Black-Right-Pointing-Pointer Pb{sub 3}OBO{sub 3}F has been grown from PbO-PbF{sub 2}-B{sub 2}O{sub 3} system for the first time. Black-Right-Pointing-Pointer It crystallizes in the orthorhombic system, space group Pbcm. Black-Right-Pointing-Pointer Pb{sub 3}OBO{sub 3}F consists of Pb(1)O{sub 3}F tetrahedra, Pb(2)O{sub 4} tetrahedra and BO{sub 3} triangles. -- Abstract: A new compound, Pb{sub 3}OBO{sub 3}F, has been grown by the high temperature solution method from the PbO-PbF{sub 2}-B{sub 2}O{sub 3} system. It crystallizes in the orthorhombic system, space group Pbcm with unit-cell parameters a = 7.6313(14) Angstrom-Sign , b = 6.5229(12) Angstrom-Sign , c = 11.906(2) Angstrom-Sign , Z = 4, volume = 592.66(19) Angstrom-Sign {sup 3}. The structure of the compound is solved by the direct methods and refined to R{sub 1} = 0.0528 and wR{sub 2} = 0.1400. Pb{sub 3}OBO{sub 3}F consists of Pb(1)O{sub 3}F tetrahedra, Pb(2)O{sub 4} tetrahedra and BO{sub 3} triangles which build up the symmetrical chains extended along the c-axis. The powder X-ray diffraction pattern of the Pb{sub 3}OBO{sub 3}F has been measured. Functional groups presented in the sample were identified by Fourier transform infrared spectrum.

Optimized orientation of 0.71Pb(Mg1/3Nb2/3)O3-0.29PbTiO3 single crystal for applications in medical ultrasonic arrays

Science.gov (United States)

Zhou, Dan; Chen, Jing; Luo, Laihui; Zhao, Xiangyong; Luo, Haosu

2008-08-01

In order to extend the potential applications of medical ultrasonic array transducers, two optimized directions with the maximal electromechanical coefficient k33' and minimal k31 are determined for [001] and [110] poled 0.71Pb(Mg1/3Nb2/3)O3-0.29PbTiO3 single crystals using the experimental method. The maximum values of k33' can reach 92.8% and 93.3%, respectively, corresponding to [001]W/[110]L and [110]W/[1-11]L cuts. Furthermore, we simulate the performances of three 3.5 MHz linear array transducers based on the determined directions by PIEZOCAD. Results indicate that under the [001]W/[110]L direction, 25% broader bandwidth, 40% shorter pulse length, and 3 dB higher sensitivity can be obtained compared to the traditional Pb(Zr1-xTix)O3 transducers.

Electronic structure of the CsPbBr3/polytriarylamine (PTAA) system

Science.gov (United States)

Endres, James; Kulbak, Michael; Zhao, Lianfeng; Rand, Barry P.; Cahen, David; Hodes, Gary; Kahn, Antoine

2017-01-01

The inorganic lead halide perovskite CsPbBr3 promises similar solar cell efficiency to its hybrid organic-inorganic counterpart CH3NH3PbBr3 but shows greater stability. Here, we exploit this stability for the study of band alignment between perovskites and carrier selective interlayers. Using ultraviolet, X-ray, and inverse photoemission spectroscopies, we measure the ionization energy and electron affinities of CsPbBr3 and the hole transport polymer polytriarylamine (PTAA). We find that undoped PTAA introduces a barrier to hole extraction of 0.2-0.5 eV, due to band bending in the PTAA and/or a dipole at the interface. p-doping the PTAA eliminates this barrier, raising PTAA's highest occupied molecular orbital to 0.2 eV above the CsPbBr3 valence band maximum and improving hole transport. However, IPES reveals the presence of states below the PTAA lowest unoccupied molecular level. If present at the CsPbBr3/PTAA interface, these states may limit the polymer's efficacy at blocking electrons in solar cells with wide band gap materials like CsPbBr3 and CH3NH3PbBr3.

Thin film bismuth iron oxides useful for piezoelectric devices

Science.gov (United States)

Zeches, Robert J.; Martin, Lane W.; Ramesh, Ramamoorthy

2016-05-31

The present invention provides for a composition comprising a thin film of BiFeO.sub.3 having a thickness ranging from 20 nm to 300 nm, a first electrode in contact with the BiFeO.sub.3 thin film, and a second electrode in contact with the BiFeO.sub.3 thin film; wherein the first and second electrodes are in electrical communication. The composition is free or essentially free of lead (Pb). The BFO thin film is has the piezoelectric property of changing its volume and/or shape when an electric field is applied to the BFO thin film.

Tensile stress-dependent fracture behavior and its influences on photovoltaic characteristics in flexible PbS/CdS thin-film solar cells.

Science.gov (United States)

Lee, Seung Min; Yeon, Deuk Ho; Mohanty, Bhaskar Chandra; Cho, Yong Soo

2015-03-04

Tensile stress-dependent fracture behavior of flexible PbS/CdS heterojunction thin-film solar cells on indium tin oxide-coated polyethylene terephthalate (PET) substrates is investigated in terms of the variations of fracture parameters with applied strains and their influences on photovoltaic properties. The PbS absorber layer that exhibits only mechanical cracks within the applied strain range from ∼0.67 to 1.33% is prepared by chemical bath deposition at different temperatures of 50, 70, and 90 °C. The PbS thin films prepared at 50 °C demonstrate better mechanical resistance against the applied bending strain with the highest crack initiating bending strain of ∼1.14% and the lowest saturated crack density of 0.036 μm(-1). Photovoltaic properties of the cells depend on the deposition temperature and the level of applied tensile stress. The values of short-circuit current density and fill factor are dramatically reduced above a certain level of applied strain, while open-circuit voltage is nearly maintained. The dependency of photovoltaic properties on the progress of fractures is understood as related to the reduced fracture energy and toughness, which is limitedly controllable by microstructural features of the absorber layer.

Adsorption-controlled growth of ferroelectric PbTiO{sub 3} and Bi{sub 4}Ti{sub 3}O{sub 12} films for nonvolatile memory applications by MBE

Energy Technology Data Exchange (ETDEWEB)

Theis, C.D.; Yeh, J.; Schlom, D.G. [Pennsylvania State Univ., University Park, PA (United States). Dept. of Materials Science and Engineering; Hawley, M.E.; Brown, G.W. [Los Alamos National Lab., NM (United States). Center for Materials Science

1997-09-01

Epitaxial PbTiO{sub 3} and Bi{sub 4}Ti{sub 3}O{sub 12} thin films have been grown on (100) SrTiO{sub 3} and (100) LaAlO{sub 3} substrates by reactive molecular beam epitaxy (MBE). Titanium is supplied to the film in the form of shuttered bursts each containing a one monolayer dose of titanium atoms for the growth of PbTiO{sub 3} and three monolayers for the growth of Bi{sub 4}Ti{sub 3}O{sub 12}. Lead, bismuth, and ozone are continuously supplied to the surface of the depositing film. Growth of phase pure, c-axis oriented epitaxial films with bulk lattice constants is achieved using an overpressure of these volatile species. With the proper choice of substrate temperature (600--650 C) and ozone background pressure (P{sub O{sub 3}} = 2 {times} 10{sup {minus}5} Torr), the excess of the volatile metals and ozone desorb from the surface of the depositing film leaving a phase-pure stoichiometric crystal. The smooth PbTiO{sub 3} surface morphology revealed by atomic force microscopy (AFM) suggests that the PbTiO{sub 3} films grow in a layer-by-layer fashion. In contrast the Bi{sub 4}Ti{sub 3}O{sub 12} films contain islands which evolve either continuously or around screw dislocations via a spiral-type growth mechanism.

