WorldWideScience

Sample records for organic semiconductor system

  1. New organic semiconductors with imide/amide-containing molecular systems.

    Science.gov (United States)

    Liu, Zitong; Zhang, Guanxin; Cai, Zhengxu; Chen, Xin; Luo, Hewei; Li, Yonghai; Wang, Jianguo; Zhang, Deqing

    2014-10-29

    Due to their high electron affinities, chemical and thermal stabilities, π-conjugated molecules with imide/amide frameworks have received considerable attentions as promising candidates for high-performance optoelectronic materials, particularly for organic semiconductors with high carrier mobilities. The purpose of this Research News is to give an overview of recent advances in development of high performance imide/amide based organic semiconductors for field-effect transistors. It covers naphthalene diimide-, perylene diimide- and amide-based conjugated molecules and polymers for organic semiconductors. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  2. Organic semiconductor crystals.

    Science.gov (United States)

    Wang, Chengliang; Dong, Huanli; Jiang, Lang; Hu, Wenping

    2018-01-22

    Organic semiconductors have attracted a lot of attention since the discovery of highly doped conductive polymers, due to the potential application in field-effect transistors (OFETs), light-emitting diodes (OLEDs) and photovoltaic cells (OPVs). Single crystals of organic semiconductors are particularly intriguing because they are free of grain boundaries and have long-range periodic order as well as minimal traps and defects. Hence, organic semiconductor crystals provide a powerful tool for revealing the intrinsic properties, examining the structure-property relationships, demonstrating the important factors for high performance devices and uncovering fundamental physics in organic semiconductors. This review provides a comprehensive overview of the molecular packing, morphology and charge transport features of organic semiconductor crystals, the control of crystallization for achieving high quality crystals and the device physics in the three main applications. We hope that this comprehensive summary can give a clear picture of the state-of-art status and guide future work in this area.

  3. Organic semiconductors in sensor applications

    CERN Document Server

    Malliaras, George; Owens, Róisín

    2008-01-01

    Organic semiconductors offer unique characteristics such as tunability of electronic properties via chemical synthesis, compatibility with mechanically flexible substrates, low-cost manufacturing, and facile integration with chemical and biological functionalities. These characteristics have prompted the application of organic semiconductors and their devices in physical, chemical, and biological sensors. This book covers this rapidly emerging field by discussing both optical and electrical sensor concepts. Novel transducers based on organic light-emitting diodes and organic thin-film transistors, as well as systems-on-a-chip architectures are presented. Functionalization techniques to enhance specificity are outlined, and models for the sensor response are described.

  4. Organic Semiconductor Photovoltaics

    Science.gov (United States)

    Sariciftci, Niyazi Serdar

    2005-03-01

    Recent developments on organic photovoltaic elements are reviewed. Semiconducting conjugated polymers and molecules as well as nanocrystalline inorganic semiconductors are used in composite thin films. The photophysics of such photoactive devices is based on the photoinduced charge transfer from donor type semiconducting molecules onto acceptor type molecules such as Buckminsterfullerene, C60 and/or nanoparticles. Similar to the first steps in natural photosynthesis, this photoinduced electron transfer leads to a number of potentially interesting applications which include sensitization of the photoconductivity and photovoltaic phenomena. Examples of photovoltaic architectures are discussed with their potential in terrestrial solar energy conversion. Several materials are introduced and discussed for their photovoltaic activities. Furthermore, nanomorphology has been investigated with AFM, SEM and TEM. The morphology/property relationship for a given photoactive system is found to be a major effect.

  5. Doping of organic semiconductors

    Energy Technology Data Exchange (ETDEWEB)

    Luessem, B.; Riede, M.; Leo, K. [Institut fuer Angewandte Photophysik, TU Dresden (Germany)

    2013-01-15

    The understanding and applications of organic semiconductors have shown remarkable progress in recent years. This material class has been developed from being a lab curiosity to the basis of first successful products as small organic LED (OLED) displays; other areas of application such as OLED lighting and organic photovoltaics are on the verge of broad commercialization. Organic semiconductors are superior to inorganic ones for low-cost and large-area optoelectronics due to their flexibility, easy deposition, and broad variety, making tailor-made materials possible. However, electrical doping of organic semiconductors, i.e. the controlled adjustment of Fermi level that has been extremely important to the success of inorganic semiconductors, is still in its infancy. This review will discuss recent work on both fundamental principles and applications of doping, focused primarily to doping of evaporated organic layers with molecular dopants. Recently, both p- and n-type molecular dopants have been developed that lead to efficient and stable doping of organic thin films. Due to doping, the conductivity of the doped layers increases several orders of magnitude and allows for quasi-Ohmic contacts between organic layers and metal electrodes. Besides reducing voltage losses, doping thus also gives design freedom in terms of transport layer thickness and electrode choice. The use of doping in applications like OLEDs and organic solar cells is highlighted in this review. Overall, controlled molecular doping can be considered as key enabling technology for many different organic device types that can lead to significant improvements in efficiencies and lifetimes. (Copyright copyright 2013 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

  6. Doping of organic semiconductors

    International Nuclear Information System (INIS)

    Luessem, B.; Riede, M.; Leo, K.

    2013-01-01

    The understanding and applications of organic semiconductors have shown remarkable progress in recent years. This material class has been developed from being a lab curiosity to the basis of first successful products as small organic LED (OLED) displays; other areas of application such as OLED lighting and organic photovoltaics are on the verge of broad commercialization. Organic semiconductors are superior to inorganic ones for low-cost and large-area optoelectronics due to their flexibility, easy deposition, and broad variety, making tailor-made materials possible. However, electrical doping of organic semiconductors, i.e. the controlled adjustment of Fermi level that has been extremely important to the success of inorganic semiconductors, is still in its infancy. This review will discuss recent work on both fundamental principles and applications of doping, focused primarily to doping of evaporated organic layers with molecular dopants. Recently, both p- and n-type molecular dopants have been developed that lead to efficient and stable doping of organic thin films. Due to doping, the conductivity of the doped layers increases several orders of magnitude and allows for quasi-Ohmic contacts between organic layers and metal electrodes. Besides reducing voltage losses, doping thus also gives design freedom in terms of transport layer thickness and electrode choice. The use of doping in applications like OLEDs and organic solar cells is highlighted in this review. Overall, controlled molecular doping can be considered as key enabling technology for many different organic device types that can lead to significant improvements in efficiencies and lifetimes. (Copyright copyright 2013 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

  7. Purcell effect in an organic-inorganic halide perovskite semiconductor microcavity system

    International Nuclear Information System (INIS)

    Wang, Jun; Wang, Yafeng; Hu, Tao; Wu, Lin; Shen, Xuechu; Chen, Zhanghai; Cao, Runan; Xu, Fei; Da, Peimei; Zheng, Gengfeng; Lu, Jian

    2016-01-01

    Organic-inorganic halide perovskite semiconductors with the attractive physics properties, including strong photoluminescence (PL), huge oscillator strengths, and low nonradiative recombination losses, are ideal candidates for studying the light-matter interaction in nanostructures. Here, we demonstrate the coupling of the exciton state and the cavity mode in the lead halide perovskite microcavity system at room temperature. The Purcell effect in the coupling system is clearly observed by using angle-resolved photoluminescence spectra. Kinetic analysis based on time-resolved PL reveals that the spontaneous emission rate of the halide perovskite semiconductor is significantly enhanced at resonance of the exciton energy and the cavity mode. Our results provide the way for developing electrically driven organic polariton lasers, optical devices, and on-chip coherent quantum light sources

  8. Effect of different conductivity between the spin polarons on spin injection in a ferromagnet/organic semiconductor system

    International Nuclear Information System (INIS)

    Mi Yilin; Zhang Ming; Yan Hui

    2008-01-01

    Spin injection across ferromagnet/organic semiconductor system with finite width of the layers was studied theoretically considering spin-dependent conductivity in the organic-semiconductor. It was found that the spin injection efficiency is directly dependent on the difference between the conductivity of the up-spin and down-spin polarons in the spin-injected organic system. Furthermore, the finite width of the structure, interfacial electrochemical-potential and conductivity mismatch have great influence on the spin injection process across ferromagnet/organic semiconductor interface

  9. Organic semiconductors in a spin

    CERN Document Server

    Samuel, I

    2002-01-01

    A little palladium can go a long way in polymer-based light-emitting diodes. Inorganic semiconductors such as silicon and gallium arsenide are essential for countless applications in everyday life, ranging from PCs to CD players. However, while they offer unrivalled computational speed, inorganic semiconductors are also rigid and brittle, which means that they are less suited to applications such as displays and flexible electronics. A completely different class of materials - organic semiconductors - are being developed for these applications. Organic semiconductors have many attractive features: they are easy to make, they can emit visible light, and there is tremendous scope for tailoring their properties to specific applications by changing their chemical structure. Research groups and companies around the world have developed a wide range of organic-semiconductor devices, including transistors, light-emitting diodes (LEDs), solar cells and lasers. (U.K.)

  10. Thiophene-Based Organic Semiconductors.

    Science.gov (United States)

    Turkoglu, Gulsen; Cinar, M Emin; Ozturk, Turan

    2017-10-24

    Thiophene-based π-conjugated organic small molecules and polymers are the research subject of significant current interest owing to their potential use as organic semiconductors in material chemistry. Despite simple and similar molecular structures, the hitherto reported properties of thiophene-based organic semiconductors are rather diverse. Design of high performance organic semiconducting materials requires a thorough understanding of inter- and intra-molecular interactions, solid-state packing, and the influence of both factors on the charge carrier transport. In this chapter, thiophene-based organic semiconductors, which are classified in terms of their chemical structures and their structure-property relationships, are addressed for the potential applications as organic photovoltaics (OPVs), organic field-effect transistors (OFETs) and organic light emitting diodes (OLEDs).

  11. High mobility emissive organic semiconductor

    Science.gov (United States)

    Liu, Jie; Zhang, Hantang; Dong, Huanli; Meng, Lingqiang; Jiang, Longfeng; Jiang, Lang; Wang, Ying; Yu, Junsheng; Sun, Yanming; Hu, Wenping; Heeger, Alan J.

    2015-01-01

    The integration of high charge carrier mobility and high luminescence in an organic semiconductor is challenging. However, there is need of such materials for organic light-emitting transistors and organic electrically pumped lasers. Here we show a novel organic semiconductor, 2,6-diphenylanthracene (DPA), which exhibits not only high emission with single crystal absolute florescence quantum yield of 41.2% but also high charge carrier mobility with single crystal mobility of 34 cm2 V−1 s−1. Organic light-emitting diodes (OLEDs) based on DPA give pure blue emission with brightness up to 6,627 cd m−2 and turn-on voltage of 2.8 V. 2,6-Diphenylanthracene OLED arrays are successfully driven by DPA field-effect transistor arrays, demonstrating that DPA is a high mobility emissive organic semiconductor with potential in organic optoelectronics. PMID:26620323

  12. Semiconductor radiation detection systems

    CERN Document Server

    2010-01-01

    Covers research in semiconductor detector and integrated circuit design in the context of medical imaging using ionizing radiation. This book explores other applications of semiconductor radiation detection systems in security applications such as luggage scanning, dirty bomb detection and border control.

  13. Controlling Molecular Doping in Organic Semiconductors.

    Science.gov (United States)

    Jacobs, Ian E; Moulé, Adam J

    2017-11-01

    The field of organic electronics thrives on the hope of enabling low-cost, solution-processed electronic devices with mechanical, optoelectronic, and chemical properties not available from inorganic semiconductors. A key to the success of these aspirations is the ability to controllably dope organic semiconductors with high spatial resolution. Here, recent progress in molecular doping of organic semiconductors is summarized, with an emphasis on solution-processed p-type doped polymeric semiconductors. Highlighted topics include how solution-processing techniques can control the distribution, diffusion, and density of dopants within the organic semiconductor, and, in turn, affect the electronic properties of the material. Research in these areas has recently intensified, thanks to advances in chemical synthesis, improved understanding of charged states in organic materials, and a focus on relating fabrication techniques to morphology. Significant disorder in these systems, along with complex interactions between doping and film morphology, is often responsible for charge trapping and low doping efficiency. However, the strong coupling between doping, solubility, and morphology can be harnessed to control crystallinity, create doping gradients, and pattern polymers. These breakthroughs suggest a role for molecular doping not only in device function but also in fabrication-applications beyond those directly analogous to inorganic doping. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  14. Self Organization in Compensated Semiconductors

    Science.gov (United States)

    Berezin, Alexander A.

    2004-03-01

    In partially compensated semiconductor (PCS) Fermi level is pinned to donor sub-band. Due to positional randomness and almost isoenergetic hoppings, donor-spanned electronic subsystem in PCS forms fluid-like highly mobile collective state. This makes PCS playground for pattern formation, self-organization, complexity emergence, electronic neural networks, and perhaps even for origins of life, bioevolution and consciousness. Through effects of impact and/or Auger ionization of donor sites, whole PCS may collapse (spinodal decomposition) into microblocks potentially capable of replication and protobiological activity (DNA analogue). Electronic screening effects may act in RNA fashion by introducing additional length scale(s) to system. Spontaneous quantum computing on charged/neutral sites becomes potential generator of informationally loaded microstructures akin to "Carl Sagan Effect" (hidden messages in Pi in his "Contact") or informational self-organization of "Library of Babel" of J.L. Borges. Even general relativity effects at Planck scale (R.Penrose) may affect the dynamics through (e.g.) isotopic variations of atomic mass and local density (A.A.Berezin, 1992). Thus, PCS can serve as toy model (experimental and computational) at interface of physics and life sciences.

  15. Photocatalytic oxidation of organic compounds in a hybrid system composed of a molecular catalyst and visible light-absorbing semiconductor.

    Science.gov (United States)

    Zhou, Xu; Li, Fei; Li, Xiaona; Li, Hua; Wang, Yong; Sun, Licheng

    2015-01-14

    Photocatalytic oxidation of organic compounds proceeded efficiently in a hybrid system with ruthenium aqua complexes as catalysts, BiVO4 as a light absorber, [Co(NH3)5Cl](2+) as a sacrificial electron acceptor and water as an oxygen source. The photogenerated holes in the semiconductor are used to oxidize molecular catalysts into the high-valent Ru(IV)=O intermediates for 2e(-) oxidation.

  16. Thienoacene-based organic semiconductors.

    Science.gov (United States)

    Takimiya, Kazuo; Shinamura, Shoji; Osaka, Itaru; Miyazaki, Eigo

    2011-10-11

    Thienoacenes consist of fused thiophene rings in a ladder-type molecular structure and have been intensively studied as potential organic semiconductors for organic field-effect transistors (OFETs) in the last decade. They are reviewed here. Despite their simple and similar molecular structures, the hitherto reported properties of thienoacene-based OFETs are rather diverse. This Review focuses on four classes of thienoacenes, which are classified in terms of their chemical structures, and elucidates the molecular electronic structure of each class. The packing structures of thienoacenes and the thus-estimated solid-state electronic structures are correlated to their carrier transport properties in OFET devices. With this perspective of the molecular structures of thienoacenes and their carrier transport properties in OFET devices, the structure-property relationships in thienoacene-based organic semiconductors are discussed. The discussion provides insight into new molecular design strategies for the development of superior organic semiconductors. Copyright © 2011 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  17. Charge transport in organic semiconductors.

    Science.gov (United States)

    Bässler, Heinz; Köhler, Anna

    2012-01-01

    Modern optoelectronic devices, such as light-emitting diodes, field-effect transistors and organic solar cells require well controlled motion of charges for their efficient operation. The understanding of the processes that determine charge transport is therefore of paramount importance for designing materials with improved structure-property relationships. Before discussing different regimes of charge transport in organic semiconductors, we present a brief introduction into the conceptual framework in which we interpret the relevant photophysical processes. That is, we compare a molecular picture of electronic excitations against the Su-Schrieffer-Heeger semiconductor band model. After a brief description of experimental techniques needed to measure charge mobilities, we then elaborate on the parameters controlling charge transport in technologically relevant materials. Thus, we consider the influences of electronic coupling between molecular units, disorder, polaronic effects and space charge. A particular focus is given to the recent progress made in understanding charge transport on short time scales and short length scales. The mechanism for charge injection is briefly addressed towards the end of this chapter.

  18. Organic semiconductor wastewater treatment using a four-stage Bardenpho with membrane system.

    Science.gov (United States)

    Chung, Jinwook; Fleege, Daniel; Ong, Say Kee; Lee, Yong-Woo

    2014-01-01

    Electronic wastewater from a semiconductor plant was treated with a pilot-scale four-stage Bardenpho process with membrane system. The system was operated over a 14-month period with an overall hydraulic retention time (HRT) ranging from 9.5 to 30 h. With a few exceptions, the pilot plant consistently treated the electronic wastewater with an average removal efficiency of chemical oxygen demand (COD) and total nitrogen of 97% and 93%, respectively, and achieving effluent quality of COD<15 mg/L, turbidity<1, and silt density index<1. Based on removal efficiencies of the pilot plant, it is possible to lower the HRT to less than 9.5 h to achieve comparable removal efficiencies. An energy-saving configuration where an internal recycle line was omitted and the biomass recycle was rerouted to the pre-anoxic tank, can reduce energy consumption by 8.6% and gave removal efficiencies that were similar to the Bardenpho process. The system achieved pre-anoxic and post-anoxic specific denitrification rate values with a 95% confidence interval of 0.091 ± 0.011 g NO₃-N/g MLVSS d and 0.087 ± 0.016 g NO₃-N/g MLVSS d, respectively. The effluent from the four-stage Bardenpho with membrane system can be paired with a reverse osmosis system to provide further treatment for reuse purposes.

  19. Nanopatterned organic semiconductors for visible light communications

    Science.gov (United States)

    Yang, Xilu; Dong, Yurong; Zeng, Pan; Yu, Yan; Xie, Yujun; Gong, Junyi; Shi, Meng; Liang, Rongqing; Ou, Qiongrong; Chi, Nan; Zhang, Shuyu

    2018-03-01

    Visible light communication (VLC) is becoming an important and promising supplement to the existing Wi-Fi network for the coming 5G communications. Organic light-emitting semiconductors present much fast fluorescent decay rates compared to those of conventional colour-converting phosphors, therefore capable of achieving much higher bandwidths. Here we explore how nanopatterned organic semiconductors can further enhance the data rates of VLC links by improving bandwidths and signal-to-noise ratios (SNRs) and by supporting spatial multiplexing. We first demonstrate a colour-converting VLC system based on nanopatterned hyperbolic metamaterials (HMM), the bandwidth of which is enhanced by 50%. With regard to enhancing SNRs, we achieve a tripling of optical gain by integrating a nanopatterned luminescent concentrator to a signal receiver. In addition, we demonstrate highly directional fluorescent VLC antennas based on nanoimprinted polymer films, paving the way to achieving parallel VLC communications via spatialmultiplexing. These results indicate nanopatterned organic semiconductors provide a promising route to high speed VLC links.

  20. Organic Donor-Acceptor Complexes as Novel Organic Semiconductors.

    Science.gov (United States)

    Zhang, Jing; Xu, Wei; Sheng, Peng; Zhao, Guangyao; Zhu, Daoben

    2017-07-18

    Organic donor-acceptor (DA) complexes have attracted wide attention in recent decades, resulting in the rapid development of organic binary system electronics. The design and synthesis of organic DA complexes with a variety of component structures have mainly focused on metallicity (or even superconductivity), emission, or ferroelectricity studies. Further efforts have been made in high-performance electronic investigations. The chemical versatility of organic semiconductors provides DA complexes with a great number of possibilities for semiconducting applications. Organic DA complexes extend the semiconductor family and promote charge separation and transport in organic field-effect transistors (OFETs) and organic photovoltaics (OPVs). In OFETs, the organic complex serves as an active layer across extraordinary charge pathways, ensuring the efficient transport of induced charges. Although an increasing number of organic semiconductors have been reported to exhibit good p- or n-type properties (mobilities higher than 1 or even 10 cm 2 V -1 s -1 ), critical scientific challenges remain in utilizing the advantages of existing semiconductor materials for more and wider applications while maintaining less complicated synthetic or device fabrication processes. DA complex materials have revealed new insight: their unique molecular packing and structure-property relationships. The combination of donors and acceptors could offer practical advantages compared with their unimolecular materials. First, growing crystals of DA complexes with densely packed structures will reduce impurities and traps from the self-assembly process. Second, complexes based on the original structural components could form superior mixture stacking, which can facilitate charge transport depending on the driving force in the coassembly process. Third, the effective use of organic semiconductors can lead to tunable band structures, allowing the operation mode (p- or n-type) of the transistor to be

  1. Organic-inorganic semiconductor hybrid systems. Structure, morphology, and electronic properties

    Energy Technology Data Exchange (ETDEWEB)

    El Helou, Mira

    2012-08-22

    This dissertation addresses the preparation and characterization of hybrid semiconducting systems combining organic with inorganic materials. Characterization methods used included to determine the structure, morphology, and thermal stability comprised X-ray diffraction (XRD), atomic force microscopy (AFM), thermal desorption spectroscopy (TDS), and X-ray photoelectron spectroscopy (XPS). One organic-inorganic semiconducting system was pentacene (C{sub 22}H{sub 14}) and zinc oxide. This interface was investigated in detail for pentacene on an oxygen-terminated zinc oxide surface, i.e. ZnO(000 anti 1). An extended study on the promising p-n junction was carried out for pentacene on ZnO with different orientations which exhibit different chemical and structural characteristics: ZnO(000 anti 1), ZnO(0001), and ZnO(10 anti 10). Moreover, the organic crystal structure of pentacene was selectively tuned by carefully choosing the substrate temperature. This defined interface with a physisorbed pentacene layer on ZnO was characterized by optical absorption which depends on the temperature of the measured system, the pentacene film thickness, and the molecular orientation and packing. The high quality of the pentacene films allowed in one case to characterize the Davydov splitting by linear polarized light focused on a single crystallite. Another subject in the field of organic-inorganic hybrid materials comprised conjugated dithiols used as self-assembled monolayers (SAMs) for immobilizing semiconducting CdS nanoparticles (NPs) on Au substrates. It was demonstrated that an appropriate selection and preparation of the conjugated SAMs is crucial for building up a light-addressable potentiometric sensor with a sufficient efficiency. An optimized electron transfer was achieved with SAMs of long range ordering, high stability, and adequate conductivity. This was examined for different linkers and was best for stilbenedithiol immobilized in solution at higher temperatures. Due

  2. Blue emitting organic semiconductors under high pressure

    DEFF Research Database (Denmark)

    Knaapila, Matti; Guha, Suchismita

    2016-01-01

    This review describes essential optical and emerging structural experiments that use high GPa range hydrostatic pressure to probe physical phenomena in blue-emitting organic semiconductors including π-conjugated polyfluorene and related compounds. The work emphasizes molecular structure and inter......This review describes essential optical and emerging structural experiments that use high GPa range hydrostatic pressure to probe physical phenomena in blue-emitting organic semiconductors including π-conjugated polyfluorene and related compounds. The work emphasizes molecular structure...... and intermolecular self-organization that typically determine transport and optical emission in π-conjugated oligomers and polymers. In this context, hydrostatic pressure through diamond anvil cells has proven to be an elegant tool to control structure and interactions without chemical intervention. This has been...... and intermolecular interactions on optical excitations, electron–phonon interaction, and changes in backbone conformations. This picture is connected to the optical high pressure studies of other π-conjugated systems and emerging x-ray scattering experiments from polyfluorenes which provides a structure-property map...

  3. Triplet exciton diffusion in organic semiconductors

    Energy Technology Data Exchange (ETDEWEB)

    Koehler, Anna [Department of Physics, University of Bayreuth (Germany)

    2010-07-01

    Efficient triplet exciton emission has allowed improved operation of organic light-emitting diodes (LEDs). To enhance the device performance, it is necessary to understand what governs the motion of triplet excitons through the organic semiconductor. We use a series of poly(p-phenylene)-type conjugated polymers and oligomers of variable degree of molecular distortion (i.e. polaron formation) and energetic disorder as model systems to study the Dexter-type triplet exciton diffusion in thin films. We show that triplet diffusion can be quantitatively described in the framework of a Holstein small polaron model (Marcus theory) that is extended to include contributions from energetic disorder. The model predicts a tunnelling process at low temperatures followed by a thermally activated hopping process above a transition temperature. In contrast to charge transfer, the activation energy required for triplet exciton transfer can be deduced from the optical spectra. We discuss the implications for device architecture.

  4. Optical, Electrical and Magnetic Studies of Pi-Conjugated Organic Semiconductor Systems

    Energy Technology Data Exchange (ETDEWEB)

    Vardeny, Zeev Valentine [Univ. of Utah, Salt Lake City, UT (United States)

    2016-09-15

    Over the duration of this grant our group has studied the transient and cw optical response of various π-conjugated polymers, oligomers, single crystals, fullerene molecules and blends of organic donor-acceptor molecules. We have been also involved in complementary experiments such as magneto-optical studies and spin-physics. We have advanced the field of photophysics of these materials by providing information on their excited state energies and primodal and long-lived photoexcitations such as singlet excitons, triplet excitons, polaron-pairs, excimers and exciplexes. We also fabricated various organic optoelectronic devices such as organic light emitting diodes (OLED), electrochemical cells, organic diodes, organic spin-valves (OSV), and organic photovoltaic (OPV) solar cells. These devices benefited the society in terms of cheap and energy saving illumination, as well as harnessing the solar energy.

  5. Architectures for Improved Organic Semiconductor Devices

    Science.gov (United States)

    Beck, Jonathan H.

    Advancements in the microelectronics industry have brought increasing performance and decreasing prices to a wide range of users. Conventional silicon-based electronics have followed Moore's law to provide an ever-increasing integrated circuit transistor density, which drives processing power, solid-state memory density, and sensor technologies. As shrinking conventional integrated circuits became more challenging, researchers began exploring electronics with the potential to penetrate new applications with a low price of entry: "Electronics everywhere." The new generation of electronics is thin, light, flexible, and inexpensive. Organic electronics are part of the new generation of thin-film electronics, relying on the synthetic flexibility of carbon molecules to create organic semiconductors, absorbers, and emitters which perform useful tasks. Organic electronics can be fabricated with low energy input on a variety of novel substrates, including inexpensive plastic sheets. The potential ease of synthesis and fabrication of organic-based devices means that organic electronics can be made at very low cost. Successfully demonstrated organic semiconductor devices include photovoltaics, photodetectors, transistors, and light emitting diodes. Several challenges that face organic semiconductor devices are low performance relative to conventional devices, long-term device stability, and development of new organic-compatible processes and materials. While the absorption and emission performance of organic materials in photovoltaics and light emitting diodes is extraordinarily high for thin films, the charge conduction mobilities are generally low. Building highly efficient devices with low-mobility materials is one challenge. Many organic semiconductor films are unstable during fabrication, storage, and operation due to reactions with water, oxygen and hydroxide. A final challenge facing organic electronics is the need for new processes and materials for electrodes

  6. The WSPC Reference on Organic Electronics: Organic Semiconductors

    KAUST Repository

    Bredas, Jean-Luc; Marder, Seth R

    2015-01-01

    In this chapter, we provide a basic theoretical perspective on charge-carrier transport in organic semiconductors, with a focus on organic molecular crystals. We introduce the microscopic parameters relevant to the intrinsic charge

  7. Organic semiconductors for organic field-effect transistors

    International Nuclear Information System (INIS)

    Yamashita, Yoshiro

    2009-01-01

    The advantages of organic field-effect transistors (OFETs), such as low cost, flexibility and large-area fabrication, have recently attracted much attention due to their electronic applications. Practical transistors require high mobility, large on/off ratio, low threshold voltage and high stability. Development of new organic semiconductors is key to achieving these parameters. Recently, organic semiconductors have been synthesized showing comparable mobilities to amorphous-silicon-based FETs. These materials make OFETs more attractive and their applications have been attempted. New organic semiconductors resulting in high-performance FET devices are described here and the relationship between transistor characteristics and chemical structure is discussed. (topical review)

  8. Organic semiconductors for organic field-effect transistors

    Directory of Open Access Journals (Sweden)

    Yoshiro Yamashita

    2009-01-01

    Full Text Available The advantages of organic field-effect transistors (OFETs, such as low cost, flexibility and large-area fabrication, have recently attracted much attention due to their electronic applications. Practical transistors require high mobility, large on/off ratio, low threshold voltage and high stability. Development of new organic semiconductors is key to achieving these parameters. Recently, organic semiconductors have been synthesized showing comparable mobilities to amorphous-silicon-based FETs. These materials make OFETs more attractive and their applications have been attempted. New organic semiconductors resulting in high-performance FET devices are described here and the relationship between transistor characteristics and chemical structure is discussed.

  9. Charge transport in amorphous organic semiconductors

    Energy Technology Data Exchange (ETDEWEB)

    Lukyanov, Alexander

    2011-03-15

    Organic semiconductors with the unique combination of electronic and mechanical properties may offer cost-effective ways of realizing many electronic applications, e. g. large-area flexible displays, printed integrated circuits and plastic solar cells. In order to facilitate the rational compound design of organic semiconductors, it is essential to understand relevant physical properties e. g. charge transport. This, however, is not straightforward, since physical models operating on different time and length scales need to be combined. First, the material morphology has to be known at an atomistic scale. For this atomistic molecular dynamics simulations can be employed, provided that an atomistic force field is available. Otherwise it has to be developed based on the existing force fields and first principle calculations. However, atomistic simulations are typically limited to the nanometer length- and nanosecond time-scales. To overcome these limitations, systematic coarse-graining techniques can be used. In the first part of this thesis, it is demonstrated how a force field can be parameterized for a typical organic molecule. Then different coarse-graining approaches are introduced together with the analysis of their advantages and problems. When atomistic morphology is available, charge transport can be studied by combining the high-temperature Marcus theory with kinetic Monte Carlo simulations. The approach is applied to the hole transport in amorphous films of tris(8- hydroxyquinoline)aluminium (Alq{sub 3}). First the influence of the force field parameters and the corresponding morphological changes on charge transport is studied. It is shown that the energetic disorder plays an important role for amorphous Alq{sub 3}, defining charge carrier dynamics. Its spatial correlations govern the Poole-Frenkel behavior of the charge carrier mobility. It is found that hole transport is dispersive for system sizes accessible to simulations, meaning that calculated

  10. Method of doping organic semiconductors

    Science.gov (United States)

    Kloc, Christian Leo [Constance, DE; Ramirez, Arthur Penn [Summit, NJ; So, Woo-Young [New Providence, NJ

    2012-02-28

    A method includes the steps of forming a contiguous semiconducting region and heating the region. The semiconducting region includes polyaromatic molecules. The heating raises the semiconducting region to a temperature above room temperature. The heating is performed in the presence of a dopant gas and the absence of light to form a doped organic semiconducting region.

  11. Spectroscopy of organic semiconductors from first principles

    Science.gov (United States)

    Sharifzadeh, Sahar; Biller, Ariel; Kronik, Leeor; Neaton, Jeffery

    2011-03-01

    Advances in organic optoelectronic materials rely on an accurate understanding their spectroscopy, motivating the development of predictive theoretical methods that accurately describe the excited states of organic semiconductors. In this work, we use density functional theory and many-body perturbation theory (GW/BSE) to compute the electronic and optical properties of two well-studied organic semiconductors, pentacene and PTCDA. We carefully compare our calculations of the bulk density of states with available photoemission spectra, accounting for the role of finite temperature and surface effects in experiment, and examining the influence of our main approximations -- e.g. the GW starting point and the application of the generalized plasmon-pole model -- on the predicted electronic structure. Moreover, our predictions for the nature of the exciton and its binding energy are discussed and compared against optical absorption data. We acknowledge DOE, NSF, and BASF for financial support and NERSC for computational resources.

  12. Thiazole-based organic semiconductors for organic electronics.

    Science.gov (United States)

    Lin, Yuze; Fan, Haijun; Li, Yongfang; Zhan, Xiaowei

    2012-06-19

    Over the past two decades, organic semiconductors have been the subject of intensive academic and commercial interests. Thiazole is a common electron-accepting heterocycle due to electron-withdrawing nitrogen of imine (C=N), several moieties based on thiazole have been widely introduced into organic semiconductors, and yielded high performance in organic electronic devices. This article reviews recent developments in the area of thiazole-based organic semiconductors, particularly thiazole, bithiazole, thiazolothiazole and benzobisthiazole-based small molecules and polymers, for applications in organic field-effect transistors, solar cells and light-emitting diodes. The remaining problems and challenges, and the key research direction in near future are discussed. Copyright © 2012 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  13. The Electrical Characteristics of The N-Organic Semiconductor/P-Inorganic Semiconductor Diode

    International Nuclear Information System (INIS)

    Aydin, M. E.

    2008-01-01

    n-organic semiconductor (PEDOT) / p-inorganic semiconductor Si diode was formed by deep coating method. The method has been achieved by coating n-inorganic semiconductor PEDOT on top of p-inorganic semiconductor. The n-organic semiconductor PEDOT/ p-inorganic semiconductor diode demonstrated rectifying behavior by the current-voltage (I-V) curves studied at room temperature. The barrier height , ideality factor values were obtained as of 0.88 eV and 1.95 respectively. The diode showed non-ideal I-V behavior with an ideality factor greater than unity that could be ascribed to the interfacial layer

  14. Charge-transport simulations in organic semiconductors

    Energy Technology Data Exchange (ETDEWEB)

    May, Falk

    2012-07-06

    a polarization-induced stabilization of a molecule in its charged and neutral states can lead to large shifts, broadening, and traps in the distribution of charge energies. These results are especially important for multi-component systems (the emission layer of an OLED or the donor-acceptor interface of an organic solar cell), if the change in polarizability upon charging (or excitation in case of energy transport) is different for the components. Thus, the polarizability change upon charging or excitation should be added to the set of molecular parameters essential for understanding charge and energy transport in organic semiconductors. We also studied charge transport in self-assembled systems, where intermolecular packing motives induced by side chains can increase electronic couplings between molecules. This leads to larger charge mobility, which is essential for devices such as organic field effect transistors. However, it is not sufficient to match the average local molecular order induced by the side chains with maxima of the electronic couplings. It is also important to make the corresponding distributions, e.g. of the pitch angle between consecutive molecules, as narrow as possible compared to the window determined by the closest minima of the electronic couplings. The immediate implication for compound design is that the side chains should assist the self-assembling process not only via ''soft'' entropic interactions, but also via stronger specific interactions, such as hydrogen bonding.

  15. Interfacial effects in organic semiconductor heterojunctions

    International Nuclear Information System (INIS)

    Stadler, P.

    2011-01-01

    The field of organic electronics has systematically gained interest in recent years, technologically and scientifically advances have been made leading to practical applications such as organic light emitting diodes, organic field-effect transistors and organic photo-voltaic cells. In this thesis a fundamental study on organic molecules is presented targeting on interfacial effects at organic heterojunctions. Generally in organic electronic devices interfaces are considered as key parameters for achieving high performance applications. Therefore in this work the emphasis is to investigate layer-by-layer heterojunctions of organic molecules. Defined heterojunctions at inorganic III-V semiconductors form superlattices and quantum-wells, which lead to interfacial effects summarized as quantum confinement and two-dimensional electron gases. Although organic molecules differ in many aspects from their inorganic counterparts, similar effects can be theoretically expected at organic heterojunctions as well. Organic molecules form van-der-Waals type crystals and domains which are macroscopically anisotropic and polycrystalline or amorphous. Organic molecules are intrinsic semiconductors and at interfaces dipoles are formed, which control the energy level alignment. In order to characterize such structures and compare them to inorganic superlattices and quantum-wells it is necessary to induce charge carriers. In this work this is established either by interfacial doping using high-performance dielectrics in a field-effect transistor structure or by photo-doping by exciting a donor-acceptor bilayer. In both cases C 60 was chosen as organic semiconductor exhibiting good acceptor properties and an electron mobility in the range of 0.5 cm 2 V -1 s -1 . The fabrication of well-defined few-molecular layers allows probing directly at the interface. Spectroscopic methods and transport measurements are applied for characterization: Photoemission spectroscopy, absorption and photo

  16. Magnetic field effects in organic semiconductors : theory and simulations

    NARCIS (Netherlands)

    Kersten, S.P.

    2013-01-01

    Organic semiconductors are a promising class of materials, offering several advantages over inorganic semiconductors. They are light, flexible, easy and cheap to produce, and easily chemically tunable. Organic semiconductors are currently used for lighting applications and in the displays of some

  17. Elementary steps in electrical doping of organic semiconductors

    KAUST Repository

    Tietze, Max Lutz; Benduhn, Johannes; Pahner, Paul; Nell, Bernhard; Schwarze, Martin; Kleemann, Hans; Krammer, Markus; Zojer, Karin; Vandewal, Koen; Leo, Karl

    2018-01-01

    Fermi level control by doping is established since decades in inorganic semiconductors and has been successfully introduced in organic semiconductors. Despite its commercial success in the multi-billion OLED display business, molecular doping

  18. The WSPC Reference on Organic Electronics: Organic Semiconductors

    KAUST Repository

    Bredas, Jean-Luc

    2015-05-12

    In this chapter, we provide a basic theoretical perspective on charge-carrier transport in organic semiconductors, with a focus on organic molecular crystals. We introduce the microscopic parameters relevant to the intrinsic charge-transport properties of these materials and describe some of the common quantum-chemical approaches used for their evaluation. We also discuss the nature of the possible charge-transport mechanisms in organic molecular crystals.

  19. Study of interfaces in organic semiconductor heterojunctions

    International Nuclear Information System (INIS)

    Maheshwari, P; Dutta, D; Sudarshan, K; Sharma, S K; Pujari, P K; Samanta, S; Singh, A; Aswal, D K

    2011-01-01

    The defect structure at the organic heterojunctions is studied using slow positron beam. The structural and electronic properties of heterojunctions are of technological and fundamental importance for understanding and optimization of electronic processes in organic devices. Interface trap centres play a significant role in the electrical conduction through the junctions. Depth dependent Doppler broadened annihilation measurements have been carried out in p- and n-type organic semiconductor thin films (30-80 nm) both single as well as multilayers grown on quartz substrate. The objective of the present study is to investigate the defect structure and to understand the behavior of positrons at the charged organic interfaces. Our result shows the sensitivity of positrons to the interfacial disorders that may be a convoluted effect of the presence of defects as well as the influence of the charge dipole in multilayers.

  20. Halopentacenes: Promising Candidates for Organic Semiconductors

    International Nuclear Information System (INIS)

    Gong-He, Du; Zhao-Yu, Ren; Ji-Ming, Zheng; Ping, Guo

    2009-01-01

    We introduce polar substituents such as F, Cl, Br into pentacene to enhance the dissolubility in common organic solvents while retaining the high charge-carrier mobilities of pentacene. Geometric structures, dipole moments, frontier molecule orbits, ionization potentials and electron affinities, as well as reorganization energies of those molecules, and of pentacene for comparison, are successively calculated by density functional theory. The results indicate that halopentacenes have rather small reorganization energies (< 0.2 eV), and when the substituents are in position 2 or positions 2 and 9, they are polarity molecules. Thus we conjecture that they can easily be dissolved in common organic solvents, and are promising candidates for organic semiconductors. (condensed matter: electronicstructure, electrical, magnetic, and opticalproperties)

  1. n-Type organic semiconductors in organic electronics.

    Science.gov (United States)

    Anthony, John E; Facchetti, Antonio; Heeney, Martin; Marder, Seth R; Zhan, Xiaowei

    2010-09-08

    Organic semiconductors have been the subject of intensive academic and commercial interest over the past two decades, and successful commercial devices incorporating them are slowly beginning to enter the market. Much of the focus has been on the development of hole transporting, or p-type, semiconductors that have seen a dramatic rise in performance over the last decade. Much less attention has been devoted to electron transporting, or so called n-type, materials, and in this paper we focus upon recent developments in several classes of n-type materials and the design guidelines used to develop them.

  2. Wannier-Frenkel hybrid exciton in organic-semiconductor quantum dot heterostructures

    International Nuclear Information System (INIS)

    Birman, Joseph L.; Huong, Nguyen Que

    2007-01-01

    The formation of a hybridization state of Wannier Mott exciton and Frenkel exciton in different hetero-structure configurations involving quantum dots is investigated. The hybrid excitons exist at the interfaces of the semiconductors quantum dots and the organic medium, having unique properties and a large optical non-linearity. The coupling at resonance is very strong and tunable by changing the parameters of the systems (dot radius, dot-dot distance, generation of the organic dendrites and the materials of the system etc...). Different semiconductor quantum dot-organic material combination systems have been considered such as a semiconductor quantum dot lattice embedded in an organic host, a semiconductor quantum dot at the center of an organic dendrite, a semiconductor quantum dot coated by an organic shell

  3. The pursuit of electrically-driven organic semiconductor lasers

    NARCIS (Netherlands)

    Bisri, Satria Zulkarnaen; Takenobu, Taishi; Iwasa, Yoshihiro

    2014-01-01

    Organic semiconductors have many favourable and plastic-like optical properties that are promising for the development of low energy consuming laser devices. Although optically-pumped organic semiconductor lasers have been demonstrated since the early days of lasers, electrically-driven organic

  4. Multi-scale modeling of spin transport in organic semiconductors

    Science.gov (United States)

    Hemmatiyan, Shayan; Souza, Amaury; Kordt, Pascal; McNellis, Erik; Andrienko, Denis; Sinova, Jairo

    In this work, we present our theoretical framework to simulate simultaneously spin and charge transport in amorphous organic semiconductors. By combining several techniques e.g. molecular dynamics, density functional theory and kinetic Monte Carlo, we are be able to study spin transport in the presence of anisotropy, thermal effects, magnetic and electric field effects in a realistic morphologies of amorphous organic systems. We apply our multi-scale approach to investigate the spin transport in amorphous Alq3 (Tris(8-hydroxyquinolinato)aluminum) and address the underlying spin relaxation mechanism in this system as a function of temperature, bias voltage, magnetic field and sample thickness.

  5. Energy position of the transport path in disordered organic semiconductors

    International Nuclear Information System (INIS)

    Oelerich, J O; Jansson, F; Gebhard, F; Baranovskii, S D; Nenashev, A V

    2014-01-01

    The concept of transport energy is the most transparent theoretical approach to describe hopping transport in disordered systems with steeply energy dependent density of states (DOS), in particular in organic semiconductors with Gaussian DOS. This concept allows one to treat hopping transport in the framework of a simple multiple-trapping model, replacing the mobility edge by a particular energy level called the transport energy. However, there is no consensus among researchers on the position of this transport level. In this article, we suggest a numerical procedure to find out the energy level most significantly contributing to charge transport in organic semiconductors. The procedure is based on studying the effects of DOS modifications on the charge carrier mobility in straightforward computer simulations. We also show why the most frequently visited energy, computed in several numerical studies to determine the transport energy, is not representative for charge transport. (paper)

  6. Study of neural cells on organic semiconductor ultra thin films

    Energy Technology Data Exchange (ETDEWEB)

    Bystrenova, Eva; Tonazzini, Ilaria; Stoliar, Pablo; Greco, Pierpaolo; Lazar, Adina; Dutta, Soumya; Dionigi, Chiara; Cacace, Marcello; Biscarini, Fabio [ISMN-CNR, Bologna (Italy); Jelitai, Marta; Madarasz, Emilia [IEM- HAS, Budapest (Hungary); Huth, Martin; Nickel, Bert [LMU, Munich (Germany); Martini, Claudia [Dept. PNPB, Univ. of Pisa (Italy)

    2008-07-01

    Many technological advances are currently being developed for nano-fabrication, offering the ability to create and control patterns of soft materials. We report the deposition of cells on organic semiconductor ultra-thin films. This is a first step towards the development of active bio/non bio systems for electrical transduction. Thin films of pentacene, whose thickness was systematically varied, were grown by high vacuum sublimation. We report adhesion, growth, and differentiation of human astroglial cells and mouse neural stem cells on an organic semiconductor. Viability of astroglial cells in time was measured as a function of the roughness and the characteristic morphology of ultra thin organic film, as well as the features of the patterned molecules. Optical fluorescence microscope coupled to atomic force microscope was used to monitor the presence, density and shape of deposited cells. Neural stem cells remain viable, differentiate by retinoic acid and form dense neuronal networks. We have shown the possibility to integrate living neural cells on organic semiconductor thin films.

  7. Spin diffusion in disordered organic semiconductors

    Science.gov (United States)

    Li, Ling; Gao, Nan; Lu, Nianduan; Liu, Ming; Bässler, Heinz

    2015-12-01

    An analytical theory for spin diffusion in disordered organic semiconductors is derived. It is based on percolation theory and variable range hopping in a disordered energy landscape with a Gaussian density of states. It describes universally the dependence of the spin diffusion on temperature, carrier density, material disorder, magnetic field, and electric field at the arbitrary magnitude of the Hubbard energy of charge pairs. It is found that, compared to the spin transport carried by carriers hopping, the spin exchange will hinder the spin diffusion process at low carrier density, even under the condition of a weak electric field. Importantly, under the influence of a bias voltage, anomalous spreading of the spin packet will lead to an abnormal temperature dependence of the spin diffusion coefficient and diffusion length. This explains the recent experimental data for spin diffusion length observed in Alq3.

  8. Theory and simulation of charge transport in disordered organic semiconductors

    NARCIS (Netherlands)

    Bobbert, P.A.; Kondov, I.; Sutman, G.

    2013-01-01

    Charge transport in polymeric or small-molecule organic semiconductors used in organic light-emitting diodes (OLEDs) occurs by hopping of charges between sites at which the charges are localized. The energetic disorder in these semiconductors has a profound influence on the charge transport: charges

  9. Self-interaction and charge transfer in organic semiconductors

    Energy Technology Data Exchange (ETDEWEB)

    Koerzdoerfer, Thomas

    2009-12-18

    This work concentrates on the problem of self-interaction, which is one of the most serious problems of commonly used approximative density functionals. As a major result of this work, it is demonstrated that self-interaction plays a decisive role for the performance of different approximative functionals in predicting accurate electronic properties of organic molecular semiconductors. In search for a solution to the self-interaction problem, a new concept for correcting commonly used density functionals for self-interaction is introduced and applied to a variety of systems, spanning small molecules, extended molecular chains, and organic molecular semiconductors. It is further shown that the performance of functionals that are not free from self-interaction can vary strongly for different systems and observables of interest, thus entailing the danger of misinterpretation of the results obtained from those functionals. The underlying reasons for the varying performance of commonly used density functionals are discussed thoroughly in this work. Finally, this thesis provides strategies that allow to analyze the reliability of commonly used approximations to the exchange-correlation functional for particular systems of interest. This cumulative dissertation is divided into three parts. Part I gives a short introduction into DFT and its time-dependent extension (TDDFT). Part II provides further insights into the self-interaction problem, presents a newly developed concept for the correction of self-interaction, gives an introduction into the publications, and discusses their basic results. Finally, the four publications on self-interaction and charge-transfer in extended molecular systems and organic molecular semiconductors are collected in Part III. (orig.)

  10. Control of the Thermal Evaporation of Organic Semiconductors via Exact Linearization

    OpenAIRE

    Martin Steinberger; Martin Horn

    2011-01-01

    In this article, a high vacuum system for the evaporation of organic semiconductors is introduced and a mathematical model is given. Based on the exact input output linearization a deposition rate controller is designed and tested with different evaporation materials.

  11. Charge carrier relaxation model in disordered organic semiconductors

    International Nuclear Information System (INIS)

    Lu, Nianduan; Li, Ling; Sun, Pengxiao; Liu, Ming

    2013-01-01

    The relaxation phenomena of charge carrier in disordered organic semiconductors have been demonstrated and investigated theoretically. An analytical model describing the charge carrier relaxation is proposed based on the pure hopping transport theory. The relation between the material disorder, electric field and temperature and the relaxation phenomena has been discussed in detail, respectively. The calculated results reveal that the increase of electric field and temperature can promote the relaxation effect in disordered organic semiconductors, while the increase of material disorder will weaken the relaxation. The proposed model can explain well the stretched-exponential law by adopting the appropriate parameters. The calculation shows a good agreement with the experimental data for organic semiconductors

  12. Organic modification of metal / semiconductor Schottky contacts

    Energy Technology Data Exchange (ETDEWEB)

    Mendez Pinzon, H.A.