Multilayer thin films with compositional PbZr0.52Ti0.48O3/Bi1.5Zn1.0Nb1.5O7 layers for tunable applications

Science.gov (United States)

Yu, Shihui; Li, Lingxia; Zhang, Weifeng; Sun, Zheng; Dong, Helei

2015-01-01

The dielectric properties and tunability of multilayer thin films with compositional PbZr0.52Ti0.48O3/Bi1.5Zn1.0Nb1.5O7 (PZT/BZN) layers (PPBLs) fabricated by pulsed laser deposition on Pt/TiO2/SiO2/Si substrate have been investigated. Dielectric measurements indicate that the PZT/BZN bilayer thin films exhibit medium dielectric constant of about 490, low loss tangent of 0.017, and superior tunable dielectric properties (tunability = 49.7% at 500 kV/cm) at a PZT/BZN thickness ratio of 3, while the largest figure of merit is obtained as 51.8. The thickness effect is discussed with a series connection model of bilayer capacitors, and the calculated dielectric constant and loss tangent are obtained. Furthermore, five kinds of thin–film samples comprising single bilayers, two, three, four and five PPBLs were also elaborated with the final same thickness. The four PPBLs show the largest dielectric constant of ~538 and tunability of 53.3% at a maximum applied bias field of 500 kV/cm and the lowest loss tangent of ~0.015, while the largest figure of merit is 65.6. The results indicate that four PPBLs are excellent candidates for applications of tunable devices. PMID:25960043

Clamping-induced changes of domain morphology in 88%Pb(Zn{sub 1/3}Nb{sub 2/3})O{sub 3}-12%PbTiO{sub 3}

Energy Technology Data Exchange (ETDEWEB)

Chang, L.-W., E-mail: lchang01@qub.ac.uk; Gregg, J. M., E-mail: m.gregg@qub.ac.uk [Centre for Nanostructured Media, School of Maths and Physics, Queen' s University Belfast, Northern Ireland BT7 1NN (United Kingdom); Nagarajan, V.; Okatan, M. B. [School of Materials Science and Engineering, University of New South Wales, New South Wales 2052 (Australia)

2014-08-14

Domain microstructures in single crystal lamellae of 88%Pb(Zn{sub 1/3}Nb{sub 2/3})O{sub 3}-12%PbTiO{sub 3} (cut from bulk using focused ion beam milling) have been mapped using both piezoresponse force microscopy and transmission electron microscopy. Dramatic changes from mottled microstructures typical of relaxors to larger scale domains typical of ferroelectrics have been noted. Stresses associated with substrate clamping are suspected as the cause for the transition from short- to long-range polar order, akin to effects induced by cation ordering achieved by thermal quenching.

Structural and optical properties of ternary Cs-Pb-Cl nanoaggregates in thin films

Czech Academy of Sciences Publication Activity Database

Somma, F.; Aloe, P.; Mastro, Lo S.; Santucci, S.; Giampaolo, C.; Nikl, Martin; Nitsch, Karel; Fabeni, P.; Pazzi, G.P.

2001-01-01

Roč. 19, č. 6 (2001), s. 2237-2239 ISSN 1071-1023 Institutional research plan: CEZ:AV0Z1010914 Keywords : CsPbCl 3 * Cs 4PbCl 6 * nanoaggreates * luminescence Subject RIV: BM - Solid Matter Physics ; Magnetism Impact factor: 1.549, year: 2001

Increasing the electrical anisotropy of solution-grown PbI2 thin films by addition of CdI2

International Nuclear Information System (INIS)

Ponpon, J.P.; Amann, M.

2010-01-01

In the present study up to 20% CdI 2 has been added to a lead iodide-water solution, which is used to grow PbI 2 polycrystalline thin films. As a result, a significant increase in the anisotropy of the lead iodide film's electrical properties has been observed: the resistivity in the direction parallel to the c-axis reached 10 15 Ω cm but did not change significantly in the orthogonal direction. This behavior can be explained by the modification of the transport properties related to the crystallographic structure of the films along the c-axis. As suggested by thermally stimulated current measurements, only a small number of the Cd atoms incorporated into the PbI 2 lattice could behave as dopants.

Growth and characterization of Pb(Lu{sub 1/2}Nb{sub 1/2})O{sub 3}-Pb(Mg{sub 1/3}Nb{sub 2/3})O{sub 3}-PbTiO{sub 3} ternary piezo-/ferroelectric crystals

Energy Technology Data Exchange (ETDEWEB)

Liu, Ying [Key Laboratory of Optoelectronic Materials Chemistry and Physics, Fujian Institute of Research on the Structure of Matter, Chinese Academy of Sciences, Fuzhou, Fujian 350002 (China); College of Physics and Energy, Fujian Normal University, Fuzhou, Fujian 350117 (China); He, Chao [Key Laboratory of Optoelectronic Materials Chemistry and Physics, Fujian Institute of Research on the Structure of Matter, Chinese Academy of Sciences, Fuzhou, Fujian 350002 (China); Yang, Xiaoming [Key Laboratory of Optoelectronic Materials Chemistry and Physics, Fujian Institute of Research on the Structure of Matter, Chinese Academy of Sciences, Fuzhou, Fujian 350002 (China); College of Physics and Energy, Fujian Normal University, Fuzhou, Fujian 350117 (China); Li, Xiuzhi; Wang, Zujian [Key Laboratory of Optoelectronic Materials Chemistry and Physics, Fujian Institute of Research on the Structure of Matter, Chinese Academy of Sciences, Fuzhou, Fujian 350002 (China); Huang, Zhigao; Lai, Fachun [College of Physics and Energy, Fujian Normal University, Fuzhou, Fujian 350117 (China); Long, Xifa, E-mail: lxf@fjirsm.ac.cn [Key Laboratory of Optoelectronic Materials Chemistry and Physics, Fujian Institute of Research on the Structure of Matter, Chinese Academy of Sciences, Fuzhou, Fujian 350002 (China)

2016-08-05

Piezo-/ferroelectric crystals of Pb(Lu{sub 1/2}Nb{sub 1/2})O{sub 3}-Pb(Mg{sub 1/3}Nb{sub 2/3})O{sub 3}-PbTiO{sub 3} ternary solid solution system with high Curie temperature, in the vicinity of morphotropic phase boundary (MPB) region, are grown by the top-seeded solution growth (TSSG) method for the first time. The compositions and structures of the crystals are analyzed, all the structures are found to have pure perovskite structure using X-ray diffraction analysis. Di-/piezo-/ferroelectric properties of the crystals are also characterized systematically. The Curie temperature T{sub c} and coercive field E{sub c}, increase gradually with increasing PbTiO{sub 3} content. In particular, the crystal with composition 0.34PLN-0.31PMN-0.35PT possesses excellent electric properties including the Curie temperature, the rhombohedral–tetragonal phase transition temperature, the piezoelectric coefficient, the remnant polarization and the coercive field, which are T{sub c} = 228 °C, T{sub RT} = 156 °C, d{sub 33} = 2092 pC N{sup −1}, Pr = 35.5 μC cm{sup −2} and E{sub c} = 8.1 kV cm{sup −1}, respectively, making it a promising material for transducers or detectors in a wide temperature range. - Highlights: • PLN-PMN-PT Piezo-/ferroelectric crystals are grown by TSSG method. • The Curie temperature and coercive field increase gradually with increasing PT. • The crystal of 0.34PLN-0.31PMN-0.35PT possesses excellent electric properties.

Electrical properties of Sb and Cr-doped PbZrO3-PbTiO3-PbMg1/3Nb2/3O3 ceramics

OpenAIRE

Whatmore, Roger W.; Molter, O.; Shaw, Christopher P.

2003-01-01

The pyroelectric, dielectric and DC resistive properties of Sb and Cr-doped ceramics with a base composition of Pb(Mg1/3Nb2/3)0.025(Zr0.825Ti0.175)0.975O3 have been studied. Sb doping has been shown to produce a linear reduction in Curie temperature (TC=−22z+294 °C) with concentration (z) and to give an increase in pyroelectric coefficient from 250 to 310 μCm−2 K−1 for z increasing from 0 to 3 at.%. It also produces first a reduction and then an increase in both dielectric constant and loss, ...

All-Ambient Processed Binary CsPbBr3-CsPb2Br5 Perovskites with Synergistic Enhancement for High-Efficiency Cs-Pb-Br-Based Solar Cells.

Science.gov (United States)

Zhang, Xisheng; Jin, Zhiwen; Zhang, Jingru; Bai, Dongliang; Bian, Hui; Wang, Kang; Sun, Jie; Wang, Qian; Liu, Shengzhong Frank

2018-02-28

All-inorganic CsPbBr 3 perovskite solar cells display outstanding stability toward moisture, light soaking, and thermal stressing, demonstrating great potential in tandem solar cells and toward commercialization. Unfortunately, it is still challenging to prepare high-performance CsPbBr 3 films at moderate temperatures. Herein, a uniform, compact CsPbBr 3 film was fabricated using its quantum dot (QD)-based ink precursor. The film was then treated using thiocyanate ethyl acetate (EA) solution in all-ambient conditions to produce a superior CsPbBr 3 -CsPb 2 Br 5 composite film with a larger grain size and minimal defects. The achievement was attributed to the surface dissolution and recrystallization of the existing SCN - and EA. More specifically, the SCN - ions were first absorbed on the Pb atoms, leading to the dissolution and stripping of Cs + and Br - ions from the CsPbBr 3 QDs. On the other hand, the EA solution enhances the diffusion dynamics of surface atoms and the surfactant species. It is found that a small amount of CsPb 2 Br 5 in the composite film gives the best surface passivation, while the Br-rich surface decreases Br vacancies (V Br ) for a prolonged carrier lifetime. As a result, the fabricated device gives a higher solar cell efficiency of 6.81% with an outstanding long-term stability.

Synthesis, vibrational and optical properties of a new three-layered organic-inorganic perovskite (C{sub 4}H{sub 9}NH{sub 3}){sub 4}Pb{sub 3}I{sub 4}Br{sub 6}

Energy Technology Data Exchange (ETDEWEB)

Dammak, T., E-mail: thameurlpa@yahoo.f [Laboratoire de Physique appliquee (LPA), Faculte des Sciences de Sfax, 3018, BP 802 (Tunisia); Elleuch, S. [Laboratoire de Physique appliquee (LPA), Faculte des Sciences de Sfax, 3018, BP 802 (Tunisia); Bougzhala, H. [Laboratoire de cristallochimie et des materiaux, Faculte des Sciences de Tunis (Tunisia); Mlayah, A. [Centre d' Elaboration de Materiaux et d' Etudes Structurales, CNRS-Universite Paul Sabatier, 29 rue Jeanne Marvig, 31055 Toulouse, Cedex 4 (France); Chtourou, R. [Centre de Recherche et des Technologies de l' Energie CRTEn BP. 95, Hammam-Lif 2050, Laboratoire de Photovoltaique et de Semiconducteur (Tunisia); Abid, Y. [Laboratoire de Physique appliquee (LPA), Faculte des Sciences de Sfax, 3018, BP 802 (Tunisia)

2009-09-15

An organic-inorganic hybrid perovskite (C{sub 4}H{sub 9}NH{sub 3}){sub 4}Pb{sub 3}I{sub 4}Br{sub 6} was synthesized and studied by X-ray diffraction, Raman and infrared spectroscopies, optical transmission and photoluminescence. The title compound, abbreviated (C{sub 4}){sub 4}Pb{sub 3}I{sub 4}Br{sub 6}, crystallises in a periodic two-dimensional multilayer structure with P2{sub 1}/a space group. The structure is built up from alternating inorganic and organic layers. Each inorganic layer consists of three sheets of PbX{sub 6} (X=I, Br) octahedra. Raman and infrared spectra of the title compound were recorded in the 100-3500 and 400-4000 cm{sup -1} frequency ranges, respectively. An assignment of the observed vibration modes is reported. Optical transmission measurements, performed on thin films of (C{sub 4}){sub 4}Pb{sub 3}I{sub 4}Br{sub 6}, revealed two absorption bands at 474 and 508 nm. Photoluminescence measurements have shown a green emission peak at 519 nm.

Tunnelling spectroscopy of BaFe{sub 2}As{sub 2}/Au/PbIn thin film junctions

Energy Technology Data Exchange (ETDEWEB)

Doering, Sebastian; Schmidt, Stefan; Schmidl, Frank; Tympel, Volker; Grosse, Veit; Seidel, Paul [Institut fuer Festkoerperphysik, Friedrich-Schiller-Universitaet Jena (Germany); Haindl, Silvia; Iida, Kazumasa; Kurth, Fritz; Holzapfel, Bernhard [IFW Dresden, Institut fuer Metallische Werkstoffe, Dresden (Germany)

2011-07-01

Tunnelling spectroscopy is an important tool to investigate the properties of iron-based superconductors. In contrast to commonly used point contact Andreev reflection (PCAR) technique, we fabricated hybrid superconductor / normal metal / superconductor (SNS) thin film structures, with tunable barrier thickness and area. For the base electrode we use Ba(Fe{sub 0.9}Co{sub 0.1}){sub 2}As{sub 2} thin films, produced via pulsed laser deposition (PLD). A gold layer was sputtered to form the barrier, while the counter electrode material is the conventional superconductor PbIn with a T{sub c} of 7.2 K. For temperatures below 7.2 K the spectrum shows a subharmonic gap structure (SGS), described by an extended model of Octavio, Tinkham, Blonder and Klapwijk (OTBK), while at higher temperatures the SGS vanishes and an SN-like behaviour can be observed.

In-situ observation of domain wall motion in Pb(In{sub 1/2}Nb{sub 1/2})O{sub 3}-Pb(Mg{sub 1/3}Nb{sub 2/3})O{sub 3}-PbTiO{sub 3} crystals

Energy Technology Data Exchange (ETDEWEB)

Lin, Dabin; Cai, Changlong [Laboratory of Thin Film Techniques and Optical Test, Xi' an Technological University, Xi' an 710032 (China); Li, Zhenrong, E-mail: zhrli@mail.xjtu.edu.cn; Li, Fei; Xu, Zhuo [Electronic Materials Research Laboratory, Key Laboratory of Education Ministry and International Center for Dielectric Research, Xi' an Jiaotong University, Xi' an 710049 (China); Zhang, Shujun, E-mail: soz1@psu.edu [Materials Research Institute, Pennsylvania State University, University Park, Pennsylvania 16802 (United States); Cheng, Yaojin [Science and Technology on Low-Light-Level Night Vision Laboratory, Xi' an 710065 (China)

2014-07-21

Various domain structures, including wave-like domains, mixed needle-like and laminar domains, typical embedded 90° and 180° domains, have been observed in unpoled rhombohedral, monoclinic, and tetragonal Pb(In{sub 1/2}Nb{sub 1/2})O{sub 3}-Pb(Mg{sub 1/3}Nb{sub 2/3})O{sub 3}-PbTiO{sub 3} (PIN-PMN-PT) crystals by polarizing light microscope; while in poled tetragonal crystals, the parallel 180° domains were reversed and only vertical 90° domain walls were observed. For 0.24PIN-0.42PMN-0.34PT crystals with morphotropic phase boundary composition, the domain wall motion was in-situ observed as a function of applied electric field along crystallographic [100] direction. With increasing the electric field from 0 to 12 kV/cm, the rhombohedral (R) domains were found to change to monoclinic (M) domains and then to tetragonal (T) domains. The electric field-induced phase transition was also confirmed by X-ray diffraction and the temperature-dependent dielectric behavior.