    2006-07-10

    In the present work a Metal / organic / inorganic semiconductor hybrid heterostructure (Ag / DiMe-PTCDI / GaAs) was built under UHV conditions and characterised in situ. The aim was to investigate the influence of the organic layer in the surface properties of GaAs(100) and in the electrical response of organic-modified Ag / GaAs Schottky diodes. The device was tested by combining surface-sensitive techniques (Photoemission spectroscopy and NEXAFS) with electrical measurements (current-voltage, capacitance-voltage, impedance and charge transient spectroscopies). Core level examination by PES confirms removal of native oxide layers on sulphur passivated (S-GaAs) and hydrogen plasma treated GaAs(100) (H+GaAs) surfaces. Additional deposition of ultrathin layers of DiMe-PTCDI may lead to a reduction of the surface defects density and thereby to an improvement of the electronic properties of GaAs. The energy level alignment through the heterostructure was deduced by combining UPS and I-V measurements. This allows fitting of the I-V characteristics with electron as majority carriers injected over a barrier by thermionic emission as a primary event. For thin organic layers (below 8 nm thickness) several techniques (UPS, I-V, C-V, QTS and AFM) show non homogeneous layer growth, leading to formation of voids. The coverage of the H+GaAs substrate as a function of the nominal thickness of DiMe-PTCDI was assessed via C-V measurements assuming a voltage independent capacitance of the organic layer. The frequency response of the device was evaluated through C-V and impedance measurements in the range 1 kHz-1 MHz. The almost independent behaviour of the capacitance in the measured frequency range confirmed the assumption of a near geometrical capacitor, which was used for modelling the impedance with an equivalent circuit of seven components. From there it was found a predominance of the space charge region impedance, so that A.C. conduction can only takes place through the

  13. Charge carrier coherence and Hall effect in organic semiconductors

    Science.gov (United States)

    Yi, H. T.; Gartstein, Y. N.; Podzorov, V.

    2016-01-01

    Hall effect measurements are important for elucidating the fundamental charge transport mechanisms and intrinsic mobility in organic semiconductors. However, Hall effect studies frequently reveal an unconventional behavior that cannot be readily explained with the simple band-semiconductor Hall effect model. Here, we develop an analytical model of Hall effect in organic field-effect transistors in a regime of coexisting band and hopping carriers. The model, which is supported by the experiments, is based on a partial Hall voltage compensation effect, occurring because hopping carriers respond to the transverse Hall electric field and drift in the direction opposite to the Lorentz force acting on band carriers. We show that this can lead in particular to an underdeveloped Hall effect observed in organic semiconductors with substantial off-diagonal thermal disorder. Our model captures the main features of Hall effect in a variety of organic semiconductors and provides an analytical description of Hall mobility, carrier density and carrier coherence factor. PMID:27025354

  14. Hybrid organic semiconductor lasers for bio-molecular sensing.

    Science.gov (United States)

    Haughey, Anne-Marie; Foucher, Caroline; Guilhabert, Benoit; Kanibolotsky, Alexander L; Skabara, Peter J; Burley, Glenn; Dawson, Martin D; Laurand, Nicolas

    2014-01-01

    Bio-functionalised luminescent organic semiconductors are attractive for biophotonics because they can act as efficient laser materials while simultaneously interacting with molecules. In this paper, we present and discuss a laser biosensor platform that utilises a gain layer made of such an organic semiconductor material. The simple structure of the sensor and its operation principle are described. Nanolayer detection is shown experimentally and analysed theoretically in order to assess the potential and the limits of the biosensor. The advantage conferred by the organic semiconductor is explained, and comparisons to laser sensors using alternative dye-doped materials are made. Specific biomolecular sensing is demonstrated, and routes to functionalisation with nucleic acid probes, and future developments opened up by this achievement, are highlighted. Finally, attractive formats for sensing applications are mentioned, as well as colloidal quantum dots, which in the future could be used in conjunction with organic semiconductors.

  15. Charge carrier coherence and Hall effect in organic semiconductors.

    Science.gov (United States)

    Yi, H T; Gartstein, Y N; Podzorov, V

    2016-03-30

    Hall effect measurements are important for elucidating the fundamental charge transport mechanisms and intrinsic mobility in organic semiconductors. However, Hall effect studies frequently reveal an unconventional behavior that cannot be readily explained with the simple band-semiconductor Hall effect model. Here, we develop an analytical model of Hall effect in organic field-effect transistors in a regime of coexisting band and hopping carriers. The model, which is supported by the experiments, is based on a partial Hall voltage compensation effect, occurring because hopping carriers respond to the transverse Hall electric field and drift in the direction opposite to the Lorentz force acting on band carriers. We show that this can lead in particular to an underdeveloped Hall effect observed in organic semiconductors with substantial off-diagonal thermal disorder. Our model captures the main features of Hall effect in a variety of organic semiconductors and provides an analytical description of Hall mobility, carrier density and carrier coherence factor.

  16. Unraveling the mechanism of molecular doping in organic semiconductors.

    Science.gov (United States)

    Mityashin, Alexander; Olivier, Yoann; Van Regemorter, Tanguy; Rolin, Cedric; Verlaak, Stijn; Martinelli, Nicolas G; Beljonne, David; Cornil, Jérôme; Genoe, Jan; Heremans, Paul

    2012-03-22

    The mechanism by which molecular dopants donate free charge carriers to the host organic semiconductor is investigated and is found to be quite different from the one in inorganic semiconductors. In organics, a strong correlation between the doping concentration and its charge donation efficiency is demonstrated. Moreover, there is a threshold doping level below which doping simply has no electrical effect. Copyright © 2012 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  17. Contorted Organic Semiconductors for Molecular Electronics

    Science.gov (United States)

    Zhong, Yu

    Chapter 4, I discuss helical molecular semiconductors as electron acceptors that are on par with fullerene derivatives in efficient solar cells. We achieved an 8.3% power conversion efficiency in a solar cell, which is a record high for non-fullerene bulk heterojunctions. Femtosecond transient absorption spectroscopy revealed both electron and hole transfer processes at the donor-acceptor interfaces. Atomic force microscopy reveals a mesh-like network of acceptors with pores that are tens of nanometers in diameter for efficient exciton separation and charge transport. This study describes a new motif for designing highly efficient acceptors for organic solar cells. In Chapter 5, I compare analogous cyclic and acyclic pi-conjugated molecules as n-type electronic materials and find that the cyclic molecules have numerous benefits in organic photovoltaics. We designed two conjugated cycles for this study. Each comprises four subunits; one combines four electron-accepting, redox-active, diphenyl-perylenediimide subunits, and the other alternates two electron-donating bithiophene units with two diphenyl-perylenediimide units. We compare the macrocycles to acyclic versions of these molecules and find that, relative to the acyclic analogs, the conjugated macrocycles have bathochromically shifted UV-vis absorbances and are more easily reduced. In blended films, macrocycle-based devices show higher electron mobility and good morphology. All of these factors contribute to the more than doubling of the power conversion efficiency observed in organic photovoltaic devices with these macrocycles as the n-type, electron transporting material. This study highlights the importance of geometric design in creating new molecular semiconductors. In Chapter 6, I describe a new molecular design that enables high performance organic photodetectors. We use a rigid, conjugated macrocycle as the electron acceptor in devices to obtain high photocurrent and low dark current. We directly compare the

  18. Elucidation and control of electronic properties related to organic semiconductors

    International Nuclear Information System (INIS)

    Yamane, Hiroyuki; Ueno, Nobuo; Seki, Kazuhiko

    2009-01-01

    The electronic structure of organic solids and interfaces plays a crucial role in the performance of optoelectronic devices using organic semiconductors such as light-emitting diodes, field-effect transistors, and photovoltaic cells. The functionality of these organic devices is seriously dominated by the geometric structure, which varies depending on the molecular structure and the sample preparation condition. Due to the rapid progress in sample preparation methods and surface science techniques, we can now discuss in detail the correlation of the electronic structure with the geometric structure of organic solids, films, and interfaces. This paper reviews the recent progress of studies in the geometric and electronic structures related to organic semiconductors. (author)

  19. Organic conductive films for semiconductor electrodes

    Science.gov (United States)

    Frank, Arthur J.

    1984-01-01

    According to the present invention, improved electrodes overcoated with conductive polymer films and preselected catalysts are provided. The electrodes typically comprise an inorganic semiconductor overcoated with a charge conductive polymer film comprising a charge conductive polymer in or on which is a catalyst or charge-relaying agent.

  20. Strong Coupling between Plasmons and Organic Semiconductors

    Directory of Open Access Journals (Sweden)

    Joel Bellessa

    2014-05-01

    Full Text Available In this paper we describe the properties of organic material in strong coupling with plasmon, mainly based on our work in this field of research. The strong coupling modifies the optical transitions of the structure, and occurs when the interaction between molecules and plasmon prevails on the damping of the system. We describe the dispersion relation of different plasmonic systems, delocalized and localized plasmon, coupled to aggregated dyes and the typical properties of these systems in strong coupling. The modification of the dye emission is also studied. In the second part, the effect of the microscopic structure of the organics, which can be seen as a disordered film, is described. As the different molecules couple to the same plasmon mode, an extended coherent state on several microns is observed.

  1. Synchrotron radiation studies of inorganic-organic semiconductor interfaces

    International Nuclear Information System (INIS)

    Evans, D.A.; Steiner, H.J.; Vearey-Roberts, A.R.; Bushell, A.; Cabailh, G.; O'Brien, S.; Wells, J.W.; McGovern, I.T.; Dhanak, V.R.; Kampen, T.U.; Zahn, D.R.T.; Batchelor, D.

    2003-01-01

    Organic semiconductors (polymers and small molecules) are widely used in electronic and optoelectronic technologies. Many devices are based on multilayer structures where interfaces play a central role in device performance and where inorganic semiconductor models are inadequate. Synchrotron radiation techniques such as photoelectron spectroscopy (PES), near-edge X-ray absorption fine structure (NEXAFS) and X-ray standing wave spectroscopy (XSW) provide a powerful means of probing the structural, electronic and chemical properties of these interfaces. The surface-specificity of these techniques allows key properties to be monitored as the heterostructure is fabricated. This methodology has been directed at the growth of hybrid organic-inorganic semiconductor interfaces involving copper phthalocyanine as the model organic material and InSb and GaAs as the model inorganic semiconductor substrates. Core level PES has revealed that these interfaces are abrupt and chemically inert due to the weak bonding between the molecules and the inorganic semiconductor. NEXAFS studies have shown that there is a preferred orientation of the molecules within the organic semiconductor layers. The valence band offsets for the heterojunctions have been directly measured using valence level PES and were found to be very different for copper phthalocyanine on InSb and GaAs (0.7 and -0.3 eV respectively) although an interface dipole is present in both cases

  2. Ultrafast dynamics and laser action of organic semiconductors

    CERN Document Server

    Vardeny, Zeev Valy

    2009-01-01

    Spurred on by extensive research in recent years, organic semiconductors are now used in an array of areas, such as organic light emitting diodes (OLEDs), photovoltaics, and other optoelectronics. In all of these novel applications, the photoexcitations in organic semiconductors play a vital role. Exploring the early stages of photoexcitations that follow photon absorption, Ultrafast Dynamics and Laser Action of Organic Semiconductors presents the latest research investigations on photoexcitation ultrafast dynamics and laser action in pi-conjugated polymer films, solutions, and microcavities.In the first few chapters, the book examines the interplay of charge (polarons) and neutral (excitons) photoexcitations in pi-conjugated polymers, oligomers, and molecular crystals in the time domain of 100 fs-2 ns. Summarizing the state of the art in lasing, the final chapters introduce the phenomenon of laser action in organics and cover the latest optoelectronic applications that use lasing based on a variety of caviti...

  3. Semiconductor Metal-Organic Frameworks: Future Low-Bandgap Materials.

    Science.gov (United States)

    Usman, Muhammad; Mendiratta, Shruti; Lu, Kuang-Lieh

    2017-02-01

    Metal-organic frameworks (MOFs) with low density, high porosity, and easy tunability of functionality and structural properties, represent potential candidates for use as semiconductor materials. The rapid development of the semiconductor industry and the continuous miniaturization of feature sizes of integrated circuits toward the nanometer (nm) scale require novel semiconductor materials instead of traditional materials like silicon, germanium, and gallium arsenide etc. MOFs with advantageous properties of both the inorganic and the organic components promise to serve as the next generation of semiconductor materials for the microelectronics industry with the potential to be extremely stable, cheap, and mechanically flexible. Here, a perspective of recent research is provided, regarding the semiconducting properties of MOFs, bandgap studies, and their potential in microelectronic devices. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  4. Ambipolar organic heterojunction transistors with various p-type semiconductors

    International Nuclear Information System (INIS)

    Shi Jianwu; Wang Haibo; Song De; Tian Hongkun; Geng Yanhou; Yan Donghang

    2008-01-01

    Ambipolar transport has been realized in organic heterojunction transistors with metal phthalocyanines, phenanthrene-based conjugated oligomers as the first semiconductors and copper-hexadecafluoro-phthalocyanine as the second semiconductor. The electron and hole mobilities of ambipolar devices with rod-like molecules were comparable to the corresponding single component devices, while the carrier mobility of ambipolar devices with disk-like molecules was much lower than the corresponding single component devices. The much difference of their device performance was attributed to the roughness of the first semiconductor films, which was original from their distinct growth habits. The flat and continuous films for the first semiconductors layer can lead to a smooth heterojunction interface, and obtained a high device performance for ambipolar organic heterojunction transistors

  5. Suppressing molecular vibrations in organic semiconductors by inducing strain.

    Science.gov (United States)

    Kubo, Takayoshi; Häusermann, Roger; Tsurumi, Junto; Soeda, Junshi; Okada, Yugo; Yamashita, Yu; Akamatsu, Norihisa; Shishido, Atsushi; Mitsui, Chikahiko; Okamoto, Toshihiro; Yanagisawa, Susumu; Matsui, Hiroyuki; Takeya, Jun

    2016-04-04

    Organic molecular semiconductors are solution processable, enabling the growth of large-area single-crystal semiconductors. Improving the performance of organic semiconductor devices by increasing the charge mobility is an ongoing quest, which calls for novel molecular and material design, and improved processing conditions. Here we show a method to increase the charge mobility in organic single-crystal field-effect transistors, by taking advantage of the inherent softness of organic semiconductors. We compress the crystal lattice uniaxially by bending the flexible devices, leading to an improved charge transport. The mobility increases from 9.7 to 16.5 cm(2) V(-1) s(-1) by 70% under 3% strain. In-depth analysis indicates that compressing the crystal structure directly restricts the vibration of the molecules, thus suppresses dynamic disorder, a unique mechanism in organic semiconductors. Since strain can be easily induced during the fabrication process, we expect our method to be exploited to build high-performance organic devices.

  6. Determination of the transport levels in thin films of organic semiconductors

    Energy Technology Data Exchange (ETDEWEB)

    Krause, Stefan

    2009-07-27

    The approach of using the combination of Ultraviolet (UPS) and Inverse Photoemission (IPS) to determine the transport levels in thin films of organic semiconductors is the scope of this work. For this matter all influences on the peak position and width in Photoelectron Spectroscopy are discussed with a special focus on organic semiconductors. Many of these influences are shown with experimental results of the investigation of diindenoperylene on Ag(111). These findings are applied to inorganic semiconductors silicon in order to establish the use of UPS and IPS on a well-understood system. Finally, the method is used to determine the transport level of several organic semiconductors (PTCDA, Alq3, CuPc, DIP, PBI-H4) and the corresponding exciton binding energies are calculated by comparison to optical absorption data. (orig.)

  7. Hybrid system of semiconductor and photosynthetic protein

    International Nuclear Information System (INIS)

    Kim, Younghye; Shin, Seon Ae; Lee, Jaehun; Yang, Ki Dong; Nam, Ki Tae

    2014-01-01

    Photosynthetic protein has the potential to be a new attractive material for solar energy absorption and conversion. The development of semiconductor/photosynthetic protein hybrids is an example of recent progress toward efficient, clean and nanostructured photoelectric systems. In the review, two biohybrid systems interacting through different communicating methods are addressed: (1) a photosynthetic protein immobilized semiconductor electrode operating via electron transfer and (2) a hybrid of semiconductor quantum dots and photosynthetic protein operating via energy transfer. The proper selection of materials and functional and structural modification of the components and optimal conjugation between them are the main issues discussed in the review. In conclusion, we propose the direction of future biohybrid systems for solar energy conversion systems, optical biosensors and photoelectric devices. (topical reviews)

  8. Crystallization of Organic Semiconductor Molecules in Nanosized Cavities

    DEFF Research Database (Denmark)

    Milita, Silvia; Dionigi, Chiara; Borgatti, Francesco

    2008-01-01

    The crystallization of an organic semiconductor, viz., tetrahexil-sexithiophene (H4T6) molecules, confined into nanosized cavities of a self-organized polystyrene beads template, has been investigated by means of in situ grazing incidence X-ray diffraction measurements, during the solvent evapora...

  9. Optical band gaps of organic semiconductor materials

    Science.gov (United States)

    Costa, José C. S.; Taveira, Ricardo J. S.; Lima, Carlos F. R. A. C.; Mendes, Adélio; Santos, Luís M. N. B. F.

    2016-08-01

    UV-Vis can be used as an easy and forthright technique to accurately estimate the band gap energy of organic π-conjugated materials, widely used as thin films/composites in organic and hybrid electronic devices such as OLEDs, OPVs and OFETs. The electronic and optical properties, including HOMO-LUMO energy gaps of π-conjugated systems were evaluated by UV-Vis spectroscopy in CHCl3 solution for a large number of relevant π-conjugated systems: tris-8-hydroxyquinolinatos (Alq3, Gaq3, Inq3, Al(qNO2)3, Al(qCl)3, Al(qBr)3, In(qNO2)3, In(qCl)3 and In(qBr)3); triphenylamine derivatives (DDP, p-TTP, TPB, TPD, TDAB, m-MTDAB, NPB, α-NPD); oligoacenes (naphthalene, anthracene, tetracene and rubrene); oligothiophenes (α-2T, β-2T, α-3T, β-3T, α-4T and α-5T). Additionally, some electronic properties were also explored by quantum chemical calculations. The experimental UV-Vis data are in accordance with the DFT predictions and indicate that the band gap energies of the OSCs dissolved in CHCl3 solution are consistent with the values presented for thin films.

  10. High throughput semiconductor deposition system

    Science.gov (United States)

    Young, David L.; Ptak, Aaron Joseph; Kuech, Thomas F.; Schulte, Kevin; Simon, John D.

    2017-11-21

    A reactor for growing or depositing semiconductor films or devices. The reactor may be designed for inline production of III-V materials grown by hydride vapor phase epitaxy (HVPE). The operating principles of the HVPE reactor can be used to provide a completely or partially inline reactor for many different materials. An exemplary design of the reactor is shown in the attached drawings. In some instances, all or many of the pieces of the reactor formed of quartz, such as welded quartz tubing, while other reactors are made from metal with appropriate corrosion resistant coatings such as quartz or other materials, e.g., corrosion resistant material, or stainless steel tubing or pipes may be used with a corrosion resistant material useful with HVPE-type reactants and gases. Using HVPE in the reactor allows use of lower-cost precursors at higher deposition rates such as in the range of 1 to 5 .mu.m/minute.

  11. Synthesis and characterization of a new organic semiconductor material

    Energy Technology Data Exchange (ETDEWEB)

    Tiffour, Imane [Laboratoire de Génie Physique, Département de Physique, Université de Tiaret, Tiaret 14000 (Algeria); Faculté des Sciences et Technologies, Université Mustapha Stambouli, Mascara 29000 (Algeria); Dehbi, Abdelkader [Laboratoire de Génie Physique, Département de Physique, Université de Tiaret, Tiaret 14000 (Algeria); Mourad, Abdel-Hamid I., E-mail: ahmourad@uaeu.ac.ae [Mechanical Engineering Department, Faculty of Engineering, United Arab Emirates University, Al-Ain, P.O. Box 15551 (United Arab Emirates); Belfedal, Abdelkader [Faculté des Sciences et Technologies, Université Mustapha Stambouli, Mascara 29000 (Algeria); LPCMME, Département de Physique, Université d' Oran Es-sénia, 3100 Oran (Algeria)

    2016-08-01

    The objective of this study is to create an ideal mixture of Acetaminophen/Curcumin leading to a new and improved semiconductor material, by a study of the electrical, thermal and optical properties. This new material will be compared with existing semiconductor technology to discuss its viability within the industry. The electrical properties were investigated using complex impedance spectroscopy and optical properties were studied by means of UV-Vis spectrophotometry. The electric conductivity σ, the dielectric constant ε{sub r}, the activation energy E{sub a}, the optical transmittance T and the gap energy E{sub g} have been investigated in order to characterize our organic material. The electrical conductivity of the material is approximately 10{sup −5} S/m at room temperature, increasing the temperature causes σ to increase exponentially to approximately 10{sup −4} S/m. The activation energy obtained for the material is equal to 0.49 ± 0.02 ev. The optical absorption spectra show that the investigating material has absorbance in the visible range with a maximum wavelength (λ{sub max}) 424 nm. From analysis, the absorption spectra it was found the optical band gap equal to 2.6 ± 0.02 eV and 2.46 ± 0.02 eV for the direct and indirect transition, respectively. In general, the study shows that the developed material has characteristics of organic semiconductor material that has a promising future in the field of organic electronics and their potential applications, e.g., photovoltaic cells. - Highlights: • Development of a new organic acetaminophen/Curcumin semiconductor material. • The developed material has characteristics of an organic semiconductor. • It has electrical conductivity comparable to available organic semiconductors. • It has high optical transmittance and low permittivity/dielectric constant.

  12. Synthesis and characterization of a new organic semiconductor material

    International Nuclear Information System (INIS)

    Tiffour, Imane; Dehbi, Abdelkader; Mourad, Abdel-Hamid I.; Belfedal, Abdelkader

    2016-01-01

    The objective of this study is to create an ideal mixture of Acetaminophen/Curcumin leading to a new and improved semiconductor material, by a study of the electrical, thermal and optical properties. This new material will be compared with existing semiconductor technology to discuss its viability within the industry. The electrical properties were investigated using complex impedance spectroscopy and optical properties were studied by means of UV-Vis spectrophotometry. The electric conductivity σ, the dielectric constant ε_r, the activation energy E_a, the optical transmittance T and the gap energy E_g have been investigated in order to characterize our organic material. The electrical conductivity of the material is approximately 10"−"5 S/m at room temperature, increasing the temperature causes σ to increase exponentially to approximately 10"−"4 S/m. The activation energy obtained for the material is equal to 0.49 ± 0.02 ev. The optical absorption spectra show that the investigating material has absorbance in the visible range with a maximum wavelength (λ_m_a_x) 424 nm. From analysis, the absorption spectra it was found the optical band gap equal to 2.6 ± 0.02 eV and 2.46 ± 0.02 eV for the direct and indirect transition, respectively. In general, the study shows that the developed material has characteristics of organic semiconductor material that has a promising future in the field of organic electronics and their potential applications, e.g., photovoltaic cells. - Highlights: • Development of a new organic acetaminophen/Curcumin semiconductor material. • The developed material has characteristics of an organic semiconductor. • It has electrical conductivity comparable to available organic semiconductors. • It has high optical transmittance and low permittivity/dielectric constant.

  13. Disorder-tuned charge transport in organic semiconductors

    Science.gov (United States)

    Xu, Feng; Qiu, Dong; Yan, Dadong

    2013-02-01

    We propose that the polaron transport in organic semiconductors is remarkably tuned by the fluctuation of polarization energy. The tuning effect of energetic fluctuation not only causes a continuous transition from non-Arrhenius to Arrhenius temperature activated charge transport with increasing moderate disorder strengths but also results in a band-like conduction in the low disorder regime which benefits from the enhanced mobilities in shallow trap states. As a result, a unified description of polaron transport is obtained for a set of typical organic semiconductors.

  14. Semiconductor

    International Nuclear Information System (INIS)

    2000-01-01

    This book deals with process and measurement of semiconductor. It contains 20 chapters, which goes as follows; semiconductor industry, introduction of semiconductor manufacturing, yield of semiconductor process, materials, crystal growth and a wafer forming, PN, control pollution, oxidation, photomasking photoresist chemistry, photomasking technologies, diffusion and ion injection, chemical vapor deposition, metallization, wafer test and way of evaluation, semiconductor elements, integrated circuit and semiconductor circuit technology.

  15. Organic semiconductor heterojunctions and its application in organic light-emitting diodes

    CERN Document Server

    Ma, Dongge

    2017-01-01

    This book systematically introduces the most important aspects of organic semiconductor heterojunctions, including the basic concepts and electrical properties. It comprehensively discusses the application of organic semiconductor heterojunctions as charge injectors and charge generation layers in organic light-emitting diodes (OLEDs). Semiconductor heterojunctions are the basis for constructing high-performance optoelectronic devices. In recent decades, organic semiconductors have been increasingly used to fabricate heterojunction devices, especially in OLEDs, and the subject has attracted a great deal of attention and evoked many new phenomena and interpretations in the field. This important application is based on the low dielectric constant of organic semiconductors and the weak non-covalent electronic interactions between them, which means that they easily form accumulation heterojunctions. As we know, the accumulation-type space charge region is highly conductive, which is an important property for high...

  16. 46 CFR 183.360 - Semiconductor rectifier systems.

    Science.gov (United States)

    2010-10-01

    ... 46 Shipping 7 2010-10-01 2010-10-01 false Semiconductor rectifier systems. 183.360 Section 183.360... TONS) ELECTRICAL INSTALLATION Power Sources and Distribution Systems § 183.360 Semiconductor rectifier systems. (a) Each semiconductor rectifier system must have an adequate heat removal system that prevents...

  17. 46 CFR 129.360 - Semiconductor-rectifier systems.

    Science.gov (United States)

    2010-10-01

    ... 46 Shipping 4 2010-10-01 2010-10-01 false Semiconductor-rectifier systems. 129.360 Section 129.360... INSTALLATIONS Power Sources and Distribution Systems § 129.360 Semiconductor-rectifier systems. (a) Each semiconductor-rectifier system must have an adequate heat-removal system to prevent overheating. (b) If a...

  18. 46 CFR 120.360 - Semiconductor rectifier systems.

    Science.gov (United States)

    2010-10-01

    ... 46 Shipping 4 2010-10-01 2010-10-01 false Semiconductor rectifier systems. 120.360 Section 120.360... INSTALLATION Power Sources and Distribution Systems § 120.360 Semiconductor rectifier systems. (a) Each semiconductor rectifier system must have an adequate heat removal system that prevents overheating. (b) Where a...

  19. Tuning polarity and improving charge transport in organic semiconductors

    Science.gov (United States)

    Oh, Joon Hak; Han, A.-Reum; Yu, Hojeong; Lee, Eun Kwang; Jang, Moon Jeong

    2013-09-01

    Although state-of-the-art ambipolar polymer semiconductors have been extensively reported in recent years, highperformance ambipolar polymers with tunable dominant polarity are still required to realize on-demand, target-specific, high-performance organic circuitry. Herein, dithienyl-diketopyrrolopyrrole (TDPP)-based polymer semiconductors with engineered side-chains have been synthesized, characterized and employed in ambipolar organic field-effect transistors, in order to achieve controllable and improved electrical properties. Thermally removable tert-butoxycarbonyl (t-BOC) groups and hybrid siloxane-solubilizing groups are introduced as the solubilizing groups, and they are found to enable the tunable dominant polarity and the enhanced ambipolar performance, respectively. Such outstanding performance based on our molecular design strategies makes these ambipolar polymer semiconductors highly promising for low-cost, large-area, and flexible electronics.

  20. MBE System for Antimonide Based Semiconductor Lasers

    National Research Council Canada - National Science Library

    Lester, Luke

    1999-01-01

    .... SLR-770 inductively coupled plasma (ICP) processing system. The SLR-770 has been invaluable in the study of plasma etching of AlGaAsSb and GaSb-materials that form the backbone of antimonide-based semiconductor lasers...

  1. Modeling of the transient mobility in disordered organic semiconductors

    NARCIS (Netherlands)

    Germs, W.C.; Van der Holst, J.M.M.; Van Mensfoort, S.L.M.; Bobbert, P.A.; Coehoorn, R.

    2011-01-01

    In non-steady-state experiments, the electrical response of devicesbased on disordered organic semiconductors often shows a large transient contribution due to relaxation of the out-of-equilibrium charge-carrier distribution. We have developed a model describing this process, based only on the

  2. Molecular fingerprints in the electronic properties of crystalline organic semiconductors

    DEFF Research Database (Denmark)

    Ciuchi, S.; Hatch, R.C.; Höchst, H.

    2012-01-01

    bands can be achieved in organic semiconductors provided that one properly accounts for the coupling to molecular vibrational modes and the presence of disorder. Our findings rationalize the growing experimental evidence that even the best band structure theories based on a many-body treatment...... of electronic interactions cannot reproduce the experimental photoemission data in this important class of materials....

  3. High Gain Hybrid Graphene-Organic Semiconductor Phototransistors

    NARCIS (Netherlands)

    Huisman, Everardus H.; Shulga, Artem G.; Zomer, Paul J.; Tombros, Nikolaos; Bartesaghi, Davide; Bisri, Satria Zulkarnaen; Loi, Maria A.; Koster, L. Jan Anton; van Wees, Bart J.

    2015-01-01

    Hybrid phototransistors of graphene and the organic semiconductor poly(3-hexylthiophene-2,5-diyl) (P3HT) are presented. Two types of phototransistors are demonstrated with a charge carrier transit time that differs by more than 6 orders of magnitude. High transit time devices are fabricated using a

  4. Two-Dimensional Charge Transport in Disordered Organic Semiconductors

    NARCIS (Netherlands)

    Brondijk, J. J.; Roelofs, W. S. C.; Mathijssen, S. G. J.; Shehu, A.; Cramer, T.; Biscarini, F.; Blom, P. W. M.; de Leeuw, D. M.

    2012-01-01

    We analyze the effect of carrier confinement on the charge-transport properties of organic field-effect transistors. Confinement is achieved experimentally by the use of semiconductors of which the active layer is only one molecule thick. The two-dimensional confinement of charge carriers provides

  5. A new electrode design for ambipolar injection in organic semiconductors.

    Science.gov (United States)

    Kanagasekaran, Thangavel; Shimotani, Hidekazu; Shimizu, Ryota; Hitosugi, Taro; Tanigaki, Katsumi

    2017-10-17

    Organic semiconductors have attracted much attention for low-cost, flexible and human-friendly optoelectronics. However, achieving high electron-injection efficiency is difficult from air-stable electrodes and cannot be equivalent to that of holes. Here, we present a novel concept of electrode composed of a bilayer of tetratetracontane (TTC) and polycrystalline organic semiconductors (pc-OSC) covered by a metal layer. Field-effect transistors of single-crystal organic semiconductors with the new electrodes of M/pc-OSC/TTC (M: Ca or Au) show both highly efficient electron and hole injection. Contact resistance for electron injection from Au/pc-OSC/TTC and hole injection from Ca/pc-OSC/TTC are comparable to those for electron injection from Ca and hole injection from Au, respectively. Furthermore, the highest field-effect mobilities of holes (22 cm 2  V -1  s -1 ) and electrons (5.0 cm 2  V -1  s -1 ) are observed in rubrene among field-effect transistors with electrodes so far proposed by employing Ca/pc-OSC/TTC and Au/pc-OSC/TTC electrodes for electron and hole injection, respectively.One of technological challenges building organic electronics is efficient injection of electrons at metal-semiconductor interfaces compared to that of holes. The authors show an air-stable electrode design with induced gap states, which support Fermi level pinning and thus ambipolar carrier injection.

  6. Charge transport in nanoscale vertical organic semiconductor pillar devices

    NARCIS (Netherlands)

    Wilbers, J.G.E.; Xu, B.; Bobbert, P.A.; de Jong, M.P.; van der Wiel, W.G.

    2017-01-01

    We report charge transport measurements in nanoscale vertical pillar structures incorporating ultrathin layers of the organic semiconductor poly(3-hexylthiophene) (P3HT). P3HT layers with thickness down to 5 nm are gently top-contacted using wedging transfer, yielding highly reproducible, robust

  7. Inkjet-Printed Organic Transistors Based on Organic Semiconductor/Insulating Polymer Blends.

    Science.gov (United States)

    Kwon, Yoon-Jung; Park, Yeong Don; Lee, Wi Hyoung

    2016-08-02

    Recent advances in inkjet-printed organic field-effect transistors (OFETs) based on organic semiconductor/insulating polymer blends are reviewed in this article. Organic semiconductor/insulating polymer blends are attractive ink candidates for enhancing the jetting properties, inducing uniform film morphologies, and/or controlling crystallization behaviors of organic semiconductors. Representative studies using soluble acene/insulating polymer blends as an inkjet-printed active layer in OFETs are introduced with special attention paid to the phase separation characteristics of such blended films. In addition, inkjet-printed semiconducting/insulating polymer blends for fabricating high performance printed OFETs are reviewed.

  8. Inkjet-Printed Organic Transistors Based on Organic Semiconductor/Insulating Polymer Blends

    Science.gov (United States)

    Kwon, Yoon-Jung; Park, Yeong Don; Lee, Wi Hyoung

    2016-01-01

    Recent advances in inkjet-printed organic field-effect transistors (OFETs) based on organic semiconductor/insulating polymer blends are reviewed in this article. Organic semiconductor/insulating polymer blends are attractive ink candidates for enhancing the jetting properties, inducing uniform film morphologies, and/or controlling crystallization behaviors of organic semiconductors. Representative studies using soluble acene/insulating polymer blends as an inkjet-printed active layer in OFETs are introduced with special attention paid to the phase separation characteristics of such blended films. In addition, inkjet-printed semiconducting/insulating polymer blends for fabricating high performance printed OFETs are reviewed. PMID:28773772

  9. Fabrication and performance of pressure-sensing device consisting of electret film and organic semiconductor

    Science.gov (United States)

    Kodzasa, Takehito; Nobeshima, Daiki; Kuribara, Kazunori; Uemura, Sei; Yoshida, Manabu

    2017-04-01

    We propose a new concept of a pressure-sensitive device that consists of an organic electret film and an organic semiconductor. This device exhibits high sensitivity and selectivity against various types of pressure. The sensing mechanism of this device originates from a modulation of the electric conductivity of the organic semiconductor film induced by the interaction between the semiconductor film and the charged electret film placed face to face. It is expected that a complicated sensor array will be fabricated by using a roll-to-roll manufacturing system, because this device can be prepared by an all-printing and simple lamination process without high-level positional adjustment for printing processes. This also shows that this device with a simple structure is suitable for application to a highly flexible device array sheet for an Internet of Things (IoT) or wearable sensing system.

  10. Organic / IV, III-V Semiconductor Hybrid Solar Cells

    Directory of Open Access Journals (Sweden)

    Pang-Leen Ong

    2010-03-01

    Full Text Available We present a review of the emerging class of hybrid solar cells based on organic-semiconductor (Group IV, III-V, nanocomposites, which states separately from dye synthesized, polymer-metal oxides and organic-inorganic (Group II-VI nanocomposite photovoltaics. The structure of such hybrid cell comprises of an organic active material (p-type deposited by coating, printing or spraying technique on the surface of bulk or nanostructured semiconductor (n-type forming a heterojunction between the two materials. Organic components include various photosensitive monomers (e.g., phtalocyanines or porphyrines, conjugated polymers, and carbon nanotubes. Mechanisms of the charge separation at the interface and their transport are discussed. Also, perspectives on the future development of such hybrid cells and comparative analysis with other classes of photovoltaics of third generation are presented.

  11. Electroless silver plating of the surface of organic semiconductors.

    Science.gov (United States)

    Campione, Marcello; Parravicini, Matteo; Moret, Massimo; Papagni, Antonio; Schröter, Bernd; Fritz, Torsten

    2011-10-04

    The integration of nanoscale processes and devices demands fabrication routes involving rapid, cost-effective steps, preferably carried out under ambient conditions. The realization of the metal/organic semiconductor interface is one of the most demanding steps of device fabrication, since it requires mechanical and/or thermal treatments which increment costs and are often harmful in respect to the active layer. Here, we provide a microscopic analysis of a room temperature, electroless process aimed at the deposition of a nanostructured metallic silver layer with controlled coverage atop the surface of single crystals and thin films of organic semiconductors. This process relies on the reaction of aqueous AgF solutions with the nonwettable crystalline surface of donor-type organic semiconductors. It is observed that the formation of a uniform layer of silver nanoparticles can be accomplished within 20 min contact time. The electrical characterization of two-terminal devices performed before and after the aforementioned treatment shows that the metal deposition process is associated with a redox reaction causing the p-doping of the semiconductor. © 2011 American Chemical Society

  12. Three-dimensional charge transport in organic semiconductor single crystals.

    Science.gov (United States)

    He, Tao; Zhang, Xiying; Jia, Jiong; Li, Yexin; Tao, Xutang

    2012-04-24

    Three-dimensional charge transport anisotropy in organic semiconductor single crystals - both plates and rods (above and below, respectively, in the figure) - is measured in well-performing organic field-effect transistors for the first time. The results provide an excellent model for molecular design and device preparation that leads to good performance. Copyright © 2012 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  13. Organic semiconductor growth and morphology considerations for organic thin-film transistors.

    Science.gov (United States)

    Virkar, Ajay A; Mannsfeld, Stefan; Bao, Zhenan; Stingelin, Natalie

    2010-09-08

    Analogous to conventional inorganic semiconductors, the performance of organic semiconductors is directly related to their molecular packing, crystallinity, growth mode, and purity. In order to achieve the best possible performance, it is critical to understand how organic semiconductors nucleate and grow. Clever use of surface and dielectric modification chemistry can allow one to control the growth and morphology, which greatly influence the electrical properties of the organic transistor. In this Review, the nucleation and growth of organic semiconductors on dielectric surfaces is addressed. The first part of the Review concentrates on small-molecule organic semiconductors. The role of deposition conditions on film formation is described. The modification of the dielectric interface using polymers or self-assembled mono-layers and their effect on organic-semiconductor growth and performance is also discussed. The goal of this Review is primarily to discuss the thin-film formation of organic semiconducting species. The patterning of single crystals is discussed, while their nucleation and growth has been described elsewhere (see the Review by Liu et. al).([¹]) The second part of the Review focuses on polymeric semiconductors. The dependence of physico-chemical properties, such as chain length (i.e., molecular weight) of the constituting macromolecule, and the influence of small molecular species on, e.g., melting temperature, as well as routes to induce order in such macromolecules, are described.

  14. Surface planarization effect of siloxane derivatives in organic semiconductor layers

    Energy Technology Data Exchange (ETDEWEB)

    Sakanoue, Kei [Center for Organic Photonics and Electronics Research, Kyushu University, Nishi-ku, Fukuoka 819-0395 (Japan); Harada, Hironobu; Ando, Kento [Department of Chemical Engineering, Graduate School of Engineering, Kyushu University, Nishi-ku, Fukuoka 819-0395 (Japan); Yahiro, Masayuki [Institute of Systems, Information Technologies and Nanotechnologies, 2-1-22, Sawara-ku, Fukuoka 814-0001 (Japan); Fukai, Jun, E-mail: jfukai@chem-eng.kyushu-u.ac.jp [Department of Chemical Engineering, Graduate School of Engineering, Kyushu University, Nishi-ku, Fukuoka 819-0395 (Japan)

    2015-12-31

    The ability of siloxane surface control additives (SCAs) to planarize organic semiconductor films with a thickness of tens of nanometers printed on indium tin oxide (ITO) surfaces with stripe-patterned bank structures using a liquid-phase method is demonstrated. Three types of SCAs with different molecular structures are examined in organic solutions of toluene, anisole and tetralin containing N,N′-bis(3-methylphenyl)-N,N′-bis(phenyl)-benzidine as a solute and typical organic semiconductor. While there is an optimum SCA and concentration for each solution, one type of SCA is comprehensively effective for all solutions. This SCA increased contact angle, which is contrary to the typical behavior of SCAs. Scanning electron microscope images of the thin films near the banks reveal that this SCA did not change the contact area between the film and substrate surface, which is related to the effectiveness of the SCA. SCAs did not affect the current–voltage characteristics of green organic light-emitting diodes, but did increase external quantum efficiencies, suggesting that SCAs can be used to improve the quality of solution-deposited films for use in optical devices. - Highlights: • Surface control additives planarize organic semiconductor films coated on surfaces. • The most effective additive increases the contact angle of solutions during drying. • The effect of additives is deduced from solutal Marangoni forces. • Additives have little effect on organic light-emitting diode performance.

  15. Surface planarization effect of siloxane derivatives in organic semiconductor layers

    International Nuclear Information System (INIS)

    Sakanoue, Kei; Harada, Hironobu; Ando, Kento; Yahiro, Masayuki; Fukai, Jun

    2015-01-01

    The ability of siloxane surface control additives (SCAs) to planarize organic semiconductor films with a thickness of tens of nanometers printed on indium tin oxide (ITO) surfaces with stripe-patterned bank structures using a liquid-phase method is demonstrated. Three types of SCAs with different molecular structures are examined in organic solutions of toluene, anisole and tetralin containing N,N′-bis(3-methylphenyl)-N,N′-bis(phenyl)-benzidine as a solute and typical organic semiconductor. While there is an optimum SCA and concentration for each solution, one type of SCA is comprehensively effective for all solutions. This SCA increased contact angle, which is contrary to the typical behavior of SCAs. Scanning electron microscope images of the thin films near the banks reveal that this SCA did not change the contact area between the film and substrate surface, which is related to the effectiveness of the SCA. SCAs did not affect the current–voltage characteristics of green organic light-emitting diodes, but did increase external quantum efficiencies, suggesting that SCAs can be used to improve the quality of solution-deposited films for use in optical devices. - Highlights: • Surface control additives planarize organic semiconductor films coated on surfaces. • The most effective additive increases the contact angle of solutions during drying. • The effect of additives is deduced from solutal Marangoni forces. • Additives have little effect on organic light-emitting diode performance.

  16. Quantitative Determination of Organic Semiconductor Microstructure from the Molecular to Device Scale

    KAUST Repository

    Rivnay, Jonathan; Mannsfeld, Stefan C. B.; Miller, Chad E.; Salleo, Alberto; Toney, Michael F.

    2012-01-01

    A study was conducted to demonstrate quantitative determination of organic semiconductor microstructure from the molecular to device scale. The quantitative determination of organic semiconductor microstructure from the molecular to device scale

  17. Interface Structure of MoO3 on Organic Semiconductors

    Science.gov (United States)

    White, Robin T.; Thibau, Emmanuel S.; Lu, Zheng-Hong

    2016-01-01

    We have systematically studied interface structure formed by vapor-phase deposition of typical transition metal oxide MoO3 on organic semiconductors. Eight organic hole transport materials have been used in this study. Ultraviolet photoelectron spectroscopy and X-ray photoelectron spectroscopy are used to measure the evolution of the physical, chemical and electronic structure of the interfaces at various stages of MoO3 deposition on these organic semiconductor surfaces. For the interface physical structure, it is found that MoO3 diffuses into the underlying organic layer, exhibiting a trend of increasing diffusion with decreasing molecular molar mass. For the interface chemical structure, new carbon and molybdenum core-level states are observed, as a result of interfacial electron transfer from organic semiconductor to MoO3. For the interface electronic structure, energy level alignment is observed in agreement with the universal energy level alignment rule of molecules on metal oxides, despite deposition order inversion. PMID:26880185

  18. Novel organic semiconductors and dielectric materials for high performance and low-voltage organic thin-film transistors

    Science.gov (United States)

    Yoon, Myung-Han

    Two novel classes of organic semiconductors based on perfluoroarene/arene-modified oligothiophenes and perfluoroacyl/acyl-derivatized quaterthiophens are developed. The frontier molecular orbital energies of these compounds are studied by optical spectroscopy and electrochemistry while solid-state/film properties are investigated by thermal analysis, x-ray diffraction, and scanning electron microscopy. Organic thin film transistors (OTFTs) performance parameters are discussed in terms of the interplay between semiconductor molecular energetics and film morphologies/microstructures. For perfluoroarene-thiophene oligomer systems, majority charge carrier type and mobility exhibit a strong correlation with the regiochemistry of perfluoroarene incorporation. In quaterthiophene-based semiconductors, carbonyl-functionalization allows tuning of the majority carrier type from p-type to ambipolar and to n-type. In situ conversion of a p-type semiconducting film to n-type film is also demonstrated. Very thin self-assembled or spin-on organic dielectric films have been integrated into OTFTs to achieve 1 - 2 V operating voltages. These new dielectrics are deposited either by layer-by-layer solution phase deposition of molecular precursors or by spin-coating a mixture of polymer and crosslinker, resulting in smooth and virtually pinhole-free thin films having exceptionally large capacitances (300--700 nF/cm2) and low leakage currents (10 -9 - 10-7 A/cm2). These organic dielectrics are compatible with various vapor- or solution-deposited p- and n-channel organic semiconductors. Furthermore, it is demonstrated that spin-on crosslinked-polymer-blend dielectrics can be employed for large-area/patterned electronics, and complementary inverters. A general approach for probing semiconductor-dielectric interface effects on OTFT performance parameters using bilayer gate dielectrics is presented. Organic semiconductors having p-, n-type, or ambipolar majority charge carriers are grown on

  19. Charging and exciton-mediated decharging of metal nanoparticles in organic semiconductor matrices

    International Nuclear Information System (INIS)

    Ligorio, Giovanni; Vittorio Nardi, Marco; Christodoulou, Christos; Florea, Ileana; Ersen, Ovidiu; Monteiro, Nicolas-Crespo; Brinkmann, Martin; Koch, Norbert

    2014-01-01

    Gold nanoparticles (Au-NPs) were deposited on the surface of n- and p-type organic semiconductors to form defined model systems for charge storage based electrically addressable memory elements. We used ultraviolet photoelectron spectroscopy to study the electronic properties and found that the Au-NPs become positively charged because of photoelectron emission, evidenced by spectral shifts to higher binding energy. Upon illumination with light that can be absorbed by the organic semiconductors, dynamic charge neutrality of the Au-NPs could be re-established through electron transfer from excitons. The light-controlled charge state of the Au-NPs could add optical addressability to memory elements

  20. Origin of poor doping efficiency in solution processed organic semiconductors.

    Science.gov (United States)

    Jha, Ajay; Duan, Hong-Guang; Tiwari, Vandana; Thorwart, Michael; Miller, R J Dwayne

    2018-05-21

    Doping is an extremely important process where intentional insertion of impurities in semiconductors controls their electronic properties. In organic semiconductors, one of the convenient, but inefficient, ways of doping is the spin casting of a precursor mixture of components in solution, followed by solvent evaporation. Active control over this process holds the key to significant improvements over current poor doping efficiencies. Yet, an optimized control can only come from a detailed understanding of electronic interactions responsible for the low doping efficiencies. Here, we use two-dimensional nonlinear optical spectroscopy to examine these interactions in the course of the doping process by probing the solution mixture of doped organic semiconductors. A dopant accepts an electron from the semiconductor and the two ions form a duplex of interacting charges known as ion-pair complexes. Well-resolved off-diagonal peaks in the two-dimensional spectra clearly demonstrate the electronic connectivity among the ions in solution. This electronic interaction represents a well resolved electrostatically bound state, as opposed to a random distribution of ions. We developed a theoretical model to recover the experimental data, which reveals an unexpectedly strong electronic coupling of ∼250 cm -1 with an intermolecular distance of ∼4.5 Å between ions in solution, which is approximately the expected distance in processed films. The fact that this relationship persists from solution to the processed film gives direct evidence that Coulomb interactions are retained from the precursor solution to the processed films. This memory effect renders the charge carriers equally bound also in the film and, hence, results in poor doping efficiencies. This new insight will help pave the way towards rational tailoring of the electronic interactions to improve doping efficiencies in processed organic semiconductor thin films.

  1. Semiconductors and semimetals nanostructured systems

    CERN Document Server

    Willardson, Robert K; Beer, Albert C; Reed, Mark A

    1992-01-01

    This is the first available volume to consolidate prominent topics in the emerging field of nanostructured systems. Recent technological advancements have led to a new era of nanostructure physics, allowing for the fabrication of nanostructures whose behavior is dominated by quantum interference effects. This new capability has enthused the experimentalist and theorist alike. Innumerable possibilities have now opened up for physical exploration and device technology on the nanoscale. This book, with contributions from five pioneering researchers, will allow the expert and novice alike to explore a fascinating new field.Provides a state-of-the-art review of quantum-scale artificially nanostructured electronic systemsIncludes contributions by world-known experts in the fieldOpens the field to the non-expert with a concise introductionFeatures discussions of:Low-dimensional condensed matter physicsProperties of nanostructured, ultrasmall electronic systemsMesoscopic physics and quantum transportPhysics of 2D ele...