Chemical U-Th-Pb dating of monazite by 3D-Micro x-ray fluorescence analysis with synchrotron radiation

DEFF Research Database (Denmark)

Schmitz, Susanne; Möller, Andreas; Wilke, Max

2009-01-01

A confocal set-up for three-dimensional (3D) micro X-ray fluorescence (micro-XRF) was used at the mySpot beamline at BESSY II, which allows compositional depth profiling for various applications. We present results obtained with a confocal 3D micro-XRF set-up for chemical age dating using the U, Th...... and Pb concentrations of monazite within rock thin sections. The probing volume was determined to be approximately 21 × 21 × 24 µm3 for W-La using an excitation energy of 19 keV. The relative detection limits particularly for Pb are below 10 ppm (for counting times of 1000 s). Therefore, this 3D micro...... of ages, varying from 20 Ma to 1.82 Ga. Reference materials (GM3, F6, 3345) can be reproduced within error. The spread in the ages of all points determined by 3D micro-XRF is within 8 % of the isotopic reference value. The average 3D micro-XRF dates reproduce the reference ages with discrepancies between...

Crystal Structure Formation of CH3NH3PbI3-xClx Perovskite

Directory of Open Access Journals (Sweden)

Shiqiang Luo

2016-02-01

Full Text Available Inorganic-organic hydride perovskites bring the hope for fabricating low-cost and large-scale solar cells. At the beginning of the research, two open questions were raised: the hysteresis effect and the role of chloride. The presence of chloride significantly improves the crystallization and charge transfer property of the perovskite. However, though the long held debate over of the existence of chloride in the perovskite seems to have now come to a conclusion, no prior work has been carried out focusing on the role of chloride on the electronic performance and the crystallization of the perovskite. Furthermore, current reports on the crystal structure of the perovskite are rather confusing. This article analyzes the role of chloride in CH3NH3PbI3-xClx on the crystal orientation and provides a new explanation about the (110-oriented growth of CH3NH3PbI3 and CH3NH3PbI3-xClx.

Properties of morphotropic phase boundary Pb(Mg1/3Nb2/3)O3PbTiO3 films with submicrometre range thickness on Si-based substrates

OpenAIRE

Algueró , M; Stewart , M; Cain , M G; Ramos , P; Ricote , J; Calzada , M L

2010-01-01

Abstract The electrical properties of (1-x)Pb(Mg 1/3 Nb 2/3)O 3 -xPbTiO 3 films with composition in the morphotropic phase boundary region around x=0.35, submicron thickness and columnar microstructure, prepared on Si based substrates by chemical solution deposition are presented and discussed in relation to the properties of coarse and fine grained ceramics. The films show relaxor characteristics that are proposed to result from a grain size effect on the kinetics of the relaxor to ferroe...

Ferroelectric thin films using oxides as raw materials

Directory of Open Access Journals (Sweden)

E.B. Araújo

1999-01-01

Full Text Available This work describes an alternative method for the preparation of ferroelectric thin films based on pre-calcination of oxides, to be used as precursor material for a solution preparation. In order to show the viability of the proposed method, PbZr0.53Ti0.47O3 and Bi4Ti3O12 thin films were prepared on fused quartz and Si substrates. The results were analyzed by X-ray Diffraction (XRD, Scanning Electron Microscopy (SEM, Infrared Spectroscopy (IR and Rutherford Backscattering Spectroscopy (RBS. The films obtained show good quality, homogeneity and the desired stoichiometry. The estimated thickness for one layer deposition was approximately 1000 Å and 1500 Å for Bi4Ti3O12 and PbZr0.53Ti0.47O3 films, respectively.

Toward a unified description of nonlinearity and frequency dispersion of piezoelectric and dielectric responses in Pb(Zr,Ti)O3

International Nuclear Information System (INIS)

Damjanovic, D.; Bharadwaja, S.S.N.; Setter, N.

2005-01-01

A phenomenological approach is proposed describing both nonlinearity and frequency dispersion in dielectric and piezoelectric properties of lead zirconate titanate, Pb(Zr,Ti)O 3 (PZT), thin films and ceramics. The approach couples the frequency dependent response in form of the power law, 1/ω β , with the rate-independent nonlinear response described by the Rayleigh law. The main experimental trends are well described by the model

Defect enhanced optic and electro-optic properties of lead zirconate titanate thin films

Directory of Open Access Journals (Sweden)

M. M. Zhu

2011-12-01

Full Text Available Pb(Zr1-xTixO3 (PZT thin films near phase morphotropic phase boundary were deposited on (Pb0.86La0.14TiO3-coated glass by radio frequency sputtering. A retrieved analysis shows that the lattice parameters of the as-grown PZT thin films were similar to that of monoclinic PZT structure. Moreover, the PZT thin films possessed refractive index as high as 2.504 in TE model and 2.431 in TM model. The as-grown PZT thin film had one strong absorption peak at 632.6 nm, which attributed to lead deficiency by quantitative XPS analysis. From the attractive properties achieved, electro-optic and photovoltaic characteristic of the films were carried out.

Effect of deposition temperature of TiO2 on the piezoelectric property of PbTiO3 film grown by PbO gas phase reaction sputtering

International Nuclear Information System (INIS)

Kim, Jiyoon; Kim, Yunseok; Park, Moonkyu; No, Kwangsoo; Hong, Seungbum; Buehlmann, Simon; Kim, Yong Kwan

2010-01-01

A 17 nm thick PbTiO 3 (PTO) films were fabricated via PbO gas phase reaction with TiO 2 starting layer in a sputtering chamber. The influence of deposition temperature of TiO 2 on the piezoelectric properties of PTO thin films was investigated. The remnant piezoresponse of PTO films nonlinearly increased as a function of TiO 2 deposition temperature, which is correlated with the increase in average grain diameter of PTO film. As grain size increases, the restriction on remnant piezoresponse imposed by the grain boundary via coupling between local strain and polarization becomes less pronounced, which results in the increase in remnant piezoresponse. Furthermore, we found that the vertical shift in piezoresponse hysteresis loops is closely related to the residual stress state. A strong correlation between the negative vertical shift and the residual tensile stress reveals that residual stress on the resulting PTO film contributed to the asymmetric piezoelectric property.

Preparation of Pb(Mg1/3Nb2/3)O3 by simultaneous precipitations

International Nuclear Information System (INIS)

Juiz, S.A.; Varela, J.A.; Santilli, C.V.; Pulcinelli, S.H.; Longo, E.

1990-01-01

Pb(Mg 1/3 Nb 2/3 )O 3 was obtained by simultaneous precipitation of Pb(NO 3 ) 2' Mg(NO 3 ) 2 . 6H 2 O and NH 4 H 2 /NbO(C 2 O 4 ) 3 ./3H 2 O in alkaline medium. DTA of the precipitates show the PMN formation between 700 and 750 0 C. XRD on powder calcined at 750 0 C indicates on other phases basiders PMN. Measurements of dielectric constants shows a Curie temperature shifted to -80 0 C. (author) [pt

Effect of structural in-depth heterogeneities on electrical properties of Pb(Zr0.52Ti0.48) O3 thin films as revealed by nano-beam X-ray diffraction

Science.gov (United States)

Vaxelaire, N.; Kovacova, V.; Bernasconi, A.; Le Rhun, G.; Alvarez-Murga, M.; Vaughan, G. B. M.; Defay, E.; Gergaud, P.

2016-09-01

A direct quantification of a structural in-depth composition in the lead zirconate titanate Pb(Zr,Ti)O3 thin films of morphotropic composition has been conducted using the newly available X-ray nano-pencil beam (i.e., beam size of 100 nm × 1 μm) diffraction approach. We tested two samples with different Zr/Ti chemical gradients. Here, we demonstrate the presence of a significant microstructural gradient between the rhombohedral and tetragonal phases through PbZrxTi1-xO3 (PZT) films with a 100 nm in-depth resolution. The phase gradient extends over around 350 nm, and it is repeated through the PZT film three times, which corresponds to the number of thermal annealings. Moreover, this microstructural gradient is in agreement with the Zr/Ti chemical gradient observed by the secondary ion mass spectroscopy (SIMS). Indeed, the quantity of tetragonal phases rises in the Ti-rich zones as revealed by SIMS, and the quantity of rhombohedral phases rises in the Zr-rich zones. We also demonstrated a huge difference in the in-depth phase variation between the two tested samples. The gradient free sample still contains 4.7% of phase variation through the film and the amplified gradient contains 9.6% of phase variation through the film. Knowing that the gradient free sample shows better electric and piezoelectric coefficients, one can draw a correlation between the chemical composition, crystallographic homogeneity, and electro-mechanical properties of the film. The more close the film is to the morphotropic composition and the more it is crystallographically homogeneous, the higher the piezoelectric coefficients of the PZT are. Finally, the adequate knowledge of phase variation and its relation to the fabrication technique are crucial for the enhancement of the PZT electro-mechanical properties. Our methodology and findings open up new perspectives in establishing a relevant quantitative feedback to reach an ultimate electro-mechanical coupling in the sol-gel PZT thin films.

Relativistic GW calculations on CH3NH3PbI3 and CH3NH3SnI3 perovskites for solar cell applications.

Science.gov (United States)

Umari, Paolo; Mosconi, Edoardo; De Angelis, Filippo

2014-03-26

Hybrid AMX3 perovskites (A = Cs, CH3NH3; M = Sn, Pb; X = halide) have revolutionized the scenario of emerging photovoltaic technologies, with very recent results demonstrating 15% efficient solar cells. The CH3NH3PbI3/MAPb(I(1-x)Cl(x))3 perovskites have dominated the field, while the similar CH3NH3SnI3 has not been exploited for photovoltaic applications. Replacement of Pb by Sn would facilitate the large uptake of perovskite-based photovoltaics. Despite the extremely fast progress, the materials electronic properties which are key to the photovoltaic performance are relatively little understood. Density Functional Theory electronic structure methods have so far delivered an unbalanced description of Pb- and Sn-based perovskites. Here we develop an effective GW method incorporating spin-orbit coupling which allows us to accurately model the electronic, optical and transport properties of CH3NH3SnI3 and CH3NH3PbI3, opening the way to new materials design. The different CH3NH3SnI3 and CH3NH3PbI3 electronic properties are discussed in light of their exploitation for solar cells, and found to be dominantly due to relativistic effects. These effects stabilize the CH3NH3PbI3 material towards oxidation, by inducing a deeper valence band edge. Relativistic effects, however, also increase the material band-gap compared to CH3NH3SnI3, due to the valence band energy downshift (~0.7 eV) being only partly compensated by the conduction band downshift (~0.2 eV).

Determination of dissociation enthalpies of KPbF3, RbPbF3, CsPbF3 complex molecules

International Nuclear Information System (INIS)

Boltalin, A.I.; Rykov, A.N.; Korenev, Yu.M.

1990-01-01

Isomolecular reactions in MPbF 3(g) -BeF 2(g) systems where M=K, Rb, Cs are studied using Knudsen effusion technique with mass-spectral analysis of evaporation products. Enthalpy values of dissociation of MPbF 3 molecules per lead difluoride and alkali metal fluoride which are equal to 212.1±12.6 kJ/mol for CsPbF 3 are determined

Evolution of electrical properties and domain configuration of Mn modified Pb(In1/2Nb1/2)O3-PbTiO3 single crystals

Science.gov (United States)

Qiao, Huimin; He, Chao; Yuan, Feifei; Wang, Zujian; Li, Xiuzhi; Liu, Ying; Guo, Haiyan; Long, Xifa

2018-04-01

The acceptor doped relaxor-based ferroelectric materials are useful for high power applications such as probes in ultrasound-guided high intensity focused ultrasound therapy. In addition, a high Curie temperature is desired because of wider temperature usage and improved temperature stability. Previous investigations have focused on Pb(Mg1/3Nb2/3)O3-PbTiO3 and Pb(Zn1/3Nb2/3)O3-PbTiO3 systems, which have a ultrahigh piezoelectric coefficient and dielectric constant, but a relatively low Curie temperature. It is desirable to study the binary relaxor-based system with a high Curie temperature. Therefore, Pb(In1/2Nb1/2)O3-PbTiO3 (PINT) single crystals were chosen to study the Mn-doped influence on their electrical properties and domain configuration. The evolution of ferroelectric hysteresis loops for doped and virgin samples exhibit the pinning effect in Mn-doped PINT crystals. The relaxation behaviors of doped and virgin samples are studied by fit of the modified Curie-Weiss law and Volgel-Fucher relation. In addition, a short-range correlation length was fitted to study the behavior of polar nanoregions based on the domain configuration obtained by piezoresponse force microscopy. Complex domain structures and smaller short-range correlation lengths (100-150 nm for Mn-doped PINT and >400 nm for pure PINT) were obtained in the Mn-doped PINT single crystals.

CH3NH3PbI3 grain growth and interfacial properties in meso-structured perovskite solar cells fabricated by two-step deposition

Science.gov (United States)

Yao, Zhibo; Wang, Wenli; Shen, Heping; Zhang, Ye; Luo, Qiang; Yin, Xuewen; Dai, Xuezeng; Li, Jianbao; Lin, Hong

2017-12-01

Although the two-step deposition (TSD) method is widely adopted for the high performance perovskite solar cells (PSCs), the CH3NH3PbI3 perovskite crystal growth mechanism during the TSD process and the photo-generated charge recombination dynamics in the mesoporous-TiO2 (mp-TiO2)/CH3NH3PbI3/hole transporting material (HTM) system remains unexploited. Herein, we modified the concentration of PbI2 (C(PbI2)) solution to control the perovskite crystal properties, and observed an abnormal CH3NH3PbI3 grain growth phenomenon atop mesoporous TiO2 film. To illustrate this abnormal grain growth mechanism, we propose that a grain ripening process is taking place during the transformation from PbI2 to CH3NH3PbI3, and discuss the PbI2 nuclei morphology, perovskite grain growing stage, as well as Pb:I atomic ratio difference among CH3NH3PbI3 grains with different morphology. These C(PbI2)-dependent perovskite morphologies resulted in varied charge carrier transfer properties throughout the mp-TiO2/CH3NH3PbI3/HTM hybrid, as illustrated by photoluminescence measurement. Furthermore, the effect of CH3NH3PbI3 morphology on light absorption and interfacial properties is investigated and correlated with the photovoltaic performance of PSCs.