  2. Toward continuous-wave operation of organic semiconductor lasers

    Science.gov (United States)

    Sandanayaka, Atula S. D.; Matsushima, Toshinori; Bencheikh, Fatima; Yoshida, Kou; Inoue, Munetomo; Fujihara, Takashi; Goushi, Kenichi; Ribierre, Jean-Charles; Adachi, Chihaya

    2017-01-01

    The demonstration of continuous-wave lasing from organic semiconductor films is highly desirable for practical applications in the areas of spectroscopy, data communication, and sensing, but it still remains a challenging objective. We report low-threshold surface-emitting organic distributed feedback lasers operating in the quasi–continuous-wave regime at 80 MHz as well as under long-pulse photoexcitation of 30 ms. This outstanding performance was achieved using an organic semiconductor thin film with high optical gain, high photoluminescence quantum yield, and no triplet absorption losses at the lasing wavelength combined with a mixed-order distributed feedback grating to achieve a low lasing threshold. A simple encapsulation technique greatly reduced the laser-induced thermal degradation and suppressed the ablation of the gain medium otherwise taking place under intense continuous-wave photoexcitation. Overall, this study provides evidence that the development of a continuous-wave organic semiconductor laser technology is possible via the engineering of the gain medium and the device architecture. PMID:28508042

  3. n-Channel semiconductor materials design for organic complementary circuits.

    Science.gov (United States)

    Usta, Hakan; Facchetti, Antonio; Marks, Tobin J

    2011-07-19

    Organic semiconductors have unique properties compared to traditional inorganic materials such as amorphous or crystalline silicon. Some important advantages include their adaptability to low-temperature processing on flexible substrates, low cost, amenability to high-speed fabrication, and tunable electronic properties. These features are essential for a variety of next-generation electronic products, including low-power flexible displays, inexpensive radio frequency identification (RFID) tags, and printable sensors, among many other applications. Accordingly, the preparation of new materials based on π-conjugated organic molecules or polymers has been a central scientific and technological research focus over the past decade. Currently, p-channel (hole-transporting) materials are the leading class of organic semiconductors. In contrast, high-performance n-channel (electron-transporting) semiconductors are relatively rare, but they are of great significance for the development of plastic electronic devices such as organic field-effect transistors (OFETs). In this Account, we highlight the advances our team has made toward realizing moderately and highly electron-deficient n-channel oligomers and polymers based on oligothiophene, arylenediimide, and (bis)indenofluorene skeletons. We have synthesized and characterized a "library" of structurally related semiconductors, and we have investigated detailed structure-property relationships through optical, electrochemical, thermal, microstructural (both single-crystal and thin-film), and electrical measurements. Our results reveal highly informative correlations between structural parameters at various length scales and charge transport properties. We first discuss oligothiophenes functionalized with perfluoroalkyl and perfluoroarene substituents, which represent the initial examples of high-performance n-channel semiconductors developed in this project. The OFET characteristics of these compounds are presented with an

  4. Progress of pyrene-based organic semiconductor in organic field effect transistors

    Institute of Scientific and Technical Information of China (English)

    Yanbin; Gong; Xuejun; Zhan; Qianqian; Li; Zhen; Li

    2016-01-01

    Thanks to the pure blue emitting, high planarity, electron rich and ease of chemical modification, pyrene has been thoroughly investigated for applications in organic electronics such as organic light emitting diodes(OLEDs), organic field effect transistors(OFETs), and organic solar cells(OSCs). Especially, great progresses have been made of pyrene-based organic semiconductors for OFETs in past decades. Due to the difference of molecular structure, pyrene-based organic semiconductors are divided into three categories, pyrene as terminal group, pyrene as center core and fused pyrene derivatives. This minireview gives a brief introduction of the structure-property relationship and application in OFETs about most of pyrene-based semiconducting materials since 2006,illustrating that pyrene is a good building block to construct semiconductors with superior transport property for OFETs. Finally, we provide a summary concerning the methodology to improve the transport property of the pyrene-based semiconducting materials as well as an outlook.

  5. Molecular and polymeric organic semiconductors for applications in photovoltaic devices

    International Nuclear Information System (INIS)

    Meinhardt, G.

    2000-01-01

    Photovoltaic devices based on molecular as well as polymeric semiconductors were investigated and characterized. The organic materials presented here exhibit the advantages of low price, low processing costs and the possibility of tuning their optical properties. The photovoltaic properties were investigated by photocurrent action spectroscopy and I/V-characterization and the electric field distribution in each layer by electroabsorption spectroscopy. Single layer devices of molecular semiconductors and semiconducting polymers like methyl-substituted polyparaphenylene, CN-Ether-PPV, copper-phthalocyanine, the terryleneimide DOTer, the perylene derivatives BBP-perylene and polyBBP-perylene show low photocurrents as well as a small photovoltaic effect in their pristine form. One way to enhance the performance is to blend the active layer with molecular dopands like a soluble form of titaniumoxophthalocyanine or the aromatic macromolecule RS19 or to combine two organic semiconductors in heterostructure devices. The motivation for these experiments was the optimization of either charge transfer or energy transfer from one molecule to its neighbor molecule. A model based on the internal filter effect was used for fitting the photoresponse of single layer devices. For optimising heterostructure solar cells a more sophisticated theoretical model taking into account interference effects was used. (author)

  6. Paramagnetic resonance and electronic conduction in organic semiconductors

    International Nuclear Information System (INIS)

    Nechtschein, M.

    1963-01-01

    As some organic bodies simultaneously display semi-conducting properties and a paramagnetism, this report addresses the study of conduction in organic bodies. The author first briefly recalls how relationships between conductibility and Electron Paramagnetic Resonance (EPR) can be noticed in a specific case (mineral and metallic semiconductors). He discusses published results related to paramagnetism and conductibility in organic bodies. He reviews various categories of organic bodies in which both properties are simultaneously present. He notably addresses radical molecular crystals, non-radical molecular crystals, charge transfer complexes, pyrolyzed coals, and pseudo-ferromagnetic organic structures. He discusses the issue of relationships between conduction (charge transfer by electrons) and ERP (which reveals the existence of non-paired electrons which provide free spins)

  7. Origin and role of gap states in organic semiconductor studied by UPS: as the nature of organic molecular crystals

    International Nuclear Information System (INIS)

    Yang, Jin-Peng; Bussolotti, Fabio; Kera, Satoshi; Ueno, Nobuo

    2017-01-01

    This article reviews experimental studies on ‘bridging electronic structure and charge transport property of organic semiconductors’ performed using ultraviolet photoelectron spectroscopy (UPS) and related methods mainly in Chiba University, Japan, in particular on the investigation of the origin and the role of electronic states existing in the highest occupied molecular orbital band–lowest unoccupied molecular orbital band (HOMO–LUMO) gap. We summarize experimental observations including direct measurements of ‘invisible’ gap states with ultrahigh sensitivity UPS, which demonstrate that there exist intrinsic gap states in organic semiconductors. We firstly describe the nature of organic molecular solids to understand features of organic semiconductors because such intrinsic gap states are a result of the interplay of these features, which give the principal difference between the organic semiconductor and inorganic counterpart. We then discuss (i) the origin and role of the band gap states in relation to intermolecular interaction/band dispersion and electron–phonon coupling, (ii) the Fermi level pinning issue in organic semiconductors, and (iii) the method of computing the Fermi level position within the HOMO–LUMO gap for experimental groups. The gap states of organic semiconductors appear easily when a weak perturbation is applied to the organic system, namely by contact with other material, by injecting a charge, by elevating temperature, and by exposure to 1 atm gas. What we finally found is that tailing states of HOMO and LUMO always exist, and their energy distributions must not be symmetric; they thus produce a larger Fermi level shift from the mid gap position than previously thought. Furthermore, as shown by computational work, Fermi level pinning , which is a well-known phenomena in semiconductor devices field, occurs in weakly interacting organic/conductor systems without any gap states if the system temperature is not zero ( T

  8. Origin and role of gap states in organic semiconductor studied by UPS: as the nature of organic molecular crystals

    Science.gov (United States)

    Yang, Jin-Peng; Bussolotti, Fabio; Kera, Satoshi; Ueno, Nobuo

    2017-10-01

    This article reviews experimental studies on ‘bridging electronic structure and charge transport property of organic semiconductors’ performed using ultraviolet photoelectron spectroscopy (UPS) and related methods mainly in Chiba University, Japan, in particular on the investigation of the origin and the role of electronic states existing in the highest occupied molecular orbital band-lowest unoccupied molecular orbital band (HOMO-LUMO) gap. We summarize experimental observations including direct measurements of ‘invisible’ gap states with ultrahigh sensitivity UPS, which demonstrate that there exist intrinsic gap states in organic semiconductors. We firstly describe the nature of organic molecular solids to understand features of organic semiconductors because such intrinsic gap states are a result of the interplay of these features, which give the principal difference between the organic semiconductor and inorganic counterpart. We then discuss (i) the origin and role of the band gap states in relation to intermolecular interaction/band dispersion and electron-phonon coupling, (ii) the Fermi level pinning issue in organic semiconductors, and (iii) the method of computing the Fermi level position within the HOMO-LUMO gap for experimental groups. The gap states of organic semiconductors appear easily when a weak perturbation is applied to the organic system, namely by contact with other material, by injecting a charge, by elevating temperature, and by exposure to 1 atm gas. What we finally found is that tailing states of HOMO and LUMO always exist, and their energy distributions must not be symmetric; they thus produce a larger Fermi level shift from the mid gap position than previously thought. Furthermore, as shown by computational work, Fermi level pinning, which is a well-known phenomena in semiconductor devices field, occurs in weakly interacting organic/conductor systems without any gap states if the system temperature is not zero (T  >  0). We

  9. Electronic and optical properties of diamond/organic semiconductor heterostructures

    Energy Technology Data Exchange (ETDEWEB)

    Gajewski, Wojciech; Garrido, Jose; Niedermeier, Martin; Stutzmann, Martin [Walter Schottky Institute, TU Muenchen, Am Coulombwall 3, 85748 Garching (Germany); Williams, Oliver; Haenen, Ken [Institute for Materials Research, University of Hasselt, Wetenschapspark 1, BE-3590 Diepenbeek (Belgium)

    2007-07-01

    Different diamond substrates (single crystalline: SCD, poly-crystalline: PCD and nano-crystalline: NCD) were used to investigate the electronic and optical properties of the diamond/organic semiconductor heterostructures. Layers of a poly[ethynyl-(2-decyloxy-5methoxy)benzene] - PEB, pentacene and 4-nitro-biphenyl-4-diazonium cations - Ph-Ph-NO{sub 2} were prepared by spin coating, thermal evaporation and grafting, respectively. The measurements of the electronic transport along the organic layer were performed using a Hg probe as well as Hall effect measurements in the temperature range 70-400 K. The I-V characteristics of the B-doped diamond/organic semiconductor heterostructures were measured at room temperature by means of the Hg probe. Undoped IIa and undoped PCD films were used for a study of the optical and optoelectronic properties of prepared heterostructures. The influence of the organic layer homogeneity and layer thickness on the optical properties will be discussed. Furthermore, preliminary data on perpendicular and parallel transport in the heterostructures layer will be reported.

  10. Strain effects on the work function of an organic semiconductor

    KAUST Repository

    Wu, Yanfei

    2016-02-01

    Establishing fundamental relationships between strain and work function (WF) in organic semiconductors is important not only for understanding electrical properties of organic thin films, which are subject to both intrinsic and extrinsic strains, but also for developing flexible electronic devices. Here we investigate tensile and compressive strain effects on the WF of rubrene single crystals. Mechanical strain induced by thermal expansion mismatch between the substrate and rubrene is quantified by X-ray diffraction. The corresponding WF change is measured by scanning Kelvin probe microscopy. The WF of rubrene increases (decreases) significantly with in-plane tensile (compressive) strain, which agrees qualitatively with density functional theory calculations. An elastic-to-plastic transition, characterized by a steep rise of the WF, occurs at ~0.05% tensile strain along the rubrene π-stacking direction. The results provide the first concrete link between mechanical strain and WF of an organic semiconductor and have important implications for understanding the connection between structural and electronic disorder in soft organic electronic materials.

  11. Electrical characterization of organic-on-inorganic semiconductor Schottky structures

    International Nuclear Information System (INIS)

    Guellue, Oe; Tueruet, A; Asubay, S

    2008-01-01

    We prepared a methyl red/p-InP organic-inorganic (OI) Schottky device formed by evaporation of an organic compound solution directly to a p-InP semiconductor wafer. The value of the optical band gap energy of the methyl red organic film on a glass substrate was obtained as 2.0 eV. It was seen that the Al/methyl red/p-InP contacts showed a good rectifying behavior. An ideality factor of 2.02 and a barrier height (Φ b ) of 1.11 eV for the Al/methyl red/p-InP contact were determined from the forward bias I-V characteristics. It was seen that the value of 1.11 eV obtained for Φ b for the Al/methyl red/p-InP contact was significantly larger than the value of 0.83 eV for conventional Al/p-InP Schottky diodes. Modification of the interfacial potential barrier for the Al/p-InP diode was achieved using a thin interlayer of the methyl red organic semiconductor. This ascribed to the fact that the methyl red interlayer increases the effective Φ b by influencing the space charge region of InP

  12. Strain effects on the work function of an organic semiconductor

    Science.gov (United States)

    Wu, Yanfei; Chew, Annabel R.; Rojas, Geoffrey A.; Sini, Gjergji; Haugstad, Greg; Belianinov, Alex; Kalinin, Sergei V.; Li, Hong; Risko, Chad; Brédas, Jean-Luc; Salleo, Alberto; Frisbie, C. Daniel

    2016-01-01

    Establishing fundamental relationships between strain and work function (WF) in organic semiconductors is important not only for understanding electrical properties of organic thin films, which are subject to both intrinsic and extrinsic strains, but also for developing flexible electronic devices. Here we investigate tensile and compressive strain effects on the WF of rubrene single crystals. Mechanical strain induced by thermal expansion mismatch between the substrate and rubrene is quantified by X-ray diffraction. The corresponding WF change is measured by scanning Kelvin probe microscopy. The WF of rubrene increases (decreases) significantly with in-plane tensile (compressive) strain, which agrees qualitatively with density functional theory calculations. An elastic-to-plastic transition, characterized by a steep rise of the WF, occurs at ∼0.05% tensile strain along the rubrene π-stacking direction. The results provide the first concrete link between mechanical strain and WF of an organic semiconductor and have important implications for understanding the connection between structural and electronic disorder in soft organic electronic materials. PMID:26831362

  13. Elementary steps in electrical doping of organic semiconductors

    KAUST Repository

    Tietze, Max Lutz

    2018-03-15

    Fermi level control by doping is established since decades in inorganic semiconductors and has been successfully introduced in organic semiconductors. Despite its commercial success in the multi-billion OLED display business, molecular doping is little understood, with its elementary steps controversially discussed and mostly-empirical-materials design. Particularly puzzling is the efficient carrier release, despite a presumably large Coulomb barrier. Here we quantitatively investigate doping as a two-step process, involving single-electron transfer from donor to acceptor molecules and subsequent dissociation of the ground-state integer-charge transfer complex (ICTC). We show that carrier release by ICTC dissociation has an activation energy of only a few tens of meV, despite a Coulomb binding of several 100 meV. We resolve this discrepancy by taking energetic disorder into account. The overall doping process is explained by an extended semiconductor model in which occupation of ICTCs causes the classically known reserve regime at device-relevant doping concentrations.

  14. New mechanism of semiconductor polarization at the interface with an organic insulator

    International Nuclear Information System (INIS)

    Yafyasov, A. M.; Bogevolnov, V. B.; Ryumtsev, E. I.; Kovshik, A. P.; Mikhailovski, V. Yu.

    2017-01-01

    A semiconductor—organic-insulator system with spatially distributed charge is created with a uniquely low density of fast surface states (N_s_s) at the interface. A system with N_s_s ≈ 5 × 10"1"0 cm"–"2 is obtained for the example of n-Ge and the physical characteristics of the interface are measured for this system with liquid and metal field electrodes. For a system with an organic insulator, the range of variation of the surface potential from enrichment of the space-charge region of the semiconductor to the inversion state is first obtained without changing the mechanism of interaction between the adsorbed layer and the semiconductor surface. The effect of enhanced polarization of the space-charge region of the semiconductor occurs due to a change in the spatial structure of mobile charge in the organic dielectric layer. The system developed in the study opens up technological opportunities for the formation of a new generation of electronic devices based on organic film structures and for experimental modeling of the electronic properties of biological membranes.

  15. New mechanism of semiconductor polarization at the interface with an organic insulator

    Energy Technology Data Exchange (ETDEWEB)

    Yafyasov, A. M., E-mail: yafyasov@gmail.com; Bogevolnov, V. B.; Ryumtsev, E. I.; Kovshik, A. P. [St. Petersburg State University (Russian Federation); Mikhailovski, V. Yu. [Interdisciplinary Resource Center for Nanotechnology at St. Petersburg University (Russian Federation)

    2017-02-15

    A semiconductor—organic-insulator system with spatially distributed charge is created with a uniquely low density of fast surface states (N{sub ss}) at the interface. A system with N{sub ss} ≈ 5 × 10{sup 10} cm{sup –2} is obtained for the example of n-Ge and the physical characteristics of the interface are measured for this system with liquid and metal field electrodes. For a system with an organic insulator, the range of variation of the surface potential from enrichment of the space-charge region of the semiconductor to the inversion state is first obtained without changing the mechanism of interaction between the adsorbed layer and the semiconductor surface. The effect of enhanced polarization of the space-charge region of the semiconductor occurs due to a change in the spatial structure of mobile charge in the organic dielectric layer. The system developed in the study opens up technological opportunities for the formation of a new generation of electronic devices based on organic film structures and for experimental modeling of the electronic properties of biological membranes.

  16. Organic-Inorganic Composites of Semiconductor Nanocrystals for Efficient Excitonics.

    Science.gov (United States)

    Guzelturk, Burak; Demir, Hilmi Volkan

    2015-06-18

    Nanocomposites of colloidal semiconductor nanocrystals integrated into conjugated polymers are the key to soft-material hybrid optoelectronics, combining advantages of both plastics and particles. Synergic combination of the favorable properties in the hybrids of colloidal nanocrystals and conjugated polymers offers enhanced performance and new functionalities in light-generation and light-harvesting applications, where controlling and mastering the excitonic interactions at the nanoscale are essential. In this Perspective, we highlight and critically consider the excitonic interactions in the organic-inorganic nanocomposites to achieve highly efficient exciton transfer through rational design of the nanocomposites. The use of strong excitonic interactions in optoelectronic devices can trigger efficiency breakthroughs in hybrid optoelectronics.

  17. Flexible Synthetic Semiconductor Applied in Optoelectronic Organic Sensor

    Directory of Open Access Journals (Sweden)

    Andre F. S. Guedes

    2017-06-01

    Full Text Available The synthesis and application of new nanostructured organic materials, for the development of technology based on organic devices, have taken great interest from the scientific community. The greatest interest in studying organic semiconductor materials has been connected to its already known potential applications, such as: batteries, organic solar cells, flexible organic solar cells, organic light emitting diodes, organic sensors and others. Phototherapy makes use of different radiation sources, and the treatment of hyperbilirubinemia the most common therapeutic intervention occurs in the neonatal period. In this work we developed an organic optoelectronic sensor capable of detecting and determining the radiation dose rate emitted by the radiation source of neonatal phototherapy equipment. The sensors were developed using optically transparent substrate with Nanostructured thin film layers of Poly(9-Vinylcarbazole covered by a layer of Poly(P-Phenylene Vinylene. The samples were characterized by UV-Vis Spectroscopy, Electrical Measurements and SEM. With the results obtained from this study can be developed dosimeters organics to the neonatal phototherapy equipment.

  18. Understanding polymorphism in organic semiconductor thin films through nanoconfinement.

    Science.gov (United States)

    Diao, Ying; Lenn, Kristina M; Lee, Wen-Ya; Blood-Forsythe, Martin A; Xu, Jie; Mao, Yisha; Kim, Yeongin; Reinspach, Julia A; Park, Steve; Aspuru-Guzik, Alán; Xue, Gi; Clancy, Paulette; Bao, Zhenan; Mannsfeld, Stefan C B

    2014-12-10

    Understanding crystal polymorphism is a long-standing challenge relevant to many fields, such as pharmaceuticals, organic semiconductors, pigments, food, and explosives. Controlling polymorphism of organic semiconductors (OSCs) in thin films is particularly important given that such films form the active layer in most organic electronics devices and that dramatic changes in the electronic properties can be induced even by small changes in the molecular packing. However, there are very few polymorphic OSCs for which the structure-property relationships have been elucidated so far. The major challenges lie in the transient nature of metastable forms and the preparation of phase-pure, highly crystalline thin films for resolving the crystal structures and evaluating the charge transport properties. Here we demonstrate that the nanoconfinement effect combined with the flow-enhanced crystal engineering technique is a powerful and likely material-agnostic method to identify existing polymorphs in OSC materials and to prepare the individual pure forms in thin films at ambient conditions. With this method we prepared high quality crystal polymorphs and resolved crystal structures of 6,13-bis(triisopropylsilylethynyl)pentacene (TIPS-pentacene), including a new polymorph discovered via in situ grazing incidence X-ray diffraction and confirmed by molecular mechanic simulations. We further correlated molecular packing with charge transport properties using quantum chemical calculations and charge carrier mobility measurements. In addition, we applied our methodology to a [1]benzothieno[3,2-b][1]1benzothiophene (BTBT) derivative and successfully stabilized its metastable form.

  19. Transport Gap and exciton binding energy determination in organic semiconductors

    Energy Technology Data Exchange (ETDEWEB)

    Krause, Stefan; Schoell, Achim; Reinert, Friedrich; Umbach, Eberhard [University of Wuerzburg (Germany). Experimental Physics II; Casu, Benedetta [Inst. f. Physik. u. Theor. Chemie, Tuebingen (Germany)

    2008-07-01

    The transport gap of an organic semiconductor is defined as the energy difference between the HOMO and LUMO levels in the presence of a hole or electron, respectively, after relaxation has occurred. Its knowledge is mandatory for the optimisation of electronic devices based on these materials. UV photoelectron spectroscopy (UPS) and inverse photoelectron spectroscopy (IPES) are routinely applied to measure these molecular levels. However, the precise determination of the transport gap on the basis of the respective data is not an easy task. It involves fundamental questions about the properties of organic molecules and their condensates, about their reaction on the experimental probe, and on the evaluation of the spectroscopic data. In particular electronic relaxation processes, which occur on the time scale of the photo excitation, have to be considered adequately. We determined the transport gap for the organic semiconductors PTCDA, Alq3, DIP, CuPc, and PBI-H4. After careful data analysis and comparison to the respective values for the optical gap we obtain values for the exciton binding energies between 0.1-0.5 eV. This is considerably smaller than commonly believed and indicates a significant delocalisation of the excitonic charge over various molecular units.

  20. Nanoscale contacts to organic molecules based on layered semiconductor substrates

    Energy Technology Data Exchange (ETDEWEB)

    Strobel, Sebastian

    2009-06-15

    This work reports on the integration of organic molecules as nanoelectronic device units on semiconductor substrates. Two novel preparation methods for sub-10-nm separated metal electrodes are presented using current microelectronics process technology. The first method utilises AlGaAs/GaAs heterostructures grown by molecular beam epitaxy (MBE) as mold to create planar metal electrodes employing a newly developed, high resolution nanotransfer printing (nTP) process. The second method uses commercially available Silicon-on-Insulator (SOI) substrates as base material for the fabrication of nanogap electrode devices. This sandwich-like material stack consists of a silicon substrate, a thin silicon oxide layer, and a capping silicon layer on top. Electronic transport measurements verified their excellent electrical properties at liquid helium temperatures. Specifically tailored nanogap devices featured an electrode insulation in the GW range even up to room temperature as well as within aqueous electrolyte solution. Finally, the well defined layer architecture facilitated the fabrication of electrodes with gap separations below-10-nm to be directly bridged by molecules. Approximately 12-nm-long conjugated molecules with extended -electron system were assembled onto the devices from solution. A large conductance gap was observed with a steep increase in current at a bias voltage of V{sub T}{approx}{+-}1.5 V. Theoretical calculations based on density functional theory and non-equilibrium Green's function formalism confirmed the measured non-linear IV-characteristics qualitatively and lead to the conclusion that the conductance gap mainly originates from the oxygen containing linker. Temperature dependent investigations of the conductance indicated a hopping charge transport mechanism through the central part of the molecule for bias voltages near but below V{sub T}. (orig.)

  1. Photoelectrochemical processes in organic semiconductor: Ambipolar perylene diimide thin film

    Science.gov (United States)

    Kim, Jung Yong; Chung, In Jae

    2018-03-01

    A thin film of N,N‧-dioctadecyl-3,4,9,10-perylene tetracarboxylic diimide (PTCDI-C18) is spin-coated on indium tin oxide (ITO) glass. Using the PTCDI-C18/ITO electrode, we fabricate a photoelectrochemical cell with the ITO/PTCDI-C18/Redox Electrolyte/Pt configuration. The electrochemical properties of this device are investigated as a function of hydroquinone (HQ) concentration, bias voltage, and wavelength of light. Anodic photocurrent is observed at V ≥ -0.2 V vs. Ag/AgCl, indicating that the PTCDI-C18 film acts as an n-type semiconductor as usual. However, when benzoquinone (BQ) is inserted into the electrolyte system instead of HQ, cathodic photocurrent is observed at V ≤ 0.0 V, displaying that PTCDI-C18 abnormally serves as a p-type semiconductor. Hence the overall results reveal that the PTCDI-C18 film can be an ambipolar functional semiconductor depending on the redox couple in the appropriate voltage.

  2. Range and energetics of charge hopping in organic semiconductors

    Science.gov (United States)

    Abdalla, Hassan; Zuo, Guangzheng; Kemerink, Martijn

    2017-12-01

    The recent upswing in attention for the thermoelectric properties of organic semiconductors (OSCs) adds urgency to the need for a quantitative description of the range and energetics of hopping transport in organic semiconductors under relevant circumstances, i.e., around room temperature (RT). In particular, the degree to which hops beyond the nearest neighbor must be accounted for at RT is still largely unknown. Here, measurements of charge and energy transport in doped OSCs are combined with analytical modeling to reach the univocal conclusion that variable-range hopping is the proper description in a large class of disordered OSC at RT. To obtain quantitative agreement with experiment, one needs to account for the modification of the density of states by ionized dopants. These Coulomb interactions give rise to a deep tail of trap states that is independent of the material's initial energetic disorder. Insertion of this effect into a classical Mott-type variable-range hopping model allows one to give a quantitative description of temperature-dependent conductivity and thermopower measurements on a wide range of disordered OSCs. In particular, the model explains the commonly observed quasiuniversal power-law relation between the Seebeck coefficient and the conductivity.

  3. Charge transport in electrically doped amorphous organic semiconductors.

    Science.gov (United States)

    Yoo, Seung-Jun; Kim, Jang-Joo

    2015-06-01

    This article reviews recent progress on charge generation by doping and its influence on the carrier mobility in organic semiconductors (OSs). The doping induced charge generation efficiency is generally low in OSs which was explained by the integer charge transfer model and the hybrid charge transfer model. The ionized dopants formed by charge transfer between hosts and dopants can act as Coulomb traps for mobile charges, and the presence of Coulomb traps in OSs broadens the density of states (DOS) in doped organic films. The Coulomb traps strongly reduce the carrier hopping rate and thereby change the carrier mobility, which was confirmed by experiments in recent years. In order to fully understand the doping mechanism in OSs, further quantitative and systematic analyses of charge transport characteristics must be accomplished. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  4. Thermoelectric transport properties of high mobility organic semiconductors

    Science.gov (United States)

    Venkateshvaran, Deepak; Broch, Katharina; Warwick, Chris N.; Sirringhaus, Henning

    2016-09-01

    Transport in organic semiconductors has traditionally been investigated using measurements of the temperature and gate voltage dependent mobility of charge carriers within the channel of organic field-effect transistors (OFETs). In such measurements, the behavior of charge carrier mobility with temperature and gate voltage, studied together with carrier activation energies, provide a metric to quantify the extent of disorder within these van der Waals bonded materials. In addition to the mobility and activation energy, another potent but often-overlooked transport coefficient useful in understanding disorder is the Seebeck coefficient (also known as thermoelectric power). Fundamentally, the Seebeck coefficient represents the entropy per charge carrier in the solid state, and thus proves powerful in distinguishing materials in which charge carriers move freely from those where a high degree of disorder causes the induced carriers to remain trapped. This paper briefly covers the recent highlights in the field of organic thermoelectrics, showing how significant strides have been made both from an applied standpoint as well as from a viewpoint of fundamental thermoelectric transport physics. It shall be illustrated how thermoelectric transport parameters in organic semiconductors can be tuned over a significant range, and how this tunability facilitates an enhanced performance for heat-to-electricity conversion as well as quantifies energetic disorder and the nature of the density of states (DOS). The work of the authors shall be spotlighted in this context, illustrating how Seebeck coefficient measurements in the polymer indacenodithiophene-co-benzothiadiazole (IDTBT) known for its ultra-low degree of torsion within the polymer backbone, has a trend consistent with low disorder. 1 Finally, using examples of the small molecules C8-BTBT and C10-DNTT, it shall be discussed how the Seebeck coefficient can aid the estimation of the density and distribution of trap states

  5. Reactivity of group IV (100) semiconductor surfaces towards organic compounds

    Science.gov (United States)

    Wang, George T.

    The reactions of simple and multifunctional organic compounds with the clean silicon, germanium, and diamond (100)-2 x 1 semiconductor surfaces have been investigated using a combination of multiple internal reflection infrared spectroscopy and quantum chemistry density functional theory calculations. From these studies, an improved understanding of the atomic level reactivity of these semiconductor surfaces has been obtained, along with insights into how to achieve their selective coupling with organics of desired and varied functionality. In addition to the Si(100) and Ge(100) surfaces, our results show that cycloaddition chemistry can also be extended to the diamond (100) surface. At room temperature, 1,3-butadiene was found to form a Diels-Alder product with the diamond (100) surface, as evidenced by isotopic substitution experiments and comparison of the surface adduct with its direct molecular analogue, cyclohexene. The reactions of other classes of molecules in addition to alkenes on the Si(100) and Ge(100) surfaces, including a series of five-membered cyclic amines, were also examined. For tertiary aliphatic amines on Si(100) and both secondary and tertiary aliphatic amines on Ge(100), a majority of the molecules were observed to become stably trapped in dative-bonded precursor states rather than form energetically favorable dissociation products. For pyrrole, aromaticity was found to play a defining role in its reactivity, and a comparison of its molecular and surface reactivity reveals interesting similarities. To probe the factors controlling the selectivity of organic reactions on clean semiconductor surfaces, the adsorption of acetone and a series of unsaturated ketones was also investigated. The reaction of acetone on Ge(100) was found to be under thermodynamic control at room temperature, resulting in the formation of an "ene" product rather than the kinetically favored [2+2] C=O cycloaddition product previously observed on the Si(100) surface. In

  6. Lewis Acid-Base Chemistry of 7-Azaisoindigo-Based Organic Semiconductors.

    Science.gov (United States)

    Randell, Nicholas M; Fransishyn, Kyle M; Kelly, Timothy L

    2017-07-26

    Low-band-gap organic semiconductors are important in a variety of organic electronics applications, such as organic photovoltaic devices, photodetectors, and field effect transistors. Building on our previous work, which introduced 7-azaisoindigo as an electron-deficient building block for the synthesis of donor-acceptor organic semiconductors, we demonstrate how Lewis acids can be used to further tune the energies of the frontier molecular orbitals. Coordination of a Lewis acid to the pyridinic nitrogen of 7-azaisoindigo greatly diminishes the electron density in the azaisoindigo π-system, resulting in a substantial reduction in the lowest unoccupied molecular orbital (LUMO) energy. This results in a smaller highest occupied molecular orbital-LUMO gap and shifts the lowest-energy electronic transition well into the near-infrared region. Both H + and BF 3 are shown to coordinate to azaisoindigo and affect the energy of the S 0 → S 1 transition. A combination of time-dependent density functional theory and UV/vis and 1 H NMR spectroscopic titrations reveal that when two azaisoindigo groups are present and high concentrations of acid are used, both pyridinic nitrogens bind Lewis acids. Importantly, we demonstrate that this acid-base chemistry can be carried out at the solid-vapor interface by exposing thin films of aza-substituted organic semiconductors to vapor-phase BF 3 ·Et 2 O. This suggests the possibility of using the BF 3 -bound 7-azaisoindigo-based semiconductors as n-type materials in various organic electronic applications.

  7. Validity of the concept of band edge in organic semiconductors

    Science.gov (United States)

    Horowitz, Gilles

    2015-09-01

    Because most organic semiconductors are disordered, the more appropriate function to describe their density of states (DOS) is the Gaussian distribution. A striking difference between the Gaussian DOS and the parabolic DOS found in conventional inorganic semiconductors is the fact that it does not allow for a simple and straightforward definition of the band edge. The most usual way found in the literature to define the band edge of a Gaussian DOS consists of extrapolating the tangent to the inflection point of the Gaussian curve. The aim of this paper is to discuss the validity of such a way of conduct. An analysis of data found in the literature shows that the width of the Gaussian distribution is significantly larger than what usually retained in transport models. It is also shown that the validity of the usual definition for the band edge is questioned by the fact that the density of charge carriers behave as a degenerate distribution, even at relatively low doping levels.

  8. Organic Semiconductors based on Dyes and Color Pigments.

    Science.gov (United States)

    Gsänger, Marcel; Bialas, David; Huang, Lizhen; Stolte, Matthias; Würthner, Frank

    2016-05-01

    Organic dyes and pigments constitute a large class of industrial products. The utilization of these compounds in the field of organic electronics is reviewed with particular emphasis on organic field-effect transistors. It is shown that for most major classes of industrial dyes and pigments, i.e., phthalocyanines, perylene and naphthalene diimides, diketopyrrolopyrroles, indigos and isoindigos, squaraines, and merocyanines, charge-carrier mobilities exceeding 1 cm(2) V(-1) s(-1) have been achieved. The most widely investigated molecules due to their n-channel operation are perylene and naphthalene diimides, for which even values close to 10 cm(2) V(-1) s(-1) have been demonstrated. The fact that all of these π-conjugated colorants contain polar substituents leading to strongly quadrupolar or even dipolar molecules suggests that indeed a much larger structural space shows promise for the design of organic semiconductor molecules than was considered in this field traditionally. In particular, because many of these dye and pigment chromophores demonstrate excellent thermal and (photo-)chemical stability in their original applications in dyeing and printing, and are accessible by straightforward synthetic protocols, they bear a particularly high potential for commercial applications in the area of organic electronics. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  9. Centro-Apical Self-Organization of Organic Semiconductors in a Line-Printed Organic Semiconductor: Polymer Blend for One-Step Printing Fabrication of Organic Field-Effect Transistors.

    Science.gov (United States)

    Lee, Su Jin; Kim, Yong-Jae; Yeo, So Young; Lee, Eunji; Lim, Ho Sun; Kim, Min; Song, Yong-Won; Cho, Jinhan; Lim, Jung Ah

    2015-09-11

    Here we report the first demonstration for centro-apical self-organization of organic semiconductors in a line-printed organic semiconductor: polymer blend. Key feature of this work is that organic semiconductor molecules were vertically segregated on top of the polymer phase and simultaneously crystallized at the center of the printed line pattern after solvent evaporation without an additive process. The thickness and width of the centro-apically segregated organic semiconductor crystalline stripe in the printed blend pattern were controlled by varying the relative content of the organic semiconductors, printing speed, and solution concentrations. The centro-apical self-organization of organic semiconductor molecules in a printed polymer blend may be attributed to the combination of an energetically favorable vertical phase-separation and hydrodynamic fluids inside the droplet during solvent evaporation. Finally, a centro-apically phase-separated bilayer structure of organic semiconductor: polymer blend was successfully demonstrated as a facile method to form the semiconductor and dielectric layer for OFETs in one- step.

  10. Plastic lab-on-a-chip for fluorescence excitation with integrated organic semiconductor lasers.

    Science.gov (United States)

    Vannahme, Christoph; Klinkhammer, Sönke; Lemmer, Uli; Mappes, Timo

    2011-04-25

    Laser light excitation of fluorescent markers offers highly sensitive and specific analysis for bio-medical or chemical analysis. To profit from these advantages for applications in the field or at the point-of-care, a plastic lab-on-a-chip with integrated organic semiconductor lasers is presented here. First order distributed feedback lasers based on the organic semiconductor tris(8-hydroxyquinoline) aluminum (Alq3) doped with the laser dye 4-dicyanomethylene-2-methyl-6-(p-dimethylaminostyril)-4H-pyrane (DCM), deep ultraviolet induced waveguides, and a nanostructured microfluidic channel are integrated into a poly(methyl methacrylate) (PMMA) substrate. A simple and parallel fabrication process is used comprising thermal imprint, DUV exposure, evaporation of the laser material, and sealing by thermal bonding. The excitation of two fluorescent marker model systems including labeled antibodies with light emitted by integrated lasers is demonstrated.

  11. Simulation of charge transport in organic semiconductors: A time-dependent multiscale method based on nonequilibrium Green's functions

    DEFF Research Database (Denmark)

    Leitherer, Susanne; Jager, C. M.; Krause, A.

    2017-01-01

    In weakly interacting organic semiconductors, static disorder and dynamic disorder often have an important impact on transport properties. Describing charge transport in these systems requires an approach that correctly takes structural and electronic fluctuations into account. Here, we present...... are used in organic field-effect transistors....

  12. Universal strategy for Ohmic hole injection into organic semiconductors with high ionization energies.

    Science.gov (United States)

    Kotadiya, Naresh B; Lu, Hao; Mondal, Anirban; Ie, Yutaka; Andrienko, Denis; Blom, Paul W M; Wetzelaer, Gert-Jan A H

    2018-04-01

    Barrier-free (Ohmic) contacts are a key requirement for efficient organic optoelectronic devices, such as organic light-emitting diodes, solar cells, and field-effect transistors. Here, we propose a simple and robust way of forming an Ohmic hole contact on organic semiconductors with a high ionization energy (IE). The injected hole current from high-work-function metal-oxide electrodes is improved by more than an order of magnitude by using an interlayer for which the sole requirement is that it has a higher IE than the organic semiconductor. Insertion of the interlayer results in electrostatic decoupling of the electrode from the semiconductor and realignment of the Fermi level with the IE of the organic semiconductor. The Ohmic-contact formation is illustrated for a number of material combinations and solves the problem of hole injection into organic semiconductors with a high IE of up to 6 eV.

  13. Electron and nuclear spin system polarization in semiconductors by light

    Energy Technology Data Exchange (ETDEWEB)

    Zakharchenya, B; Flejsher, V

    1981-02-01

    Discussed are the principles of optical electron spin orientation, dynamic polarization and cooling of nuclear spin systems in optical electron orientation, and behavioural characteristics of bound electron and nuclear spin systems of a semiconductor in the optical orientation situation.

  14. Organic Spin-Valves and Beyond: Spin Injection and Transport in Organic Semiconductors and the Effect of Interfacial Engineering.

    Science.gov (United States)

    Jang, Hyuk-Jae; Richter, Curt A

    2017-01-01

    Since the first observation of the spin-valve effect through organic semiconductors, efforts to realize novel spintronic technologies based on organic semiconductors have been rapidly growing. However, a complete understanding of spin-polarized carrier injection and transport in organic semiconductors is still lacking and under debate. For example, there is still no clear understanding of major spin-flip mechanisms in organic semiconductors and the role of hybrid metal-organic interfaces in spin injection. Recent findings suggest that organic single crystals can provide spin-transport media with much less structural disorder relative to organic thin films, thus reducing momentum scattering. Additionally, modification of the band energetics, morphology, and even spin magnetic moment at the metal-organic interface by interface engineering can greatly impact the efficiency of spin-polarized carrier injection. Here, progress on efficient spin-polarized carrier injection into organic semiconductors from ferromagnetic metals by using various interface engineering techniques is presented, such as inserting a metallic interlayer, a molecular self-assembled monolayer (SAM), and a ballistic carrier emitter. In addition, efforts to realize long spin transport in single-crystalline organic semiconductors are discussed. The focus here is on understanding and maximizing spin-polarized carrier injection and transport in organic semiconductors and insight is provided for the realization of emerging organic spintronics technologies. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  15. Applications of confocal laser scanning microscopy in research into organic semiconductor thin films

    DEFF Research Database (Denmark)

    Schiek, Manuela; Balzer, Frank

    2014-01-01

    At the center of opto-electronic devices are thin layers of organic semiconductors, which need to be sandwiched between planar electrodes. With the growing demand for opto-electronic devices now and in the future, new electrode materials are needed to meet the requirements of organic semiconductors...

  16. Study of charge-carrier relaxation in a disordered organic semiconductor by simulating impedance spectroscopy

    NARCIS (Netherlands)

    Mesta, M.; Cottaar, J.; Coehoorn, R.; Bobbert, P.A.

    2014-01-01

    Impedance spectroscopy is a very sensitive probe of nonstationary charge transport governed by charge-carrier relaxation in devices of disordered organic semiconductors. We simulate impedance spectroscopy measurements of hole-only devices of a polyfluorene-based disordered organic semiconductor by

  17. Room temperature triplet state spectroscopy of organic semiconductors.

    Science.gov (United States)

    Reineke, Sebastian; Baldo, Marc A

    2014-01-21

    Organic light-emitting devices and solar cells are devices that create, manipulate, and convert excited states in organic semiconductors. It is crucial to characterize these excited states, or excitons, to optimize device performance in applications like displays and solar energy harvesting. This is complicated if the excited state is a triplet because the electronic transition is 'dark' with a vanishing oscillator strength. As a consequence, triplet state spectroscopy must usually be performed at cryogenic temperatures to reduce competition from non-radiative rates. Here, we control non-radiative rates by engineering a solid-state host matrix containing the target molecule, allowing the observation of phosphorescence at room temperature and alleviating constraints of cryogenic experiments. We test these techniques on a wide range of materials with functionalities spanning multi-exciton generation (singlet exciton fission), organic light emitting device host materials, and thermally activated delayed fluorescence type emitters. Control of non-radiative modes in the matrix surrounding a target molecule may also have broader applications in light-emitting and photovoltaic devices.

  18. On the Effect of Confinement on the Structure and Properties of Small-Molecular Organic Semiconductors

    KAUST Repository

    Martin, Jaime; Dyson, Matthew; Reid, Obadiah G.; Li, Ruipeng; Nogales, Aurora; Smilgies, Detlef-M.; Silva, Carlos; Rumbles, Garry; Amassian, Aram; Stingelin, Natalie

    2017-01-01

    Many typical organic optoelectronic devices, such as light-emitting diodes, field-effect transistors, and photovoltaic cells, use an ultrathin active layer where the organic semiconductor is confined within nanoscale dimensions. However, the question of how this spatial constraint impacts the active material is rarely addressed, although it may have a drastic influence on the phase behavior and microstructure of the active layer and hence the final performance. Here, the small-molecule semiconductor p-DTS(FBTTh) is used as a model system to illustrate how sensitive this class of material can be to spatial confinement on device-relevant length scales. It is also shown that this effect can be exploited; it is demonstrated, for instance, that spatial confinement is an efficient tool to direct the crystal orientation and overall texture of p-DTS(FBTTh) structures in a controlled manner, allowing for the manipulation of properties including photoluminescence and charge transport characteristics. This insight should be widely applicable as the temperature/confinement phase diagrams established via differential scanning calorimetry and grazing-incidence X-ray diffraction are used to identify specific processing routes that can be directly extrapolated to other functional organic materials, such as polymeric semiconductors, ferroelectrics or high-refractive-index polymers, to induce desired crystal textures or specific (potentially new) polymorphs.

  19. On the Effect of Confinement on the Structure and Properties of Small-Molecular Organic Semiconductors

    KAUST Repository

    Martín, Jaime

    2017-12-11

    Many typical organic optoelectronic devices, such as light-emitting diodes, field-effect transistors, and photovoltaic cells, use an ultrathin active layer where the organic semiconductor is confined within nanoscale dimensions. However, the question of how this spatial constraint impacts the active material is rarely addressed, although it may have a drastic influence on the phase behavior and microstructure of the active layer and hence the final performance. Here, the small-molecule semiconductor p-DTS(FBTTh) is used as a model system to illustrate how sensitive this class of material can be to spatial confinement on device-relevant length scales. It is also shown that this effect can be exploited; it is demonstrated, for instance, that spatial confinement is an efficient tool to direct the crystal orientation and overall texture of p-DTS(FBTTh) structures in a controlled manner, allowing for the manipulation of properties including photoluminescence and charge transport characteristics. This insight should be widely applicable as the temperature/confinement phase diagrams established via differential scanning calorimetry and grazing-incidence X-ray diffraction are used to identify specific processing routes that can be directly extrapolated to other functional organic materials, such as polymeric semiconductors, ferroelectrics or high-refractive-index polymers, to induce desired crystal textures or specific (potentially new) polymorphs.

  20. Highly Sensitive Flexible Pressure Sensors Based on Printed Organic Transistors with Centro-Apically Self-Organized Organic Semiconductor Microstructures.

    Science.gov (United States)

    Yeo, So Young; Park, Sangsik; Yi, Yeon Jin; Kim, Do Hwan; Lim, Jung Ah

    2017-12-13

    A highly sensitive pressure sensor based on printed organic transistors with three-dimensionally self-organized organic semiconductor microstructures (3D OSCs) was demonstrated. A unique organic transistor with semiconductor channels positioned at the highest summit of printed cylindrical microstructures was achieved simply by printing an organic semiconductor and polymer blend on the plastic substrate without the use of additional etching or replication processes. A combination of the printed organic semiconductor microstructure and an elastomeric top-gate dielectric resulted in a highly sensitive organic field-effect transistor (FET) pressure sensor with a high pressure sensitivity of 1.07 kPa -1 and a rapid response time of <20 ms with a high reliability over 1000 cycles. The flexibility and high performance of the 3D OSC FET pressure sensor were exploited in the successful application of our sensors to real-time monitoring of the radial artery pulse, which is useful for healthcare monitoring, and to touch sensing in the e-skin of a realistic prosthetic hand.

  1. Directional Charge Separation in Isolated Organic Semiconductor Crystalline Nanowires

    Energy Technology Data Exchange (ETDEWEB)

    Barnes, Michael; Labastide, Joelle; Bond-Thompson, Hilary; Briseno, Alejandro; Collela, Nicolas

    2017-03-01

    In the conventional view of organic photovoltaics (OPV), localized electronic excitations (excitons) formed in the active layer are transported by random 3D diffusion to an interface where charge separation and extraction take place. Because radiative de-excitation is usually strongly allowed in organic semiconductors, efficient charge separation requires high exciton mobility, with much of the diffusive motion ‘wasted’ in directions that don’t result in an interface encounter. Our research efforts are focused on ways to enforce a preferred directionality in energy and/or charge transport using ordered crystalline nanowires in which the intermolecular interactions that facilitate transport along, for example, the pi-stacking axis, can be made several orders of magnitude stronger than those in a transverse direction. The results presented in our recent work (Nature Communications) is a first step towards realizing the goal of directional control of both energy transport and charge separation, where excitons shared between adjacent molecules dissociate exclusively along the pi-stacking direction.

  2. Assembly, Structure, and Functionality of Metal-Organic Networks and Organic Semiconductor Layers at Surfaces

    Science.gov (United States)

    Tempas, Christopher D.