The crystal structure of Kirkiite, Pb10Bi3As3S19

DEFF Research Database (Denmark)

Makovicky, Emil; Balic Zunic, Tonci; Karanovic, Ljiljana

2006-01-01

and chemical analysis resulted in comparable formulae, Pb10Bi2.16As3.84S19 and Pb10.08Bi2.55Sb0.13As2.91S19, respectively, which are close to the ideal formula Pb10Bi3As3S19. The crystal lattice shows a pseudohexagonal symmetry, which is the cause of common twinning in this mineral. The main twin-law has (20...... layers parallel to (083) of kirkiite; the slabs are unit-cell-twinned on (010) refl ection planes. The structure contains one split As position, and two additional sites that could accommodate both As and Bi. The As,Bi distribution over these two sites is determined by the trapezoidal distortion...... of the half-octahedral coordination environment inside the tightly bonded double layers of the PbS-SnS archetype slabs. Owing to the stoichiometry requirements in this structure, Bi must also substitute for 1/11 of the Pb sites. Bond-valence calculations and the volumes of coordination polyhedra show...

Evolution of Chemical Composition, Morphology, and Photovoltaic Efficiency of CH 3 NH 3 PbI 3 Perovskite under Ambient Conditions

KAUST Repository

Huang, Weixin; Manser, Joseph S.; Kamat, Prashant V.; Ptasinska, Sylwia

2016-01-01

© 2015 American Chemical Society. The surface composition and morphology of CH3NH3PbI3 perovskite films stored for several days under ambient conditions were investigated by X-ray photoelectron spectroscopy, scanning electron microscopy, and X-ray diffraction techniques. Chemical analysis revealed the loss of CH3NH3 + and I- species from CH3NH3PbI3 and its subsequent decomposition into lead carbonate, lead hydroxide, and lead oxide. After long-term storage under ambient conditions, morphological analysis revealed the transformation of randomly distributed defects and cracks, initially present in the densely packed crystalline structure, into relatively small grains. In contrast to PbI2 powder, CH3NH3PbI3 exhibited a different degradation trend under ambient conditions. Therefore, we propose a plausible CH3NH3PbI3 decomposition pathway that explains the changes in the chemical composition of CH3NH3PbI3 under ambient conditions. In addition, films stored under such conditions were incorporated into photovoltaic cells, and their performances were examined. The chemical changes in the decomposed films were found to cause a significant decrease in the photovoltaic efficiency of CH3NH3PbI3.

Evolution of Chemical Composition, Morphology, and Photovoltaic Efficiency of CH 3 NH 3 PbI 3 Perovskite under Ambient Conditions

KAUST Repository

Huang, Weixin

2016-01-12

© 2015 American Chemical Society. The surface composition and morphology of CH3NH3PbI3 perovskite films stored for several days under ambient conditions were investigated by X-ray photoelectron spectroscopy, scanning electron microscopy, and X-ray diffraction techniques. Chemical analysis revealed the loss of CH3NH3 + and I- species from CH3NH3PbI3 and its subsequent decomposition into lead carbonate, lead hydroxide, and lead oxide. After long-term storage under ambient conditions, morphological analysis revealed the transformation of randomly distributed defects and cracks, initially present in the densely packed crystalline structure, into relatively small grains. In contrast to PbI2 powder, CH3NH3PbI3 exhibited a different degradation trend under ambient conditions. Therefore, we propose a plausible CH3NH3PbI3 decomposition pathway that explains the changes in the chemical composition of CH3NH3PbI3 under ambient conditions. In addition, films stored under such conditions were incorporated into photovoltaic cells, and their performances were examined. The chemical changes in the decomposed films were found to cause a significant decrease in the photovoltaic efficiency of CH3NH3PbI3.

Ab initio study for the IR spectroscopy of PbTiO3 and PbZrO3, primary blocks of PbZr1‑x Ti x O3

Science.gov (United States)

Peperstraete, Yoann; Amzallag, Emilie; Tétot, Robert; Roy, Pascale

2018-05-01

PbTiO3 (PT) and PbZrO3 (PZ) are the two primary blocks of the solid solution PbZr1‑x Ti x O3 (PZT). They can be modelled in different ways; but, in order to do comparable DFT calculations on PZT, with different values of x, one must find a unique method that can be used for both PT and PZ. In particular, we want to evaluate their vibrational properties to compare them with experimental data. Density functional theory (DFT) is used to perform structure geometry optimizations and electronic structure calculations, both on low- and high-temperature phase. Then, harmonic vibrational frequencies of their low-temperature phase are determined for transverse and longitudinal optical (TO & LO) phonons. Moreover, a detailed study of the eigenvectors shows that accurate calculations are necessary to correctly interpret and understand the IR spectra. In the end, the comparison of our theoretical results with previous experimental and theoretical data confirm the strong potential of the SOGGA (second-order generalized gradient approximation) functional to correctly describe PT, PZ and, hopefully, PZT; especially their structural and vibrational properties.

A novel UV-emitting phosphor: NaSr{sub 4}(BO{sub 3}){sub 3}: Pb{sup 2+}

Energy Technology Data Exchange (ETDEWEB)

Pekgözlü, İlhan, E-mail: pekgozluilhan@yahoo.com

2016-01-15

Pb{sup 2+} doped NaSr{sub 4}(BO{sub 3}){sub 3} materials were prepared by a solution combustion synthesis method. The phase analysis of all synthesized materials was carried out using the powder XRD. The synthesized materials were investigated using spectrofluorometer at room temperature. The excitation and emission bands of NaSr{sub 4}(BO{sub 3}){sub 3}: Pb{sup 2+} were observed at 291 and 368 nm, respectively. The dependence of the emission intensity on the Pb{sup 2+} concentration for the NaSr{sub 4}(BO{sub 3}){sub 3} was studied in detail. It was observed that the concentration quenching of Pb{sup 2+} in NaSr{sub 4}(BO{sub 3}){sub 3} is 0.01 mol. The Stokes shifts of NaSr{sub 4}(BO{sub 3}){sub 3}: Pb{sup 2+} phosphor were calculated to be 7190 cm{sup −1}. - Highlights: • A novel UV-emitting phosphor, NaSr{sub 4}(BO{sub 3}){sub 3}: Pb{sup 2+}, was prepared by combustion method. • The excitation and emission bands of NaSr{sub 4}(BO{sub 3}){sub 3}: Pb{sup 2+} were observed at 291 and 368 nm, respectively. • It was observed that the concentration quenching of Pb{sup 2+} in NaSr{sub 4}(BO{sub 3}){sub 3} is 0.01 mol.

Effect of fabrication conditions on phase formation and properties of epitaxial (PbMg{sub 1/3}Nb{sub 2/3}O{sub 3}){sub 0.67}-(PbTiO{sub 3}){sub 0.33} thin films on (001) SrTiO{sub 3}

Energy Technology Data Exchange (ETDEWEB)

Boota, Muhammad [MESA+ Institute for Nanotechnology, Faculty of Science and Technology, University of Twente, P.O. Box 217, 7500AE Enschede (Netherlands); Engineering Department, University of Rome “ROMA TRE”, Via della Vasca Navale 79, 00146 Rome (Italy); Houwman, Evert P., E-mail: e.p.houwman@utwente.nl; Nguyen, Minh D.; Rijnders, Guus [MESA+ Institute for Nanotechnology, Faculty of Science and Technology, University of Twente, P.O. Box 217, 7500AE Enschede (Netherlands); Lanzara, Giulia [Engineering Department, University of Rome “ROMA TRE”, Via della Vasca Navale 79, 00146 Rome (Italy)

2016-05-15

The pulsed laser deposition process of 300 nm thick films of Pb(Mg{sub 1/3}Nb{sub 2/3})O{sub 3}){sub 0.67}-(PbTiO{sub 3}){sub 0.33} on (001)-oriented SrTiO{sub 3} was studied by varying deposition pressure, substrate deposition temperature, laser fluence on the target and target-substrate distance. Perovskite phase pure, (001)-oriented, epitaxial smooth films were obtained in a narrow range of deposition parameters. The ferroelectric and dielectric properties of films fabricated within this parameter range still vary significantly. This shows the sensitivity of the system for growth conditions. The best film has a polarization value close to that expected for a (001) poled, stress free single crystal film. All films show deposition conditions dependent variations in the self-bias field. The self-bias is very stable during long cycling for films made at optimum deposition conditions. The piezoelectric coefficients of the films are strongly reduced with respect to bulk single crystal values due to the film clamping. The properties variations are ascribed to changes in the grain boundary properties in which film defects are expected to accumulate. Notably slight off-stoichiometry may cause localized screening charges, affecting specifically the polarization and dielectric constant.