    Self-assembled nanostructures at surfaces show promise for the development of next generation technologies including organic electronic devices and heterogeneous catalysis. In many cases, the functionality of these nanostructures is not well understood. This thesis presents strategies for the structural design of new on-surface metal-organic networks and probes their chemical reactivity. It is shown that creating uniform metal sites greatly increases selectivity when compared to ligand-free metal islands. When O2 reacts with single-site vanadium centers, in redox-active self-assembled coordination networks on the Au(100) surface, it forms one product. When O2 reacts with vanadium metal islands on the same surface, multiple products are formed. Other metal-organic networks described in this thesis include a mixed valence network containing Pt0 and PtII and a network where two Fe centers reside in close proximity. This structure is stable to temperatures >450 °C. These new on-surface assemblies may offer the ability to perform reactions of increasing complexity as future heterogeneous catalysts. The functionalization of organic semiconductor molecules is also shown. When a few molecular layers are grown on the surface, it is seen that the addition of functional groups changes both the film's structure and charge transport properties. This is due to changes in both first layer packing structure and the pi-electron distribution in the functionalized molecules compared to the original molecule. The systems described in this thesis were studied using high-resolution scanning tunneling microscopy, non-contact atomic force microscopy, and X-ray photoelectron spectroscopy. Overall, this work provides strategies for the creation of new, well-defined on-surface nanostructures and adds additional chemical insight into their properties.

  3. Pseudomorphic growth of organic semiconductor thin films driven by incommensurate epitaxy

    International Nuclear Information System (INIS)

    Sassella, A.; Campione, M.; Raimondo, L.; Borghesi, A.; Bussetti, G.; Cirilli, S.; Violante, A.; Goletti, C.; Chiaradia, P.

    2009-01-01

    A stable pseudomorphic phase of α-quaterthiophene, a well known organic semiconductor, is obtained by growing films with organic molecular beam epitaxy (OMBE) on a single crystal of another organic semiconductor, namely, tetracene. The structural characteristics of the new phase are investigated by monitoring in situ the OMBE process by reflectance anisotropy spectroscopy; thus assessing that incommensurate epitaxy is in this case, the driving force for tuning the molecular packing in organic molecular films and in turn, their solid state properties

  4. Impact of Molecular Orientation and Packing Density on Electronic Polarization in the Bulk and at Surfaces of Organic Semiconductors

    KAUST Repository

    Ryno, Sean; Risko, Chad; Bredas, Jean-Luc

    2016-01-01

    The polarizable environment surrounding charge carriers in organic semiconductors impacts the efficiency of the charge transport process. Here, we consider two representative organic semiconductors, tetracene and rubrene, and evaluate

  5. Front-end electronics for multichannel semiconductor detector systems

    CERN Document Server

    Grybos, P

    2010-01-01

    Front-end electronics for multichannel semiconductor detektor systems Volume 08, EuCARD Editorial Series on Accelerator Science and Technology The monograph is devoted to many different aspects related to front-end electronics for semiconductor detector systems, namely: − designing and testing silicon position sensitive detectors for HEP experiments and X-ray imaging applications, − designing and testing of multichannel readout electronics for semiconductor detectors used in X-ray imaging applications, especially for noise minimization, fast signal processing, crosstalk reduction and good matching performance, − optimization of semiconductor detection systems in respect to the effects of radiation damage. The monograph is the result mainly of the author's experience in the above-mentioned areas and it is an attempt of a comprehensive presentation of issues related to the position sensitive detection system working in a single photon counting mode and intended to X-ray imaging applications. The structure...

  6. Monolayer-Mediated Growth of Organic Semiconductor Films with Improved Device Performance.

    Science.gov (United States)

    Huang, Lizhen; Hu, Xiaorong; Chi, Lifeng

    2015-09-15

    Increased interest in wearable and smart electronics is driving numerous research works on organic electronics. The control of film growth and patterning is of great importance when targeting high-performance organic semiconductor devices. In this Feature Article, we summarize our recent work focusing on the growth, crystallization, and device operation of organic semiconductors intermediated by ultrathin organic films (in most cases, only a monolayer). The site-selective growth, modified crystallization and morphology, and improved device performance of organic semiconductor films are demonstrated with the help of the inducing layers, including patterned and uniform Langmuir-Blodgett monolayers, crystalline ultrathin organic films, and self-assembled polymer brush films. The introduction of the inducing layers could dramatically change the diffusion of the organic semiconductors on the surface and the interactions between the active layer with the inducing layer, leading to improved aggregation/crystallization behavior and device performance.

  7. Ferromagnetism in diluted magnetic semiconductor heterojunction systems

    Czech Academy of Sciences Publication Activity Database

    Lee, B.; Jungwirth, Tomáš; MacDonald, A. H.

    2002-01-01

    Roč. 17, - (2002), s. 393-403 ISSN 0268-1242 R&D Projects: GA ČR GA202/98/0085; GA MŠk OC P5.10 Institutional research plan: CEZ:AV0Z1010914 Keywords : ferromagnetic semiconductors * heterostructures Subject RIV: BM - Solid Matter Physics ; Magnetism Impact factor: 1.241, year: 2002

  8. Extrinsic photoresponse enhancement under additional intrinsic photoexcitation in organic semiconductors

    Energy Technology Data Exchange (ETDEWEB)

    Kounavis, P., E-mail: pkounavis@upatras.gr [Department of Electrical and Computer Engineering, School of Engineering, University of Patras, 26504 Patras (Greece)

    2016-06-28

    Dual light beam photoresponse experiments are employed to explore the photoresponse under simultaneous extrinsic and intrinsic photoexcitation of organic semiconductors. The photoresponse of a red modulated light extrinsic photoexcitation is found that can be significantly enhanced under an additional blue bias-light intrinsic photoexcitation in two terminal pentacene films on glass substrates. From the frequency resolved photoresponse, it is deduced that the phenomenon of photoresponse enhancement can be attributed to an increase in the extrinsic photogeneration rate of the red modulated light and/or an improvement of the drift velocity of carriers under an additional blue light intrinsic photoexcitation. The possible predominant extrinsic photogeneration mechanism, which can be compatible with the observed dependence of the photoresponse enhancement on the frequency and on the light intensities of the red and blue light excitation, is the singlet exciton dissociation through electron transfer to acceptor-like traps. Moreover, an improvement in the drift velocity of carriers traversing grain boundaries with potential energy barriers, which may be reduced by trapping of minority carriers created from the intrinsic photoexcitation, may partly contribute to the photoresponse enhancement.

  9. Extrinsic photoresponse enhancement under additional intrinsic photoexcitation in organic semiconductors

    International Nuclear Information System (INIS)

    Kounavis, P.

    2016-01-01

    Dual light beam photoresponse experiments are employed to explore the photoresponse under simultaneous extrinsic and intrinsic photoexcitation of organic semiconductors. The photoresponse of a red modulated light extrinsic photoexcitation is found that can be significantly enhanced under an additional blue bias-light intrinsic photoexcitation in two terminal pentacene films on glass substrates. From the frequency resolved photoresponse, it is deduced that the phenomenon of photoresponse enhancement can be attributed to an increase in the extrinsic photogeneration rate of the red modulated light and/or an improvement of the drift velocity of carriers under an additional blue light intrinsic photoexcitation. The possible predominant extrinsic photogeneration mechanism, which can be compatible with the observed dependence of the photoresponse enhancement on the frequency and on the light intensities of the red and blue light excitation, is the singlet exciton dissociation through electron transfer to acceptor-like traps. Moreover, an improvement in the drift velocity of carriers traversing grain boundaries with potential energy barriers, which may be reduced by trapping of minority carriers created from the intrinsic photoexcitation, may partly contribute to the photoresponse enhancement.

  10. Drift of charge carriers in crystalline organic semiconductors

    Energy Technology Data Exchange (ETDEWEB)

    Dong, Jingjuan; Si, Wei [State Key Laboratory of Surface Physics and Department of Physics, Fudan University, Shanghai 200433 (China); Wu, Chang-Qin, E-mail: cqw@fudan.edu.cn [State Key Laboratory of Surface Physics and Department of Physics, Fudan University, Shanghai 200433 (China); Collaborative Innovation Center of Advanced Microstructures, Fudan University, Shanghai 200433 (China)

    2016-04-14

    We investigate the direct-current response of crystalline organic semiconductors in the presence of finite external electric fields by the quantum-classical Ehrenfest dynamics complemented with instantaneous decoherence corrections (IDC). The IDC is carried out in the real-space representation with the energy-dependent reweighing factors to account for both intermolecular decoherence and energy relaxation by which conduction occurs. In this way, both the diffusion and drift motion of charge carriers are described in a unified framework. Based on an off-diagonal electron-phonon coupling model for pentacene, we find that the drift velocity initially increases with the electric field and then decreases at higher fields due to the Wannier-Stark localization, and a negative electric-field dependence of mobility is observed. The Einstein relation, which is a manifestation of the fluctuation-dissipation theorem, is found to be restored in electric fields up to ∼10{sup 5} V/cm for a wide temperature region studied. Furthermore, we show that the incorporated decoherence and energy relaxation could explain the large discrepancy between the mobilities calculated by the Ehrenfest dynamics and the full quantum methods, which proves the effectiveness of our approach to take back these missing processes.

  11. Metal complexation and monolayer self-assembly of the bio-organic semiconductor Alizarin

    Energy Technology Data Exchange (ETDEWEB)

    Uppal, Neeti [Dept. Earth and Environmental Sciences, Ludwig-Maximilians-Universitaet Muenchen (LMU) and Center for NanoSciences (CeNS), Muenchen (Germany); Institut fuer Physik, Universitaet Augsburg (Germany); Gast, Norbert [Dept. Earth and Environmental Sciences, Ludwig-Maximilians-Universitaet Muenchen (LMU) and Center for NanoSciences (CeNS), Muenchen (Germany); Zentrum Neue Technologien, Deutsches Museum, Muenchen (Germany); Bueno, Martin [Fakultaet Feinwerk- und Mikrotechnik, Physikalische Technik, Hochschule Muenchen (Germany); Heckl, Wolfgang M. [Dept. of Physics, Technische Universitaet Muenchen (TUM), Garching (Germany); Zentrum Neue Technologien, Deutsches Museum, Muenchen (Germany); Trixler, Frank [Dept. Earth and Environmental Sciences, Ludwig-Maximilians-Universitaet Muenchen (LMU) and Center for NanoSciences (CeNS), Muenchen (Germany); Dept. of Physics, Technische Universitaet Muenchen (TUM), Garching (Germany); Zentrum Neue Technologien, Deutsches Museum, Muenchen (Germany)

    2010-07-01

    Organic Solid/Solid Wetting Deposition (OSWD) (Trixler et al.: Chem.Eur.J. 13 (2007), 7785) enables to deposit insoluble molecules such as organic pigments and semiconductors on substrate surfaces under ambient conditions. We explore the potential of OSWD to grow and manipulate monolayers of biomolecules and their chelates on graphite and use Alizarin as a model system - a natural organic compound which occurs mainly as an anthraquinone glycoside in plants. Our investigations via Scanning Tunneling Microscopy (STM), Tunneling Spectroscopy (TS) and Molecular Modelling reveal that OSWD works also with bio-organic molecules and chelate complexes and show that the advantages of OSWD (self-assembly under ambient conditions in a non-solvent environment, nanomanipulation via molecular extraction) can all be tapped.

  12. Controlled Quantum Operations of a Semiconductor Three-Qubit System

    Science.gov (United States)

    Li, Hai-Ou; Cao, Gang; Yu, Guo-Dong; Xiao, Ming; Guo, Guang-Can; Jiang, Hong-Wen; Guo, Guo-Ping

    2018-02-01

    In a specially designed semiconductor device consisting of three capacitively coupled double quantum dots, we achieve strong and tunable coupling between a target qubit and two control qubits. We demonstrate how to completely switch on and off the target qubit's coherent rotations by presetting two control qubits' states. A Toffoli gate is, therefore, possible based on these control effects. This research paves a way for realizing full quantum-logic operations in semiconductor multiqubit systems.

  13. Semiconductor terahertz technology devices and systems at room temperature operation

    CERN Document Server

    Carpintero, G; Hartnagel, H; Preu, S; Raisanen, A

    2015-01-01

    Key advances in Semiconductor Terahertz (THz) Technology now promises important new applications enabling scientists and engineers to overcome the challenges of accessing the so-called "terahertz gap".  This pioneering reference explains the fundamental methods and surveys innovative techniques in the generation, detection and processing of THz waves with solid-state devices, as well as illustrating their potential applications in security and telecommunications, among other fields. With contributions from leading experts, Semiconductor Terahertz Technology: Devices and Systems at Room Tempe

  14. Distribution of volatile organic compounds over a semiconductor Industrial Park in Taiwan.

    Science.gov (United States)

    Chiu, Kong-Hwa; Wu, Ben-Zen; Chang, Chih-Chung; Sree, Usha; Lo, Jiunn-Guang

    2005-02-15

    This study examined volatile organic compounds (VOC) concentration in ambient air collected during the years 2000--2003 at several different locations of Hsinchu Science-based Industrial Park (HSIP) in Taiwan. A canister automated GC-MS system analyzed the volatile organics in ambient air grasp samples according to T0-15 method. Oxygenated volatiles were the most abundant VOC detected in HSIP followed by aromatics that are commonly used as solvents in the semiconductor industries. The major components measured in the ambient air are 2-propanol (29-135 ppbv), acetone (12-164 ppbv), benzene (0.7-1.7 ppbv), and toluene (13-20 ppbv). At some of the sampling locations, odorous compounds such as carbon disulfide and dimethyl sulfide levels exceed threshold values. The estimated toluene/benzene ratio is very high at most of the sites. However, the total amount of VOC is reduced over the years from 2000 to 2003 due to strict implementation on use and discharge of solvents in industries. There exists no definite seasonal pattern for sporadic occurrence of high levels of some of the volatile organics. Stagnant weather conditions with low wind speeds aid accumulation of toxic species at ground level. The results entail that hi-tech semiconductor industries are still a potential source for harmful organic substances to surrounding microenvironment.

  15. Dark Current And Voltage Measurements Of Metal-Organic-Semiconductor (M-Or-S) Diode

    International Nuclear Information System (INIS)

    Adianto

    1996-01-01

    . Some Metal-Organic-Semiconductor (M-Or-S) thin film diodes, constructed with an organic polymer (polymerized toluene) as an active component has been successfully fabricated. The thin film M-Or-S diodes were fabricated on an n-type silicon with resistivity of 250-500 Ocm and p type silicon with resistivity of 10-20 Ocm as a substrate with polymerized toluene used as insulator. When deposited on silicon wafers with electrode of evaporated Ni on the n-type silicon and evaporated Au as the electrode on the polymerized toluene film, the electronic devices of Metal-Organic- Semiconductor (M-Or-S) type can be produced with one of its characteristics is that their light sensitivity. A plasma ion deposition system was constructed and used to deposit organic monomeric substance (toluene) that functioned as an isolator between semiconductor and the evaporated metal electrodes. The current-voltage measurements for different configurations of M-Or-S devices were carried out to determine the current-voltage (1-V) characteristics for M-Or-S devices with different materials and thicknesses. In addition to the 1-V measurement mentioned before, 1-V measurements of the devices were also carried out by using a curve tracer oscilloscope, and the picture of the effective parameters of each of the device could be taken by using a polaroid camera. Since the devices are very sensitive to light, the devices were all tested in a black-box which was covered by a black cloth to make sure that there was no light coming through. The experimental results for p- and n-type silicon substrates showed that an M-Or-S diode with n-type gave a higher breakdown voltage than that p- type silicon. In addition, the reverse bias breakdown voltage increased as the thickness of the thin film increased in the range of 50 -2500 V/μm

  16. Preparations and Characterizations of Luminescent Two Dimensional Organic-inorganic Perovskite Semiconductors

    Directory of Open Access Journals (Sweden)

    Sanjun Zhang

    2010-05-01

    Full Text Available This article reviews the synthesis, structural and optical characterizations of some novel luminescent two dimensional organic-inorganic perovskite (2DOIP semiconductors. These 2DOIP semiconductors show a self-assembled nano-layered structure, having the electronic structure of multi-quantum wells. 2DOIP thin layers and nanoparticles have been prepared through different methods. The structures of the 2DOIP semiconductors are characterized by atomic force microscopy and X-ray diffraction. The optical properties of theb DOIP semiconductors are characterized from absorption and photoluminescence spectra measured at room and low temperatures. Influences of different components, in particular the organic parts, on the structural and optical properties of the 2DOIP semiconductors are discussed.

  17. Controlled Growth of Ultrathin Film of Organic Semiconductors by Balancing the Competitive Processes in Dip-Coating for Organic Transistors.

    Science.gov (United States)

    Wu, Kunjie; Li, Hongwei; Li, Liqiang; Zhang, Suna; Chen, Xiaosong; Xu, Zeyang; Zhang, Xi; Hu, Wenping; Chi, Lifeng; Gao, Xike; Meng, Yancheng

    2016-06-28

    Ultrathin film with thickness below 15 nm of organic semiconductors provides excellent platform for some fundamental research and practical applications in the field of organic electronics. However, it is quite challenging to develop a general principle for the growth of uniform and continuous ultrathin film over large area. Dip-coating is a useful technique to prepare diverse structures of organic semiconductors, but the assembly of organic semiconductors in dip-coating is quite complicated, and there are no reports about the core rules for the growth of ultrathin film via dip-coating until now. In this work, we develop a general strategy for the growth of ultrathin film of organic semiconductor via dip-coating, which provides a relatively facile model to analyze the growth behavior. The balance between the three direct factors (nucleation rate, assembly rate, and recession rate) is the key to determine the growth of ultrathin film. Under the direction of this rule, ultrathin films of four organic semiconductors are obtained. The field-effect transistors constructed on the ultrathin film show good field-effect property. This work provides a general principle and systematic guideline to prepare ultrathin film of organic semiconductors via dip-coating, which would be highly meaningful for organic electronics as well as for the assembly of other materials via solution processes.

  18. Visualizing excitations at buried heterojunctions in organic semiconductor blends.

    Science.gov (United States)

    Jakowetz, Andreas C; Böhm, Marcus L; Sadhanala, Aditya; Huettner, Sven; Rao, Akshay; Friend, Richard H

    2017-05-01

    Interfaces play a crucial role in semiconductor devices, but in many device architectures they are nanostructured, disordered and buried away from the surface of the sample. Conventional optical, X-ray and photoelectron probes often fail to provide interface-specific information in such systems. Here we develop an all-optical time-resolved method to probe the local energetic landscape and electronic dynamics at such interfaces, based on the Stark effect caused by electron-hole pairs photo-generated across the interface. Using this method, we found that the electronically active sites at the polymer/fullerene interfaces in model bulk-heterojunction blends fall within the low-energy tail of the absorption spectrum. This suggests that these sites are highly ordered compared with the bulk of the polymer film, leading to large wavefunction delocalization and low site energies. We also detected a 100 fs migration of holes from higher- to lower-energy sites, consistent with these charges moving ballistically into more ordered polymer regions. This ultrafast charge motion may be key to separating electron-hole pairs into free charges against the Coulomb interaction.

  19. Spectroscopy of Charge Carriers and Traps in Field-Doped Single Crystal Organic Semiconductors

    Energy Technology Data Exchange (ETDEWEB)

    Zhu, Xiaoyang [Columbia Univ., New York, NY (United States); Frisbie, Daniel [Univ. of Minnesota, Minneapolis, MN (United States)

    2017-03-31

    The proposed research aims to achieve quantitative, molecular level understanding of charge carriers and traps in field-doped crystalline organic semiconductors via in situ linear and nonlinear optical spectroscopy, in conjunction with transport measurements and molecular/crystal engineering.

  20. Organic Semiconductor-Containing Supramolecules: Effect of Small Molecule Crystallization and Molecular Packing

    KAUST Repository

    Rancatore, Benjamin J.; Kim, BongSoo; Mauldin, Clayton E.; Frechet, Jean; Xu, Ting

    2016-01-01

    on these highly crystalline molecules differs from their less crystalline counterparts. Here, two families of organic semiconductor SMs are investigated, where the composition of the crystalline core, the location (side- vs end-functionalization) of the alkyl

  1. Rational design of organic semiconductors for texture control and self-patterning on halogenated surfaces

    KAUST Repository

    Ward, Jeremy W.; Li, Ruipeng; Obaid, Abdulmalik; Payne, Marcia M.; Smilgies, Detlef Matthias; Anthony, John Edward; Amassian, Aram; Jurchescu, Oana D.

    2014-01-01

    new materials. Here, the influence of the interactions at the interface between a halogenated organic semiconductor (OSC) thin film and a halogenated self-assembled monolayer on the formation of the crystalline texture directly affecting

  2. Effects of electric field and magnetic induction on spin injection into organic semiconductors

    International Nuclear Information System (INIS)

    Wang, Y.M.; Ren, J.F.; Yuan, X.B.; Dou, Z.T.; Hu, G.C.

    2011-01-01

    Spin-polarized injection and transport into ferromagnetic/organic semiconductor structure are studied theoretically in the presence of the external electric field and magnetic induction. Based on the spin-drift-diffusion theory and Ohm's law, we obtain the charge current polarization, which takes into account the special carriers of organic semiconductors. From the calculation, it is found that the current spin polarization is enhanced by several orders of magnitude by tuning the magnetic induction and electric fields. To get an apparent current spin polarization, the effects of spin-depended interfacial resistances and the special carriers in the organic semiconductor, which are polarons and bipolarons, are also discussed. -- Research highlights: → Current polarization in ferromagnetic/organic semiconductor structure is obtained. → Calculations are based on spin-drift-diffusion theory and Ohm's law. → Current polarization is enhanced by tuning magnetic induction and electric fields. → Effects of interfacial resistances and the special carriers are also discussed.

  3. Microscopic properties of ionic liquid/organic semiconductor interfaces revealed by molecular dynamics simulations.

    Science.gov (United States)

    Yokota, Yasuyuki; Miyamoto, Hiroo; Imanishi, Akihito; Takeya, Jun; Inagaki, Kouji; Morikawa, Yoshitada; Fukui, Ken-Ichi

    2018-05-09

    Electric double-layer transistors based on ionic liquid/organic semiconductor interfaces have been extensively studied during the past decade because of their high carrier densities at low operation voltages. Microscopic structures and the dynamics of ionic liquids likely determine the device performance; however, knowledge of these is limited by a lack of appropriate experimental tools. In this study, we investigated ionic liquid/organic semiconductor interfaces using molecular dynamics to reveal the microscopic properties of ionic liquids. The organic semiconductors include pentacene, rubrene, fullerene, and 7,7,8,8-tetracyanoquinodimethane (TCNQ). While ionic liquids close to the substrate always form the specific layered structures, the surface properties of organic semiconductors drastically alter the ionic dynamics. Ionic liquids at the fullerene interface behave as a two-dimensional ionic crystal because of the energy gain derived from the favorable electrostatic interaction on the corrugated periodic substrate.

  4. Solution coating of large-area organic semiconductor thin films with aligned single-crystalline domains

    KAUST Repository

    Diao, Ying; Tee, Benjamin C-K.; Giri, Gaurav; Xu, Jie; Kim, Do Hwan; Becerril, Hector A.; Stoltenberg, Randall M.; Lee, Tae Hoon; Xue, Gi; Mannsfeld, Stefan C. B.; Bao, Zhenan

    2013-01-01

    Solution coating of organic semiconductors offers great potential for achieving low-cost manufacturing of large-area and flexible electronics. However, the rapid coating speed needed for industrial-scale production poses challenges to the control

  5. Modeling space-charge-limited currents in organic semiconductors: Extracting trap density and mobility

    KAUST Repository

    Dacuñ a, Javier; Salleo, Alberto

    2011-01-01

    We have developed and have applied a mobility edge model that takes drift and diffusion currents to characterize the space-charge-limited current in organic semiconductors into account. The numerical solution of the drift-diffusion equation allows

  6. Multifunctional Organic-Semiconductor Interfacial Layers for Solution-Processed Oxide-Semiconductor Thin-Film Transistor.

    Science.gov (United States)

    Kwon, Guhyun; Kim, Keetae; Choi, Byung Doo; Roh, Jeongkyun; Lee, Changhee; Noh, Yong-Young; Seo, SungYong; Kim, Myung-Gil; Kim, Choongik

    2017-06-01

    The stabilization and control of the electrical properties in solution-processed amorphous-oxide semiconductors (AOSs) is crucial for the realization of cost-effective, high-performance, large-area electronics. In particular, impurity diffusion, electrical instability, and the lack of a general substitutional doping strategy for the active layer hinder the industrial implementation of copper electrodes and the fine tuning of the electrical parameters of AOS-based thin-film transistors (TFTs). In this study, the authors employ a multifunctional organic-semiconductor (OSC) interlayer as a solution-processed thin-film passivation layer and a charge-transfer dopant. As an electrically active impurity blocking layer, the OSC interlayer enhances the electrical stability of AOS TFTs by suppressing the adsorption of environmental gas species and copper-ion diffusion. Moreover, charge transfer between the organic interlayer and the AOS allows the fine tuning of the electrical properties and the passivation of the electrical defects in the AOS TFTs. The development of a multifunctional solution-processed organic interlayer enables the production of low-cost, high-performance oxide semiconductor-based circuits. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  7. Ambipolar Small-Molecule:Polymer Blend Semiconductors for Solution-Processable Organic Field-Effect Transistors.

    Science.gov (United States)

    Kang, Minji; Hwang, Hansu; Park, Won-Tae; Khim, Dongyoon; Yeo, Jun-Seok; Kim, Yunseul; Kim, Yeon-Ju; Noh, Yong-Young; Kim, Dong-Yu

    2017-01-25

    We report on the fabrication of an organic thin-film semiconductor formed using a blend solution of soluble ambipolar small molecules and an insulating polymer binder that exhibits vertical phase separation and uniform film formation. The semiconductor thin films are produced in a single step from a mixture containing a small molecular semiconductor, namely, quinoidal biselenophene (QBS), and a binder polymer, namely, poly(2-vinylnaphthalene) (PVN). Organic field-effect transistors (OFETs) based on QBS/PVN blend semiconductor are then assembled using top-gate/bottom-contact device configuration, which achieve almost four times higher mobility than the neat QBS semiconductor. Depth profile via secondary ion mass spectrometry and atomic force microscopy images indicate that the QBS domains in the films made from the blend are evenly distributed with a smooth morphology at the bottom of the PVN layer. Bias stress test and variable-temperature measurements on QBS-based OFETs reveal that the QBS/PVN blend semiconductor remarkably reduces the number of trap sites at the gate dielectric/semiconductor interface and the activation energy in the transistor channel. This work provides a one-step solution processing technique, which makes use of soluble ambipolar small molecules to form a thin-film semiconductor for application in high-performance OFETs.

  8. Interface properties of Fe/MgO/Cu-phthalocyanine metal-insulator-organic semiconductor structures

    International Nuclear Information System (INIS)

    Lee, Nyunjong; Bae, Yujeong; Kim, Taehee; Ito, Eisuke; Hara, Masahiko

    2014-01-01

    Hybrid interface structures consisting of organic copper-phthalocyanine (CuPc) and ferromagnetic metal Fe(001) with and without a MgO(001) cover were investigated by using surface sensitive techniques of X-ray photoemission spectroscopy and ultraviolet photoemission spectroscopy. A systematic study of the energy level alignment at the interfaces was carried out. For the hybrid interfaces considered here, our results indicate that the insertion of an artificially-grown ultra-thin oxide layer MgO(001) can prevent Femi level pinning and induce a rather large interface dipole, thereby resulting in remarkable CuPc Fermi level shifts when the thickness of the CuPc film is less than 3 nm. This study provides a better understanding of spin filtering in MgO-based organic spin devices and a new way to alter the interface electronic structure of metal/organic semiconductor hybrid systems.

  9. Photoelectron spectroscopy on doped organic semiconductors and related interfaces

    Energy Technology Data Exchange (ETDEWEB)

    Olthof, Selina Sandra

    2010-06-08

    Using photoelectron spectroscopy, we show measurements of energy level alignment of organic semiconducting layers. The main focus is on the properties and the influence of doped layers. The investigations on the p-doping process in organic semiconductors show typical charge carrier concentrations up to 2.10{sup 20} cm{sup -3}. By a variation of the doping concentration, an over proportional influence on the position of the Fermi energy is observed. Comparing the number of charge carriers with the amount of dopants present in the layer, it is found that only 5% of the dopants undergo a full charge transfer. Furthermore, a detailed investigation of the density of states beyond the HOMO onset reveals that an exponentially decaying density of states reaches further into the band gap than commonly assumed. For an increasing amount of doping, the Fermi energy gets pinned on these states which suggests that a significant amount of charge carriers is present there. The investigation of metal top and bottom contacts aims at understanding the asymmetric current-voltage characteristics found for some symmetrically built device stacks. It can be shown that a reaction between the atoms from the top contact with the molecules of the layer leads to a change in energy level alignment that produces a 1.16 eV lower electron injection barrier from the top. Further detailed investigations on such contacts show that the formation of a silver top contact is dominated by diffusion processes, leading to a broadened interface. However, upon insertion of a thin aluminum interlayer this diffusion can be stopped and an abrupt interface is achieved. Furthermore, in the case of a thick silver top contact, a monolayer of molecules is found to oat on top of the metal layer, almost independent on the metal layer thickness. Finally, several device stacks are investigated, regarding interface dipoles, formation of depletion regions, energy alignment in mixed layers, and the influence of the built

  10. Quantum dynamics of nuclear spins and spin relaxation in organic semiconductors

    Science.gov (United States)

    Mkhitaryan, V. V.; Dobrovitski, V. V.

    2017-06-01

    We investigate the role of the nuclear-spin quantum dynamics in hyperfine-induced spin relaxation of hopping carriers in organic semiconductors. The fast-hopping regime, when the carrier spin does not rotate much between subsequent hops, is typical for organic semiconductors possessing long spin coherence times. We consider this regime and focus on a carrier random-walk diffusion in one dimension, where the effect of the nuclear-spin dynamics is expected to be the strongest. Exact numerical simulations of spin systems with up to 25 nuclear spins are performed using the Suzuki-Trotter decomposition of the evolution operator. Larger nuclear-spin systems are modeled utilizing the spin-coherent state P -representation approach developed earlier. We find that the nuclear-spin dynamics strongly influences the carrier spin relaxation at long times. If the random walk is restricted to a small area, it leads to the quenching of carrier spin polarization at a nonzero value at long times. If the random walk is unrestricted, the carrier spin polarization acquires a long-time tail, decaying as 1 /√{t } . Based on the numerical results, we devise a simple formula describing the effect quantitatively.

  11. Diketopyrrolopyrrole polymers as organic semiconductors and optical materials

    NARCIS (Netherlands)

    2008-01-01

    The present invention relates to polymers comprising diketopyrrolopyrrole repeating units and their use as org. semiconductor in org. devices, esp. a diode, an org. field effect transistor and/or a solar cell, or a device contg. a diode and/or an org. field effect transistor, and/or a solar cell.

  12. Validity of the Einstein Relation in Disordered Organic Semiconductors

    NARCIS (Netherlands)

    Wetzelaer, G. A. H.; Koster, L. J. A.; Blom, P. W. M.

    2011-01-01

    It is controversial whether energetic disorder in semiconductors is already sufficient to violate the classical Einstein relation, even in the case of thermal equilibrium. We demonstrate that the Einstein relation is violated only under nonequilibrium conditions due to deeply trapped carriers, as in

  13. Modeling charge transfer at organic donor-acceptor semiconductor interfaces

    NARCIS (Netherlands)

    Cakir, Deniz; Bokdam, Menno; de Jong, Machiel Pieter; Fahlman, M.; Brocks, G.

    2012-01-01

    We develop an integer charge transfer model for the potential steps observed at interfaces between donor and acceptor molecular semiconductors. The potential step can be expressed as the difference between the Fermi energy pinning levels of electrons on the acceptor material and holes on the donor

  14. Electron and nuclear spin system polarization in semiconductors by light

    International Nuclear Information System (INIS)

    Zakharchenya, B.; Flejsher, V.

    1981-01-01

    Discussed are the principles of optical electron spin orientation, dynamic polarization and cooling of nuclear spin systems in optical electron orientation, and behavioural characteristics of bound electron and nuclear spin systems of a semiconductor in the optical orientation situation. (J.P.)

  15. Semiconductor Mode-Locked Lasers for Optical Communication Systems

    DEFF Research Database (Denmark)

    Yvind, Kresten

    2003-01-01

    The thesis deals with the design and fabrication of semiconductor mode-locked lasers for use in optical communication systems. The properties of pulse sources and characterization methods are described as well as requirements for application in communication systems. Especially, the importance of...

  16. Achieving Optimal Self-Adaptivity for Dynamic Tuning of Organic Semiconductors through Resonance Engineering.

    Science.gov (United States)

    Tao, Ye; Xu, Lijia; Zhang, Zhen; Chen, Runfeng; Li, Huanhuan; Xu, Hui; Zheng, Chao; Huang, Wei

    2016-08-03

    Current static-state explorations of organic semiconductors for optimal material properties and device performance are hindered by limited insights into the dynamically changed molecular states and charge transport and energy transfer processes upon device operation. Here, we propose a simple yet successful strategy, resonance variation-based dynamic adaptation (RVDA), to realize optimized self-adaptive properties in donor-resonance-acceptor molecules by engineering the resonance variation for dynamic tuning of organic semiconductors. Organic light-emitting diodes hosted by these RVDA materials exhibit remarkably high performance, with external quantum efficiencies up to 21.7% and favorable device stability. Our approach, which supports simultaneous realization of dynamically adapted and selectively enhanced properties via resonance engineering, illustrates a feasible design map for the preparation of smart organic semiconductors capable of dynamic structure and property modulations, promoting the studies of organic electronics from static to dynamic.

  17. Charge Saturation and Intrinsic Doping in Electrolyte-Gated Organic Semiconductors.

    Science.gov (United States)

    Atallah, Timothy L; Gustafsson, Martin V; Schmidt, Elliot; Frisbie, C Daniel; Zhu, X-Y

    2015-12-03

    Electrolyte gating enables low voltage operation of organic thin film transistors, but little is known about the nature of the electrolyte/organic interface. Here we apply charge-modulation Fourier transform infrared spectroscopy, in conjunction with electrical measurements, on a model electrolyte gated organic semiconductor interface: single crystal rubrene/ion-gel. We provide spectroscopic signature for free-hole like carriers in the organic semiconductor and unambiguously show the presence of a high density of intrinsic doping of the free holes upon formation of the rubrene/ion-gel interface, without gate bias (Vg = 0 V). We explain this intrinsic doping as resulting from a thermodynamic driving force for the stabilization of free holes in the organic semiconductor by anions in the ion-gel. Spectroscopy also reveals the saturation of free-hole like carrier density at the rubrene/ion-gel interface at Vg < -0.5 V, which is commensurate with the negative transconductance seen in transistor measurements.

  18. Rational In Silico Design of an Organic Semiconductor with Improved Electron Mobility.

    Science.gov (United States)

    Friederich, Pascal; Gómez, Verónica; Sprau, Christian; Meded, Velimir; Strunk, Timo; Jenne, Michael; Magri, Andrea; Symalla, Franz; Colsmann, Alexander; Ruben, Mario; Wenzel, Wolfgang

    2017-11-01

    Organic semiconductors find a wide range of applications, such as in organic light emitting diodes, organic solar cells, and organic field effect transistors. One of their most striking disadvantages in comparison to crystalline inorganic semiconductors is their low charge-carrier mobility, which manifests itself in major device constraints such as limited photoactive layer thicknesses. Trial-and-error attempts to increase charge-carrier mobility are impeded by the complex interplay of the molecular and electronic structure of the material with its morphology. Here, the viability of a multiscale simulation approach to rationally design materials with improved electron mobility is demonstrated. Starting from one of the most widely used electron conducting materials (Alq 3 ), novel organic semiconductors with tailored electronic properties are designed for which an improvement of the electron mobility by three orders of magnitude is predicted and experimentally confirmed. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  19. Electrical properties of GaAs metal–oxide–semiconductor structure comprising Al2O3 gate oxide and AlN passivation layer fabricated in situ using a metal–organic vapor deposition/atomic layer deposition hybrid system

    Directory of Open Access Journals (Sweden)

    Takeshi Aoki

    2015-08-01

    Full Text Available This paper presents a compressive study on the fabrication and optimization of GaAs metal–oxide–semiconductor (MOS structures comprising a Al2O3 gate oxide, deposited via atomic layer deposition (ALD, with an AlN interfacial passivation layer prepared in situ via metal–organic chemical vapor deposition (MOCVD. The established protocol afforded self-limiting growth of Al2O3 in the atmospheric MOCVD reactor. Consequently, this enabled successive growth of MOCVD-formed AlN and ALD-formed Al2O3 layers on the GaAs substrate. The effects of AlN thickness, post-deposition anneal (PDA conditions, and crystal orientation of the GaAs substrate on the electrical properties of the resulting MOS capacitors were investigated. Thin AlN passivation layers afforded incorporation of optimum amounts of nitrogen, leading to good capacitance–voltage (C–V characteristics with reduced frequency dispersion. In contrast, excessively thick AlN passivation layers degraded the interface, thereby increasing the interfacial density of states (Dit near the midgap and reducing the conduction band offset. To further improve the interface with the thin AlN passivation layers, the PDA conditions were optimized. Using wet nitrogen at 600 °C was effective to reduce Dit to below 2 × 1012 cm−2 eV−1. Using a (111A substrate was also effective in reducing the frequency dispersion of accumulation capacitance, thus suggesting the suppression of traps in GaAs located near the dielectric/GaAs interface. The current findings suggest that using an atmosphere ALD process with in situ AlN passivation using the current MOCVD system could be an efficient solution to improving GaAs MOS interfaces.

  20. Yarr: A PCIe based readout system for semiconductor tracking systems

    Energy Technology Data Exchange (ETDEWEB)

    Heim, Timon [Bergische Universitaet Wuppertal, Wuppertal (Germany); CERN, Geneva (Switzerland); Maettig, Peter [Bergische Universitaet Wuppertal, Wuppertal (Germany); Pernegger, Heinz [CERN, Geneva (Switzerland)

    2015-07-01

    The Yarr readout system is a novel DAQ concept, using an FPGA board connected via PCIe to a computer, to read out semiconductor tracking systems. The system uses the FPGA as a reconfigurable IO interface which, in conjunction with the very high speed of the PCIe bus, enables a focus of processing the data stream coming from the pixel detector in software. Modern computer system could potentially make the need of custom signal processing hardware in readout systems obsolete and the Yarr readout system showcases this for FE-I4 chips, which are state-of-the-art readout chips used in the ATLAS Pixel Insertable B-Layer and developed for tracking in high multiplicity environments. The underlying concept of the Yarr readout system tries to move intelligence from hardware into the software without the loss of performance, which is made possible by modern multi-core processors. The FPGA board firmware acts like a buffer and does no further processing of the data stream, enabling rapid integration of new hardware due to minimal firmware minimisation.

  1. Decoherence in semiconductor cavity QED systems due to phonon couplings

    DEFF Research Database (Denmark)

    Nielsen, Per Kær; Mørk, Jesper

    2014-01-01

    We investigate the effect of electron-phonon interactions on the coherence properties of single photons emitted from a semiconductor cavity QED (quantum electrodynamics) system, i.e., a quantum dot embedded in an optical cavity. The degree of indistinguishability, governing the quantum mechanical...

  2. Semiconductor dosimetry system for gamma and neutron radiation

    International Nuclear Information System (INIS)

    Savic, Z.; Pavlovic, Z.

    1995-01-01

    The semiconductor dosimetry system for gamma and neutron radiation based on pMOS transistor and PIN diode is described. It is intended for tactical or accidental personal dosimetry. The production steps are given. The temperature, dose and time (fading) response are reported. Hardware and software requirements which are needed for obtaining the desired measurement error are pointed. (author)

  3. Synthesis and optical properties of novel organic-inorganic hybrid nanolayer structure semiconductors

    International Nuclear Information System (INIS)

    Zhang Sanjun; Lanty, Gaetan; Lauret, Jean-Sebastien; Deleporte, Emmanuelle; Audebert, Pierre; Galmiche, Laurent

    2009-01-01

    We report on the synthesis of some novel organic-inorganic hybrid 2D perovskite semiconductors (R-(CH 2 ) n NH 3 ) 2 PbX 4 . These semiconductors are self-assembled intercalation nanolayers and have a multi-quantum-well energy level structure. We systematically vary the characteristic of organic groups (R-(CH 2 ) n NH 3 + ) to study the relationship between their structures and the optical properties of (R-(CH 2 ) n NH 3 ) 2 PbX 4 . From optical absorption and photoluminescence spectroscopy experiments performed on series of samples, we find some trends of choosing the organic groups to improve the optical performance of (R-(CH 2 ) n NH 3 ) 2 PbX 4 . A new organic group, which allows synthesis of nanolayer perovskite semiconductors with quite high photoluminescence efficiency and better long-term stability, has been found.

  4. Organic semiconductor density of states controls the energy level alignment at electrode interfaces

    Science.gov (United States)

    Oehzelt, Martin; Koch, Norbert; Heimel, Georg

    2014-01-01

    Minimizing charge carrier injection barriers and extraction losses at interfaces between organic semiconductors and metallic electrodes is critical for optimizing the performance of organic (opto-) electronic devices. Here, we implement a detailed electrostatic model, capable of reproducing the alignment between the electrode Fermi energy and the transport states in the organic semiconductor both qualitatively and quantitatively. Covering the full phenomenological range of interfacial energy level alignment regimes within a single, consistent framework and continuously connecting the limiting cases described by previously proposed models allows us to resolve conflicting views in the literature. Our results highlight the density of states in the organic semiconductor as a key factor. Its shape and, in particular, the energy distribution of electronic states tailing into the fundamental gap is found to determine both the minimum value of practically achievable injection barriers as well as their spatial profile, ranging from abrupt interface dipoles to extended band-bending regions. PMID:24938867

  5. All-polymer organic semiconductor laser chips: Parallel fabrication and encapsulation

    DEFF Research Database (Denmark)

    Vannahme, Christoph; Klinkhammer, Sönke; Christiansen, Mads Brøkner

    2010-01-01

    Organic semiconductor lasers are of particular interest as tunable visible laser light sources. For bringing those to market encapsulation is needed to ensure practicable lifetimes. Additionally, fabrication technologies suitable for mass production must be used. We introduce all-polymer chips...... comprising encapsulated distributed feedback organic semiconductor lasers. Several chips are fabricated in parallel by thermal nanoimprint of the feedback grating on 4? wafer scale out of poly(methyl methacrylate) (PMMA) and cyclic olefin copolymer (COC). The lasers consisting of the organic semiconductor...... tris(8- hydroxyquinoline) aluminum (Alq3) doped with the laser dye 4-dicyanomethylene-2- methyl-6-(p-dimethylaminostyril)-4H-pyrane (DCM) are hermetically sealed by thermally bonding a polymer lid. The organic thin film is placed in a basin within the substrate and is not in direct contact to the lid...

  6. Design strategies for organic semiconductors beyond the molecular formula.

    Science.gov (United States)

    Henson, Zachary B; Müllen, Klaus; Bazan, Guillermo C

    2012-09-01

    Organic semiconducting materials based on polymers and molecular systems containing an electronically delocalized structure are the basis of emerging optoelectronic technologies such as plastic solar cells and flexible transistors. For isolated molecules, guidelines exist that rely on the molecular formula to tailor the frontier (highest occupied or lowest unoccupied) molecular orbital energy levels and optical absorption profiles. Much less control can be achieved over relevant properties, however, as one makes the transition to the ensemble behaviour characteristic of the solid state. Polymeric materials are also challenging owing to the statistical description of the average number of repeat units. Here we draw attention to the limitations of molecular formulae as predictive tools for achieving properties relevant to device performances. Illustrative examples highlight the relevance of organization across multiple length scales, and how device performances--although relevant for practical applications--poorly reflect the success of molecular design.

  7. Extension of spatiotemporal chaos in glow discharge-semiconductor systems.

    Science.gov (United States)

    Akhmet, Marat; Rafatov, Ismail; Fen, Mehmet Onur

    2014-12-01

    Generation of chaos in response systems is discovered numerically through specially designed unidirectional coupling of two glow discharge-semiconductor systems. By utilizing the auxiliary system approach, [H. D. I. Abarbanel, N. F. Rulkov, and M. M. Sushchik, Phys. Rev. E 53, 4528-4535 (1996)] it is verified that the phenomenon is not a chaos synchronization. Simulations demonstrate various aspects of the chaos appearance in both drive and response systems. Chaotic control is through the external circuit equation and governs the electrical potential on the boundary. The expandability of the theory to collectives of glow discharge systems is discussed, and this increases the potential of applications of the results. Moreover, the research completes the previous discussion of the chaos appearance in a glow discharge-semiconductor system [D. D. Šijačić U. Ebert, and I. Rafatov, Phys. Rev. E 70, 056220 (2004).].

  8. Extension of spatiotemporal chaos in glow discharge-semiconductor systems

    International Nuclear Information System (INIS)

    Akhmet, Marat; Fen, Mehmet Onur; Rafatov, Ismail

    2014-01-01

    Generation of chaos in response systems is discovered numerically through specially designed unidirectional coupling of two glow discharge-semiconductor systems. By utilizing the auxiliary system approach, [H. D. I. Abarbanel, N. F. Rulkov, and M. M. Sushchik, Phys. Rev. E 53, 4528–4535 (1996)] it is verified that the phenomenon is not a chaos synchronization. Simulations demonstrate various aspects of the chaos appearance in both drive and response systems. Chaotic control is through the external circuit equation and governs the electrical potential on the boundary. The expandability of the theory to collectives of glow discharge systems is discussed, and this increases the potential of applications of the results. Moreover, the research completes the previous discussion of the chaos appearance in a glow discharge-semiconductor system [D. D. Šijačić U. Ebert, and I. Rafatov, Phys. Rev. E 70, 056220 (2004).

  9. Mechanical Properties of Organic Semiconductors for Stretchable, Highly Flexible, and Mechanically Robust Electronics.

    Science.gov (United States)

    Root, Samuel E; Savagatrup, Suchol; Printz, Adam D; Rodriquez, Daniel; Lipomi, Darren J

    2017-05-10

    Mechanical deformability underpins many of the advantages of organic semiconductors. The mechanical properties of these materials are, however, diverse, and the molecular characteristics that permit charge transport can render the materials stiff and brittle. This review is a comprehensive description of the molecular and morphological parameters that govern the mechanical properties of organic semiconductors. Particular attention is paid to ways in which mechanical deformability and electronic performance can coexist. The review begins with a discussion of flexible and stretchable devices of all types, and in particular the unique characteristics of organic semiconductors. It then discusses the mechanical properties most relevant to deformable devices. In particular, it describes how low modulus, good adhesion, and absolute extensibility prior to fracture enable robust performance, along with mechanical "imperceptibility" if worn on the skin. A description of techniques of metrology precedes a discussion of the mechanical properties of three classes of organic semiconductors: π-conjugated polymers, small molecules, and composites. The discussion of each class of materials focuses on molecular structure and how this structure (and postdeposition processing) influences the solid-state packing structure and thus the mechanical properties. The review concludes with applications of organic semiconductor devices in which every component is intrinsically stretchable or highly flexible.