Polarized emission from CsPbX3 perovskite quantum dots

Science.gov (United States)

Wang, Dan; Wu, Dan; Dong, Di; Chen, Wei; Hao, Junjie; Qin, Jing; Xu, Bing; Wang, Kai; Sun, Xiaowei

2016-06-01

Compared to organic/inorganic hybrid perovskites, full inorganic perovskite quantum dots (QDs) exhibit higher stability. In this study, full inorganic CsPbX3 (X = Br, I and mixed halide systems Br/I) perovskite QDs have been synthesized and interestingly, these QDs showed highly polarized photoluminescence which is systematically studied for the first time. Furthermore, the polarization of CsPbI3 was as high as 0.36 in hexane and 0.40 as a film. The CsPbX3 perovskite QDs with high polarization properties indicate that they possess great potential for application in new generation displays with wide colour gamut and low power consumption.Compared to organic/inorganic hybrid perovskites, full inorganic perovskite quantum dots (QDs) exhibit higher stability. In this study, full inorganic CsPbX3 (X = Br, I and mixed halide systems Br/I) perovskite QDs have been synthesized and interestingly, these QDs showed highly polarized photoluminescence which is systematically studied for the first time. Furthermore, the polarization of CsPbI3 was as high as 0.36 in hexane and 0.40 as a film. The CsPbX3 perovskite QDs with high polarization properties indicate that they possess great potential for application in new generation displays with wide colour gamut and low power consumption. Electronic supplementary information (ESI) available. See DOI: 10.1039/c6nr01915c

Degradation mechanism of CH{sub 3}NH{sub 3}PbI{sub 3} perovskite materials upon exposure to humid air

Energy Technology Data Exchange (ETDEWEB)

Shirayama, Masaki; Kato, Masato; Fujiseki, Takemasa; Hara, Shota; Kadowaki, Hideyuki; Murata, Daisuke; Fujiwara, Hiroyuki, E-mail: fujiwara@gifu-u.ac.jp [Department of Electrical, Electronic and Computer Engineering, Gifu University, 1-1 Yanagido, Gifu 501-1193 (Japan); Miyadera, Tetsuhiko; Sugita, Takeshi; Chikamatsu, Masayuki [Research Center for Photovoltaics, National Institute of Advanced Industrial Science and Technology (AIST), Central 5, 1-1-1 Higashi, Tsukuba, Ibaraki 305-8568 (Japan)

2016-03-21

Low stability of organic-inorganic perovskite (CH{sub 3}NH{sub 3}PbI{sub 3}) solar cells in humid air environments is a serious drawback which could limit practical application of this material severely. In this study, from real-time spectroscopic ellipsometry characterization, the degradation mechanism of ultra-smooth CH{sub 3}NH{sub 3}PbI{sub 3} layers prepared by a laser evaporation technique is studied. We present evidence that the CH{sub 3}NH{sub 3}PbI{sub 3} degradation in humid air proceeds by two competing reactions of (i) the PbI{sub 2} formation by the desorption of CH{sub 3}NH{sub 3}I species and (ii) the generation of a CH{sub 3}NH{sub 3}PbI{sub 3} hydrate phase by H{sub 2}O incorporation. In particular, rapid phase change occurs in the near-surface region and the CH{sub 3}NH{sub 3}PbI{sub 3} layer thickness reduces rapidly in the initial 1 h air exposure even at a low relative humidity of 40%. After the prolonged air exposure, the CH{sub 3}NH{sub 3}PbI{sub 3} layer is converted completely to hexagonal platelet PbI{sub 2}/hydrate crystals that have a distinct atomic-scale multilayer structure with a period of 0.65 ± 0.05 nm. We find that conventional x-ray diffraction and optical characterization in the visible region, used commonly in earlier works, are quite insensitive to the surface phase change. Based on results obtained in this work, we discuss the degradation mechanism of CH{sub 3}NH{sub 3}PbI{sub 3} in humid air.

Growth of PbX2 and CsPbX3 (X = Cl, Br) mesoscopic phases in alkali halide host lattices

Science.gov (United States)

Polak, K.; Nitsch, K.; Nikl, M.

Formation of PbCl2 and CsPbBr3 microphases in NaCl and CsBr respectively is studied using mainly an absorption spectroscopy. The absorption of NaCl: Pb crystal was investigated as a function of annealing temperature and duration of thermal treatment. Changes in the position and shape of the exciton band were studied in CsBr: Pb absorption spectrum. The results showed that the shape of CsPbBr3 microcrystals is far from a spherical one. The microcrystals probably grow as highly elongated discs.

Enhanced photovoltaic performance of CH3NH3PbBrXI3-X-based perovskite solar cells via anti-solvent extraction

Science.gov (United States)

Jiang, Zhaoyi; Zhang, Weijia; Lu, Chaoqun; Ma, Denghao; Liu, Haixu; Yu, Wei; Zhang, Yu; Ma, Qiang; Zhang, Yulong

2018-06-01

In this paper, the two-step sequential deposition method was used to prepare the CH3NH3PbBrXI3-X films by introducing CH3NH3Br in the precursors. The surface morphology of the PbI2 films was controlled by anti-solvent extraction (ASE) to improve the microstructure and photo-physical properties of the perovskite films. It was noteworthy that, compared to the compact PbI2 films, the porous PbI2 films facilitated the growth of crystals and bromine incorporation in films, and the prepared perovskite films exhibited enlarged grain size, increased light absorption, enhanced Br incorporation and prolonged carrier lifetime, which resulted in excellent photo-electrical properties of the CH3NH3PbBrXI3-X films. With porous PbI2 templates, the inverted planar perovskite solar cells based on films with appropriate Br incorporation (CH3NH3Br/CH3NH3I mole ratio = 3/7) showed a photovoltaic conversion efficiency (PCE) of 14.9%, and the stability of the devices in air was elevated. Consequently, the high-quality CH3NH3PbBrXI3-X films can be obtained with porous PbI2 templates for improving the performance of the perovskite solar cells.

Micro-Raman study of the microheterogeneity in the MA-MC phase transition in 0.67PbMg1/3Nb2/3O3-0.33PbTiO3 single crystal

KAUST Repository

Yang, Y.; Zhang, L. Y.; Zhu, K.; Liu, Y. L.