  10. Collection-limited theory interprets the extraordinary response of single semiconductor organic solar cells

    Science.gov (United States)

    Ray, Biswajit; Baradwaj, Aditya G.; Khan, Mohammad Ryyan; Boudouris, Bryan W.; Alam, Muhammad Ashraful

    2015-01-01

    The bulk heterojunction (BHJ) organic photovoltaic (OPV) architecture has dominated the literature due to its ability to be implemented in devices with relatively high efficiency values. However, a simpler device architecture based on a single organic semiconductor (SS-OPV) offers several advantages: it obviates the need to control the highly system-dependent nanoscale BHJ morphology, and therefore, would allow the use of broader range of organic semiconductors. Unfortunately, the photocurrent in standard SS-OPV devices is typically very low, which generally is attributed to inefficient charge separation of the photogenerated excitons. Here we show that the short-circuit current density from SS-OPV devices can be enhanced significantly (∼100-fold) through the use of inverted device configurations, relative to a standard OPV device architecture. This result suggests that charge generation may not be the performance bottleneck in OPV device operation. Instead, poor charge collection, caused by defect-induced electric field screening, is most likely the primary performance bottleneck in regular-geometry SS-OPV cells. We justify this hypothesis by: (i) detailed numerical simulations, (ii) electrical characterization experiments of functional SS-OPV devices using multiple polymers as active layer materials, and (iii) impedance spectroscopy measurements. Furthermore, we show that the collection-limited photocurrent theory consistently interprets typical characteristics of regular SS-OPV devices. These insights should encourage the design and OPV implementation of high-purity, high-mobility polymers, and other soft materials that have shown promise in organic field-effect transistor applications, but have not performed well in BHJ OPV devices, wherein they adopt less-than-ideal nanostructures when blended with electron-accepting materials. PMID:26290582

  11. Organic-inorganic semiconductor devices and 3, 4, 9, 10 perylenetetracarboxylic dianhydride: an early history of organic electronics

    International Nuclear Information System (INIS)

    Forrest, S R

    2003-01-01

    The demonstration, over 20 years ago, of an organic-inorganic heterojunction (OI HJ) device along with investigations of the growth and physical properties of the archetypal crystalline molecular organic semiconductor 3, 4, 9, 10 perylenetetracarboxylic dianhydride are discussed. Possible applications of OI HJ devices are introduced and the dramatic change in conductive properties of these materials when exposed to high-energy ion beams is described. The past and future prospects for hybrid organic-on-inorganic semiconductor structures for use in electronic and photonic applications are also presented

  12. New Organic Semiconductor Materials Applied in Organic Photovoltaic and Optical Devices

    Directory of Open Access Journals (Sweden)

    Andre F. S. Guedes

    2015-04-01

    Full Text Available The development of flexible organic photovoltaic solar cells, using an optically transparent substrate material and organic semiconductor materials, has been widely utilized by the electronic industry when producing new technological products. The flexible organic photovoltaic solar cells are the base Poly (3,4-ethylenedioxythiophene, PEDOT, Poly(3-hexyl thiophene, P3HT, Phenyl-C61-butyric acid methyl ester, PCBM and Polyaniline, PANI, were deposited in Indium Tin Oxide, ITO, and characterized by Electrical Measurements and Scanning Electron Microscopy (SEM. In addition, the thin film obtained by the deposition of PANI, prepared in perchloric acid solution, was identified through PANI-X1. The result obtained by electrical Measurements has demonstrated that the PET/ITO/PEDOT/P3HT:PCBM Blend/PANI-X1 layer presents the characteristic curve of standard solar cell after spin-coating and electrodeposition. The Thin film obtained by electrodeposition of PANI-X1 on P3HT/PCBM Blend was prepared in perchloric acid solution. These flexible organic photovoltaic solar cells presented power conversion efficiency of 12%. The inclusion of the PANI-X1 layer reduced the effects of degradation these organic photovoltaic panels induced for solar irradiation. In Scanning Electron Microscopy (SEM these studies reveal that the surface of PANI-X1 layers is strongly conditioned by the surface morphology of the dielectric.

  13. Smooth Growth of Organic Semiconductor Films on Graphene for High-Efficiency Electronics

    NARCIS (Netherlands)

    Hlawacek, G.; Khokhar, F.S.; van Gastel, Raoul; Poelsema, Bene; Teichert, Christian

    2011-01-01

    High-quality thin films of conjugated molecules with smooth interfaces are important to assist the advent of organic electronics. Here, we report on the layer-by-layer growth of the organic semiconductor molecule p-sexiphenyl (6P) on the transparent electrode material graphene. Low energy electron

  14. Integrated Materials Design of Organic Semiconductors for Field-Effect Transistors

    KAUST Repository

    Mei, Jianguo; Diao, Ying; Appleton, Anthony L.; Fang, Lei; Bao, Zhenan

    2013-01-01

    The past couple of years have witnessed a remarkable burst in the development of organic field-effect transistors (OFETs), with a number of organic semiconductors surpassing the benchmark mobility of 10 cm2/(V s). In this perspective, we highlight

  15. N-doping of organic semiconductors by bis-metallosandwich compounds

    Science.gov (United States)

    Barlow, Stephen; Qi, Yabing; Kahn, Antoine; Marder, Seth; Kim, Sang Bok; Mohapatra, Swagat K.; Guo, Song

    2016-01-05

    The various inventions disclosed, described, and/or claimed herein relate to the field of methods for n-doping organic semiconductors with certain bis-metallosandwich compounds, the doped compositions produced, and the uses of the doped compositions in organic electronic devices. Metals can be manganese, rhenium, iron, ruthenium, osmium, rhodium, or iridium. Stable and efficient doping can be achieved.

  16. Prediction and theoretical characterization of p-type organic semiconductor crystals for field-effect transistor applications.

    Science.gov (United States)

    Atahan-Evrenk, Sule; Aspuru-Guzik, Alán

    2014-01-01

    The theoretical prediction and characterization of the solid-state structure of organic semiconductors has tremendous potential for the discovery of new high performance materials. To date, the theoretical analysis mostly relied on the availability of crystal structures obtained through X-ray diffraction. However, the theoretical prediction of the crystal structures of organic semiconductor molecules remains a challenge. This review highlights some of the recent advances in the determination of structure-property relationships of the known organic semiconductor single-crystals and summarizes a few available studies on the prediction of the crystal structures of p-type organic semiconductors for transistor applications.

  17. Synthesis of Perylene Imide Diones as Platforms for the Development of Pyrazine Based Organic Semiconductors.

    Science.gov (United States)

    de Echegaray, Paula; Mancheño, María J; Arrechea-Marcos, Iratxe; Juárez, Rafael; López-Espejo, Guzmán; López Navarrete, J Teodomiro; Ramos, María Mar; Seoane, Carlos; Ortiz, Rocío Ponce; Segura, José L

    2016-11-18

    There is a great interest in peryleneimide (PI)-containing compounds given their unique combination of good electron accepting ability, high abosorption in the visible region, and outstanding chemical, thermal, and photochemical stabilities. Thus, herein we report the synthesis of perylene imide derivatives endowed with a 1,2-diketone functionality (PIDs) as efficient intermediates to easily access peryleneimide (PI)-containing organic semiconductors with enhanced absorption cross-section for the design of tunable semiconductor organic materials. Three processable organic molecular semiconductors containing thiophene and terthiophene moieties, PITa, PITb, and PITT, have been prepared from the novel PIDs. The tendency of these semiconductors for molecular aggregation have been investigated by NMR spectroscopy and supported by quantum chemical calculations. 2D NMR experiments and theoretical calculations point to an antiparallel π-stacking interaction as the most stable conformation in the aggregates. Investigation of the optical and electrochemical properties of the materials is also reported and analyzed in combination with DFT calculations. Although the derivatives presented here show modest electron mobilities of ∼10 -4 cm 2 V -1 s -1 , these preliminary studies of their performance in organic field effect transistors (OFETs) indicate the potential of these new building blocks as n-type semiconductors.

  18. Continuous-wave lasing in an organic-inorganic lead halide perovskite semiconductor

    Science.gov (United States)

    Jia, Yufei; Kerner, Ross A.; Grede, Alex J.; Rand, Barry P.; Giebink, Noel C.

    2017-12-01

    Hybrid organic-inorganic perovskites have emerged as promising gain media for tunable, solution-processed semiconductor lasers. However, continuous-wave operation has not been achieved so far1-3. Here, we demonstrate that optically pumped continuous-wave lasing can be sustained above threshold excitation intensities of 17 kW cm-2 for over an hour in methylammonium lead iodide (MAPbI3) distributed feedback lasers that are maintained below the MAPbI3 tetragonal-to-orthorhombic phase transition temperature of T ≈ 160 K. In contrast with the lasing death phenomenon that occurs for pure tetragonal-phase MAPbI3 at T > 160 K (ref. 4), we find that continuous-wave gain becomes possible at T ≈ 100 K from tetragonal-phase inclusions that are photogenerated by the pump within the normally existing, larger-bandgap orthorhombic host matrix. In this mixed-phase system, the tetragonal inclusions function as carrier recombination sinks that reduce the transparency threshold, in loose analogy to inorganic semiconductor quantum wells, and may serve as a model for engineering improved perovskite gain media.

  19. High-resolution charge carrier mobility mapping of heterogeneous organic semiconductors

    Science.gov (United States)

    Button, Steven W.; Mativetsky, Jeffrey M.

    2017-08-01

    Organic electronic device performance is contingent on charge transport across a heterogeneous landscape of structural features. Methods are therefore needed to unravel the effects of local structure on overall electrical performance. Using conductive atomic force microscopy, we construct high-resolution out-of-plane hole mobility maps from arrays of 5000 to 16 000 current-voltage curves. To demonstrate the efficacy of this non-invasive approach for quantifying and mapping local differences in electrical performance due to structural heterogeneities, we investigate two thin film test systems, one bearing a heterogeneous crystal structure [solvent vapor annealed 5,11-Bis(triethylsilylethynyl)anthradithiophene (TES-ADT)—a small molecule organic semiconductor] and one bearing a heterogeneous chemical composition [p-DTS(FBTTh2)2:PC71BM—a high-performance organic photovoltaic active layer]. TES-ADT shows nearly an order of magnitude difference in hole mobility between semicrystalline and crystalline areas, along with a distinct boundary between the two regions, while p-DTS(FBTTh2)2:PC71BM exhibits subtle local variations in hole mobility and a nanoscale domain structure with features below 10 nm in size. We also demonstrate mapping of the built-in potential, which plays a significant role in organic light emitting diode and organic solar cell operation.

  20. Preparative semiconductor photoredox catalysis: An emerging theme in organic synthesis

    Directory of Open Access Journals (Sweden)

    David W. Manley

    2015-09-01

    Full Text Available Heterogeneous semiconductor photoredox catalysis (SCPC, particularly with TiO2, is evolving to provide radically new synthetic applications. In this review we describe how photoactivated SCPCs can either (i interact with a precursor that donates an electron to the semiconductor thus generating a radical cation; or (ii interact with an acceptor precursor that picks up an electron with production of a radical anion. The radical cations of appropriate donors convert to neutral radicals usually by loss of a proton. The most efficient donors for synthetic purposes contain adjacent functional groups such that the neutral radicals are resonance stabilized. Thus, ET from allylic alkenes and enol ethers generated allyl type radicals that reacted with 1,2-diazine or imine co-reactants to yield functionalized hydrazones or benzylanilines. SCPC with tertiary amines enabled electron-deficient alkenes to be alkylated and furoquinolinones to be accessed. Primary amines on their own led to self-reactions involving C–N coupling and, with terminal diamines, cyclic amines were produced. Carboxylic acids were particularly fruitful affording C-centered radicals that alkylated alkenes and took part in tandem addition cyclizations producing chromenopyrroles; decarboxylative homo-dimerizations were also observed. Acceptors initially yielding radical anions included nitroaromatics and aromatic iodides. The latter led to hydrodehalogenations and cyclizations with suitable precursors. Reductive SCPC also enabled electron-deficient alkenes and aromatic aldehydes to be hydrogenated without the need for hydrogen gas.

  1. Heteroepitaxial growth of 3-5 semiconductor compounds by metal-organic chemical vapor deposition for device applications

    Science.gov (United States)

    Collis, Ward J.; Abul-Fadl, Ali

    1988-01-01

    The purpose of this research is to design, install and operate a metal-organic chemical vapor deposition system which is to be used for the epitaxial growth of 3-5 semiconductor binary compounds, and ternary and quaternary alloys. The long-term goal is to utilize this vapor phase deposition in conjunction with existing current controlled liquid phase epitaxy facilities to perform hybrid growth sequences for fabricating integrated optoelectronic devices.

  2. Quantitative Determination of Organic Semiconductor Microstructure from the Molecular to Device Scale

    KAUST Repository

    Rivnay, Jonathan

    2012-10-10

    A study was conducted to demonstrate quantitative determination of organic semiconductor microstructure from the molecular to device scale. The quantitative determination of organic semiconductor microstructure from the molecular to device scale was key to obtaining precise description of the molecular structure and microstructure of the materials of interest. This information combined with electrical characterization and modeling allowed for the establishment of general design rules to guide future rational design of materials and devices. Investigations revealed that a number and variety of defects were the largest contributors to the existence of disorder within a lattice, as organic semiconductor crystals were dominated by weak van der Waals bonding. Crystallite size, texture, and variations in structure due to spatial confinement and interfaces were also found to be relevant for transport of free charge carriers and bound excitonic species over distances that were important for device operation.

  3. Soft liquid phase adsorption for fabrication of organic semiconductor films on wettability patterned surfaces.

    Science.gov (United States)

    Watanabe, Satoshi; Akiyoshi, Yuri; Matsumoto, Mutsuyoshi

    2014-01-01

    We report a soft liquid-phase adsorption (SLPA) technique for the fabrication of organic semiconductor films on wettability-patterned substrates using toluene/water emulsions. Wettability-patterned substrates were obtained by the UV-ozone treatment of self-assembled monolayers of silane coupling agents on glass plates using a metal mask. Organic semiconductor polymer films were formed selectively on the hydrophobic part of the wettability-patterned substrates. The thickness of the films fabricated by the SLPA technique is significantly larger than that of the films fabricated by dip-coating and spin-coating techniques. The film thickness can be controlled by adjusting the volume ratio of toluene to water, immersion angle, immersion temperature, and immersion time. The SLPA technique allows for the direct production of organic semiconductor films on wettability-patterned substrates with minimized material consumption and reduced number of fabrication steps.

  4. Self-aligned metallization on organic semiconductor through 3D dual-layer thermal nanoimprint

    International Nuclear Information System (INIS)

    Jung, Y; Cheng, X

    2014-01-01

    High-resolution patterning of metal structures on organic semiconductors is important to the realization of high-performance organic transistors for organic integrated circuit applications. The traditional shadow mask technique has a limited resolution, precluding sub-micron metal structures on organic semiconductors. Thus organic transistors cannot benefit from scaling into the deep sub-micron region to improve their dc and ac performances. In this work, we report an efficient multiple-level metallization on poly (3-hexylthiophene) (P3HT) with a deep sub-micron lateral gap. By using a 3D nanoimprint mold in a dual-layer thermal nanoimprint process, we achieved self-aligned two-level metallization on P3HT. The 3D dual-layer thermal nanoimprint enables the first metal patterns to have suspending side-wings that can clearly define a distance from the second metal patterns. Isotropic and anisotropic side-wing structures can be fabricated through two different schemes. The process based on isotropic side-wings achieves a lateral-gap in the order of 100 nm (scheme 1). A gap of 60 nm can be achieved from the process with anisotropic side-wings (scheme 2). Because of the capability of nanoscale metal patterning on organic semiconductors with high overlay accuracy, this self-aligned metallization technique can be utilized to fabricate high-performance organic metal semiconductor field-effect transistor. (paper)

  5. Low-voltage organic electronics based on a gate-tunable injection barrier in vertical graphene-organic semiconductor heterostructures.

    Science.gov (United States)

    Hlaing, Htay; Kim, Chang-Hyun; Carta, Fabio; Nam, Chang-Yong; Barton, Rob A; Petrone, Nicholas; Hone, James; Kymissis, Ioannis

    2015-01-14

    The vertical integration of graphene with inorganic semiconductors, oxide semiconductors, and newly emerging layered materials has recently been demonstrated as a promising route toward novel electronic and optoelectronic devices. Here, we report organic thin film transistors based on vertical heterojunctions of graphene and organic semiconductors. In these thin heterostructure devices, current modulation is accomplished by tuning of the injection barriers at the semiconductor/graphene interface with the application of a gate voltage. N-channel devices fabricated with a thin layer of C60 show a room temperature on/off ratio >10(4) and current density of up to 44 mAcm(-2). Because of the ultrashort channel intrinsic to the vertical structure, the device is fully operational at a driving voltage of 200 mV. A complementary p-channel device is also investigated, and a logic inverter based on two complementary transistors is demonstrated. The vertical integration of graphene with organic semiconductors via simple, scalable, and low-temperature fabrication processes opens up new opportunities to realize flexible, transparent organic electronic, and optoelectronic devices.

  6. Development of the power control system for semiconductor lasers

    International Nuclear Information System (INIS)

    Kim, Kwang Suk; Kim, Cheol Jung

    1997-12-01

    For the first year plan of this program, we developed the power control system for semiconductor lasers. We applied the high-current switching mode techniques to fabricating a power control system. Then, we investigated the direct side pumping techniques with GaA1As diode laser bars to laser crystal without pumping optics. We obtained 0.5W average output power from this DPSSL. (author). 54 refs., 3 tabs., 18 figs

  7. Molecular Electrical Doping of Organic Semiconductors: Fundamental Mechanisms and Emerging Dopant Design Rules.

    Science.gov (United States)

    Salzmann, Ingo; Heimel, Georg; Oehzelt, Martin; Winkler, Stefanie; Koch, Norbert

    2016-03-15

    Today's information society depends on our ability to controllably dope inorganic semiconductors, such as silicon, thereby tuning their electrical properties to application-specific demands. For optoelectronic devices, organic semiconductors, that is, conjugated polymers and molecules, have emerged as superior alternative owing to the ease of tuning their optical gap through chemical variability and their potential for low-cost, large-area processing on flexible substrates. There, the potential of molecular electrical doping for improving the performance of, for example, organic light-emitting devices or organic solar cells has only recently been established. The doping efficiency, however, remains conspicuously low, highlighting the fact that the underlying mechanisms of molecular doping in organic semiconductors are only little understood compared with their inorganic counterparts. Here, we review the broad range of phenomena observed upon molecularly doping organic semiconductors and identify two distinctly different scenarios: the pairwise formation of both organic semiconductor and dopant ions on one hand and the emergence of ground state charge transfer complexes between organic semiconductor and dopant through supramolecular hybridization of their respective frontier molecular orbitals on the other hand. Evidence for the occurrence of these two scenarios is subsequently discussed on the basis of the characteristic and strikingly different signatures of the individual species involved in the respective doping processes in a variety of spectroscopic techniques. The critical importance of a statistical view of doping, rather than a bimolecular picture, is then highlighted by employing numerical simulations, which reveal one of the main differences between inorganic and organic semiconductors to be their respective density of electronic states and the doping induced changes thereof. Engineering the density of states of doped organic semiconductors, the Fermi

  8. The development of intelligent expert system with SAT for semiconductor

    International Nuclear Information System (INIS)

    Kim, Jae Yeol; Shim, Jae Gi; Jeong, Hyun Jo; Cho, Young Tae; Kim, Chang Hyun; Ko, Myung Soo

    2001-01-01

    In this study, the researches classifying the artificial flaws in semiconductor packages are performed using pattern recognition technology. For this purposes image pattern recognition package including the user made software was developed and total procedure including ultrasonic image acquisition, equalization filtering, binary processing, edge detection and classifier selection is treated by BP(backpropagation). Specially, it is compared IP(image processing) and SOM(self-organizing map) as preprocessing method for dimensionality reduction for entrance into multi-layer perceptron(backpropagation). Also, the pattern recognition techniques is applied to the classification problem of semiconductor flaws as crack, delamination. According to this results, it is possible to acquire the recognition rate of 83.4% about delamination, 75.7% about crack for SOM, and to acquire the recognition rate of 100% for BP.

  9. Doping Polymer Semiconductors by Organic Salts: Toward High-Performance Solution-Processed Organic Field-Effect Transistors.

    Science.gov (United States)

    Hu, Yuanyuan; Rengert, Zachary D; McDowell, Caitlin; Ford, Michael J; Wang, Ming; Karki, Akchheta; Lill, Alexander T; Bazan, Guillermo C; Nguyen, Thuc-Quyen

    2018-04-24

    Solution-processed organic field-effect transistors (OFETs) were fabricated with the addition of an organic salt, trityl tetrakis(pentafluorophenyl)borate (TrTPFB), into thin films of donor-acceptor copolymer semiconductors. The performance of OFETs is significantly enhanced after the organic salt is incorporated. TrTPFB is confirmed to p-dope the organic semiconductors used in this study, and the doping efficiency as well as doping physics was investigated. In addition, systematic electrical and structural characterizations reveal how the doping enhances the performance of OFETs. Furthermore, it is shown that this organic salt doping method is feasible for both p- and n-doping by using different organic salts and, thus, can be utilized to achieve high-performance OFETs and organic complementary circuits.

  10. Unipolar resistive switching in metal oxide/organic semiconductor non-volatile memories as a critical phenomenon

    International Nuclear Information System (INIS)

    Bory, Benjamin F.; Meskers, Stefan C. J.; Rocha, Paulo R. F.; Gomes, Henrique L.; Leeuw, Dago M. de

    2015-01-01

    Diodes incorporating a bilayer of an organic semiconductor and a wide bandgap metal oxide can show unipolar, non-volatile memory behavior after electroforming. The prolonged bias voltage stress induces defects in the metal oxide with an areal density exceeding 10 17  m −2 . We explain the electrical bistability by the coexistence of two thermodynamically stable phases at the interface between an organic semiconductor and metal oxide. One phase contains mainly ionized defects and has a low work function, while the other phase has mainly neutral defects and a high work function. In the diodes, domains of the phase with a low work function constitute current filaments. The phase composition and critical temperature are derived from a 2D Ising model as a function of chemical potential. The model predicts filamentary conduction exhibiting a negative differential resistance and nonvolatile memory behavior. The model is expected to be generally applicable to any bilayer system that shows unipolar resistive switching

  11. Quantifying resistances across nanoscale low- and high-angle interspherulite boundaries in solution-processed organic semiconductor thin films.

    Science.gov (United States)

    Lee, Stephanie S; Mativetsky, Jeffrey M; Loth, Marsha A; Anthony, John E; Loo, Yueh-Lin

    2012-11-27

    The nanoscale boundaries formed when neighboring spherulites impinge in polycrystalline, solution-processed organic semiconductor thin films act as bottlenecks to charge transport, significantly reducing organic thin-film transistor mobility in devices comprising spherulitic thin films as the active layers. These interspherulite boundaries (ISBs) are structurally complex, with varying angles of molecular orientation mismatch along their lengths. We have successfully engineered exclusively low- and exclusively high-angle ISBs to elucidate how the angle of molecular orientation mismatch at ISBs affects their resistivities in triethylsilylethynyl anthradithiophene thin films. Conductive AFM and four-probe measurements reveal that current flow is unaffected by the presence of low-angle ISBs, whereas current flow is significantly disrupted across high-angle ISBs. In the latter case, we estimate the resistivity to be 22 MΩμm(2)/width of the ISB, only less than a quarter of the resistivity measured across low-angle grain boundaries in thermally evaporated sexithiophene thin films. This discrepancy in resistivities across ISBs in solution-processed organic semiconductor thin films and grain boundaries in thermally evaporated organic semiconductor thin films likely arises from inherent differences in the nature of film formation in the respective systems.

  12. Effect of Structure and Disorder on the Charge Transport in Defined Self-Assembled Monolayers of Organic Semiconductors.

    Science.gov (United States)

    Schmaltz, Thomas; Gothe, Bastian; Krause, Andreas; Leitherer, Susanne; Steinrück, Hans-Georg; Thoss, Michael; Clark, Timothy; Halik, Marcus

    2017-09-26

    Self-assembled monolayer field-effect transistors (SAMFETs) are not only a promising type of organic electronic device but also allow detailed analyses of structure-property correlations. The influence of the morphology on the charge transport is particularly pronounced, due to the confined monolayer of 2D-π-stacked organic semiconductor molecules. The morphology, in turn, is governed by relatively weak van-der-Waals interactions and is thus prone to dynamic structural fluctuations. Accordingly, combining electronic and physical characterization and time-averaged X-ray analyses with the dynamic information available at atomic resolution from simulations allows us to characterize self-assembled monolayer (SAM) based devices in great detail. For this purpose, we have constructed transistors based on SAMs of two molecules that consist of the organic p-type semiconductor benzothieno[3,2-b][1]benzothiophene (BTBT), linked to a C 11 or C 12 alkylphosphonic acid. Both molecules form ordered SAMs; however, our experiments show that the size of the crystalline domains and the charge-transport properties vary considerably in the two systems. These findings were confirmed by molecular dynamics (MD) simulations and semiempirical molecular-orbital electronic-structure calculations, performed on snapshots from the MD simulations at different times, revealing, in atomistic detail, how the charge transport in organic semiconductors is influenced and limited by dynamic disorder.

  13. Photocatalysis of irradiated semiconductor surfaces: Its application to water splitting and some organic reactions

    Energy Technology Data Exchange (ETDEWEB)

    Sakata, T

    1985-05-01

    Hydrogen production from organic compounds and water was investigated using powdered semiconductor photocatalysts. The complete decomposition observed for several organic compounds demonstrated that water is involved in the reactions as an oxidizing agent. Photocatalyses of dyes and semiconductors were found to be applicable to amino acid synthesis. The quantum yields of photocatalytic amino acid synthesis using visible light are about 20%-40% in the absence of a metal catalyst such as platinum. Moreover the reactions are highly selective and depend strongly on the type of semiconductor. This method was applied to the asymmetric synthesis of amino acids using asymmetric catalysts. Rather high optical yields of 50% were achieved for the synthesis of L-phenylalanine.

  14. Development of n-type polymer semiconductors for organic field-effect transistors

    International Nuclear Information System (INIS)

    Choi, Jongwan; Kim, Nakjoong; Song, Heeseok; Kim, Felix Sunjoo

    2015-01-01

    We review herein the development of unipolar n-type polymer semiconductors in organic field-effect transistors, which would enable large-scale deployment of printed electronics in combination with a fast-growing area of p-type counterparts. After discussing general features of electron transport in organic semiconductors, various π-conjugated polymers that are capable of transporting electrons are selected and summarized to outline the design principles for enhancing electron mobility and stability in air. The n-type polymer semiconductors with high electron mobility and good stability in air share common features of low-lying frontier molecular orbital energy levels achieved by design. In this review, materials are listed in roughly chronological order of the appearance of the key building blocks, such as various arylene diimides, or structural characteristics, including nitrile and fluorinated groups, in order to present the progress in the area of n-type polymers. (paper)

  15. Charge carrier mobility in thin films of organic semiconductors by the gated van der Pauw method

    Science.gov (United States)

    Rolin, Cedric; Kang, Enpu; Lee, Jeong-Hwan; Borghs, Gustaaf; Heremans, Paul; Genoe, Jan

    2017-01-01

    Thin film transistors based on high-mobility organic semiconductors are prone to contact problems that complicate the interpretation of their electrical characteristics and the extraction of important material parameters such as the charge carrier mobility. Here we report on the gated van der Pauw method for the simple and accurate determination of the electrical characteristics of thin semiconducting films, independently from contact effects. We test our method on thin films of seven high-mobility organic semiconductors of both polarities: device fabrication is fully compatible with common transistor process flows and device measurements deliver consistent and precise values for the charge carrier mobility and threshold voltage in the high-charge carrier density regime that is representative of transistor operation. The gated van der Pauw method is broadly applicable to thin films of semiconductors and enables a simple and clean parameter extraction independent from contact effects. PMID:28397852

  16. COHERENT LIDAR SYSTEM BASED ON A SEMICONDUCTOR LASER AND AMPLIFIER

    DEFF Research Database (Denmark)

    2009-01-01

    The present invention relates to a compact, reliable and low-cost coherent LIDAR (Light Detection And Ranging) system for remote wind-speed determination, determination of particle concentration, and/or temperature based on an all semiconductor light source and related methods. The present...... invention provides a coherent LIDAR system comprising a semiconductor laser for emission of a measurement beam of electromagnetic radiation directed towards a measurement volume for illumination of particles in the measurement volume, a reference beam generator for generation of a reference beam, a detector...... for generation of a detector signal by mixing of the reference beam with light emitted from the particles in the measurement volume illuminated by the measurement beam, and a signal processor for generating a velocity signal corresponding to the velocity of the particles based on the detector signal....

  17. High-mobility pyrene-based semiconductor for organic thin-film transistors.

    Science.gov (United States)

    Cho, Hyunduck; Lee, Sunyoung; Cho, Nam Sung; Jabbour, Ghassan E; Kwak, Jeonghun; Hwang, Do-Hoon; Lee, Changhee

    2013-05-01

    Numerous conjugated oligoacenes and polythiophenes are being heavily studied in the search for high-mobility organic semiconductors. Although many researchers have designed fused aromatic compounds as organic semiconductors for organic thin-film transistors (OTFTs), pyrene-based organic semiconductors with high mobilities and on-off current ratios have not yet been reported. Here, we introduce a new pyrene-based p-type organic semiconductor showing liquid crystal behavior. The thin film characteristics of this material are investigated by varying the substrate temperature during the deposition and the gate dielectric condition using the surface modification with a self-assembled monolayer, and systematically studied in correlation with the performances of transistor devices with this compound. OTFT fabricated under the optimum deposition conditions of this compound, namely, 1,6-bis(5'-octyl-2,2'-bithiophen-5-yl)pyrene (BOBTP) shows a high-performance transistor behavior with a field-effect mobility of 2.1 cm(2) V(-1) s(-1) and an on-off current ratio of 7.6 × 10(6) and enhanced long-term stability compared to the pentacene thin-film transistor.

  18. Charge-transfer mobility and electrical conductivity of PANI as conjugated organic semiconductors.

    Science.gov (United States)

    Zhang, Yahong; Duan, Yuping; Song, Lulu; Zheng, Daoyuan; Zhang, Mingxing; Zhao, Guangjiu

    2017-09-21

    The intramolecular charge transfer properties of a phenyl-end-capped aniline tetramer (ANIH) and a chloro-substituted derivative (ANICl) as organic semiconductors were theoretically studied through the first-principles calculation based on the Marcus-Hush theory. The reorganization energies, intermolecular electronic couplings, angular resolution anisotropic mobilities, and density of states of the two crystals were evaluated. The calculated results demonstrate that both ANIH and ANICl crystals show the higher electron transfer mobilities than the hole-transfer mobilities, which means that the two crystals should prefer to function as n-type organic semiconductors. Furthermore, the angle dependence mobilities of the two crystals show remarkable anisotropic character. The maximum mobility μ max of ANIH and ANICl crystals is 1.3893 and 0.0272 cm 2 V -1 s -1 , which appear at the orientation angles near 176°/356° and 119°/299° of a conducting channel on the a-b reference plane. It is synthetically evaluated that the ANIH crystal possesses relatively lower reorganization energy, higher electronic coupling, and electron transfer mobility, which means that the ANIH crystal may be the more ideal candidate as a high performance n-type organic semiconductor material. The systematic theoretical studies on organic crystals should be conducive to evaluating the charge-transport properties and designing higher performance organic semiconductor materials.

  19. Efficient light emission from inorganic and organic semiconductor hybrid structures by energy-level tuning

    Science.gov (United States)

    Schlesinger, R.; Bianchi, F.; Blumstengel, S.; Christodoulou, C.; Ovsyannikov, R.; Kobin, B.; Moudgil, K.; Barlow, S.; Hecht, S.; Marder, S.R.; Henneberger, F.; Koch, N.

    2015-01-01

    The fundamental limits of inorganic semiconductors for light emitting applications, such as holographic displays, biomedical imaging and ultrafast data processing and communication, might be overcome by hybridization with their organic counterparts, which feature enhanced frequency response and colour range. Innovative hybrid inorganic/organic structures exploit efficient electrical injection and high excitation density of inorganic semiconductors and subsequent energy transfer to the organic semiconductor, provided that the radiative emission yield is high. An inherent obstacle to that end is the unfavourable energy level offset at hybrid inorganic/organic structures, which rather facilitates charge transfer that quenches light emission. Here, we introduce a technologically relevant method to optimize the hybrid structure's energy levels, here comprising ZnO and a tailored ladder-type oligophenylene. The ZnO work function is substantially lowered with an organometallic donor monolayer, aligning the frontier levels of the inorganic and organic semiconductors. This increases the hybrid structure's radiative emission yield sevenfold, validating the relevance of our approach. PMID:25872919

  20. Steady-state photoconductivity and multi-particle interactions in high-mobility organic semiconductors.

    Science.gov (United States)

    Irkhin, P; Najafov, H; Podzorov, V

    2015-10-19

    Fundamental understanding of photocarrier generation, transport and recombination under a steady-state photoexcitation has been an important goal of organic electronics and photonics, since these processes govern such electronic properties of organic semiconductors as, for instance, photoconductivity. Here, we discovered that photoconductivity of a highly ordered organic semiconductor rubrene exhibits several distinct regimes, in which photocurrent as a function of cw (continuous wave) excitation intensity is described by a power law with exponents sequentially taking values 1, 1/3 and ¼. We show that in pristine crystals this photocurrent is generated at the very surface of the crystals, while the bulk photocurrent is drastically smaller and follows a different sequence of exponents, 1 and ½. We describe a simple experimental procedure, based on an application of "gauge effect" in high vacuum, that allows to disentangle the surface and bulk contributions to photoconductivity. A model based on singlet exciton fission, triplet fusion and triplet-charge quenching that can describe these non-trivial effects in photoconductivity of highly ordered organic semiconductors is proposed. Observation of these effects in photoconductivity and modeling of the underlying microscopic mechanisms described in this work represent a significant step forward in our understanding of electronic properties of organic semiconductors.

  1. Efficient light emission from inorganic and organic semiconductor hybrid structures by energy-level tuning.

    Science.gov (United States)

    Schlesinger, R; Bianchi, F; Blumstengel, S; Christodoulou, C; Ovsyannikov, R; Kobin, B; Moudgil, K; Barlow, S; Hecht, S; Marder, S R; Henneberger, F; Koch, N

    2015-04-15

    The fundamental limits of inorganic semiconductors for light emitting applications, such as holographic displays, biomedical imaging and ultrafast data processing and communication, might be overcome by hybridization with their organic counterparts, which feature enhanced frequency response and colour range. Innovative hybrid inorganic/organic structures exploit efficient electrical injection and high excitation density of inorganic semiconductors and subsequent energy transfer to the organic semiconductor, provided that the radiative emission yield is high. An inherent obstacle to that end is the unfavourable energy level offset at hybrid inorganic/organic structures, which rather facilitates charge transfer that quenches light emission. Here, we introduce a technologically relevant method to optimize the hybrid structure's energy levels, here comprising ZnO and a tailored ladder-type oligophenylene. The ZnO work function is substantially lowered with an organometallic donor monolayer, aligning the frontier levels of the inorganic and organic semiconductors. This increases the hybrid structure's radiative emission yield sevenfold, validating the relevance of our approach.

  2. An Ultrasensitive Organic Semiconductor NO2 Sensor Based on Crystalline TIPS-Pentacene Films.

    Science.gov (United States)

    Wang, Zi; Huang, Lizhen; Zhu, Xiaofei; Zhou, Xu; Chi, Lifeng

    2017-10-01

    Organic semiconductor gas sensor is one of the promising candidates of room temperature operated gas sensors with high selectivity. However, for a long time the performance of organic semiconductor sensors, especially for the detection of oxidizing gases, is far behind that of the traditional metal oxide gas sensors. Although intensive attempts have been made to address the problem, the performance and the understanding of the sensing mechanism are still far from sufficient. Herein, an ultrasensitive organic semiconductor NO 2 sensor based on 6,13-bis(triisopropylsilylethynyl)-pentacene (TIPS-petacene) is reported. The device achieves a sensitivity over 1000%/ppm and fast response/recovery, together with a low limit of detection (LOD) of 20 ppb, all of which reach the level of metal oxide sensors. After a comprehensive analysis on the morphology and electrical properties of the organic films, it is revealed that the ultrahigh performance is largely related to the film charge transport ability, which was less concerned in the studies previously. And the combination of efficient charge transport and low original charge carrier concentration is demonstrated to be an effective access to obtain high performance organic semiconductor gas sensors. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  3. Mask alignment system for semiconductor processing

    Science.gov (United States)

    Webb, Aaron P.; Carlson, Charles T.; Weaver, William T.; Grant, Christopher N.

    2017-02-14

    A mask alignment system for providing precise and repeatable alignment between ion implantation masks and workpieces. The system includes a mask frame having a plurality of ion implantation masks loosely connected thereto. The mask frame is provided with a plurality of frame alignment cavities, and each mask is provided with a plurality of mask alignment cavities. The system further includes a platen for holding workpieces. The platen may be provided with a plurality of mask alignment pins and frame alignment pins configured to engage the mask alignment cavities and frame alignment cavities, respectively. The mask frame can be lowered onto the platen, with the frame alignment cavities moving into registration with the frame alignment pins to provide rough alignment between the masks and workpieces. The mask alignment cavities are then moved into registration with the mask alignment pins, thereby shifting each individual mask into precise alignment with a respective workpiece.

  4. Toward quantitative prediction of charge mobility in organic semiconductors: tunneling enabled hopping model.

    Science.gov (United States)

    Geng, Hua; Peng, Qian; Wang, Linjun; Li, Haijiao; Liao, Yi; Ma, Zhiying; Shuai, Zhigang

    2012-07-10

    A tunneling-enabled hopping mechanism is proposed, providing a pratical tool to quantitatively assess charge mobility in organic semiconductors. The paradoxical phenomena in TIPS-pentacene is well explained in that the optical probe indicates localized charges while transport measurements show bands of charge. Copyright © 2012 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  5. Tunable Injection Barrier in Organic Resistive Switches Based on Phase-Separated Ferroelectric-Semiconductor Blends

    NARCIS (Netherlands)

    Asadi, Kamal; de Boer, Tom G.; Blom, Paul W. M.; de Leeuw, Dago M.

    2009-01-01

    Organic non-volatile resistive bistable diodes based on phase-separated blends of ferroelectric and semiconducting polymers are fabricated. The polarization field of the ferroelectric modulates the injection barrier at the semiconductor-electrode contact and, hence, the resistance of the comprising

  6. Reactivity and morphology of vapor-deposited Al/polymer interfaces for organic semiconductor devices

    International Nuclear Information System (INIS)

    Demirkan, K.; Mathew, A.; Weiland, C.; Opila, R. L.; Reid, M.

    2008-01-01

    The chemistry and the morphology of metal-deposited organic semiconductor interfaces play a significant role in determining the performance and reliability of organic semiconductor devices. We investigated the aluminum metallization of poly(2-methoxy-5,2 ' -ethyl-hexyloxy-phenylene vinylene) (MEH-PPV), polystyrene, and ozone-treated polystyrene surfaces by chemical (x-ray and ultraviolet photoelectron spectroscopy) and microscopic [atomic force microscopy, scanning electron microscopy (SEM), focused ion beam (FIB)] analyses. Photoelectron spectroscopy showed the degree of chemical interaction between Al and each polymer; for MEH-PPV, the chemical interactions were mainly through the C-O present in the side chain of the polymer structure. The chemical interaction of aluminum with polystyrene was less significant, but it showed a dramatic increase after ozone treatment of the polystyrene surface (due to the formation of exposed oxygen sites). Results showed a strong relationship between the surface reactivity and the condensation/sticking of the aluminum atoms on the surface. SEM analysis showed that, during the initial stages of the metallization, a significant clustering of aluminum takes place. FIB analysis showed that such clustering yields a notably porous structure. The chemical and the morphological properties of the vapor-deposited Al on organic semiconductor surfaces makes such electrical contacts more complicated. The possible effects of surface chemistry and interface morphology on the electrical properties and reliability of organic semiconductor devices are discussed in light of the experimental findings

  7. Temperature-dependent built-in potential in organic semiconductor devices

    NARCIS (Netherlands)

    Kemerink, M.; Kramer, J.M.; Gommans, H.H.P.; Janssen, R.A.J.

    2006-01-01

    The temperature dependence of the built-in voltage of organic semiconductor devices is studied. The results are interpreted using a simple analytical model for the band bending at the electrodes. It is based on the notion that, even at zero current, diffusion may cause a significant charge density

  8. Crystal step edges can trap electrons on the surfaces of n-type organic semiconductors.

    Science.gov (United States)

    He, Tao; Wu, Yanfei; D'Avino, Gabriele; Schmidt, Elliot; Stolte, Matthias; Cornil, Jérôme; Beljonne, David; Ruden, P Paul; Würthner, Frank; Frisbie, C Daniel

    2018-05-30

    Understanding relationships between microstructure and electrical transport is an important goal for the materials science of organic semiconductors. Combining high-resolution surface potential mapping by scanning Kelvin probe microscopy (SKPM) with systematic field effect transport measurements, we show that step edges can trap electrons on the surfaces of single crystal organic semiconductors. n-type organic semiconductor crystals exhibiting positive step edge surface potentials display threshold voltages that increase and carrier mobilities that decrease with increasing step density, characteristic of trapping, whereas crystals that do not have positive step edge surface potentials do not have strongly step density dependent transport. A device model and microelectrostatics calculations suggest that trapping can be intrinsic to step edges for crystals of molecules with polar substituents. The results provide a unique example of a specific microstructure-charge trapping relationship and highlight the utility of surface potential imaging in combination with transport measurements as a productive strategy for uncovering microscopic structure-property relationships in organic semiconductors.

  9. Tunable injection barrier in organic resistive switches based on phase-separated ferroelectric-semiconductor blends

    NARCIS (Netherlands)

    Asadi, K.; Boer, T.G. de; Blom, P.W.M.; Leeuw, D.M. de

    2009-01-01

    Organic non-volatile resistive bistable diodes based on phase-separated blends of ferroelectric and semiconducting polymers are fabricated. The polarization field of the ferroelectric modulates the injection barrier at the semiconductor-electrode contact and, hence, the resistance of the comprising

  10. Preparative semiconductor photoredox catalysis: An emerging theme in organic synthesis

    Czech Academy of Sciences Publication Activity Database

    Manley, David W.; Walton, J. C.

    2015-01-01

    Roč. 11, Sep 9 (2015), s. 1570-1582 ISSN 1860-5397 Institutional support: RVO:61388963 Keywords : carboxylic acids * free radicals * organic synthesis * photocatalysis * titania Subject RIV: CC - Organic Chemistry Impact factor: 2.697, year: 2015 http://www.beilstein-journals.org/bjoc/single/articleFullText.htm?publicId=1860-5397-11-173

  11. Precise, Self-Limited Epitaxy of Ultrathin Organic Semiconductors and Heterojunctions Tailored by van der Waals Interactions.

    Science.gov (United States)

    Wu, Bing; Zhao, Yinghe; Nan, Haiyan; Yang, Ziyi; Zhang, Yuhan; Zhao, Huijuan; He, Daowei; Jiang, Zonglin; Liu, Xiaolong; Li, Yun; Shi, Yi; Ni, Zhenhua; Wang, Jinlan; Xu, Jian-Bin; Wang, Xinran

    2016-06-08

    Precise assembly of semiconductor heterojunctions is the key to realize many optoelectronic devices. By exploiting the strong and tunable van der Waals (vdW) forces between graphene and organic small molecules, we demonstrate layer-by-layer epitaxy of ultrathin organic semiconductors and heterostructures with unprecedented precision with well-defined number of layers and self-limited characteristics. We further demonstrate organic p-n heterojunctions with molecularly flat interface, which exhibit excellent rectifying behavior and photovoltaic responses. The self-limited organic molecular beam epitaxy (SLOMBE) is generically applicable for many layered small-molecule semiconductors and may lead to advanced organic optoelectronic devices beyond bulk heterojunctions.

  12. Quantitative analysis and optimization of gravure printed metal ink, dielectric, and organic semiconductor films.

    Science.gov (United States)

    Higgins, Stuart G; Boughey, Francesca L; Hills, Russell; Steinke, Joachim H G; Muir, Beinn V O; Campbell, Alasdair J

    2015-03-11

    Here we demonstrate the optimization of gravure printed metal ink, dielectric, and semiconductor formulations. We present a technique for nondestructively imaging printed films using a commercially available flatbed scanner, combined with image analysis to quantify print behavior. Print speed, cliché screen density, nip pressure, the orientation of print structures, and doctor blade extension were found to have a significant impact on the quality of printed films, as characterized by the spreading of printed structures and variation in print homogeneity. Organic semiconductor prints were observed to exhibit multiple periodic modulations, which are correlated to the underlying cell structure.

  13. Digital Inverter Amine Sensing via Synergistic Responses by n and p Organic Semiconductors.

    Science.gov (United States)

    Tremblay, Noah J; Jung, Byung Jun; Breysse, Patrick; Katz, Howard E

    2011-11-22

    Chemiresistors and sensitive OFETs have been substantially developed as cheap, scalable, and versatile sensing platforms. While new materials are expanding OFET sensing capabilities, the device architectures have changed little. Here we report higher order logic circuits utilizing OFETs sensitive to amine vapors. The circuits depend on the synergistic responses of paired p- and n-channel organic semiconductors, including an unprecedented analyte-induced current increase by the n-channel semiconductor. This represents the first step towards 'intelligent sensors' that utilize analog signal changes in sensitive OFETs to produce direct digital readouts suitable for further logic operations.

  14. Disorder effect on carrier mobility in Fullerene organic semiconductor

    International Nuclear Information System (INIS)

    Mendil, N; Daoudi, M; Berkai, Z; Belghachi, A

    2015-01-01

    The critical factor that limits the efficiencies of organic electronic devices is the low charge carrier mobility which is attributed to disorder in organic films. In this context, we have studied the effects of disorder on carrier mobility in organic Schottky diode of electrons for the fullerene (C 60 ). Our results show that the mobility is sensitive probes of structural phase transitions and order-disorder underlying C 60 . Where it is one reason behind the low mobility which it take as value 1.4x10 -2 cm 2 /V.s above critical temperature Tc =289K. (paper)

  15. Optically Detected Magnetic Resonance and Thermal Activation Spectroscopy Study of Organic Semiconductors

    International Nuclear Information System (INIS)

    Chang-Hwan Kim

    2003-01-01

    Organic electronic materials are a new class of emerging materials. Organic light emitting devices (OLEDs) are the most promising candidates for future flat panel display technologies. The photophysical characterization is the basic research step one must follow to understand this new class of materials and devices. The light emission properties are closely related to the transport properties of these materials. The objective of this dissertation is to probe the relation between transport and photophysical properties of organic semiconductors. The transport characteristics were evaluated by using thermally stimulated current and thermally stimulated luminescence techniques. The photoluminescence detected magnetic resonance and photoluminescence quantum yield studies provide valuable photophysical information on this class of materials. OLEDs are already in the market. However, detailed studies on the degradation mechanisms are still lacking. Since both optically detected magnetic resonance and thermal activation spectroscopy probe long-lived defect-related states in organic semiconductors, the combined study generates new insight on the OLED operation and degradation mechanisms

  16. Optically Detected Magnetic Resonance and Thermal Activation Spectroscopy Study of Organic Semiconductors

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Chang-Hwan [Iowa State Univ., Ames, IA (United States)

    2003-01-01

    Organic electronic materials are a new class of emerging materials. Organic light emitting devices (OLEDs) are the most promising candidates for future flat panel display technologies. The photophysical characterization is the basic research step one must follow to understand this new class of materials and devices. The light emission properties are closely related to the transport properties of these materials. The objective of this dissertation is to probe the relation between transport and photophysical properties of organic semiconductors. The transport characteristics were evaluated by using thermally stimulated current and thermally stimulated luminescence techniques. The photoluminescence detected magnetic resonance and photoluminescence quantum yield studies provide valuable photophysical information on this class of materials. OLEDs are already in the market. However, detailed studies on the degradation mechanisms are still lacking. Since both optically detected magnetic resonance and thermal activation spectroscopy probe long-lived defect-related states in organic semiconductors, the combined study generates new insight on the OLED operation and degradation mechanisms.

  17. Spin Coulomb Dragging Inhibition of Spin-Polarized Electric Current Injecting into Organic Semiconductors

    International Nuclear Information System (INIS)

    Jun-Qing, Zhao; Shi-Zhu, Qiao; Zhen-Feng, Jia; Ning-Yu, Zhang; Yan-Ju, Ji; Yan-Tao, Pang; Ying, Chen; Gang, Fu

    2008-01-01

    We introduce a one-dimensional spin injection structure comprising a ferromagnetic metal and a nondegenerate organic semiconductor to model electric current polarizations. With this model we analyse spin Coulomb dragging (SCD) effects on the polarization under various electric fields, interface and conductivity conditions. The results show that the SCD inhibits the current polarization. Thus the SCD inhibition should be well considered for accurate evaluation of current polarization in the design of organic spin devices

  18. Organic Single-Crystal Semiconductor Films on a Millimeter Domain Scale.

    Science.gov (United States)

    Kwon, Sooncheol; Kim, Jehan; Kim, Geunjin; Yu, Kilho; Jo, Yong-Ryun; Kim, Bong-Joong; Kim, Junghwan; Kang, Hongkyu; Park, Byoungwook; Lee, Kwanghee

    2015-11-18

    Nucleation and growth processes can be effectively controlled in organic semiconductor films through a new concept of template-mediated molecular crystal seeds during the phase transition; the effective control of these processes ensures millimeter-scale crystal domains, as well as the performance of the resulting organic films with intrinsic hole mobility of 18 cm(2) V(-1) s(-1). © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  19. Quantum interference measurement of spin interactions in a bio-organic/semiconductor device structure

    Science.gov (United States)

    Deo, Vincent; Zhang, Yao; Soghomonian, Victoria; Heremans, Jean J.

    2015-03-01

    Quantum interference is used to measure the spin interactions between an InAs surface electron system and the iron center in the biomolecule hemin in nanometer proximity in a bio-organic/semiconductor device structure. The interference quantifies the influence of hemin on the spin decoherence properties of the surface electrons. The decoherence times of the electrons serve to characterize the biomolecule, in an electronic complement to the use of spin decoherence times in magnetic resonance. Hemin, prototypical for the heme group in hemoglobin, is used to demonstrate the method, as a representative biomolecule where the spin state of a metal ion affects biological functions. The electronic determination of spin decoherence properties relies on the quantum correction of antilocalization, a result of quantum interference in the electron system. Spin-flip scattering is found to increase with temperature due to hemin, signifying a spin exchange between the iron center and the electrons, thus implying interactions between a biomolecule and a solid-state system in the hemin/InAs hybrid structure. The results also indicate the feasibility of artificial bioinspired materials using tunable carrier systems to mediate interactions between biological entities.

  20. Testing methodologies and systems for semiconductor optical amplifiers

    Science.gov (United States)

    Wieckowski, Michael

    Semiconductor optical amplifiers (SOA's) are gaining increased prominence in both optical communication systems and high-speed optical processing systems, due primarily to their unique nonlinear characteristics. This in turn, has raised questions regarding their lifetime performance reliability and has generated a demand for effective testing techniques. This is especially critical for industries utilizing SOA's as components for system-in-package products. It is important to note that very little research to date has been conducted in this area, even though production volume and market demand has continued to increase. In this thesis, the reliability of dilute-mode InP semiconductor optical amplifiers is studied experimentally and theoretically. The aging characteristics of the production level devices are demonstrated and the necessary techniques to accurately characterize them are presented. In addition, this work proposes a new methodology for characterizing the optical performance of these devices using measurements in the electrical domain. It is shown that optical performance degradation, specifically with respect to gain, can be directly qualified through measurements of electrical subthreshold differential resistance. This metric exhibits a linear proportionality to the defect concentration in the active region, and as such, can be used for prescreening devices before employing traditional optical testing methods. A complete theoretical analysis is developed in this work to explain this relationship based upon the device's current-voltage curve and its associated leakage and recombination currents. These results are then extended to realize new techniques for testing semiconductor optical amplifiers and other similarly structured devices. These techniques can be employed after fabrication and during packaged operation through the use of a proposed stand-alone testing system, or using a proposed integrated CMOS self-testing circuit. Both methods are capable

  1. Bilayer polymer/oxide coating for organic semiconductors

    DEFF Research Database (Denmark)

    Tavares, Luciana; Kjelstrup-Hansen, Jakob; Rubahn, Horst-Günter

    Organic materials have been given much attention due to their intriguing properties that can be tailored via synthetic chemistry for specific applications combined with their low price and fairly straight-forward large-scale synthesis. p6P nanofibers can emit polarized light with a highly anisotr...

  2. Bilayer polymer/oxide coating for electroluminescent organic semiconductors

    DEFF Research Database (Denmark)

    Tavares, Luciana

    Organic materials have been given much attention due to their intriguing properties that can be tailored via synthetic chemistry for specific applications combined with their low price and fairly straight-forward large-scale synthesis. Para-hexaphenylene (p6P) nanofibers emit polarized light with...

  3. Separating positive and negative magnetoresistance in organic semiconductor devices

    NARCIS (Netherlands)

    Bloom, F.L.; Wagemans, W.; Kemerink, M.; Koopmans, B.

    2007-01-01

    We study the transition between positive and negative organic magnetoresistance (OMAR) in tris-(8 hydroxyquinoline) aluminium (Alq3), in order to identify the elementary mechanisms governing this phenomenon. We show how the sign of OMAR changes as function of the applied voltage and temperature. The

  4. Charge equilibration and potential steps in organic semiconductor multilayers

    NARCIS (Netherlands)

    Brocks, G.; Cakir, Deniz; Bokdam, Menno; de Jong, Machiel Pieter; Fahlman, M.

    2012-01-01

    Substantial potential steps ∼0.5 eV are frequently observed in organic multilayers of donor and acceptor molecules. Often such potential steps depend on the order in which the individual layers are deposited, or on which substrate they are deposited. In this paper we outline a model for these

  5. Switchable charge injection barrier in an organic supramolecular semiconductor

    NARCIS (Netherlands)

    Gorbunov, A.V.; Haedler, A.T.; Putzeys, T.; Zha, R.H.; Schmidt, H.W.; Kivala, M.; Urbanavičiutec, I.; Wübbenhorst, M.; Meijer, E.W.; Kemerink, M.

    2016-01-01

    We disclose a supramolecular material that combines semiconducting and dipolar functionalities. The material consists of a discotic semiconducting carbonyl-bridged triarylamine core, which is surrounded by three dipolar amide groups. In thin films, the material self-organizes in a hexagonal columnar

  6. Solution-printed organic semiconductor blends exhibiting transport properties on par with single crystals.

    Science.gov (United States)

    Niazi, Muhammad R; Li, Ruipeng; Qiang Li, Er; Kirmani, Ahmad R; Abdelsamie, Maged; Wang, Qingxiao; Pan, Wenyang; Payne, Marcia M; Anthony, John E; Smilgies, Detlef-M; Thoroddsen, Sigurdur T; Giannelis, Emmanuel P; Amassian, Aram

    2015-11-23

    Solution-printed organic semiconductors have emerged in recent years as promising contenders for roll-to-roll manufacturing of electronic and optoelectronic circuits. The stringent performance requirements for organic thin-film transistors (OTFTs) in terms of carrier mobility, switching speed, turn-on voltage and uniformity over large areas require performance currently achieved by organic single-crystal devices, but these suffer from scale-up challenges. Here we present a new method based on blade coating of a blend of conjugated small molecules and amorphous insulating polymers to produce OTFTs with consistently excellent performance characteristics (carrier mobility as high as 6.7 cm(2) V(-1) s(-1), low threshold voltages oforganic semiconductor films with transport properties and other figures of merit on par with their single-crystal counterparts.

  7. Fabrication of combinatorial nm-planar electrode array for high throughput evaluation of organic semiconductors

    International Nuclear Information System (INIS)

    Haemori, M.; Edura, T.; Tsutsui, K.; Itaka, K.; Wada, Y.; Koinuma, H.

    2006-01-01

    We have fabricated a combinatorial nm-planar electrode array by using photolithography and chemical mechanical polishing processes for high throughput electrical evaluation of organic devices. Sub-nm precision was achieved with respect to the average level difference between each pair of electrodes and a dielectric layer. The insulating property between the electrodes is high enough to measure I-V characteristics of organic semiconductors. Bottom-contact field-effect-transistors (FETs) of pentacene were fabricated on this electrode array by use of molecular beam epitaxy. It was demonstrated that the array could be used as a pre-patterned device substrate for high throughput screening of the electrical properties of organic semiconductors

  8. Application of organic semiconductors for the detection of ionizing radiations

    International Nuclear Information System (INIS)

    Kozelj, M.; Cvikl, B.; Korosak, D.

    2006-01-01

    One year aged organic bilayer Al/PCTDA/CuPc/ITO structure prepared with ICB deposition method has been used to evaluate the influence of ionising radiation to electrical properties of the structure. Small sources of α, β and γ radiation were used for preliminary measurements. Capacitance and current measurements were performed on samples with and without presence of ionising radiation and results compared. Effect of β and γ radiation has not been confirmed due to the limited activity of available sources. Presence of α radiation has noticeably changed the capacitance of reversely biased structure and produced increase of current through the structure. We have tried to explain the capacitance properties using the model previously developed for the organic bilayer structures, but we did not manage to resolve all effects involved. (author)

  9. Tuning spin-polarized transport in organic semiconductors

    Science.gov (United States)

    Mattana, Richard; Galbiati, Marta; Delprat, Sophie; Tatay, Sergio; Deranlot, Cyrile; Seneor, Pierre; Petroff, Frederic

    Molecular spintronics is an emerging research field at the frontier between organic chemistry and the spintronics. Compared to traditional inorganic materials molecules are flexible and can be easily tailored by chemical synthesis. Due to their theoretically expected very long spin lifetime, they were first only seen as the ultimate media for spintronics devices. It was recently that new spintronics tailoring could arise from the chemical versatility brought by molecules. The hybridization between a ferromagnet and molecules induces a spin dependent broadening and energy shifting of the molecular orbitals leading to an induced spin polarization on the first molecular layer. This spin dependent hybridization can be used to tailor the spin dependent transport in organic spintronics devices. We have studied vertical Co/Alq3/Co organic spin valves. The negative magnetoresistance observed is the signature of different coupling strengths at the top and bottom interfaces. We have then inserted an inorganic tunnel barrier at the bottom interface in order to suppress the spin-dependent hybridization. In this case we restore a positive magnetoresistance. This demonstrates that at the bottom Co/Alq3 interface a stronger coupling occurs which induces an inversion of the spin polarization.

  10. Freescale Semiconductor Successfully Implements an Energy Management System

    Energy Technology Data Exchange (ETDEWEB)

    None

    2011-06-30

    Through the Superior Energy Performance (SEP) plant certification program, Freescale Semiconductor implemented projects at the company's Oak Hill Fab plant that reduced annual energy consumption by 28 million kilowatt hours (kWh) of electricity and 26,000 million British thermal units (Btu) of natural gas between 2006 and 2009, saving more than $2 million each year. The plant is now certified at the SEP silver level, and has a management system in place to proactively manage the facility's energy resources in the future.

  11. Semiclassical theory of magnetoresistance in positionally disordered organic semiconductors

    Science.gov (United States)

    Harmon, N. J.; Flatté, M. E.

    2012-02-01

    A recently introduced percolative theory of unipolar organic magnetoresistance is generalized by treating the hyperfine interaction semiclassically for an arbitrary hopping rate. Compact analytic results for the magnetoresistance are achievable when carrier hopping occurs much more frequently than the hyperfine field precession period. In other regimes the magnetoresistance can be straightforwardly evaluated numerically. Slow and fast hopping magnetoresistance are found to be uniquely characterized by their line shapes. We find that the threshold hopping distance is analogous a phenomenological two-site model's branching parameter, and that the distinction between slow and fast hopping is contingent on the threshold hopping distance.

  12. Synthesis and optical properties of novel organic-inorganic hybrid nanolayer structure semiconductors

    Energy Technology Data Exchange (ETDEWEB)

    Zhang Sanjun; Lanty, Gaetan; Lauret, Jean-Sebastien [Laboratoire de Photonique Quantique et Moleculaire de l' Ecole Normale Superieure de Cachan, 61 avenue du President Wilson, 94235 Cachan (France); Deleporte, Emmanuelle, E-mail: Emmanuelle.Deleporte@lpqm.ens-cachan.fr [Laboratoire de Photonique Quantique et Moleculaire de l' Ecole Normale Superieure de Cachan, 61 avenue du President Wilson, 94235 Cachan (France); Audebert, Pierre; Galmiche, Laurent [Laboratoire de Photophysique et Photochimie Supramoleculaires et Macromoleculaires de l' Ecole Normale Superieure de Cachan, 61 avenue du President Wilson, 94235 Cachan (France)

    2009-06-15

    We report on the synthesis of some novel organic-inorganic hybrid 2D perovskite semiconductors (R-(CH{sub 2}){sub n}NH{sub 3}){sub 2}PbX{sub 4}. These semiconductors are self-assembled intercalation nanolayers and have a multi-quantum-well energy level structure. We systematically vary the characteristic of organic groups (R-(CH{sub 2}){sub n}NH{sub 3}{sup +}) to study the relationship between their structures and the optical properties of (R-(CH{sub 2}){sub n}NH{sub 3}){sub 2}PbX{sub 4}. From optical absorption and photoluminescence spectroscopy experiments performed on series of samples, we find some trends of choosing the organic groups to improve the optical performance of (R-(CH{sub 2}){sub n}NH{sub 3}){sub 2}PbX{sub 4}. A new organic group, which allows synthesis of nanolayer perovskite semiconductors with quite high photoluminescence efficiency and better long-term stability, has been found.

  13. Thermionic emission and tunneling at carbon nanotube-organic semiconductor interface.

    Science.gov (United States)

    Sarker, Biddut K; Khondaker, Saiful I

    2012-06-26

    We study the charge carrier injection mechanism across the carbon nanotube (CNT)-organic semiconductor interface using a densely aligned carbon nanotube array as electrode and pentacene as organic semiconductor. The current density-voltage (J-V) characteristics measured at different temperatures show a transition from a thermal emission mechanism at high temperature (above 200 K) to a tunneling mechanism at low temperature (below 200 K). A barrier height of ∼0.16 eV is calculated from the thermal emission regime, which is much lower compared to the metal/pentacene devices. At low temperatures, the J-V curves exhibit a direct tunneling mechanism at low bias, corresponding to a trapezoidal barrier, while at high bias the mechanism is well described by Fowler-Nordheim tunneling, which corresponds to a triangular barrier. A transition from direct tunneling to Fowler-Nordheim tunneling further signifies a small injection barrier at the CNT/pentacene interface. Our results presented here are the first direct experimental evidence of low charge carrier injection barrier between CNT electrodes and an organic semiconductor and are a significant step forward in realizing the overall goal of using CNT electrodes in organic electronics.

  14. Photophysical Properties of Novel Organic, Inorganic, and Hybrid Semiconductor Materials

    Science.gov (United States)

    Chang, Angela Yenchi

    For the past 200 years, novel materials have driven technological progress, and going forward these advanced materials will continue to deeply impact virtually all major industrial sectors. Therefore, it is vital to perform basic and applied research on novel materials in order to develop new technologies for the future. This dissertation describes the results of photophysical studies on three novel materials with electronic and optoelectronic applications, namely organic small molecules DTDCTB with C60 and C70, colloidal indium antimonide (InSb) nanocrystals, and an organic-inorganic hybrid perovskite with the composition CH3NH3PbI 3-xClx, using transient absorption (TA) and photoluminescence (PL) spectroscopy. In chapter 2, we characterize the timescale and efficiency of charge separation and recombination in thin film blends comprising DTDCTB, a narrow-band gap electron donor, and either C60 or C70 as an electron acceptor. TA and time-resolved PL studies show correlated, sub-picosecond charge separation times and multiple timescales of charge recombination. Our results indicate that some donors fail to charge separate in donor-acceptor mixed films, which suggests material manipulations may improve device efficiency. Chapter 3 describes electron-hole pair dynamics in strongly quantum-confined, colloidal InSb nanocrystal quantum dots. For all samples, TA shows a bleach feature that, for several picoseconds, dramatically red-shifts prior to reaching a time-independent position. We suggest this unusual red-shift relates transient population flow through two energetically comparable conduction band states. From pump-power-dependent measurements, we also determine biexciton lifetimes. In chapter 4, we examine carrier dynamics in polycrystalline methylammonium lead mixed halide perovskite (CH3NH3PbI3-xCl x) thin films as functions of temperature and photoexcitation wavelength. At room temperature, the long-lived TA signals stand in contrast to PL dynamics, where the

  15. Rotator side chains trigger cooperative transition for shape and function memory effect in organic semiconductors.

    Science.gov (United States)

    Chung, Hyunjoong; Dudenko, Dmytro; Zhang, Fengjiao; D'Avino, Gabriele; Ruzié, Christian; Richard, Audrey; Schweicher, Guillaume; Cornil, Jérôme; Beljonne, David; Geerts, Yves; Diao, Ying

    2018-01-18

    Martensitic transition is a solid-state phase transition involving cooperative movement of atoms, mostly studied in metallurgy. The main characteristics are low transition barrier, ultrafast kinetics, and structural reversibility. They are rarely observed in molecular crystals, and hence the origin and mechanism are largely unexplored. Here we report the discovery of martensitic transition in single crystals of two different organic semiconductors. In situ microscopy, single-crystal X-ray diffraction, Raman and nuclear magnetic resonance spectroscopy, and molecular simulations combined indicate that the rotating bulky side chains trigger cooperative transition. Cooperativity enables shape memory effect in single crystals and function memory effect in thin film transistors. We establish a molecular design rule to trigger martensitic transition in organic semiconductors, showing promise for designing next-generation smart multifunctional materials.

  16. Preparation and dielectric investigation of organic metal insulator semiconductor (MIS) structures with a ferroelectric polymer

    Energy Technology Data Exchange (ETDEWEB)

    Kalbitz, Rene; Fruebing, Peter; Gerhard, Reimund [Department of Physics and Astronomy, University of Potsdam (Germany); Taylor, Martin [School of Electronic Engineering, Bangor University (United Kingdom)

    2010-07-01

    Ferroelectric field effect transistors (FeFETs) offer the prospect of an organic-based memory device. Since the charge transport in the semiconductor is confined to the interface region between the insulator and the semiconductor, the focus of the present study was on the investigation of this region in metal-insulator-semiconductor (MIS) capacitors using dielectric spectroscopy. Capacitance-Voltage (C-V) measurements at different frequencies as well as capacitance-frequency (C-f) measurements after applying different poling voltages were carried out. The C-V measurements yielded information about the frequency dependence of the depletion layer width as well as the number of charges stored at the semiconductor/ insulator interface. The results are compared to numerical calculations based on a model introduced by S. L. Miller (JAP, 72(12), 1992). The C-f measurements revealed three main relaxation processes. An equivalent circuit has been developed to model the frequency response of the MIS capacitor. With this model the origin of the three relaxations may be deduced.

  17. Scalable fabrication of strongly textured organic semiconductor micropatterns by capillary force lithography.

    Science.gov (United States)

    Jo, Pil Sung; Vailionis, Arturas; Park, Young Min; Salleo, Alberto

    2012-06-26

    Strongly textured organic semiconductor micropatterns made of the small molecule dioctylbenzothienobenzothiophene (C(8)-BTBT) are fabricated by using a method based on capillary force lithography (CFL). This technique provides the C(8)-BTBT solution with nucleation sites for directional growth, and can be used as a scalable way to produce high quality crystalline arrays in desired regions of a substrate for OFET applications. Copyright © 2012 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  18. Rational design of organic semiconductors for texture control and self-patterning on halogenated surfaces

    KAUST Repository

    Ward, Jeremy W.

    2014-05-15

    Understanding the interactions at interfaces between the materials constituting consecutive layers within organic thin-film transistors (OTFTs) is vital for optimizing charge injection and transport, tuning thin-film microstructure, and designing new materials. Here, the influence of the interactions at the interface between a halogenated organic semiconductor (OSC) thin film and a halogenated self-assembled monolayer on the formation of the crystalline texture directly affecting the performance of OTFTs is explored. By correlating the results from microbeam grazing incidence wide angle X-ray scattering (μGIWAXS) measurements of structure and texture with OTFT characteristics, two or more interaction paths between the terminating atoms of the semiconductor and the halogenated surface are found to be vital to templating a highly ordered morphology in the first layer. These interactions are effective when the separating distance is lower than 2.5 dw, where dw represents the van der Waals distance. The ability to modulate charge carrier transport by several orders of magnitude by promoting "edge-on" versus "face-on" molecular orientation and crystallographic textures in OSCs is demonstrated. It is found that the "edge-on" self-assembly of molecules forms uniform, (001) lamellar-textured crystallites which promote high charge carrier mobility, and that charge transport suffers as the fraction of the "face-on" oriented crystallites increases. The role of interfacial halogenation in mediating texture formation and the self-patterning of organic semiconductor films, as well as the resulting effects on charge transport in organic thin-film transistors, are explored. The presence of two or more anchoring sites between a halogenated semiconductor and a halogenated self-assembled monolayer, closer than about twice the corresponding van der Waals distance, alter the microstructure and improve electrical properties. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  19. Dry lithography of large-area, thin-film organic semiconductors using frozen CO(2) resists.

    Science.gov (United States)

    Bahlke, Matthias E; Mendoza, Hiroshi A; Ashall, Daniel T; Yin, Allen S; Baldo, Marc A

    2012-12-04

    To address the incompatibility of organic semiconductors with traditional photolithography, an inert, frozen CO(2) resist is demonstrated that forms an in situ shadow mask. Contact with a room-temperature micro-featured stamp is used to pattern the resist. After thin film deposition, the remaining CO(2) is sublimed to lift off unwanted material. Pixel densities of 325 pixels-per-inch are shown. Copyright © 2012 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  20. Solution coating of large-area organic semiconductor thin films with aligned single-crystalline domains

    KAUST Repository

    Diao, Ying

    2013-06-02

    Solution coating of organic semiconductors offers great potential for achieving low-cost manufacturing of large-area and flexible electronics. However, the rapid coating speed needed for industrial-scale production poses challenges to the control of thin-film morphology. Here, we report an approach - termed fluid-enhanced crystal engineering (FLUENCE) - that allows for a high degree of morphological control of solution-printed thin films. We designed a micropillar-patterned printing blade to induce recirculation in the ink for enhancing crystal growth, and engineered the curvature of the ink meniscus to control crystal nucleation. Using FLUENCE, we demonstrate the fast coating and patterning of millimetre-wide, centimetre-long, highly aligned single-crystalline organic semiconductor thin films. In particular, we fabricated thin films of 6,13-bis(triisopropylsilylethynyl) pentacene having non-equilibrium single-crystalline domains and an unprecedented average and maximum mobilities of 8.1±1.2 cm2 V-1 s -1 and 11 cm2 V-1 s-1. FLUENCE of organic semiconductors with non-equilibrium single-crystalline domains may find use in the fabrication of high-performance, large-area printed electronics. © 2013 Macmillan Publishers Limited. All rights reserved.

  1. Localised states in organic semiconductors and their detection

    Science.gov (United States)

    Imperia, Paolo

    2002-06-01

    New polymers and low molecular compounds, suitable for organic light emitting devices and organic electronic applications, have been synthesised in this years in order to obtain electron transport characteristics compatible with requirements for applications in real plastic devices. However, despite of the technological importance and of the relevant progress in devices manufacture, fundamental physical properties of such class of materials are still not enough studied. In particular extensive presence of distributions of localised states inside the band gap has a deep impact on their electronic properties. Such presence of shallow traps as well as the influence of the sample preparation conditions on deep and shallow localised states have not been, until now, systematically explored. The thermal techniques are powerful tools in order to study localised levels in inorganic and organic materials. Thermally stimulated luminescence (TSL), thermally stimulated currents (TSC) and thermally stimulated depolarisation currents (TSDC) allow to deeply look to shallow and deep trap levels as well as they permit to study, in synergy with dielectric spectroscopy (DES), polarisation and depolarisation effects. We studied, by means of numerical simulations, the first and the second order kinetic equations characterised by negligible and strong re-trapping respectively. We included in the equations Gaussian, exponential and quasi-continuous distributions of localised states. The shapes of the theoretical peaks have been investigated by means of systematic variation of the two main parameters of the equations, i. e. the energy trap depth E and the frequency factor a and of the parameters regulating the distributions, in particular for a Gaussian distribution the distribution width s and the integration limits. The theoretical findings have been applied to experimental glow curves. Thin films of polymers and low molecular compounds. Polyphenylquinoxalines, trisphenylquinoxalines and

  2. Role of band states and trap states in the electrical properties of organic semiconductors: Hopping versus mobility edge model

    KAUST Repository

    Mehraeen, Shafigh; Coropceanu, Veaceslav; Bré das, Jean-Luc

    2013-01-01

    We compare the merits of a hopping model and a mobility edge model in the description of the effect of charge-carrier concentration on the electrical conductivity, carrier mobility, and Fermi energy of organic semiconductors. We consider the case

  3. Material degradation of liquid organic semiconductors analyzed by nuclear magnetic resonance spectroscopy

    Energy Technology Data Exchange (ETDEWEB)

    Fukushima, Tatsuya; Yamamoto, Junichi; Fukuchi, Masashi; Kaji, Hironori, E-mail: kaji@scl.kyoto-u.ac.jp [Institute for Chemical Research, Kyoto University, Uji, Kyoto 611-0011 (Japan); Hirata, Shuzo; Jung, Heo Hyo; Adachi, Chihaya [Center for Organic Photonics and Electronics Research (OPERA), Kyusyu University, 744 Motooka, Nishi, Fukuoka 819-0395 (Japan); Hirata, Osamu; Shibano, Yuki [Nissan Chemical Industries, LTD, 722-1 Tsuboi, Funabashi 274-8507 (Japan)

    2015-08-15

    Liquid organic light-emitting diodes (liquid OLEDs) are unique devices consisting only of liquid organic semiconductors in the active layer, and the device performances have been investigated recently. However, the device degradation, especially, the origin has been unknown. In this study, we show that material degradation occurs in liquid OLEDs, whose active layer is composed of carbazole with an ethylene glycol chain. Nuclear magnetic resonance (NMR) experiments clearly exhibit that the dimerization reaction of carbazole moiety occurs in the liquid OLEDs during driving the devices. In contrast, cleavages of the ethylene glycol chain are not detected within experimental error. The dimerization reaction is considered to be related to the device degradation.

  4. Integrated Materials Design of Organic Semiconductors for Field-Effect Transistors

    KAUST Repository

    Mei, Jianguo

    2013-05-08

    The past couple of years have witnessed a remarkable burst in the development of organic field-effect transistors (OFETs), with a number of organic semiconductors surpassing the benchmark mobility of 10 cm2/(V s). In this perspective, we highlight some of the major milestones along the way to provide a historical view of OFET development, introduce the integrated molecular design concepts and process engineering approaches that lead to the current success, and identify the challenges ahead to make OFETs applicable in real applications. © 2013 American Chemical Society.

  5. Integrated materials design of organic semiconductors for field-effect transistors.

    Science.gov (United States)

    Mei, Jianguo; Diao, Ying; Appleton, Anthony L; Fang, Lei; Bao, Zhenan

    2013-05-08

    The past couple of years have witnessed a remarkable burst in the development of organic field-effect transistors (OFETs), with a number of organic semiconductors surpassing the benchmark mobility of 10 cm(2)/(V s). In this perspective, we highlight some of the major milestones along the way to provide a historical view of OFET development, introduce the integrated molecular design concepts and process engineering approaches that lead to the current success, and identify the challenges ahead to make OFETs applicable in real applications.

  6. Nanoimprinted organic semiconductor laser pumped by a light-emitting diode.

    Science.gov (United States)

    Tsiminis, Georgios; Wang, Yue; Kanibolotsky, Alexander L; Inigo, Anto R; Skabara, Peter J; Samuel, Ifor D W; Turnbull, Graham A

    2013-05-28

    An organic semiconductor laser, simply fabricated by UV-nanoimprint lithography (UV-NIL), that is pumped with a pulsed InGaN LED is demonstrated. Molecular weight optimization of the polymer gain medium on a nanoimprinted polymer distributed feedback resonator enables the lowest reported UV-NIL laser threshold density of 770 W cm(-2) , establishing the potential for scalable organic laser fabrication compatible with mass-produced LEDs. Copyright © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

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

    International Nuclear Information System (INIS)

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

    2007-01-01

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

  8. Energy resolved electrochemical impedance spectroscopy for electronic structure mapping in organic semiconductors

    Energy Technology Data Exchange (ETDEWEB)

    Nádaždy, V., E-mail: nadazdy@savba.sk; Gmucová, K. [Institute of Physics SAS, Dúbravská cesta 9, 845 11 Bratislava (Slovakia); Schauer, F. [Faculty of Education, Trnava University in Trnava, 918 43 Trnava (Slovakia); Faculty of Applied Informatics, Tomas Bata University in Zlin, 760 05 Zlin (Czech Republic)

    2014-10-06

    We introduce an energy resolved electrochemical impedance spectroscopy method to map the electronic density of states (DOS) in organic semiconductor materials. The method consists in measurement of the charge transfer resistance of a semiconductor/electrolyte interface at a frequency where the redox reactions determine the real component of the impedance. The charge transfer resistance value provides direct information about the electronic DOS at the energy given by the electrochemical potential of the electrolyte, which can be adjusted using an external voltage. A simple theory for experimental data evaluation is proposed, along with an explanation of the corresponding experimental conditions. The method allows mapping over unprecedentedly wide energy and DOS ranges. Also, important DOS parameters can be determined directly from the raw experimental data without the lengthy analysis required in other techniques. The potential of the proposed method is illustrated by tracing weak bond defect states induced by ultraviolet treatment above the highest occupied molecular orbital in a prototypical σ-conjugated polymer, poly[methyl(phenyl)silylene]. The results agree well with those of our previous DOS reconstruction by post-transient space-charge-limited-current spectroscopy, which was, however, limited to a narrow energy range. In addition, good agreement of the DOS values measured on two common π-conjugated organic polymer semiconductors, polyphenylene vinylene and poly(3-hexylthiophene), with the rather rare previously published data demonstrate the accuracy of the proposed method.

  9. Influences of semiconductor morphology on the mechanical fatigue behavior of flexible organic electronics

    Energy Technology Data Exchange (ETDEWEB)

    Lee, Young-Joo; Yeon, Han-Wool; Shin, Hae-A-Seul; Joo, Young-Chang, E-mail: ycjoo@snu.ac.kr [Department of Materials Science and Engineering, Seoul National University, 151-744 Seoul (Korea, Republic of); Uk Lee, Yong; Evans, Louise A. [Center for Process Innovation Limited, Thomas Wright Way, NETPark, Sedgefield, TS21 3FG County Durham (United Kingdom)

    2013-12-09

    The influence of crystalline morphology on the mechanical fatigue of organic semiconductors (OSCs) was investigated using 6,13-bis(triisopropylsilylethynyl)pentacene (TIPS-pentacene) as a crystalline OSC and poly(triarylamine) (PTAA) as an amorphous OSC. During cyclic bending, resistances of the OSCs were monitored using the transmission-line method on a metal-semiconductor-metal structure. The resistance of the TIPS-pentacene increased under fatigue damage in tensile-stress mode, but no such degradation was observed in the PTAA. Both OSCs were stable under compressive bending fatigue. The formation of intergranular cracks at the domain boundaries of the TIPS-pentacene was responsible for the degradation of its electrical properties under tensile bending fatigue.

  10. Two-photon Photoemission of Organic Semiconductor Molecules on Ag(111)

    Energy Technology Data Exchange (ETDEWEB)

    Yang, Aram [Univ. of California, Berkeley, CA (United States)

    2008-05-01

    Angle- and time-resolved two-photon photoemission (2PPE) was used to study systems of organic semiconductors on Ag(111). The 2PPE studies focused on electronic behavior specific to interfaces and ultrathin films. Electron time dynamics and band dispersions were characterized for ultrathin films of a prototypical n-type planar aromatic hydrocarbon, PTCDA, and representatives from a family of p-type oligothiophenes.In PTCDA, electronic behavior was correlated with film morphology and growth modes. Within a fewmonolayers of the interface, image potential states and a LUMO+1 state were detected. The degree to which the LUMO+1 state exhibited a band mass less than a free electron mass depended on the crystallinity of the layer. Similarly, image potential states were measured to have free electron-like effective masses on ordered surfaces, and the effective masses increased with disorder within the thin film. Electron lifetimes were correlated with film growth modes, such that the lifetimes of electrons excited into systems created by layer-by-layer, amorphous film growth increased by orders of magnitude by only a few monolayers from the surface. Conversely, the decay dynamics of electrons in Stranski-Krastanov systems were limited by interaction with the exposed wetting layer, which limited the barrier to decay back into the metal.Oligothiophenes including monothiophene, quaterthiophene, and sexithiophene were deposited on Ag(111), and their electronic energy levels and effective masses were studied as a function of oligothiophene length. The energy gap between HOMO and LUMO decreased with increasing chain length, but effective mass was found to depend on domains from high- or low-temperature growth conditions rather than chain length. In addition, the geometry of the molecule on the surface, e.g., tilted or planar, substantially affected the electronic structure.

  11. Femtosecond time-resolved two-photon photoemission study of organic semiconductor copper phthalocyanine film

    International Nuclear Information System (INIS)

    Tanaka, A.; Tohoku University; University of Rochester, NY; Yan, L.; Watkins, N.J.; Gao, Y.

    2004-01-01

    Full text: Organic semiconductors are recently attracting much interest from the viewpoints of both device and fundamental physics. These organic semiconductors are considered to be important constituents of the future devices, such as organic light-emitting diode, organic field effect transistor, and organic solid-state injection laser. In order to elucidate their detailed physical properties and to develop the future devices, it is indispensable to understand their excited-state dynamics as well as their electronic structures. The femtosecond time-resolved two-photon photoemission (TR-2PPE) spectroscopy is attracting much interest because of its capability to observe the energy-resolved excited electron dynamics. In this work, we have carried out a TR-2PPE study of the organic semiconductor copper phthalocyanine (CuPc) film. Furthermore, we have investigated the detailed electronic structure of CuPc film using the photoemission (PES) and inverse photoemission (IPES) spectroscopies. From the simultaneous PES and IPES measurements for CuPc film with a thickness of 100 nm, the lowest unoccupied molecular orbital (LUMO), highest occupied molecular orbital, and ionization potential of CuPc film have been directly determined. The observed two-photon photoemission (2PPE) spectrum of the present CuPc film, measured with photon energy of about hv=3.3 eV, exhibits a broad feature. From the energy diagram of CuPc film determined by the PES and IPES measurements, the intermediate state observed in the present 2PPE spectrum of CuPc film corresponds to the energy region between about 0.4 and 1.7 eV above the LUMO energy. From the time-resolved pump-probe measurements, it is found that the relaxation lifetimes of excited states in the present CuPc films are very short (all below 50 fs) and monotonously become faster with increasing excitation energy. We attribute this extremely fast relaxation process of photoexcitation to a rapid internal conversion process. From these results

  12. "Liquid-liquid-solid"-type superoleophobic surfaces to pattern polymeric semiconductors towards high-quality organic field-effect transistors.

    Science.gov (United States)

    Wu, Yuchen; Su, Bin; Jiang, Lei; Heeger, Alan J

    2013-12-03

    Precisely aligned organic-liquid-soluble semiconductor microwire arrays have been fabricated by "liquid-liquid-solid" type superoleophobic surfaces directed fluid drying. Aligned organic 1D micro-architectures can be built as high-quality organic field-effect transistors with high mobilities of >10 cm(2) ·V(-1) ·s(-1) and current on/off ratio of more than 10(6) . All these studies will boost the development of 1D microstructures of organic semiconductor materials for potential application in organic electronics. © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  13. Production Performance of the ATLAS Semiconductor Tracker Readout System

    CERN Document Server

    Mitsou, V A

    2006-01-01

    The ATLAS Semiconductor Tracker (SCT) together with the pixel and the transition radiation detectors will form the tracking system of the ATLAS experiment at LHC. It will consist of 20000 single-sided silicon microstrip sensors assembled back-to-back into modules mounted on four concentric barrels and two end-cap detectors formed by nine disks each. The SCT module production and testing has finished while the macro-assembly is well under way. After an overview of the layout and the operating environment of the SCT, a description of the readout electronics design and operation requirements will be given. The quality control procedure and the DAQ software for assuring the electrical functionality of hybrids and modules will be discussed. The focus will be on the electrical performance results obtained during the assembly and testing of the end-cap SCT modules.

  14. Anion-induced N-doping of naphthalenediimide polymer semiconductor in organic thin-film transistors

    KAUST Repository

    Han, Yang

    2018-03-13

    Molecular doping is an important strategy to improve the charge transport properties of organic semiconductors in various electronic devices. Compared to p-type dopants, the development of n-type dopants is especially challenging due to poor dopant stability against atmospheric conditions. In this article, we report the n-doping of the milestone naphthalenediimide-based conjugated polymer P(NDI2OD-T2) in organic thin film transistor devices by soluble anion dopants. The addition of the dopants resulted in the formation of stable radical anions in thin films, as confirmed by EPR spectroscopy. By tuning the dopant concentration via simple solution mixing, the transistor parameters could be readily controlled. Hence the contact resistance between the electrodes and the semiconducting polymer could be significantly reduced, which resulted in the transistor behaviour approaching the desirable gate voltage-independent model. Reduced hysteresis was also observed, thanks to the trap filling by the dopant. Under optimal doping concentrations the channel on-current was increased several fold whilst the on/off ratio was simultaneously increased by around one order of magnitude. Hence doping with soluble organic salts appears to be a promising route to improve the charge transport properties of n-type organic semiconductors.

  15. Solution-printed organic semiconductor blends exhibiting transport properties on par with single crystals

    KAUST Repository

    Niazi, Muhammad Rizwan; Li, Ruipeng; Li, Erqiang; Kirmani, Ahmad R.; Abdelsamie, Maged; Wang, Qingxiao; Pan, Wenyang; Payne, Marcia M.; Anthony, John E.; Smilgies, Detlef-M.; Thoroddsen, Sigurdur T; Giannelis, Emmanuel P.; Amassian, Aram

    2015-01-01

    Solution-printed organic semiconductors have emerged in recent years as promising contenders for roll-to-roll manufacturing of electronic and optoelectronic circuits. The stringent performance requirements for organic thin-film transistors (OTFTs) in terms of carrier mobility, switching speed, turn-on voltage and uniformity over large areas require performance currently achieved by organic single-crystal devices, but these suffer from scale-up challenges. Here we present a new method based on blade coating of a blend of conjugated small molecules and amorphous insulating polymers to produce OTFTs with consistently excellent performance characteristics (carrier mobility as high as 6.7 cm2 V−1 s−1, low threshold voltages of<1 V and low subthreshold swings <0.5 V dec−1). Our findings demonstrate that careful control over phase separation and crystallization can yield solution-printed polycrystalline organic semiconductor films with transport properties and other figures of merit on par with their single-crystal counterparts.

  16. Lead Halide Perovskites as Charge Generation Layers for Electron Mobility Measurement in Organic Semiconductors.

    Science.gov (United States)

    Love, John A; Feuerstein, Markus; Wolff, Christian M; Facchetti, Antonio; Neher, Dieter

    2017-12-06

    Hybrid lead halide perovskites are introduced as charge generation layers (CGLs) for the accurate determination of electron mobilities in thin organic semiconductors. Such hybrid perovskites have become a widely studied photovoltaic material in their own right, for their high efficiencies, ease of processing from solution, strong absorption, and efficient photogeneration of charge. Time-of-flight (ToF) measurements on bilayer samples consisting of the perovskite CGL and an organic semiconductor layer of different thickness are shown to be determined by the carrier motion through the organic material, consistent with the much higher charge carrier mobility in the perovskite. Together with the efficient photon-to-electron conversion in the perovskite, this high mobility imbalance enables electron-only mobility measurement on relatively thin application-relevant organic films, which would not be possible with traditional ToF measurements. This architecture enables electron-selective mobility measurements in single components as well as bulk-heterojunction films as demonstrated in the prototypical polymer/fullerene blends. To further demonstrate the potential of this approach, electron mobilities were measured as a function of electric field and temperature in an only 127 nm thick layer of a prototypical electron-transporting perylene diimide-based polymer, and found to be consistent with an exponential trap distribution of ca. 60 meV. Our study furthermore highlights the importance of high mobility charge transporting layers when designing perovskite solar cells.

  17. Solution-printed organic semiconductor blends exhibiting transport properties on par with single crystals

    KAUST Repository

    Niazi, Muhammad Rizwan

    2015-11-23

    Solution-printed organic semiconductors have emerged in recent years as promising contenders for roll-to-roll manufacturing of electronic and optoelectronic circuits. The stringent performance requirements for organic thin-film transistors (OTFTs) in terms of carrier mobility, switching speed, turn-on voltage and uniformity over large areas require performance currently achieved by organic single-crystal devices, but these suffer from scale-up challenges. Here we present a new method based on blade coating of a blend of conjugated small molecules and amorphous insulating polymers to produce OTFTs with consistently excellent performance characteristics (carrier mobility as high as 6.7 cm2 V−1 s−1, low threshold voltages of<1 V and low subthreshold swings <0.5 V dec−1). Our findings demonstrate that careful control over phase separation and crystallization can yield solution-printed polycrystalline organic semiconductor films with transport properties and other figures of merit on par with their single-crystal counterparts.

  18. Anion-induced N-doping of naphthalenediimide polymer semiconductor in organic thin-film transistors

    KAUST Repository

    Han, Yang; Fei, Zhuping; Lin, Yen-Hung; Martin, Jaime; Tuna, Floriana; Anthopoulos, Thomas D.; Heeney, Martin

    2018-01-01

    Molecular doping is an important strategy to improve the charge transport properties of organic semiconductors in various electronic devices. Compared to p-type dopants, the development of n-type dopants is especially challenging due to poor dopant stability against atmospheric conditions. In this article, we report the n-doping of the milestone naphthalenediimide-based conjugated polymer P(NDI2OD-T2) in organic thin film transistor devices by soluble anion dopants. The addition of the dopants resulted in the formation of stable radical anions in thin films, as confirmed by EPR spectroscopy. By tuning the dopant concentration via simple solution mixing, the transistor parameters could be readily controlled. Hence the contact resistance between the electrodes and the semiconducting polymer could be significantly reduced, which resulted in the transistor behaviour approaching the desirable gate voltage-independent model. Reduced hysteresis was also observed, thanks to the trap filling by the dopant. Under optimal doping concentrations the channel on-current was increased several fold whilst the on/off ratio was simultaneously increased by around one order of magnitude. Hence doping with soluble organic salts appears to be a promising route to improve the charge transport properties of n-type organic semiconductors.

  19. Photoelectrical Stimulation of Neuronal Cells by an Organic Semiconductor-Electrolyte Interface.

    Science.gov (United States)

    Abdullaeva, Oliya S; Schulz, Matthias; Balzer, Frank; Parisi, Jürgen; Lützen, Arne; Dedek, Karin; Schiek, Manuela

    2016-08-23

    As a step toward the realization of neuroprosthetics for vision restoration, we follow an electrophysiological patch-clamp approach to study the fundamental photoelectrical stimulation mechanism of neuronal model cells by an organic semiconductor-electrolyte interface. Our photoactive layer consisting of an anilino-squaraine donor blended with a fullerene acceptor is supporting the growth of the neuronal model cell line (N2A cells) without an adhesion layer on it and is not impairing cell viability. The transient photocurrent signal upon illumination from the semiconductor-electrolyte layer is able to trigger a passive response of the neuronal cells under physiological conditions via a capacitive coupling mechanism. We study the dynamics of the capacitive transmembrane currents by patch-clamp recordings and compare them to the dynamics of the photocurrent signal and its spectral responsivity. Furthermore, we characterize the morphology of the semiconductor-electrolyte interface by atomic force microscopy and study the stability of the interface in dark and under illuminated conditions.

  20. Role of transport band edge variation on delocalized charge transport in high-mobility crystalline organic semiconductors

    Science.gov (United States)

    Kadashchuk, Andrey; Tong, Fei; Janneck, Robby; Fishchuk, Ivan I.; Mityashin, Alexander; Pavlica, Egon; Köhler, Anna; Heremans, Paul; Rolin, Cedric; Bratina, Gvido; Genoe, Jan

    2017-09-01

    We demonstrate that the degree of charge delocalization has a strong impact on polarization energy and thereby on the position of the transport band edge in organic semiconductors. This gives rise to long-range potential fluctuations, which govern the electronic transport through delocalized states in organic crystalline layers. This concept is employed to formulate an analytic model that explains a negative field dependence coupled with a positive temperature dependence of the charge mobility observed by a lateral time-of-flight technique in a high-mobility crystalline organic layer. This has important implications for the further understanding of the charge transport via delocalized states in organic semiconductors.

  1. General Observation of Photocatalytic Oxygen Reduction to Hydrogen Peroxide by Organic Semiconductor Thin Films and Colloidal Crystals.

    Science.gov (United States)

    Gryszel, Maciej; Sytnyk, Mykhailo; Jakešová, Marie; Romanazzi, Giuseppe; Gabrielsson, Roger; Heiss, Wolfgang; Głowacki, Eric Daniel

    2018-04-25

    Low-cost semiconductor photocatalysts offer unique possibilities for industrial chemical transformations and energy conversion applications. We report that a range of organic semiconductors are capable of efficient photocatalytic oxygen reduction to H 2 O 2 in aqueous conditions. These semiconductors, in the form of thin films, support a 2-electron/2-proton redox cycle involving photoreduction of dissolved O 2 to H 2 O 2 , with the concurrent photooxidation of organic substrates: formate, oxalate, and phenol. Photochemical oxygen reduction is observed in a pH range from 2 to 12. In cases where valence band energy of the semiconductor is energetically high, autoxidation competes with oxidation of the donors, and thus turnover numbers are low. Materials with deeper valence band energies afford higher stability and also oxidation of H 2 O to O 2 . We found increased H 2 O 2 evolution rate for surfactant-stabilized nanoparticles versus planar thin films. These results evidence that photochemical O 2 reduction may be a widespread feature of organic semiconductors, and open potential avenues for organic semiconductors for catalytic applications.

  2. Structural Design Principle of Small-Molecule Organic Semiconductors for Metal-Free, Visible-Light-Promoted Photocatalysis.

    Science.gov (United States)

    Wang, Lei; Huang, Wei; Li, Run; Gehrig, Dominik; Blom, Paul W M; Landfester, Katharina; Zhang, Kai A I

    2016-08-08

    Herein, we report on the structural design principle of small-molecule organic semiconductors as metal-free, pure organic and visible light-active photocatalysts. Two series of electron-donor and acceptor-type organic semiconductor molecules were synthesized to meet crucial requirements, such as 1) absorption range in the visible region, 2) sufficient photoredox potential, and 3) long lifetime of photogenerated excitons. The photocatalytic activity was demonstrated in the intermolecular C-H functionalization of electron-rich heteroaromates with malonate derivatives. A mechanistic study of the light-induced electron transport between the organic photocatalyst, substrate, and the sacrificial agent are described. With their tunable absorption range and defined energy-band structure, the small-molecule organic semiconductors could offer a new class of metal-free and visible light-active photocatalysts for chemical reactions. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  3. Defect-driven interfacial electronic structures at an organic/metal-oxide semiconductor heterojunction.

    Science.gov (United States)

    Winget, Paul; Schirra, Laura K; Cornil, David; Li, Hong; Coropceanu, Veaceslav; Ndione, Paul F; Sigdel, Ajaya K; Ginley, David S; Berry, Joseph J; Shim, Jaewon; Kim, Hyungchui; Kippelen, Bernard; Brédas, Jean-Luc; Monti, Oliver L A

    2014-07-16

    The electronic structure of the hybrid interface between ZnO and the prototypical organic semiconductor PTCDI is investigated via a combination of ultraviolet and X-ray photoelectron spectroscopy (UPS/XPS) and density functional theory (DFT) calculations. The interfacial electronic interactions lead to a large interface dipole due to substantial charge transfer from ZnO to 3,4,9,10-perylenetetracarboxylicdiimide (PTCDI), which can be properly described only when accounting for surface defects that confer ZnO its n-type properties. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  4. Chemical engineering in the electronics industry: progress towards the rational design of organic semiconductor heterojunctions

    KAUST Repository

    Clancy, Paulette

    2012-01-01

    We review the current status of heterojunction design for combinations of organic semiconductor materials, given its central role in affecting the device performance for electronic devices and solar cell applications. We provide an emphasis on recent progress towards the rational design of heterojunctions that may lead to higher performance of charge separation and mobility. We also play particular attention to the role played by computational approaches and its potential to help define the best choice of materials for solar cell development in the future. We report the current status of the field with respect to such goals. © 2012 Elsevier Ltd.

  5. Towards high charge carrier mobilities by rational design of organic semiconductors

    Energy Technology Data Exchange (ETDEWEB)

    Andrienko, Denis; Ruehle, Victor; Baumeier, Bjoern; Vehoff, Thorsten; Lukyanov, Alexander; Kremer, Kurt [Max Planck Institute for Polymer Research, Mainz (Germany); Marcon, Valentina [Technische Universitaet Darmstadt (Germany); Kirkpatrick, James; Nelson, Jenny [Imperial College London (United Kingdom); Lennartz, Christian [BASF AG, Ludwigshafen (Germany)

    2010-07-01

    The role of material morphology on charge carrier mobility in partially disordered organic semiconductors is discussed for several classes of materials: derivatives of hexabenzocoronenens, perylenediimides, triangularly-shaped polyaromatic hydrocarbons, and Alq{sub 3}. Simulations are performed using a package developed by Imperial College, London and Max Planck Institute for Polymer Research, Mainz (votca.org). This package combines several techniques into one scheme: quantum chemical methods for the calculation of molecular electronic structures and reorganization energies; molecular dynamics and systematic coarse-graining approaches for simulation of self-assembly and relative positions and orientations of molecules on large scales; kinetic Monte Carlo and master equation for studies of charge transport.