2011-01-01

Polarized Raman spectroscopy has been employed to investigate the evolution of the microstructure of 0.67PbMg1/3Nb2/3O3-0.33PbTiO3 (PMN-33%PT) single crystal in the temperature range from −195 to 300 °C. The M A-M C-cubic transition sequence

Ultrasonic irradiation-promoted one-pot synthesis of CH3NH3PbBr3 quantum dots without using flammable CH3NH2 precursor

Science.gov (United States)

Jiang, Han; Wang, Chunlei; Lv, Changgui; Xu, Shuhong; Zhu, Li; Zhang, Ruohu; Cui, Yiping

2017-02-01

At present, the CH3NH3PbBr3 quantum dots (QDs) reported in the literature usually contain two synthesis steps: the initial preparation of CH3NH3Br via the reaction of flammable CH3NH2 and HBr, together with the subsequent formation of CH3NH3PbBr3 QDs. To avoid the use of dangerous CH3NH2, this work develops a novel one-pot method for synthesizing CH3NH3PbBr3 QDs using safe and commercially available reactants (CH3NH3Cl, KBr and PbCl2). It is found that ultrasonic treatment plays a key role during the synthesis of CH3NH3PbBr3 QDs. Without ultrasonic irradiation, it is not possible to synthesize CH3NH3PbBr3 QDs under heating or vigorous stirring. Aliquots of samples taken at different ultrasonic irradiation time intervals show a time-dependent redshift in the emission wavelength. This suggests the formation of CH3NH3PbCl3 QDs first, followed by the formation of CH3NH3PbBr3 QDs through ultrasonically promoted halide exchange. Moreover, mixed CH3NH3PbCl x Br3-x QDs with a tunable emission wavelength can also be prepared through this one-pot method by controlling the ultrasonic irradiation time. In comparison to the previous two-step method, the current one-pot method is simpler, less time-consuming and does not use flammable CH3NH2. The as-prepared CH3NH3PbBr3 QDs show a comparable photoluminescence (PL) quantum yield (QY) to that of the literature. What is more, the ultrasonic time-controlled emission wavelength of CH3NH3PbCl x Br3-x QDs also provides an alternative way of tuning QD emission to the traditional way of controlling the halide ratios.

Enhanced dielectric nonlinearity in epitaxial Pb0.92La0.08Zr0.52Ti0.48O3 thin films

International Nuclear Information System (INIS)

Ma, Chunrui; Wu, Judy; Ma, Beihai; Mi, Shao-Bo; Liu, Ming

2014-01-01

High quality c-axis oriented epitaxial Pb 0.92 La 0.08 Zr 0.52 Ti 0.48 O 3 films were fabricated using pulsed laser deposition on (001) LaAlO 3 substrates with conductive LaNiO 3 buffers. Besides confirmation of the in-plane and out-of-plane orientations using X-ray diffraction, transmission electron microscopy study has revealed columnar structure across the film thickness with column width around 100 nm. Characterization of ferroelectric properties was carried out in comparison with polycrystalline Pb 0.92 La 0.08 Zr 0.52 Ti 0.48 O 3 films to extract the effect of epitaxial growth. It is found that the ratio between the irreversible Rayleigh parameter and reversible parameter increased up to 0.028 cm/kV at 1 kHz on epitaxial samples, which is more than twice of that on their polycrystalline counterparts. While this ratio decreased to 0.022 cm/kV with increasing frequency to100 kHz, a much less frequency dependence was observed as compared to the polycrystalline case. The epitaxial Pb 0.92 La 0.08 Zr 0.52 Ti 0.48 O 3 films exhibited a higher mobility of domain wall and the higher extrinsic contribution to the dielectric properties, as well as reduced density of defects, indicating that it is promising for tunable and low power consumption devices

Structural study on cubic-tetragonal transition of CH3NH3PbI3

International Nuclear Information System (INIS)

Kawamura, Yukihiko; Mashiyama, Hiroyuki; Hasebe, Katsuhiko

2002-01-01

The cubic-tetragonal phase transition of CH 3 NH 3 PbI 3 was investigated by single crystal X-ray diffractometry. The crystal structure was refined at five temperatures in the tetragonal phase. The PbI 6 octahedron rotates around the c-axis alternatively to construct the SrTiO 3 -type tetragonal structure. A methylammonium ion is partially ordered; 24 disordered states in the cubic phase are reduced to 8. With decreasing temperature, the rotation angle of the octahedron increases monotonically, which indicates it is an order parameter of the cubic-tetragonal transition. (author)

Optical characterization and bandgap engineering of flat and wrinkle-textured FA0.83Cs0.17Pb(I1-xBrx)3 perovskite thin films

Science.gov (United States)

Tejada, A.; Braunger, S.; Korte, L.; Albrecht, S.; Rech, B.; Guerra, J. A.

2018-05-01

The complex refractive indices of formamidinium cesium lead mixed-halide [FA0.83Cs0.17Pb(I1- xBrx)3] perovskite thin films of compositions ranging from x = 0 to 0.4, with both flat and wrinkle-textured surface topographies, are reported. The films are characterized using a combination of variable angle spectroscopic ellipsometry and spectral transmittance in the wavelength range of 190 nm to 850 nm. Optical constants, film thicknesses and roughness layers are obtained point-by-point by minimizing a global error function, without using optical dispersion models, and including topographical information supplied by a laser confocal microscope. To evaluate the bandgap engineering potential of the material, the optical bandgaps and Urbach energies are then accurately determined by applying a band fluctuation model for direct semiconductors, which considers both the Urbach tail and the fundamental band-to-band absorption region in a single equation. With this information, the composition yielding the optimum bandgap of 1.75 eV for a Si-perovskite tandem solar cell is determined.

PbCl2-tuned inorganic cubic CsPbBr3(Cl) perovskite solar cells with enhanced electron lifetime, diffusion length and photovoltaic performance

Science.gov (United States)

Li, Bo; Zhang, Yanan; Zhang, Luyuan; Yin, Longwei

2017-08-01

Inorganic CsPbBr3 perovskite is arousing great interest following after organic-inorganic hybrid halide perovskites, and is found as a good candidate for photovoltaic devices for its prominent photoelectric property and stability. Herein, we for the first time report on PbCl2-tuned inorganic Cl-doped CsPbBr3(Cl) perovskite solar cells with adjustable crystal structure and Cl doping for enhanced carrier lifetime, extraction rate and photovoltaic performance. The effect of PbCl2 on the morphologies, structures, optical, and photovoltaic performance of CsPbBr3 perovskite solar cells is investigated systemically. Compared with orthorhombic CsPbBr3, cubic CsPbBr3 demonstrates a significant improvement for electron lifetime (from 6.7 ns to 12.3 ns) and diffusion length (from 69 nm to 197 nm), as well as the enhanced electron extraction rate from CsPbBr3 to TiO2. More importantly, Cl doping benefits the further enhancement of carrier lifetime (14.3 ns) and diffusion length (208 nm). The Cl doped cubic CsPbBr3(Cl) perovskite solar cell exhibits a Jsc of 8.47 mA cm-2 and a PCE of 6.21%, superior to that of pure orthorhombic CsPbBr3 (6.22 mA cm-2 and 3.78%). The improvement of photovoltaic performance can be attributed to enhanced carrier lifetime, diffusion length and extraction rates, as well as suppressed nonradiative recombination.

Current and potential distributions on positive plates with conductive Pb{sub 3}O{sub 4} and BaPbO{sub 3} in their formation and discharge

Energy Technology Data Exchange (ETDEWEB)

Guo, Yonglang; Liu, Huan [College of Chemistry and Chemical Engineering, Fuzhou University, Fuzhou 350108 (China)

2008-08-15

The positive plates with conductive materials, Pb{sub 3}O{sub 4} and BaPbO{sub 3}, in automotive lead-acid batteries were investigated by measuring their current and potential distributions in the course of formation and discharge. It is found that these two conductive materials, especially Pb{sub 3}O{sub 4}, enhance the formation in the initial stage greatly and that they make the current and potential distributions more uniform. In the discharge, the addition of Pb{sub 3}O{sub 4} increases the capacity of the positive plate, but it is unfavorable to the paste curing and causes poor contact between active mass (AM) particles so that the polarization increases greatly at 3 C discharge rate. The BaPbO{sub 3} additive improves not only the formation but also the discharge performance because of its stability in acidic media and at high polarization. The violent charge at high polarization around the plates in the initial formation can lead to poor AM contact and high polarization resistance. (author)