  6. Chemical engineering in the electronics industry: progress towards the rational design of organic semiconductor heterojunctions

    KAUST Repository

    Clancy, Paulette

    2012-05-01

    We review the current status of heterojunction design for combinations of organic semiconductor materials, given its central role in affecting the device performance for electronic devices and solar cell applications. We provide an emphasis on recent progress towards the rational design of heterojunctions that may lead to higher performance of charge separation and mobility. We also play particular attention to the role played by computational approaches and its potential to help define the best choice of materials for solar cell development in the future. We report the current status of the field with respect to such goals. © 2012 Elsevier Ltd.

  7. Dithienocoronenediimide-based copolymers as novel ambipolar semiconductors for organic thin-film transistors.

    Science.gov (United States)

    Usta, Hakan; Newman, Christopher; Chen, Zhihua; Facchetti, Antonio

    2012-07-17

    A new class of ambipolar donor-acceptor π-conjugated polymers based on a dithienocoronenediimide core is presented. Solution-processed top-gate/bottom-contact thin film transistors (TFTs) exhibit electron and hole mobilities of up to 0.30 cm(2)/V·s and 0.04 cm(2)/V·s, respectively, which are the highest reported to date for an ambipolar polymer in ambient conditions. The polymers presented here are the first examples of coronenediimide-based semiconductors showing high organic TFT performances. Copyright © 2012 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  8. An Imide-Based Pentacyclic Building Block for n-Type Organic Semiconductors

    Energy Technology Data Exchange (ETDEWEB)

    Wu, Fu-Peng [Soochow Univ., Suzhou (China). Inst. of Functional Nano & Soft Materials (FUNSOM); Un, Hio-Ieng [Peking Univ., Beijing (China). Beijing National Lab. for Molecular Sciences, Key Lab. of Bioorganic Chemistry and Molecular Engineering of Ministry of Education, Key Lab. of Polymer Chemistry and Physics of Ministry of Education, Center for Soft Matter Science and Engineering, College of Chemistry and Molecular Engineering; Li, Yongxi [Soochow Univ., Suzhou (China). Inst. of Functional Nano & Soft Materials (FUNSOM); Hu, Hailiang [Soochow Univ., Suzhou (China). Inst. of Functional Nano & Soft Materials (FUNSOM); Yuan, Yi [Soochow Univ., Suzhou (China). Inst. of Functional Nano & Soft Materials (FUNSOM); Yang, Bin [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States). Center for Nanophase Materials Science (CNMS); Xiao, Kai [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States). Center for Nanophase Materials Science (CNMS); Chen, Wei [Argonne National Lab. (ANL), Lemont, IL (United States). Science Div.; Wang, Jie-Yu [Peking Univ., Beijing (China). Beijing National Lab. for Molecular Sciences, Key Lab. of Bioorganic Chemistry and Molecular Engineering of Ministry of Education, Key Lab. of Polymer Chemistry and Physics of Ministry of Education, Center for Soft Matter Science and Engineering, College of Chemistry and Molecular Engineering; Jiang, Zuo-Quan [Soochow Univ., Suzhou (China). Inst. of Functional Nano & Soft Materials (FUNSOM); Pei, Jian [Peking Univ., Beijing (China). Beijing National Lab. for Molecular Sciences, Key Lab. of Bioorganic Chemistry and Molecular Engineering of Ministry of Education, Key Lab. of Polymer Chemistry and Physics of Ministry of Education, Center for Soft Matter Science and Engineering, College of Chemistry and Molecular Engineering; Liao, Liang-Sheng [Soochow Univ., Suzhou (China). Inst. of Functional Nano & Soft Materials (FUNSOM)

    2017-10-09

    A new electron-deficient unit with fused 5-heterocyclic ring was developed by replacing a cyclopenta-1,3-diene from electron-rich donor indacenodithiophene (IDT) with cyclohepta- 4,6-diene-1,3-diimde unit. The imide bridging endows BBI with fixed planar configuration and both low the highest occupied molecular orbital (HOMO) and the lowest unoccupied molecular orbit (LUMO) energy levels. Organic field-effect transistors (OFETs) based on BBI polymers exhibit electron mobility up to 0.34 cm2 V-1 s-1, which indicates that the BBI is a promising ntype semiconductor for optoelectronics.

  9. Vacuum-and-solvent-free fabrication of organic semiconductor layers for field-effect transistors

    Science.gov (United States)

    Matsushima, Toshinori; Sandanayaka, Atula S. D.; Esaki, Yu; Adachi, Chihaya

    2015-09-01

    We demonstrate that cold and hot isostatic pressing (CIP and HIP) is a novel, alternative method for organic semiconductor layer fabrication, where organic powder is compressed into a layer shape directly on a substrate with 200 MPa pressure. Spatial gaps between powder particles and the other particles, substrates, or electrodes are crushed after CIP and HIP, making it possible to operate organic field-effect transistors (OFETs) containing the compressed powder as the semiconductor. The CIP-compressed powder of 2,7-dioctyl[1]benzothieno[3,2-b][1]benzothiophene (C8-BTBT) had a hole mobility of (1.6 ± 0.4) × 10-2 cm2/Vs. HIP of C8-BTBT powder increased the hole mobility to an amorphous silicon-like value (0.22 ± 0.07 cm2/Vs) because of the growth of the C8-BTBT crystallites and the improved continuity between the powder particles. The vacuum and solution processes are not involved in our CIP and HIP techniques, offering a possibility of manufacturing OFETs at low cost.

  10. Surface-segregated monolayers: a new type of ordered monolayer for surface modification of organic semiconductors.

    Science.gov (United States)

    Wei, Qingshuo; Tajima, Keisuke; Tong, Yujin; Ye, Shen; Hashimoto, Kazuhito

    2009-12-09

    We report a new type of ordered monolayer for the surface modification of organic semiconductors. Fullerene derivatives with fluorocarbon chains ([6,6]-phenyl-C(61)-buryric acid 1H,1H-perfluoro-1-alkyl ester or FC(n)) spontaneously segregated as a monolayer on the surface of a [6,6]-phenyl-C(61)-butyric acid methyl ester (PCBM) film during a spin-coating process from the mixture solutions, as confirmed by X-ray photoelectron spectroscopy (XPS). Ultraviolet photoelectron spectroscopy (UPS) showed the shift of ionization potentials (IPs) depending on the fluorocarbon chain length, indicating the formation of surface dipole moments. Surface-sensitive vibrational spectroscopy, sum frequency generation (SFG) revealed the ordered molecular orientations of the C(60) moiety in the surface FC(n) layers. The intensity of the SFG signals from FC(n) on the surface showed a clear odd-even effect when the length of the fluorocarbon chain was changed. This new concept of the surface-segregated monolayer provides a facile and versatile approach to modifying the surface of organic semiconductors and is applicable to various organic optoelectronic devices.

  11. Hydrogen-Bonded Organic Semiconductor Micro- And Nanocrystals: From Colloidal Syntheses to (Opto-)Electronic Devices

    Science.gov (United States)

    2014-01-01

    Organic pigments such as indigos, quinacridones, and phthalocyanines are widely produced industrially as colorants for everyday products as various as cosmetics and printing inks. Herein we introduce a general procedure to transform commercially available insoluble microcrystalline pigment powders into colloidal solutions of variously sized and shaped semiconductor micro- and nanocrystals. The synthesis is based on the transformation of the pigments into soluble dyes by introducing transient protecting groups on the secondary amine moieties, followed by controlled deprotection in solution. Three deprotection methods are demonstrated: thermal cleavage, acid-catalyzed deprotection, and amine-induced deprotection. During these processes, ligands are introduced to afford colloidal stability and to provide dedicated surface functionality and for size and shape control. The resulting micro- and nanocrystals exhibit a wide range of optical absorption and photoluminescence over spectral regions from the visible to the near-infrared. Due to excellent colloidal solubility offered by the ligands, the achieved organic nanocrystals are suitable for solution processing of (opto)electronic devices. As examples, phthalocyanine nanowire transistors as well as quinacridone nanocrystal photodetectors, with photoresponsivity values by far outperforming those of vacuum deposited reference samples, are demonstrated. The high responsivity is enabled by photoinduced charge transfer between the nanocrystals and the directly attached electron-accepting vitamin B2 ligands. The semiconducting nanocrystals described here offer a cheap, nontoxic, and environmentally friendly alternative to inorganic nanocrystals as well as a new paradigm for obtaining organic semiconductor materials from commercial colorants. PMID:25253644

  12. Vacuum-and-solvent-free fabrication of organic semiconductor layers for field-effect transistors

    Science.gov (United States)

    Matsushima, Toshinori; Sandanayaka, Atula S. D.; Esaki, Yu; Adachi, Chihaya

    2015-01-01

    We demonstrate that cold and hot isostatic pressing (CIP and HIP) is a novel, alternative method for organic semiconductor layer fabrication, where organic powder is compressed into a layer shape directly on a substrate with 200 MPa pressure. Spatial gaps between powder particles and the other particles, substrates, or electrodes are crushed after CIP and HIP, making it possible to operate organic field-effect transistors (OFETs) containing the compressed powder as the semiconductor. The CIP-compressed powder of 2,7-dioctyl[1]benzothieno[3,2-b][1]benzothiophene (C8-BTBT) had a hole mobility of (1.6 ± 0.4) × 10–2 cm2/Vs. HIP of C8-BTBT powder increased the hole mobility to an amorphous silicon-like value (0.22 ± 0.07 cm2/Vs) because of the growth of the C8-BTBT crystallites and the improved continuity between the powder particles. The vacuum and solution processes are not involved in our CIP and HIP techniques, offering a possibility of manufacturing OFETs at low cost. PMID:26416434

  13. Pump spot size dependent lasing threshold in organic semiconductor DFB lasers fabricated via nanograting transfer.

    Science.gov (United States)

    Liu, Xin; Klinkhammer, Sönke; Wang, Ziyao; Wienhold, Tobias; Vannahme, Christoph; Jakobs, Peter-Jürgen; Bacher, Andreas; Muslija, Alban; Mappes, Timo; Lemmer, Uli

    2013-11-18

    Optically excited organic semiconductor distributed feedback (DFB) lasers enable efficient lasing in the visible spectrum. Here, we report on the rapid and parallel fabrication of DFB lasers via transferring a nanograting structure from a flexible mold onto an unstructured film of the organic gain material. This geometrically well-defined structure allows for a systematic investigation of the laser threshold behavior. The laser thresholds for these devices show a strong dependence on the pump spot diameter. This experimental finding is in good qualitative agreement with calculations based on coupled-wave theory. With further investigations on various DFB laser geometries prepared by different routes and based on different organic gain materials, we found that these findings are quite general. This is important for the comparison of threshold values of various devices characterized under different excitation areas.

  14. Pump spot size dependent lasing threshold in organic semiconductor DFB lasers fabricated via nanograting transfer

    DEFF Research Database (Denmark)

    Liu, Xin; Klinkhammer, Sönke; Wang, Ziyao

    2013-01-01

    material. This geometrically well-defined structure allows for a systematic investigation of the laser threshold behavior. The laser thresholds for these devices show a strong dependence on the pump spot diameter. This experimental finding is in good qualitative agreement with calculations based on coupled......Optically excited organic semiconductor distributed feedback (DFB) lasers enable efficient lasing in the visible spectrum. Here, we report on the rapid and parallel fabrication of DFB lasers via transferring a nanograting structure from a flexible mold onto an unstructured film of the organic gain......-wave theory. With further investigations on various DFB laser geometries prepared by different routes and based on different organic gain materials, we found that these findings are quite general. This is important for the comparison of threshold values of various devices characterized under different...

  15. Solution-Processed Wide-Bandgap Organic Semiconductor Nanostructures Arrays for Nonvolatile Organic Field-Effect Transistor Memory.

    Science.gov (United States)

    Li, Wen; Guo, Fengning; Ling, Haifeng; Liu, Hui; Yi, Mingdong; Zhang, Peng; Wang, Wenjun; Xie, Linghai; Huang, Wei

    2018-01-01

    In this paper, the development of organic field-effect transistor (OFET) memory device based on isolated and ordered nanostructures (NSs) arrays of wide-bandgap (WBG) small-molecule organic semiconductor material [2-(9-(4-(octyloxy)phenyl)-9H-fluoren-2-yl)thiophene]3 (WG 3 ) is reported. The WG 3 NSs are prepared from phase separation by spin-coating blend solutions of WG 3 /trimethylolpropane (TMP), and then introduced as charge storage elements for nonvolatile OFET memory devices. Compared to the OFET memory device with smooth WG 3 film, the device based on WG 3 NSs arrays exhibits significant improvements in memory performance including larger memory window (≈45 V), faster switching speed (≈1 s), stable retention capability (>10 4 s), and reliable switching properties. A quantitative study of the WG 3 NSs morphology reveals that enhanced memory performance is attributed to the improved charge trapping/charge-exciton annihilation efficiency induced by increased contact area between the WG 3 NSs and pentacene layer. This versatile solution-processing approach to preparing WG 3 NSs arrays as charge trapping sites allows for fabrication of high-performance nonvolatile OFET memory devices, which could be applicable to a wide range of WBG organic semiconductor materials. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  16. Bi-component semiconductor oxide photoanodes for the photoelectrocatalytic oxidation of organic solutes and vapours: a short review with emphasis to TiO2-WO3 photoanodes.

    Science.gov (United States)

    Georgieva, J; Valova, E; Armyanov, S; Philippidis, N; Poulios, I; Sotiropoulos, S

    2012-04-15

    The use of binary semiconductor oxide anodes for the photoelectrocatalytic oxidation of organic species (both in solution and gas phase) is reviewed. In the first part of the review, the principle of electrically assisted photocatalysis is presented, the preparation methods for the most common semiconductor oxide catalysts are briefly mentioned, while the advantages of appropriately chosen semiconductor combinations for efficient UV and visible (vis) light utilization are highlighted. The second part of the review focuses on the discussion of TiO(2)-WO(3) photoanodes (among the most studied bi-component semiconductor oxide systems) and in particular on coatings prepared by electrodeposition/electrosynthesis or powder mixtures (the focus of the authors' research during recent years). Studies concerning the microscopic, spectroscopic and photoelectrochemical characterization of the catalysts are presented and examples of photoanode activity towards typical dissolved organic contaminants as well as organic vapours are given. Particular emphasis is paid to: (a) The dependence of photoactivity on catalyst morphology and composition and (b) the possibility of carrying out photoelectrochemistry in all-solid cells, thus opening up the opportunity for photoelectrocatalytic air treatment. Copyright © 2011 Elsevier B.V. All rights reserved.

  17. Organic semiconductors based on [1]benzothieno[3,2-b][1]benzothiophene substructure.

    Science.gov (United States)

    Takimiya, Kazuo; Osaka, Itaru; Mori, Takamichi; Nakano, Masahiro

    2014-05-20

    The design, synthesis, and characterization of organic semiconductors applicable to organic electronic devices, such as organic field-effect transistors (OFETs) and organic photovoltaics (OPVs), had been one of the most important topics in materials chemistry in the past decade. Among the vast number of materials developed, much expectation had been placed on thienoacenes, which are rigid and planar structures formed by fusing thiophenes and other aromatic rings, as a promising candidate for organic semiconductors for high-performance OFETs. However, the thienoacenes examined as an active material in OFETs in the 1990s afforded OFETs with only moderate hole mobilities (approximately 0.1 cm(2) V(-1) s(-1)). We speculated that this was due to the sulfur atoms in the thienoacenes, which hardly contributed to the intermolecular orbital overlap in the solid state. On the other hand, we have focused on other types of thienoacenes, such as [1]benzothieno[3,2-b][1]benzothiophene (BTBT), which seem to have appropriate HOMO spatial distribution for effective intermolecular orbital overlap. In fact, BTBT derivatives and their related materials, including dinaphtho[2,3-b:2',3'-f]thieno[3,2-b]thiophene (DNTT), have turned out to be superior organic semiconductors, affording OFETs with very high mobilities. To illustrate some examples, we have developed 2,7-diphenyl BTBT (DPh-BTBT) that yields vapor-deposited OFETs having mobilities of up to 2.0 cm(2) V(-1) s(-1) under ambient conditions, highly soluble dialkyl-BTBTs (Cn-BTBTs) that afford solution-processed OFETs with mobilities higher than 1.0 cm(2) V(-1) s(-1), and DNTT and its derivatives that yield OFETs with even higher mobilities (>3.0 cm(2) V(-1) s(-1)) and stability under ambient conditions. Such high performances are rationalized by their solid-state electronic structures that are calculated based on their packing structures: the large intermolecular orbital overlap and the isotropic two-dimensional electronic

  18. Photoinduced electron transfer from organic semiconductors onto redox mediators for CO2

    International Nuclear Information System (INIS)

    Portenkirchner, E.

    2014-01-01

    In this work the photoinduced electron transfer from organic semiconductors onto redox mediator catalysts for CO 2 reduction has been investigated. In the beginning, the work focuses on the identication, characterization and test of suitable catalyst materials. For this purpose, rhenium compounds with 2,2'-bipyridine bis(arylimino) acenaphthene ligands and pyridinium were tested for molecular homogenous catalysis. Infrared, ultraviolet-visible (UV-Vis) and nuclear magnetic resonance (NMR) spectroscopy were used for initial characterization of the catalyst substances. Since the interpretation of infrared spectra was difficult for large molecules based on measured data only, additionally infrared absorption spectra obtained by quantum mechanical density functional theory(DFT) calculations were successfully used to correlate characteristic features in the measured spectra to their molecular origin. It was found that experimentally observed data and quantum chemical predictions for the infrared spectra of the novel compounds are in good agreement. Additionally, quantum mechanical calculations were carried out for the determination of molecular orbital frontier energy levels and correlated to UV-Vis absorption and cyclic voltammetry measurements. Extensive cyclic voltammetry measurements and bulk controlled-potential electrolysis experiments were performed using a N 2 - and CO 2 -saturated electrolyte solution. Together with a detailed product analysis via infrared spectroscopy, gas and ion chromatography the results allowed electrochemical characterizations of the novel catalysts regarding their suitability for electrochemical CO 2 reduction. Once suitable catalysts were identied, the materials were immobilized on the electrode surface by electro-polymerization of the catalyst (5,5'bisphenylethynyl-2,2'-bipyridyl)Re(CO) 3 Cl itself or by incorporation of (2,2'-bipyridyl)Re(CO) 3 Cl into a polypyrrole matrix, thereby changing from homogeneous to

  19. Structural and optical studies of local disorder sensitivity in natural organic-inorganic self-assembled semiconductors

    Energy Technology Data Exchange (ETDEWEB)

    Vijaya Prakash, G; Pradeesh, K [Nanophotonics Lab, Department of Physics, Indian Institute of Technology Delhi, New Delhi (India); Ratnani, R; Saraswat, K [Department of Pure and Applied Chemistry, MDS University, Ajmer (India); Light, M E [School of Chemistry, University of Southampton, Southampton (United Kingdom); Baumberg, J J, E-mail: prakash@physics.iitd.ac.i [Nanophotonic Centre, Cavendish Laboratory, University Cambridge, Cambridge CB3 OHE (United Kingdom)

    2009-09-21

    The structural and optical spectra of two related lead iodide (PbI) based self-assembled hybrid organic-inorganic semiconductors are compared. During the synthesis, depending on the bridging of organic moiety intercalated between the PbI two-dimensional planes, different crystal structures are produced. These entirely different networks show different structural and optical features, including excitonic bandgaps. In particular, the modified organic environment of the excitons is sensitive to the local disorder both in single crystal and thin film forms. Such information is vital for incorporating these semiconductors into photonic device architectures.

  20. Optical and spectroscopic studies on tannery wastes as a possible source of organic semiconductors

    Science.gov (United States)

    Nashy, El-Shahat H. A.; Al-Ashkar, Emad; Abdel Moez, A.

    2012-02-01

    Tanning industry produces a large quantity of solid wastes which contain hide proteins in the form of protein shavings containing chromium salts. The chromium wastes are the main concern from an environmental stand point of view, because chrome wastes posses a significant disposal problem. The present work is devoted to investigate the possibility of utilizing these wastes as a source of organic semi-conductors as an alternative method instead of the conventional ones. The chemical characterization of these wastes was determined. In addition, the Horizontal Attenuated Total Reflection (HATR) FT-IR spectroscopic analysis and optical parameters were also carried out for chromated samples. The study showed that the chromated samples had suitable absorbance and transmittance in the wavelength range (500-850 nm). Presence of chromium salt in the collagen samples increases the absorbance which improves the optical properties of the studied samples and leads to decrease the optical energy gap. The obtained optical energy gap gives an impression that the environmentally hazardous chrome shavings wastes can be utilized as a possible source of natural organic semiconductors with direct and indirect energy gap. This work opens the door to use some hazardous wastes in the manufacture of electronic devices such as IR-detectors, solar cells and also as solar cell windows.

  1. Organic Semiconductor-Containing Supramolecules: Effect of Small Molecule Crystallization and Molecular Packing

    KAUST Repository

    Rancatore, Benjamin J.

    2016-01-21

    © 2016 American Chemical Society. Small molecules (SMs) with unique optical or electronic properties provide an opportunity to incorporate functionality into block copolymer (BCP)-based supramolecules. However, the assembly of supramolecules based on these highly crystalline molecules differs from their less crystalline counterparts. Here, two families of organic semiconductor SMs are investigated, where the composition of the crystalline core, the location (side- vs end-functionalization) of the alkyl solubilizing groups, and the constitution (branched vs linear) of the alkyl groups are varied. With these SMs, we present a systematic study of how the phase behavior of the SMs affects the overall assembly of these organic semiconductor-based supramolecules. The incorporation of SMs has a large effect on the interfacial curvature, the supramolecular periodicity, and the overall supramolecular morphology. The crystal packing of the SM within the supramolecule does not necessarily lead to the assembly of the comb block within the BCP microdomains, as is normally observed for alkyl-containing supramolecules. An unusual lamellar morphology with a wavy interface between the microdomains is observed due to changes in the packing structure of the small molecule within BCP microdomains. Since the supramolecular approach is modular and small molecules can be readily switched out, present studies provide useful guidance toward access supramolecular assemblies over several length scales using optically active and semiconducting small molecules.

  2. Optical and spectroscopic studies on tannery wastes as a possible source of organic semiconductors.

    Science.gov (United States)

    Nashy, El-Shahat H A; Al-Ashkar, Emad; Moez, A Abdel

    2012-02-01

    Tanning industry produces a large quantity of solid wastes which contain hide proteins in the form of protein shavings containing chromium salts. The chromium wastes are the main concern from an environmental stand point of view, because chrome wastes posses a significant disposal problem. The present work is devoted to investigate the possibility of utilizing these wastes as a source of organic semi-conductors as an alternative method instead of the conventional ones. The chemical characterization of these wastes was determined. In addition, the Horizontal Attenuated Total Reflection (HATR) FT-IR spectroscopic analysis and optical parameters were also carried out for chromated samples. The study showed that the chromated samples had suitable absorbance and transmittance in the wavelength range (500-850 nm). Presence of chromium salt in the collagen samples increases the absorbance which improves the optical properties of the studied samples and leads to decrease the optical energy gap. The obtained optical energy gap gives an impression that the environmentally hazardous chrome shavings wastes can be utilized as a possible source of natural organic semiconductors with direct and indirect energy gap. This work opens the door to use some hazardous wastes in the manufacture of electronic devices such as IR-detectors, solar cells and also as solar cell windows. Copyright © 2011 Elsevier B.V. All rights reserved.

  3. Stability of polarization in organic ferroelectric metal-insulator-semiconductor (MIS) structures

    Energy Technology Data Exchange (ETDEWEB)

    Kalbitz, Rene; Fruebing, Peter; Gerhard, Reimund [Department of Physics and Astronomy, University of Potsdam, Karl-Liebknecht-Strasse 24-25, 14476, Potsdam (Germany); Taylor, Martin [School of Electronic Engineering, Bangor University, Dean Street, Bangor Gwynedd, LL57 1UT (United Kingdom)

    2011-07-01

    Ferroelectric field effect transistors (FeFETs) offer the prospect of an organic-based memory device. Since the charge transport in such devices is confined to the interface between the insulator and the semiconductor, the focus of the present study was on the investigation of this region. Capacitance-voltage (C-V) measurements of all-organic MIS devices with poly(vinylidenefluoride- trifluoroethylene) (P(VDF-TrFE)) as gate insulator and poly(3-hexylthiophene)(P3HT) as semiconductor were carried out. When the structure was driven into depletion, a positive flat-band voltage shift was observed arising from the change in polarization state of the ferroelectric insulator. When driven into accumulation, the polarization was reversed. It is shown that both polarization states are stable. However, negative charge trapped at the interface during the depletion cycle masks the negative shift in flat-band voltage expected during the sweep to accumulation voltages. Measurements on P(VDF-TrFE)/P3HT based FeFETs yield further evidence for fixed charges at the interface. Output characteristics suggest the injection of negative charges into the interface region when a depletion voltage is applied between source and gate contact.

  4. Late stage crystallization and healing during spin-coating enhance carrier transport in small-molecule organic semiconductors

    KAUST Repository

    Chou, Kang Wei; Khan, Hadayat Ullah; Niazi, Muhammad Rizwan; Yan, Buyi; Li, Ruipeng; Payne, Marcia M.; Anthony, John Edward; Smilgies, Detlef Matthias; Amassian, Aram

    2014-01-01

    Spin-coating is currently the most widely used solution processing method in organic electronics. Here, we report, for the first time, a direct investigation of the formation process of the small-molecule organic semiconductor (OSC) 6,13-bis

  5. Fabrication and Characterization of Copper System Compound Semiconductor Solar Cells

    Directory of Open Access Journals (Sweden)

    Ryosuke Motoyoshi

    2010-01-01

    Full Text Available Copper system compound semiconductor solar cells were produced by a spin-coating method, and their cell performance and structures were investigated. Copper indium disulfide- (CIS- based solar cells with titanium dioxide (TiO2 were produced on F-doped SnO2 (FTO. A device based on an FTO/CIS/TiO2 structure provided better cell performance compared to that based on FTO/TiO2/CIS structure. Cupric oxide- (CuO- and cuprous oxide- (Cu2O- based solar cells with fullerene (C60 were also fabricated on FTO and indium tin oxide (ITO. The microstructure and cell performance of the CuO/C60 heterojunction and the Cu2O:C60 bulk heterojunction structure were investigated. The photovoltaic devices based on FTO/CuO/C60 and ITO/Cu2O:C60 structures provided short-circuit current density of 0.015 mAcm−2 and 0.11 mAcm−2, and open-circuit voltage of 0.045 V and 0.17 V under an Air Mass 1.5 illumination, respectively. The microstructures of the active layers were examined by X-ray diffraction and transmission electron microscopy.

  6. Material degradation of liquid organic semiconductors analyzed by nuclear magnetic resonance spectroscopy

    Directory of Open Access Journals (Sweden)

    Tatsuya Fukushima

    2015-08-01

    Full Text Available Liquid organic light-emitting diodes (liquid OLEDs are unique devices consisting only of liquid organic semiconductors in the active layer, and the device performances have been investigated recently. However, the device degradation, especially, the origin has been unknown. In this study, we show that material degradation occurs in liquid OLEDs, whose active layer is composed of carbazole with an ethylene glycol chain. Nuclear magnetic resonance (NMR experiments clearly exhibit that the dimerization reaction of carbazole moiety occurs in the liquid OLEDs during driving the devices. In contrast, cleavages of the ethylene glycol chain are not detected within experimental error. The dimerization reaction is considered to be related to the device degradation.

  7. Bio-recognitive photonics of a DNA-guided organic semiconductor

    Science.gov (United States)

    Back, Seung Hyuk; Park, Jin Hyuk; Cui, Chunzhi; Ahn, Dong June

    2016-01-01

    Incorporation of duplex DNA with higher molecular weights has attracted attention for a new opportunity towards a better organic light-emitting diode (OLED) capability. However, biological recognition by OLED materials is yet to be addressed. In this study, specific oligomeric DNA-DNA recognition is successfully achieved by tri (8-hydroxyquinoline) aluminium (Alq3), an organic semiconductor. Alq3 rods crystallized with guidance from single-strand DNA molecules show, strikingly, a unique distribution of the DNA molecules with a shape of an `inverted' hourglass. The crystal's luminescent intensity is enhanced by 1.6-fold upon recognition of the perfect-matched target DNA sequence, but not in the case of a single-base mismatched one. The DNA-DNA recognition forming double-helix structure is identified to occur only in the rod's outer periphery. This study opens up new opportunities of Alq3, one of the most widely used OLED materials, enabling biological recognition.

  8. Interface engineering of semiconductor/dielectric heterojunctions toward functional organic thin-film transistors.

    Science.gov (United States)

    Zhang, Hongtao; Guo, Xuefeng; Hui, Jingshu; Hu, Shuxin; Xu, Wei; Zhu, Daoben

    2011-11-09

    Interface modification is an effective and promising route for developing functional organic field-effect transistors (OFETs). In this context, however, researchers have not created a reliable method of functionalizing the interfaces existing in OFETs, although this has been crucial for the technological development of high-performance CMOS circuits. Here, we demonstrate a novel approach that enables us to reversibly photocontrol the carrier density at the interface by using photochromic spiropyran (SP) self-assembled monolayers (SAMs) sandwiched between active semiconductors and gate insulators. Reversible changes in dipole moment of SPs in SAMs triggered by lights with different wavelengths produce two distinct built-in electric fields on the OFET that can modulate the channel conductance and consequently threshold voltage values, thus leading to a low-cost noninvasive memory device. This concept of interface functionalization offers attractive new prospects for the development of organic electronic devices with tailored electronic and other properties.

  9. Hybrid organic-inorganic porous semiconductor transducer for multi-parameters sensing.

    Science.gov (United States)

    Caliò, Alessandro; Cassinese, Antonio; Casalino, Maurizio; Rea, Ilaria; Barra, Mario; Chiarella, Fabio; De Stefano, Luca

    2015-07-06

    Porous silicon (PSi) non-symmetric multi-layers are modified by organic molecular beam deposition of an organic semiconductor, namely the N,N'-1H,1H-perfluorobutyldicyanoperylene-carboxydi-imide (PDIF-CN2). Joule evaporation of PDIF-CN2 into the PSi sponge-like matrix not only improves but also adds transducing skills, making this solid-state device a dual signal sensor for chemical monitoring. PDIF-CN2 modified PSi optical microcavities show an increase of about five orders of magnitude in electric current with respect to the same bare device. This feature can be used to sense volatile substances. PDIF-CN2 also improves chemical resistance of PSi against alkaline and acid corrosion. © 2015 The Author(s) Published by the Royal Society. All rights reserved.

  10. Bio-recognitive photonics of a DNA-guided organic semiconductor.

    Science.gov (United States)

    Back, Seung Hyuk; Park, Jin Hyuk; Cui, Chunzhi; Ahn, Dong June

    2016-01-04

    Incorporation of duplex DNA with higher molecular weights has attracted attention for a new opportunity towards a better organic light-emitting diode (OLED) capability. However, biological recognition by OLED materials is yet to be addressed. In this study, specific oligomeric DNA-DNA recognition is successfully achieved by tri (8-hydroxyquinoline) aluminium (Alq3), an organic semiconductor. Alq3 rods crystallized with guidance from single-strand DNA molecules show, strikingly, a unique distribution of the DNA molecules with a shape of an 'inverted' hourglass. The crystal's luminescent intensity is enhanced by 1.6-fold upon recognition of the perfect-matched target DNA sequence, but not in the case of a single-base mismatched one. The DNA-DNA recognition forming double-helix structure is identified to occur only in the rod's outer periphery. This study opens up new opportunities of Alq3, one of the most widely used OLED materials, enabling biological recognition.

  11. An improved synthesis of pentacene: rapid access to a benchmark organic semiconductor.

    Science.gov (United States)

    Pramanik, Chandrani; Miller, Glen P

    2012-04-20

    Pentacene is an organic semiconductor used in a variety of thin-film organic electronic devices. Although at least six separate syntheses of pentacene are known (two from dihydropentacenes, two from 6,13-pentacenedione and two from 6,13-dihydro-6,13-dihydroxypentacene), none is ideal and several utilize elevated temperatures that may facilitate the oxidation of pentacene as it is produced. Here, we present a fast (-2 min of reaction time), simple, high-yielding (≥ 90%), low temperature synthesis of pentacene from readily available 6,13-dihydro-6,13-dihydroxypentacene. Further, we discuss the mechanism of this highly efficient reaction. With this improved synthesis, researchers gain rapid, affordable access to high purity pentacene in excellent yield and without the need for a time consuming sublimation.

  12. An Improved Synthesis of Pentacene: Rapid Access to a Benchmark Organic Semiconductor

    Directory of Open Access Journals (Sweden)

    Glen P. Miller

    2012-04-01

    Full Text Available Pentacene is an organic semiconductor used in a variety of thin-film organic electronic devices. Although at least six separate syntheses of pentacene are known (two from dihydropentacenes, two from 6,13-pentacenedione and two from 6,13-dihydro-6,13-dihydroxypentacene, none is ideal and several utilize elevated temperatures that may facilitate the oxidation of pentacene as it is produced. Here, we present a fast (~2 min of reaction time, simple, high-yielding (≥90%, low temperature synthesis of pentacene from readily available 6,13-dihydro-6,13-dihydroxypentacene. Further, we discuss the mechanism of this highly efficient reaction. With this improved synthesis, researchers gain rapid, affordable access to high purity pentacene in excellent yield and without the need for a time consuming sublimation.

  13. Flexible Electronics: Integration Processes for Organic and Inorganic Semiconductor-Based Thin-Film Transistors

    Directory of Open Access Journals (Sweden)

    Fábio F. Vidor

    2015-07-01

    Full Text Available Flexible and transparent electronics have been studied intensively during the last few decades. The technique establishes the possibility of fabricating innovative products, from flexible displays to radio-frequency identification tags. Typically, large-area polymeric substrates such as polypropylene (PP or polyethylene terephthalate (PET are used, which produces new requirements for the integration processes. A key element for flexible and transparent electronics is the thin-film transistor (TFT, as it is responsible for the driving current in memory cells, digital circuits or organic light-emitting devices (OLEDs. In this paper, we discuss some fundamental concepts of TFT technology. Additionally, we present a comparison between the use of the semiconducting organic small-molecule pentacene and inorganic nanoparticle semiconductors in order to integrate TFTs suitable for flexible electronics. Moreover, a technique for integration with a submicron resolution suitable for glass and foil substrates is presented.

  14. Universal Disorder in Organic Semiconductors Due to Fluctuations in Space Charge

    Science.gov (United States)

    Wu, Tzu-Cheng

    This thesis concerns the study of charge transport in organic semiconductors. These materials are widely used as thin-film photoconductors in copiers and laser printers, and for their electroluminescent properties in organic light-emitting diodes. Much contemporary research is directed towards improving the efficiency of organic photovoltaic devices, which is limited to a large extent by the spatial and energetic disorder that hinders the charge mobility. One contribution to energetic disorder arises from the strong Coulomb interactions between injected charges with one another, but to date this has been largely ignored. We present a mean-field model for the effect of mutual interactions between injected charges hopping from site to site in an organic semiconductor. Our starting point is a modified Fröhlich Hamiltonian in which the charge is linearly coupled to the amplitudes of a wide band of dispersionless plasma modes having a Lorentzian distribution of frequencies. We show that in most applications of interest the hopping rates are fast enough while the plasma frequencies are low enough that random thermal fluctuations in the plasma density give rise to an energetically disordered landscape that is effectively stationary for many thousands of hops. Moreover, the distribution of site energies is Gaussian, and the energy-energy correlation function decays inversely with distance; as such, it can be argued that this disorder contributes to the Poole-Frenkel field dependence seen in a wide variety of experiments. Remarkably, the energetic disorder is universal; although it is caused by the fluctuations in the charge density, it is independent of the charge concentration.

  15. The rates of charge separation and energy destructive charge recombination processes within an organic dyad in presence of metal-semiconductor core shell nanocomposites.

    Science.gov (United States)

    Mandal, Gopa; Bhattacharya, Sudeshna; Das, Subrata; Ganguly, Tapan

    2012-01-01

    Steady state and time resolved spectroscopic measurements were made at the ambient temperature on an organic dyad, 1-(4-Chloro-phenyl)-3-(4-methoxy-naphthalen-1-yl)-propenone (MNCA), where the donor 1-methoxynaphthalene (1 MNT) is connected with the acceptor p-chloroacetophenone (PCA) by an unsaturated olefinic bond, in presence of Ag@TiO2 nanoparticles. Time resolved fluorescence and absorption measurements reveal that the rate parameters associated with charge separation, k(CS), within the dyad increases whereas charge recombination rate k(CR) reduces significantly when the surrounding medium is changed from only chloroform to mixture of chloroform and Ag@TiO2 (noble metal-semiconductor) nanocomposites. The observed results indicate that the dyad being combined with core-shell nanocomposites may form organic-inorganic nanocomposite system useful for developing light energy conversion devices. Use of metal-semiconductor nanoparticles may provide thus new ways to modulate charge recombination processes in light energy conversion devices. From comparison with the results obtained in our earlier investigations with only TiO2 nanoparticles, it is inferred that much improved version of light energy conversion device, where charge-separated species could be protected for longer period of time of the order of millisecond, could be designed by using metal-semiconductor core-shell nanocomposites rather than semiconductor nanoparticles only.

  16. Ionic behavior of organic-inorganic metal halide perovskite based metal-oxide-semiconductor capacitors.

    Science.gov (United States)

    Wang, Yucheng; Zhang, Yuming; Pang, Tiqiang; Xu, Jie; Hu, Ziyang; Zhu, Yuejin; Tang, Xiaoyan; Luan, Suzhen; Jia, Renxu

    2017-05-24

    Organic-inorganic metal halide perovskites are promising semiconductors for optoelectronic applications. Despite the achievements in device performance, the electrical properties of perovskites have stagnated. Ion migration is speculated to be the main contributing factor for the many unusual electrical phenomena in perovskite-based devices. Here, to understand the intrinsic electrical behavior of perovskites, we constructed metal-oxide-semiconductor (MOS) capacitors based on perovskite films and performed capacitance-voltage (C-V) and current-voltage (I-V) measurements of the capacitors. The results provide direct evidence for the mixed ionic-electronic transport behavior within perovskite films. In the dark, there is electrical hysteresis in both the C-V and I-V curves because the mobile negative ions take part in charge transport despite frequency modulation. However, under illumination, the large amount of photoexcited free carriers screens the influence of the mobile ions with a low concentration, which is responsible for the normal C-V properties. Validation of ion migration for the gate-control ability of MOS capacitors is also helpful for the investigation of perovskite MOS transistors and other gate-control photovoltaic devices.

  17. A High-Performance Optical Memory Array Based on Inhomogeneity of Organic Semiconductors.

    Science.gov (United States)

    Pei, Ke; Ren, Xiaochen; Zhou, Zhiwen; Zhang, Zhichao; Ji, Xudong; Chan, Paddy Kwok Leung

    2018-03-01

    Organic optical memory devices keep attracting intensive interests for diverse optoelectronic applications including optical sensors and memories. Here, flexible nonvolatile optical memory devices are developed based on the bis[1]benzothieno[2,3-d;2',3'-d']naphtho[2,3-b;6,7-b']dithiophene (BBTNDT) organic field-effect transistors with charge trapping centers induced by the inhomogeneity (nanosprouts) of the organic thin film. The devices exhibit average mobility as high as 7.7 cm 2 V -1 s -1 , photoresponsivity of 433 A W -1 , and long retention time for more than 6 h with a current ratio larger than 10 6 . Compared with the standard floating gate memory transistors, the BBTNDT devices can reduce the fabrication complexity, cost, and time. Based on the reasonable performance of the single device on a rigid substrate, the optical memory transistor is further scaled up to a 16 × 16 active matrix array on a flexible substrate with operating voltage less than 3 V, and it is used to map out 2D optical images. The findings reveal the potentials of utilizing [1]benzothieno[3,2-b][1]benzothiophene (BTBT) derivatives as organic semiconductors for high-performance optical memory transistors with a facile structure. A detailed study on the charge trapping mechanism in the derivatives of BTBT materials is also provided, which is closely related to the nanosprouts formed inside the organic active layer. © 2018 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  18. Principle and application of low energy inverse photoemission spectroscopy: A new method for measuring unoccupied states of organic semiconductors

    Energy Technology Data Exchange (ETDEWEB)

    Yoshida, Hiroyuki, E-mail: hyoshida@chiba-u.jp

    2015-10-01

    Highlights: • Principle of low energy inverse photoemission spectroscopy is described. • Instruments including electron sources and photon detectors are shown. • Recent results about organic devices and fundamental studies are reviewed. • Electron affinities of typical organic semiconductors are compiled. - Abstract: Information about the unoccupied states is crucial to both fundamental and applied physics of organic semiconductors. However, there were no available experimental methods that meet the requirement of such research. In this review, we describe a new experimental method to examine the unoccupied states, called low-energy inverse photoemission spectroscopy (LEIPS). An electron having the kinetic energy lower than the damage threshold of organic molecules is introduced to a sample film, and an emitted photon in the near-ultraviolet range is detected with high resolution and sensitivity. Unlike the previous inverse photoemission spectroscopy, the sample damage is negligible and the overall resolution is a factor of two improved to 0.25 eV. Using LEIPS, electron affinity of organic semiconductor can be determined with the same precision as photoemission spectroscopy for ionization energy. The instruments including an electron source and photon detectors as well as application to organic semiconductors are presented.

  19. Principle and application of low energy inverse photoemission spectroscopy: A new method for measuring unoccupied states of organic semiconductors

    International Nuclear Information System (INIS)

    Yoshida, Hiroyuki

    2015-01-01

    Highlights: • Principle of low energy inverse photoemission spectroscopy is described. • Instruments including electron sources and photon detectors are shown. • Recent results about organic devices and fundamental studies are reviewed. • Electron affinities of typical organic semiconductors are compiled. - Abstract: Information about the unoccupied states is crucial to both fundamental and applied physics of organic semiconductors. However, there were no available experimental methods that meet the requirement of such research. In this review, we describe a new experimental method to examine the unoccupied states, called low-energy inverse photoemission spectroscopy (LEIPS). An electron having the kinetic energy lower than the damage threshold of organic molecules is introduced to a sample film, and an emitted photon in the near-ultraviolet range is detected with high resolution and sensitivity. Unlike the previous inverse photoemission spectroscopy, the sample damage is negligible and the overall resolution is a factor of two improved to 0.25 eV. Using LEIPS, electron affinity of organic semiconductor can be determined with the same precision as photoemission spectroscopy for ionization energy. The instruments including an electron source and photon detectors as well as application to organic semiconductors are presented.

  20. Effects of Bimolecular Recombination on Impedance Spectra in Organic Semiconductors: Analytical Approach.

    Science.gov (United States)

    Takata, Masashi; Takagi, Kenichiro; Nagase, Takashi; Kobayashi, Takashi; Naito, Hiroyoshi

    2016-04-01

    An analytical expression for impedance spectra in the case of double injection (both electrons and holes are injected into an organic semiconductor thin film) has been derived from the basic transport equations (the current density equation, the continuity equation and the Possion's equation). Capacitance-frequency characteristics calculated from the analytical expression have been examined at different recombination constants and different values of mobility balance defined by a ratio of electron mobility to hole mobility. Negative capacitance appears when the recombination constant is lower than the Langevin recombination constant and when the value of the mobility balance approaches unity. These results are consistent with the numerical results obtained by a device simulator (Atlas, Silvaco).

  1. Molecular-scale shear response of the organic semiconductor β -DBDCS (100) surface

    Science.gov (United States)

    Álvarez-Asencio, Rubén; Moreno-Ramírez, Jorge S.; Pimentel, Carlos; Casado, Santiago; Matta, Micaela; Gierschner, Johannes; Muccioli, Luca; Yoon, Seong-Jun; Varghese, Shinto; Park, Soo Young; Gnecco, Enrico; Pina, Carlos M.

    2017-09-01

    In this work we present friction-force microscopy (FFM) lattice-resolved images acquired on the (100) facet of the semiconductor organic oligomer (2 Z ,2'Z )-3 , 3' -(1,4-phenylene)bis(2-(4-butoxyphenyl)acrylonitrile) (β -DBDCS) crystal in water at room temperature. Stick-slip contrast, lateral contact stiffness, and friction forces are found to depend strongly on the sliding direction due to the anisotropic packing of the molecular chains forming the crystal surface along the [010] and [001] directions. The anisotropy also causes the maximum value of the normal force applicable before wearing to increase by a factor of 3 when the scan is performed along the [001] direction on the (100) face. Altogether, our results contribute to achieving a better understanding of the molecular origin of friction anisotropy on soft crystalline surfaces, which has been often hypothesized but rarely investigated in the literature.

  2. Crossover from Super- to Subdiffusive Motion and Memory Effects in Crystalline Organic Semiconductors

    Science.gov (United States)

    De Filippis, G.; Cataudella, V.; Mishchenko, A. S.; Nagaosa, N.; Fierro, A.; de Candia, A.

    2015-02-01

    The transport properties at finite temperature of crystalline organic semiconductors are investigated, within the Su-Schrieffer-Heeger model, by combining an exact diagonalization technique, Monte Carlo approaches, and a maximum entropy method. The temperature-dependent mobility data measured in single crystals of rubrene are successfully reproduced: a crossover from super- to subdiffusive motion occurs in the range 150 ≤T ≤200 K , where the mean free path becomes of the order of the lattice parameter and strong memory effects start to appear. We provide an effective model, which can successfully explain features of the absorption spectra at low frequencies. The observed response to slowly varying electric field is interpreted by means of a simple model where the interaction between the charge carrier and lattice polarization modes is simulated by a harmonic interaction between a fictitious particle and an electron embedded in a viscous fluid.

  3. The effect of spin-orbit coupling on magnetoresistance in nonmagnetic organic semiconductors

    International Nuclear Information System (INIS)

    Zhao Jun-Qing; Ding Meng; Zhang Tian-You; Zhang Ning-Yu; Pang Yan-Tao; Ji Yan-Ju; Chen Ying; Wang Feng-Xiang; Fu Gang

    2012-01-01

    We investigated the effect of spin-orbit coupling on magnetoresistance in nonmagnetic organic semiconductors. A Lorentz-type magnetoresistance is obtained from spin-orbit coupling-dependent spin precession under the condition of a space-charge-limited current. The magnetoresistance depends on the initial spin orientation of the electron with respect to the hole in electron—hole pairs, and the increasing spin-orbit coupling slows down the change in magnetoresistance with magnetic field. The field dependence, the sign and the saturation value of the magnetoresistance are composite effects of recombination and dissociation rate constants of singlet and triplet electron—hole pairs. The simulated magnetoresistance shows good consistency with the experimental results. (condensed matter: electronic structure, electrical, magnetic, and optical properties)

  4. Materials for n-type organic electronics: synthesis and properties of fluoroarene-thiophene semiconductors

    Science.gov (United States)

    Facchetti, Antonio; Yoon, Myung-Han; Katz, Howard E.; Marks, Tobin J.

    2003-11-01

    Recent progress in the field of organic electronics is due to a fruitful combination of both innovative molecular design and promising low-cost material/device assembly. Targeting the first strategy, we present here the general synthesis of fluoroarene-containing thiophene-based semiconductors and the study of their properties with respect to the corresponding fluorine-free hole-transporting analogues. The new compounds have been characterized by elemental analysis, mass spectrometry, and 1H- and 19F NMR. The dramatic influence of fluorine substitution and molecular architecture has been investigated by solution/film optical absorption, fluorescence emission, and cyclic voltammetry. Single crystal data for all of the oligomers have been obtained and will be presented. Film microstructure and morphology of this new class of materials have been studied by XRD and SEM. Particular emphasis will be posed on the solution-processable oligomers and polymers.

  5. Production planning and control for semiconductor wafer fabrication facilities modeling, analysis, and systems

    CERN Document Server

    Mönch, Lars; Mason, Scott J

    2012-01-01

    Over the last fifty-plus years, the increased complexity and speed of integrated circuits have radically changed our world. Today, semiconductor manufacturing is perhaps the most important segment of the global manufacturing sector. As the semiconductor industry has become more competitive, improving planning and control has become a key factor for business success. This book is devoted to production planning and control problems in semiconductor wafer fabrication facilities. It is the first book that takes a comprehensive look at the role of modeling, analysis, and related information systems

  6. Exploring the energy landscape of the charge transport levels in organic semiconductors at the molecular scale.

    Science.gov (United States)

    Cornil, J; Verlaak, S; Martinelli, N; Mityashin, A; Olivier, Y; Van Regemorter, T; D'Avino, G; Muccioli, L; Zannoni, C; Castet, F; Beljonne, D; Heremans, P

    2013-02-19

    The extraordinary semiconducting properties of conjugated organic materials continue to attract attention across disciplines including materials science, engineering, chemistry, and physics, particularly with application to organic electronics. Such materials are used as active components in light-emitting diodes, field-effect transistors, or photovoltaic cells, as a substitute for (mostly Si-based) inorganic semiconducting materials. Many strategies developed for inorganic semiconductor device building (doping, p-n junctions, etc.) have been attempted, often successfully, with organics, even though the key electronic and photophysical properties of organic thin films are fundamentally different from those of their bulk inorganic counterparts. In particular, organic materials consist of individual units (molecules or conjugated segments) that are coupled by weak intermolecular forces. The flexibility of organic synthesis has allowed the development of more efficient opto-electronic devices including impressive improvements in quantum yields for charge generation in organic solar cells and in light emission in electroluminescent displays. Nonetheless, a number of fundamental questions regarding the working principles of these devices remain that preclude their full optimization. For example, the role of intermolecular interactions in driving the geometric and electronic structures of solid-state conjugated materials, though ubiquitous in organic electronic devices, has long been overlooked, especially when it comes to these interfaces with other (in)organic materials or metals. Because they are soft and in most cases disordered, conjugated organic materials support localized electrons or holes associated with local geometric distortions, also known as polarons, as primary charge carriers. The spatial localization of excess charges in organics together with low dielectric constant (ε) entails very large electrostatic effects. It is therefore not obvious how these

  7. High Photoluminescence Quantum Yields in Organic Semiconductor-Perovskite Composite Thin Films.

    Science.gov (United States)

    Longo, Giulia; La-Placa, Maria-Grazia; Sessolo, Michele; Bolink, Henk J

    2017-10-09

    One of the obstacles towards efficient radiative recombination in hybrid perovskites is a low exciton binding energy, typically in the orders of tens of meV. It has been shown that the use of electron-donor additives can lead to a substantial reduction of the non-radiative recombination in perovskite films. Herein, the approach using small molecules with semiconducting properties, which are candidates to be implemented in future optoelectronic devices, is presented. In particular, highly luminescent perovskite-organic semiconductor composite thin films have been developed, which can be processed from solution in a simple coating step. By tuning the relative concentration of methylammonium lead bromide (MAPbBr 3 ) and 9,9spirobifluoren-2-yl-diphenyl-phosphine oxide (SPPO1), it is possible to achieve photoluminescent quantum yields (PLQYs) as high as 85 %. This is attributed to the dual functions of SPPO1 that limit the grain growth while passivating the perovskite surface. The electroluminescence of these materials was investigated by fabricating multilayer LEDs, where charge injection and transport was found to be severely hindered for the perovskite/SPPO1 material. This was alleviated by partially substituting SPPO1 with a hole-transporting material, 1,3-bis(N-carbazolyl)benzene (mCP), leading to bright electroluminescence. The potential of combining perovskite and organic semiconductors to prepare materials with improved properties opens new avenues for the preparation of simple lightemitting devices using perovskites as the emitter. © 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

  8. Determination of the Orbital Lineup at Reactive Organic Semiconductor Interfaces Using Photoemission Spectroscopy

    National Research Council Canada - National Science Library

    Schlaf, R; Merritt, C. D; Picciolo, L. C; Kafafi, Zakya H

    2001-01-01

    ... (XPS and UPS) measurements. The Gaq3 /Mg system is a prototypical model structure for organic electron/low work function electrode transporting materials interfaces found in organic light emitting diodes (OLED...

  9. Nanoimprint system development and status for high volume semiconductor manufacturing

    Science.gov (United States)

    Hiura, Hiromi; Takabayashi, Yukio; Takashima, Tsuneo; Emoto, Keiji; Choi, Jin; Schumaker, Phil

    2016-10-01

    Imprint lithography has been shown to be an effective technique for replication of nano-scale features. Jet and Flash Imprint Lithography* (J-FIL*) involves the field-by-field deposition and exposure of a low viscosity resist deposited by jetting technology onto the substrate. The patterned mask is lowered into the fluid which then quickly flows into the relief patterns in the mask by capillary action. Following this filling step, the resist is crosslinked under UV radiation, and then the mask is removed, leaving a patterned resist on the substrate. There are many criteria that determine whether a particular technology is ready for wafer manufacturing. For imprint lithography, recent attention has been given to the areas of overlay, throughput, defectivity, and mask replication. This paper reviews progress in these critical areas. Recent demonstrations have proven that mix and match overlay of less than 5nm can achieved. Further reductions require a higher order correction system. Modeling and experimental data are presented which provide a path towards reducing the overlay errors to less than 3nm. Throughput is mainly impacted by the fill time of the relief images on the mask. Improvement in resist materials provides a solution that allows 15 wafers per hour per station, or a tool throughput of 60 wafers per hour. Defectivity and mask life play a significant role relative to meeting the cost of ownership (CoO) requirements in the production of semiconductor devices. Hard particles on a wafer or mask create the possibility of inducing a permanent defect on the mask that can impact device yield and mask life. By using material methods to reduce particle shedding and by introducing an air curtain system, the lifetime of both the master mask and the replica mask can be extended. In this work, we report results that demonstrate a path towards achieving mask lifetimes of better than 1000 wafers. Finally, on the mask side, a new replication tool, the FPA-1100NR2 is

  10. Synchrotron-based measurements of the electronic structure of the organic semiconductor copper phthalocyanine

    International Nuclear Information System (INIS)

    Downes, J.E.

    2004-01-01

    Full text: Copper phthalocyanine (CuPc) is a prototypical molecular organic semiconductor that is currently used in the construction of many organic electronic devices such as organic light emitting diodes (OLEDs). Although the material is currently being used, and despite many experimental and theoretical studies, it's detailed electronic structure is still not completely understood. This is likely due to two key factors. Firstly, the interaction of the Cu 3d and phthalocyanine ligand 2p electrons leads to the formation of a complex arrangement of localized and delocalized states near the Fermi level. Secondly, thin films of the material are subject to damage by the photon beam used to make measurements of their electronic structure. Using the synchrotron-based techniques of soft x-ray emission spectroscopy (XES) and x-ray photoemission spectroscopy (XPS), we have measured the detailed electronic structure of in-situ grown thin film samples of CuPc. Beam damage was minimized by continuous translation of the sample during data acquisition. The results obtained differ significantly from previous XES and ultraviolet photoemission measurements, but are in excellent agreement with recent density functional calculations. The reasons for these discrepancies will be explained, and their implications for future measurements on similar materials will be explored

  11. Hydrogen-bonding versus .pi.-.pi. stacking in the design of organic semiconductors: from dyes to oligomers

    Czech Academy of Sciences Publication Activity Database

    Gospodinova, Natalia; Tomšík, Elena

    2015-01-01

    Roč. 43, April (2015), s. 33-47 ISSN 0079-6700 R&D Projects: GA ČR(CZ) GA13-00270S; GA ČR GPP108/11/P763 Institutional support: RVO:61389013 Keywords : organic semiconductors * hydrogen bonds * nematic liquid crystals Subject RIV: CD - Macromolecular Chemistry Impact factor: 27.184, year: 2015

  12. A photoemission study of interfaces between organic semiconductors and Co as well as Al2O3/Co contacts

    NARCIS (Netherlands)

    Grobosch, M.; Schmidt, C.; Naber, W.J.M.; van der Wiel, Wilfred Gerard; Knupfer, M.

    We have studied the energy-level alignment of ex situ, acetone cleaned Co and Al2O3/Co contacts to the organic semiconductors pentacene and rubrene by combined X-ray and ultraviolet photoemission spectroscopy. Our results demonstrate that the work function under these conditions is smaller than in

  13. Current-Voltage Characteristics of the Metal / Organic Semiconductor / Metal Structures: Top and Bottom Contact Configuration Case

    Directory of Open Access Journals (Sweden)

    Šarūnas MEŠKINIS

    2013-03-01

    Full Text Available In present study five synthesized organic semiconductor compounds have been used for fabrication of the planar metal / organic semiconductor / metal structures. Both top electrode and bottom electrode configurations were used. Current-voltage (I-V characteristics of the samples were investigated. Effect of the hysteresis of the I-V characteristics was observed for all the investigated samples. However, strength of the hysteresis was dependent on the organic semiconductor used. Study of I-V characteristics of the top contact Al/AT-RB-1/Al structures revealed, that in (0 – 500 V voltages range average current of the samples measured in air is only slightly higher than current measured in nitrogen ambient. Deposition of the ultra-thin diamond like carbon interlayer resulted in both decrease of the hysteresis of I-V characteristics of top contact Al/AT-RB-1/Al samples. However, decreased current and decreased slope of the I-V characteristics of the samples with diamond like carbon interlayer was observed as well. I-V characteristic hysteresis effect was less pronounced in the case of the bottom contact metal/organic semiconductor/metal samples. I-V characteristics of the bottom contact samples were dependent on electrode metal used.DOI: http://dx.doi.org/10.5755/j01.ms.19.1.3816

  14. Molecular dynamics simulations of graphoepitaxy of organic semiconductors, sexithiophene, and pentacene: Molecular-scale mechanisms of organic graphoepitaxy

    Science.gov (United States)

    Ikeda, Susumu

    2018-03-01

    Molecular dynamics (MD) simulations of the organic semiconductors α-sexithiophene (6T) and pentacene were carried out to clarify the mechanism of organic graphoepitaxy at the molecular level. First, the models of the grooved substrates were made and the surfaces of the inside of the grooves were modified with -OH or -OSi(CH3)3, making the surfaces hydrophilic or hydrophobic. By the MD simulations of 6T, it was found that three stable azimuthal directions exist (0, ˜45, and 90° the angle that the c-axis makes with the groove), being consistent with experimental results. MD simulations of deposition processes of 6T and pentacene were also carried out, and pentacene molecules showed the spontaneous formation of herringbone packing during deposition. Some pentacene molecules stood on the surface and formed a cluster whose a-axis was parallel to the groove. It is expected that a deep understanding of the molecular-scale mechanisms will lead graphoepitaxy to practical applications, improving the performance of organic devices.

  15. Photooxidation of organic wastes using semiconductor nanoclusters. 1998 annual progress report

    International Nuclear Information System (INIS)

    Wilcoxon, J.P.

    1998-01-01

    'This report summarizes work after 1.5 years of a 3-year project. The authors efforts have focused on demonstration of photocatalysis of organic pollutants using nanosize MoS 2 . They investigated the effects of (1) bandgap, valence and conduction band energies; (2) surface modification of MoS 2 by deposition of metal and metal oxide islands to enhance electron transfer; and (3) use of semi-conductor semi-conductor composites to achieve improved charge separation and thus photooxidation of pollutants. They synthesized and studied nanosize MoS 2 of three different sizes and associated bandgaps and studied photoredox reactions of nanosize MoS 2 dispersed in solution and supported on a macroscopic powder. The latter would be the method of choice for use as a practical photocatalyst for water purification. As they emphasized in the original proposal, MoS 2 in nanosize form can be tuned to absorb various amounts of the solar spectrum. They discovered there is an optimal choice of absorbance characteristics and valence and conduction band levels which allow the rapid photo-oxidation of a chosen organic molecule. The advantages of having a photostable material with a tunable bandgap were demonstrated in an experiment where phenol destruction with visible (> 450 nm) light occurred at a dramatically faster rate with nanoscale MoS 2 catalysts compared to the best available previous material TiO 2 . This was the first demonstration of rapid photooxidation of an organic molecule using a completely photostable catalyst and only visible light. The possibility of transferring electrons or holes between nanoscale MoS 2 and other semiconductor materials in order to increase electron/hole lifetimes were explored. It was shown that small amounts ( 2 deposited on to TiO 2 can lead to significant (∼2) enhancements of phenol destruction rates. A number of different chemicals were photocatalyzed sucessfully to CO 2 , but most of the work centered on the destruction of phenol. This

  16. Theoretical proposal for a magnetic resonance study of charge transport in organic semiconductors

    Science.gov (United States)

    Mkhitaryan, Vagharsh

    Charge transport in disordered organic semiconductors occurs via carrier incoherent hops in a band of localized states. In the framework of continuous-time random walk the carrier on-site waiting time distribution (WTD) is one of the basic characteristics of diffusion. Besides, WTD is fundamentally related to the density of states (DOS) of localized states, which is a key feature of a material determining the optoelectric properties. However, reliable first-principle calculations of DOS in organic materials are not yet available and experimental characterization of DOS and WTD is desirable. We theoretically study the spin dynamics of hopping carriers and propose measurement schemes directly probing WTD, based on the zero-field spin relaxation and the primary (Hahn) spin echo. The proposed schemes are possible because, as we demonstrate, the long-time behavior of the zero-field relaxation and the primary echo is determined by WTD, both for the hyperfine coupling dominated and the spin-orbit coupling dominated spin dynamics. We also examine the dispersive charge transport, which is a non-Markovian sub-diffusive process characterized by non-stationarity. We show that the proposed schemes unambiguously capture the effects of non-stationarity, e.g., the aging behavior of random walks. This work was supported by the Department of Energy-Basic Energy Sciences under Contract No. DE-AC02-07CH11358.

  17. In situ X-ray synchrotron study of organic semiconductor ultra-thin films growth

    International Nuclear Information System (INIS)

    Moulin, J.-F.; Dinelli, F.; Massi, M.; Albonetti, C.; Kshirsagar, R.; Biscarini, F.

    2006-01-01

    In this work we present an X-ray diffraction study of the early stages of growth of an organic semiconductor (sexithiophene, T 6 ) thin film prepared by high vacuum sublimation. Specular reflectometry and grazing incidence X-ray diffraction were used to monitor the formation of T 6 films on silicon oxide. Our results show that T 6 grows as a crystalline layer from the beginning of the evaporation. The reflectometry analysis suggests that, in the range of rates and temperatures studied, the growth is never layer by layer but rather 3D in nature. In-plane GIXD has allowed us to observe for the first time a thin film phase of T 6 formed of molecules standing normal to the substrate and arranged in a compressed unit cell with respect to the bulk, i.e. the unit cell parameters b and c are relatively smaller. We have followed the dynamics of formation of this new phase and identified the threshold of appearance of the bulk phase, which occurs above ∼5-6 monolayers. These results are relevant to the problem of organic thin film transistors, for which we have previously demonstrated experimentally that only the first two monolayers of T 6 films are involved in the electrical transport. The layers above the second one do not effectively contribute to charge mobility, either because they are more 'disordered' or because of a screening of the gate field

  18. Functionalized organic semiconductor molecules to enhance charge carrier injection in electroluminescent cell

    Science.gov (United States)

    Yalcin, Eyyup; Kara, Duygu Akin; Karakaya, Caner; Yigit, Mesude Zeliha; Havare, Ali Kemal; Can, Mustafa; Tozlu, Cem; Demic, Serafettin; Kus, Mahmut; Aboulouard, Abdelkhalk

    2017-07-01

    Organic semiconductor (OSC) materials as a charge carrier interface play an important role to improve the device performance of organic electroluminescent cells. In this study, 4,4″-bis(diphenyl amino)-1,1':3‧,1″-terphenyl-5'-carboxylic acid (TPA) and 4,4″-di-9H-carbazol-9-yl-1,1':3‧,1″-terphenyl-5'-carboxylic acid (CAR) has been designed and synthesized to modify indium tin oxide (ITO) layer as interface. Bare ITO and PEDOT:PSS coated on ITO was used as reference anode electrodes for comparison. Furthermore, PEDOT:PSS coated over CAR/ITO and TPA/ITO to observe stability of OSC molecules and to completely cover the ITO surface. Electrical, optical and surface characterizations were performed for each device. Almost all modified devices showed around 36% decrease at the turn on voltage with respect to bare ITO. The current density of bare ITO, ITO/CAR and ITO/TPA were measured as 288, 1525 and 1869 A/m2, respectively. By increasing current density, luminance of modified devices showed much better performance with respect to unmodified devices.

  19. Stoichiometric and Oxygen-Deficient VO2 as Versatile Hole Injection Electrode for Organic Semiconductors.

    Science.gov (United States)

    Fu, Keke; Wang, Rongbin; Katase, Takayoshi; Ohta, Hiromichi; Koch, Norbert; Duhm, Steffen

    2018-03-28

    Using photoemission spectroscopy, we show that the surface electronic structure of VO 2 is determined by the temperature-dependent metal-insulator phase transition and the density of oxygen vacancies, which depends on the temperature and ultrahigh vacuum (UHV) conditions. The atomically clean and stoichiometric VO 2 surface is insulating at room temperature and features an ultrahigh work function of up to 6.7 eV. Heating in UHV just above the phase transition temperature induces the expected metallic phase, which goes in hand with the formation of oxygen defects (up to 6% in this study), but a high work function >6 eV is maintained. To demonstrate the suitability of VO 2 as hole injection contact for organic semiconductors, we investigated the energy-level alignment with the prototypical organic hole transport material N, N'-di(1-naphthyl)- N, N'-diphenyl-(1,1'-biphenyl)-4,4'-diamine (NPB). Evidence for strong Fermi-level pinning and the associated energy-level bending in NPB is found, rendering an Ohmic contact for holes.

  20. Phototreatment of Water by Organic Photosensitizers and Comparison with Inorganic Semiconductors

    Directory of Open Access Journals (Sweden)

    Merlyn Thandu

    2015-01-01

    Full Text Available Phototreatment of water is drawing the attention of many as a promising alternative to replace methods like chlorination, ozonization, and other oxidation processes, used in current disinfection methods limiting harmful side-products and by-products that can cause damage to the fauna and flora. Porphyrins, phthalocyanines, and other related organic dyes are well known for their use in photodynamic therapy (PDT. These photosensitizers cause cell death by generating reactive oxygen species (ROS especially singlet oxygen in the presence of light. Such molecules are also being explored for photodynamically treating microbial infections, killing of unwanted pathogens in the environment, and oxidation of chemical pollutants. The process of photosensitisation (phototreatment can be applied for obtaining clean, microbe-free water, thus exploiting the versatile properties of photosensitizers. This review collects the various attempts carried out for phototreatment of water using organic photosensitizers. For comparison, some reports of semiconductors (especially TiO2 used in photocatalytic treatment of water are also mentioned.

  1. Emission and Dynamics of Charge Carriers in Uncoated and Organic/Metal Coated Semiconductor Nanowires

    Science.gov (United States)

    Kaveh Baghbadorani, Masoud

    In this dissertation, the dynamics of excitons in hybrid metal/organic/nanowire structures possessing nanometer thick deposited molecular and metal films on top of InP and GaAs nanowire (NW) surfaces were investigated. Optical characterizations were carried out as a function of the semiconductor NW material, design, NW size and the type and thickness of the organic material and metal used. Hybrid organic and plasmonic semiconductor nanowire heterostructures were fabricated using organic molecular beam deposition technique. I investigated the photon emission of excitons in 150 nm diameter polytype wurtzite/zincblende InP NWs and the influence of a few ten nanometer thick organic and metal films on the emission using intensity- and temperature-dependent time-integrated and time resolved (TR) photoluminescence (PL). The plasmonic NWs were coated with an Aluminum quinoline (Alq3) interlayer and magnesium-silver (Mg0.9:Ag0.1) top layer. In addition, the nonlinear optical technique of heterodyne four-wave mixing was used (in collaboration with Prof. Wolfgang Langbein, University of Cardiff) to study incoherent and coherent carrier relaxation processes on bare nanowires on a 100 femtosecond time-scale. Alq3 covered NWs reveal a stronger emission and a longer decay time of exciton transitions indicating surface state passivation at the Alq3/NW interface. Alq3/Mg:Ag NWs reveal a strong quenching of the exciton emission which is predominantly attributed to Forster energy-transfer from excitons to plasmon oscillations in the metal cluster film. Changing the Mg:Ag to gold and the organic Alq3 spacer layer to PTCDA leads to a similar behavior, but the PL quenching is strongly increased. The observed behavior is attributed to a more continuous gold deposition leading to an increased Forster energy transfer and to a metal induced band-bending. I also investigated ensembles of bare and gold/Alq3 coated GaAs-AlGaAs-GaAs core shell NWs of 130 nm diameter. Plasmonic NWs with Au

  2. High-Performance Nonvolatile Organic Field-Effect Transistor Memory Based on Organic Semiconductor Heterostructures of Pentacene/P13/Pentacene as Both Charge Transport and Trapping Layers.

    Science.gov (United States)

    Li, Wen; Guo, Fengning; Ling, Haifeng; Zhang, Peng; Yi, Mingdong; Wang, Laiyuan; Wu, Dequn; Xie, Linghai; Huang, Wei

    2017-08-01

    Nonvolatile organic field-effect transistor (OFET) memory devices based on pentacene/ N , N '-ditridecylperylene-3,4,9,10-tetracarboxylic diimide (P13)/pentacene trilayer organic heterostructures have been proposed. The discontinuous n-type P13 embedded in p-type pentacene layers can not only provide electrons in the semiconductor layer that facilitates electron trapping process; it also works as charge trapping sites, which is attributed to the quantum well-like pentacene/P13/pentacene organic heterostructures. The synergistic effects of charge trapping in the discontinuous P13 and the charge-trapping property of the poly(4-vinylphenol) (PVP) layer remarkably improve the memory performance. In addition, the trilayer organic heterostructures have also been successfully applied to multilevel and flexible nonvolatile memory devices. The results provide a novel design strategy to achieve high-performance nonvolatile OFET memory devices and allow potential applications for different combinations of various organic semiconductor materials in OFET memory.

  3. Quantum theory of the electronic and optical properties of low-dimensional semiconductor systems

    Science.gov (United States)

    Lau, Wayne Heung

    This thesis examines the electronic and optical properties of low-dimensional semiconductor systems. A theory is developed to study the electron-hole generation-recombination process of type-II semimetallic semiconductor heterojunctions based on a 3 x 3 k·p matrix Hamiltonian (three-band model) and an 8 x 8 k·p matrix Hamiltonian (eight-band model). A novel electron-hole generation and recombination process, which is called activationless generation-recombination process, is predicted. It is demonstrated that the current through the type-II semimetallic semiconductor heterojunctions is governed by the activationless electron-hole generation-recombination process at the heterointerfaces, and that the current-voltage characteristics are essentially linear. A qualitative agreement between theory and experiments is observed. The numerical results of the eight-band model are compared with those of the threeband model. Based on a lattice gas model, a theory is developed to study the influence of a random potential on the ionization equilibrium conditions for bound electron-hole pairs (excitons) in III--V semiconductor heterostructures. It is demonstrated that ionization equilibrium conditions for bound electron-hole pairs change drastically in the presence of strong disorder. It is predicted that strong disorder promotes dissociation of excitons in III--V semiconductor heterostructures. A theory of polariton (photon dressed by phonon) spontaneous emission in a III--V semiconductor doped with semiconductor quantum dots (QDs) or quantum wells (QWs) is developed. For the first time, superradiant and subradiant polariton spontaneous emission phenomena in a polariton-QD (QW) coupled system are predicted when the resonance energies of the two identical QDs (QWs) lie outside the polaritonic energy gap. It is also predicted that when the resonance energies of the two identical QDs (QWs) lie inside the polaritonic energy gap, spontaneous emission of polariton in the polariton

  4. P-doped organic semiconductor: Potential replacement for PEDOT:PSS in organic photodetectors

    Energy Technology Data Exchange (ETDEWEB)

    Herrbach, J.; Revaux, A., E-mail: amelie.revaux@cea.fr [University of Grenoble Alpes, CEA-LITEN, Grenoble 38000 (France); Vuillaume, D. [IEMN, CNRS, University of Lille, Villeneuve d' Ascq 59652 (France); Kahn, A. [Department of Electrical Engineering, Princeton University, Princeton, New Jersey 08544 (United States)

    2016-08-15

    In this work, we present an alternative to the use of PEDOT:PSS as hole transport and electron blocking layers in organic photodetectors processed by solution. As Poly(3,4-ethylenedioxythiophene)-poly(styrenesulfonate) (PEDOT:PSS) is known to be sensitive to humidity, oxygen, and UV, removing this layer is essential for lifetime improvements. As a first step to achieving this goal, we need to find an alternative layer that fulfills the same role in order to obtain a working diode with similar or better performance. As a replacement, a layer of poly[(4,8-bis-(2-ethylhexyloxy)-benzo(1,2-b:4,5-b′)dithiophene)-2, 6-diyl-alt-(4-(2-ethylhexanoyl)-thieno[3,4-b]thiophene-)-2-6-diyl)] (PBDTTT-c) p-doped with the dopant tris-[1-(trifluoroethanoyl)-2-(trifluoromethyl)ethane-1,2-dithiolene] (Mo(tfd-COCF{sub 3}){sub 3}) is used. This p-doped layer effectively lowers the hole injection barrier, and the low electron affinity of the polymer prevents the injection of electrons into the active layer. We show similar device performance under light and the improvements of detection performance with the doped layer in comparison with PEDOT:PSS, leading to a detectivity of 1.9 × 10{sup 13} cm (Hz){sup 1/2} (W){sup −1}, competitive with silicon diodes used in imaging applications. Moreover, contrary to PEDOT:PSS, no localization of the p-doped layer is needed, leading to a diode active area defined by the patterned electrodes.

  5. Organic semiconductor rubrene thin films deposited by pulsed laser evaporation of solidified solutions

    Science.gov (United States)

    Majewska, N.; Gazda, M.; Jendrzejewski, R.; Majumdar, S.; Sawczak, M.; Śliwiński, G.

    2017-08-01

    Organic semiconductor rubrene (C42H28) belongs to most preferred spintronic materials because of the high charge carrier mobility up to 40 cm2(V·s)-1. However, the fabrication of a defect-free, polycrystalline rubrene for spintronic applications represents a difficult task. We report preparation and properties of rubrene thin films deposited by pulsed laser evaporation of solidified solutions. Samples of rubrene dissolved in aromatic solvents toluene, xylene, dichloromethane and 1,1-dichloroethane (0.23-1% wt) were cooled to temperatures in the range of 16.5-163 K and served as targets. The target ablation was provided by a pulsed 1064 nm or 266 nm laser. For films of thickness up to 100 nm deposited on Si, glass and ITO glass substrates, the Raman and AFM data show presence of the mixed crystalline and amorphous rubrene phases. Agglomerates of rubrene crystals are revealed by SEM observation too, and presence of oxide/peroxide (C42H28O2) in the films is concluded from matrix-assisted laser desorption/ionization time-of-flight spectroscopic analysis.

  6. Studies on applications of functional organic-thin-films for lithography on semiconductor device production

    International Nuclear Information System (INIS)

    Ogawa, Kazufumi

    1988-12-01

    This report describes some experimental results of studies in an attempt to contribute to the development of ultra-fine lithography which is used for the manufacture of semiconductor devices with design rule below 0.5 μm, and contains (1) manufacture of the exposure apparatus, (2) establishment of the resist process technology, and (3) preparation of the resist materials. The author designed and manufactured the KrF excimer laser stepper which is supposed to be most promising for practical uses. In the resist processing technology, the water-soluble contrast enhanced lithography (CEL) process was developed and this process has advantages is that high pattern contrast and large focus depth latitude were easily obtained. Finally, for resist materials, use of Langmuir-Blodgett (LB) films was investigated since the LB technique provides the method to prepare extremely thin organic films which are uniform in molecular level, and the reaction mechanism of the LB films of unsaturated compounds under irradiation with high energy beams was elucidated. (author)

  7. Self-Aligned Growth of Organic Semiconductor Single Crystals by Electric Field.

    Science.gov (United States)

    Kotsuki, Kenji; Obata, Seiji; Saiki, Koichiro

    2016-01-19

    We proposed a novel but facile method for growing organic semiconductor single-crystals via solvent vapor annealing (SVA) under electric field. In the conventional SVA growth process, nuclei of crystals appeared anywhere on the substrate and their crystallographic axes were randomly distributed. We applied electric field during the SVA growth of 2,7-dioctyl[1]benzothieno[3,2-b][1]benzothiophene (C8-BTBT) on the SiO2/Si substrate on which a pair of electrodes had been deposited beforehand. Real-time observation of the SVA process revealed that rodlike single crystals grew with their long axes parallel to the electric field and bridged the prepatterned electrodes. As a result, C8-BTBT crystals automatically formed a field effect transistor (FET) structure and the mobility reached 1.9 cm(2)/(V s). Electric-field-assisted SVA proved a promising method for constructing high-mobility single-crystal FETs at the desired position by a low-cost solution process.

  8. Improving the Stability of Organic Semiconductors: Distortion Energy versus Aromaticity in Substituted Bistetracene

    KAUST Repository

    Thomas, Simil

    2016-11-15

    Polycyclic aromatic hydrocarbons (PAHs) have been widely explored as molecular semiconductors in organic electronic devices such as field-effect transistors or solar cells. However, their tendency to undergo photooxidation is a primary limitation to their practical applications. Bistetracene derivatives have recently been demonstrated to possess much larger photo oxidation stability than the widely investigated pentacene and rubrene, while maintaining high charge-carrier mobilities. Here, using several levels of density functional theory, we identify the origin of the increased stability of bistetracene with respect to molecular oxygen by systematically investigating the [4 + 2] cycloaddition (Diels Alder) photooxidation reaction mechanism. Importantly, our computational results indicate that endoperoxide formation in bis(2-(trimethylsilyl)ethynyl) bistetracene (BT) occurs not on the ring with least aromaticity, but rather on the ring with smallest distortion energy. This feature was subsequently confirmed by experimental NMR analyses. The oxidation activation barriers of bistetracene, pentacene, and rubrene are found to be 17.7, 13.6, and 14.4 kcal/mol, respectively, in agreement with the observed order of stability of these molecules with respect to oxidation reactions in solution. In the cases of BT and pentacene, the rates of electron transfer to create charged species (PAH(+) and O-2) are at least two orders of magnitude lower than that of the charge recombination process (back to PAH and O-2); for rubrene, both of these processes are calculated to be of the same order of magnitude, in agreement with experimental electron paramagnetic resonance spectroscopy observations.

  9. Theoretical study of substitution effects on molecular reorganization energy in organic semiconductors.

    Science.gov (United States)

    Geng, Hua; Niu, Yingli; Peng, Qian; Shuai, Zhigang; Coropceanu, Veaceslav; Brédas, Jean-Luc

    2011-09-14

    Chemical substitutions are powerful molecular design tools to enhance the performance of organic semiconductors, for instance, to improve solubility, intermolecular stacking, or film quality. However, at the microscopic level, substitutions in general tend to increase the molecular reorganization energy and thus decrease the intrinsic charge-carrier mobility. Through density functional theory calculations, we elucidate strategies that could be followed to reduce the reorganization energy upon chemical substitution. Specific examples are given here for hole-transport materials including indolo-carbazoles and several triarylamine derivatives. Through decomposition of the total reorganization energy into the internal coordinate space, we are able to identify the molecular segment that provides the most important contributions to the reorganization energy. It is found that when substitution reduces (enhances) the amplitude of the relevant frontier molecular orbital in that segment, the total reorganization energy decreases (increases). In particular, chlorination at appropriate positions can significantly reduce the reorganization energy. Several other substituents are shown to play a similar role, to a greater or lesser extent. © 2011 American Institute of Physics

  10. Low dielectric constant-based organic field-effect transistors and metal-insulator-semiconductor capacitors

    Science.gov (United States)

    Ukah, Ndubuisi Benjamin

    This thesis describes a study of PFB and pentacene-based organic field-effect transistors (OFET) and metal-insulator-semiconductor (MIS) capacitors with low dielectric constant (k) poly(methyl methacrylate) (PMMA), poly(4-vinyl phenol) (PVP) and cross-linked PVP (c-PVP) gate dielectrics. A physical method -- matrix assisted pulsed laser evaporation (MAPLE) -- of fabricating all-polymer field-effect transistors and MIS capacitors that circumvents inherent polymer dissolution and solvent-selectivity problems, is demonstrated. Pentacene-based OFETs incorporating PMMA and PVP gate dielectrics usually have high operating voltages related to the thickness of the dielectric layer. Reduced PMMA layer thickness (≤ 70 nm) was obtained by dissolving the PMMA in propylene carbonate (PC). The resulting pentacene-based transistors exhibited very low operating voltage (below -3 V), minimal hysteresis in their transfer characteristics, and decent electrical performance. Also low voltage (within -2 V) operation using thin (≤ 80 nm) low-k and hydrophilic PVP and c-PVP dielectric layers obtained via dissolution in high dipole moment and high-k solvents -- PC and dimethyl sulfoxide (DMSO), is demonstrated to be a robust means of achieving improved electrical characteristics and high operational stability in OFETs incorporating PVP and c-PVP dielectrics.

  11. Madelung and Hubbard interactions in polaron band model of doped organic semiconductors

    Science.gov (United States)

    Png, Rui-Qi; Ang, Mervin C.Y.; Teo, Meng-How; Choo, Kim-Kian; Tang, Cindy Guanyu; Belaineh, Dagmawi; Chua, Lay-Lay; Ho, Peter K.H.

    2016-01-01

    The standard polaron band model of doped organic semiconductors predicts that density-of-states shift into the π–π* gap to give a partially filled polaron band that pins the Fermi level. This picture neglects both Madelung and Hubbard interactions. Here we show using ultrahigh workfunction hole-doped model triarylamine–fluorene copolymers that Hubbard interaction strongly splits the singly-occupied molecular orbital from its empty counterpart, while Madelung (Coulomb) interactions with counter-anions and other carriers markedly shift energies of the frontier orbitals. These interactions lower the singly-occupied molecular orbital band below the valence band edge and give rise to an empty low-lying counterpart band. The Fermi level, and hence workfunction, is determined by conjunction of the bottom edge of this empty band and the top edge of the valence band. Calculations are consistent with the observed Fermi-level downshift with counter-anion size and the observed dependence of workfunction on doping level in the strongly doped regime. PMID:27582355

  12. Tuning polymorphism and orientation in organic semiconductor thin films via post-deposition processing.

    Science.gov (United States)

    Hiszpanski, Anna M; Baur, Robin M; Kim, Bumjung; Tremblay, Noah J; Nuckolls, Colin; Woll, Arthur R; Loo, Yueh-Lin

    2014-11-05

    Though both the crystal structure and molecular orientation of organic semiconductors are known to impact charge transport in thin-film devices, separately accessing different polymorphs and varying the out-of-plane molecular orientation is challenging, typically requiring stringent control over film deposition conditions, film thickness, and substrate chemistry. Here we demonstrate independent tuning of the crystalline polymorph and molecular orientation in thin films of contorted hexabenzocoronene, c-HBC, during post-deposition processing without the need to adjust deposition conditions. Three polymorphs are observed, two of which have not been previously reported. Using our ability to independently tune the crystal structure and out-of-plane molecular orientation in thin films of c-HBC, we have decoupled and evaluated the effects that molecular packing and orientation have on device performance in thin-film transistors (TFTs). In the case of TFTs comprising c-HBC, polymorphism and molecular orientation are equally important; independently changing either one affects the field-effect mobility by an order of magnitude.

  13. Nucleation and strain-stabilization during organic semiconductor thin film deposition.

    Science.gov (United States)

    Li, Yang; Wan, Jing; Smilgies, Detlef-M; Bouffard, Nicole; Sun, Richard; Headrick, Randall L

    2016-09-07

    The nucleation mechanisms during solution deposition of organic semiconductor thin films determine the grain morphology and may influence the crystalline packing in some cases. Here, in-situ optical spectromicroscopy in reflection mode is used to study the growth mechanisms and thermal stability of 6,13-bis(trisopropylsilylethynyl)-pentacene thin films. The results show that the films form in a supersaturated state before transforming to a solid film. Molecular aggregates corresponding to subcritical nuclei in the crystallization process are inferred from optical spectroscopy measurements of the supersaturated region. Strain-free solid films exhibit a temperature-dependent blue shift of optical absorption peaks due to a continuous thermally driven change of the crystalline packing. As crystalline films are cooled to ambient temperature they become strained although cracking of thicker films is observed, which allows the strain to partially relax. Below a critical thickness, cracking is not observed and grazing incidence X-ray diffraction measurements confirm that the thinnest films are constrained to the lattice constants corresponding to the temperature at which they were deposited. Optical spectroscopy results show that the transition temperature between Form I (room temperature phase) and Form II (high temperature phase) depends on the film thickness, and that Form I can also be strain-stabilized up to 135 °C.

  14. Thermal stability and molecular ordering of organic semiconductor monolayers: effect of an anchor group.

    Science.gov (United States)

    Jones, Andrew O F; Knauer, Philipp; Resel, Roland; Ringk, Andreas; Strohriegl, Peter; Werzer, Oliver; Sferrazza, Michele

    2015-06-08

    The thermal stability and molecular order in monolayers of two organic semiconductors, PBI-PA and PBI-alkyl, based on perylene derivatives with an identical molecular structure except for an anchor group for attachment to the substrate in PBI-PA, are reported. In situ X-ray reflectivity measurements are used to follow the stability of these monolayers in terms of order and thickness as temperature is increased. Films have thicknesses corresponding approximately to the length of one molecule; molecules stand upright on the substrate with a defined structure. PBI-PA monolayers have a high degree of order at room temperature and a stable film exists up to 250 °C, but decomposes rapidly above 300 °C. In contrast, stable physisorbed PBI-alkyl monolayers only exist up to 100 °C. Above the bulk melting point at 200 °C no more order exists. The results encourage using anchor groups in monolayers for various applications as it allows enhanced stability at the interface with the substrate. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  15. Organic-inorganic Au/PVP/ZnO/Si/Al semiconductor heterojunction characteristics

    Science.gov (United States)

    Mokhtari, H.; Benhaliliba, M.

    2017-11-01

    The paper reports the fabrication and characterization of a novel Au/PVP/ZnO/Si/Al semiconductor heterojunction (HJ) diode. Both inorganic n type ZnO and organic polyvinyl pyrrolidone (PVP) layers have grown by sol-gel spin-coating route at 2000 rpm. The front and back metallic contacts are thermally evaporated in a vacuum at pressure of 10-6 Torr having a diameter of 1.5 mm and a thickness of 250 nm. The detailed analysis of the forward and reverse bias current-voltage characteristics has been provided. Consequently, many electronic parameters, such as ideality factor, rectification coefficient, carrier concentration, series resistance, are then extracted. Based upon our results a non-ideal diode behavior is revealed and ideality factor exceeds the unity (n > 4). A high rectifying (~4.6 × 10 4) device is demonstrated. According to Cheung-Cheung and Norde calculation models, the barrier height and series resitance are respectively of 0.57 eV and 30 kΩ. Ohmic and space charge limited current (SCLC) conduction mechanisms are demonstrated. Such devices will find applications as solar cell, photodiode and photoconductor.

  16. In situ synchrotron X-ray studies during metal-organic chemical vapor deposition of semiconductors

    Energy Technology Data Exchange (ETDEWEB)

    Thompson, Carol [Northern Illinois Univ., DeKalb, IL (United States); Argonne National Lab., Argonne, IL (United States); Highland, Matthew J.; Perret, Edith; Fuoss, Paul H.; Streiffer, Stephen K.; Stephenson, G. Brian [Argonne National Lab., Argonne, IL (United States); Richard, Marie-Ingrid [Universite Paul Cezanne Aix-Marseille, Marseille (France)

    2012-07-01

    In-situ, time-resolved techniques provide valuable insight into the complex interplay of surface structural and chemical evolution occurring during materials synthesis and processing of semiconductors. Our approach is to observe the evolution of surface structure and morphology at the atomic scale in real-time during metal organic vapor phase deposition (MOCVD) by using grazing incidence x-ray scattering and X-ray fluorescence, coupled with visible light scattering. Our vertical-flow MOCVD chamber is mounted on a 'z-axis' surface diffractometer designed specifically for these studies of the film growth, surface evolution and the interactions within a controlled growth environment. These techniques combine the ability of X-rays to penetrate a complex environment for measurements during growth and processing, with the sensitivity of surface scattering techniques to atomic and nanoscale structure. In this talk, we outline our program and discuss examples from our in-situ and real-time X-ray diffraction and fluorescence studies of InN, GaN, and InGaN growth on GaN(0001).

  17. Density and mobility effects of the majority carriers in organic semiconductors under light excitation

    Energy Technology Data Exchange (ETDEWEB)

    Vagenas, N.; Giannopoulou, A.; Kounavis, P., E-mail: pkounavis@upatras.gr [Department of Electrical and Computer Engineering, University of Patras, 26504 Patra (Greece)

    2015-01-21

    This study demonstrates that the effect of light excitation on the density and the mobility of the majority carriers can be explored in organic semiconductors by modulated photocurrent spectroscopy. The spectra of phase and amplitude of the modulated photocurrent of pentacene films indicate a significant increase in the density of the photogenerated mobile holes (majority carriers). This increase is accompanied by a comparatively much smaller increase of the steady state photocurrent response which can be reconciled with a decrease in the mobility (μ) of holes. The decrease of μ is supported from an unusual increase of the Y/μ ratio of the out-of-phase modulated photocurrent (Y) signal to the mobility under light excitation. It is proposed that the mobile holes, which are generated from the dissociation of the light-created excitons more likely near the pentacene-substrate interface by electron trapping, populate grain boundaries charging them and producing a downward band bending. As a result, potential energy barriers are build up which limit the transport of holes interacting through trapping-detrapping with deep partially occupied traps in the charged grain boundaries. On the other hand, the transport of holes interacting through trapping-detrapping with empty traps is found unaffected.

  18. Investigation of defect states in organic semiconductors. Towards long term stable materials for organic photovoltaics

    Energy Technology Data Exchange (ETDEWEB)

    Schafferhans, Julia

    2011-07-01

    In this work, the trap states in the conjugated polymer P3HT, often used as electron donor in organic bulk heterojunction solar cells, three commonly used fullerene based electron acceptors and P3HT:PC{sub 61}BM blends were investigated. Concerning the lifetime of organic solar cells the influence of oxygen on P3HT and P3HT:PC{sub 61}BM blends was studied. Fractional TSC measurements on P3HT diodes revealed a quasi-continuous trap distribution. The deeper traps exhibited a strong dependence on oxygen. Exposure of the P3HT diodes to oxygen, ambient air and synthetic (dry) air all revealed an increase of the deeper traps density with exposure time in the same manner. While the lower limit of the trap density in non aged P3HT samples was in the range of (1.0-1.2) x 10{sup 22} m{sup -3}, it was more than doubled after an exposure of 50 h to air. An increase of the trap density with oxygen exposure time was also seen in the Q-DLTS measurements accompanied with an increase of the temperature dependence of the emission rates. Due to the raise in density of the deeper traps, the charge carrier mobility in P3HT significantly decreased, as revealed by photo-CELIV measurements, resulting in a loss in mobility of about two orders of magnitude after 100 h exposure to synthetic air. This effect was partially reversible by applying vacuum to the sample for several hours or, more significantly, by a thermal treatment of the devices in nitrogen atmosphere. The trap states in the methanofullerenes PC{sub 61}BM, bisPC{sub 61}BM and PC71BM were investigated by TSC measurements. PC{sub 61}BM yielded a broad quasi-continuous trap distribution with the maximum of the distribution at about 75 meV. The comparison of the TSC spectra of the three methanofullerenes exhibited significant differences in the trap states with higher activation energies of the most prominent traps in bisPC{sub 61}BM and PC71BM compared to PC{sub 61}BM. The lower limit of the trap density of all of the three

  19. Solvent-free directed patterning of a highly ordered liquid crystalline organic semiconductor via template-assisted self-assembly for organic transistors.

    Science.gov (United States)

    Kim, Aryeon; Jang, Kwang-Suk; Kim, Jinsoo; Won, Jong Chan; Yi, Mi Hye; Kim, Hanim; Yoon, Dong Ki; Shin, Tae Joo; Lee, Myong-Hoon; Ka, Jae-Won; Kim, Yun Ho

    2013-11-20

    Highly ordered organic semiconductor micropatterns of the liquid-crystalline small molecule 2,7-didecylbenzothienobenzothiophene (C10 -BTBT) are fabricated using a simple method based on template-assisted self-assembly (TASA). The liquid crystallinity of C10 -BTBT allows solvent-free fabrication of high-performance printed organic field-effect transistors (OFETs). © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  20. Quantitative analysis of lattice disorder and crystallite size in organic semiconductor thin films

    KAUST Repository

    Rivnay, Jonathan; Noriega, Rodrigo; Kline, R. Joseph; Salleo, Alberto; Toney, Michael F.

    2011-01-01

    and qualitatively assess the amount and type of disorder present in a sample. While applied directly to organic systems, this methodology is general for the accurate deconvolution of crystalline size and lattice disorder for any material investigated

  1. Blending crystalline/liquid crystalline small molecule semiconductors: A strategy towards high performance organic thin film transistors

    Science.gov (United States)

    He, Chao; He, Yaowu; Li, Aiyuan; Zhang, Dongwei; Meng, Hong

    2016-10-01

    Solution processed small molecule polycrystalline thin films often suffer from the problems of inhomogeneity and discontinuity. Here, we describe a strategy to solve these problems through deposition of the active layer from a blended solution of crystalline (2-phenyl[1]benzothieno[3,2-b][1]benzothiophene, Ph-BTBT) and liquid crystalline (2-(4-dodecylphenyl) [1]benzothieno[3,2-b]benzothiophene, C12-Ph-BTBT) small molecule semiconductors with the hot spin-coating method. Organic thin film transistors with average hole mobility approaching 1 cm2/V s, much higher than that of single component devices, have been demonstrated, mainly due to the improved uniformity, continuity, crystallinity, and stronger intermolecular π-π stacking in blend thin films. Our results indicate that the crystalline/liquid crystalline semiconductor blend method is an effective way to enhance the performance of organic transistors.

  2. Thermal and Optical Modulation of the Carrier Mobility in OTFTs Based on an Azo-anthracene Liquid Crystal Organic Semiconductor.

    Science.gov (United States)

    Chen, Yantong; Li, Chao; Xu, Xiuru; Liu, Ming; He, Yaowu; Murtaza, Imran; Zhang, Dongwei; Yao, Chao; Wang, Yongfeng; Meng, Hong

    2017-03-01

    One of the most striking features of organic semiconductors compared with their corresponding inorganic counterparts is their molecular diversity. The major challenge in organic semiconductor material technology is creating molecular structural motifs to develop multifunctional materials in order to achieve the desired functionalities yet to optimize the specific device performance. Azo-compounds, because of their special photoresponsive property, have attracted extensive interest in photonic and optoelectronic applications; if incorporated wisely in the organic semiconductor groups, they can be innovatively utilized in advanced smart electronic applications, where thermal and photo modulation is applied to tune the electronic properties. On the basis of this aspiration, a novel azo-functionalized liquid crystal semiconductor material, (E)-1-(4-(anthracen-2-yl)phenyl)-2-(4-(decyloxy)phenyl)diazene (APDPD), is designed and synthesized for application in organic thin-film transistors (OTFTs). The UV-vis spectra of APDPD exhibit reversible photoisomerizaton upon photoexcitation, and the thin films of APDPD show a long-range orientational order based on its liquid crystal phase. The performance of OTFTs based on this material as well as the effects of thermal treatment and UV-irradiation on mobility are investigated. The molecular structure, stability of the material, and morphology of the thin films are characterized by thermal gravimetric analysis (TGA), polarizing optical microscopy (POM), (differential scanning calorimetry (DSC), UV-vis spectroscopy, atomic force microscopy (AFM), and scanning tunneling microscopy (STM). This study reveals that our new material has the potential to be applied in optical sensors, memories, logic circuits, and functional switches.

  3. Integration of near infrared and visible organic photodiodes on a complementary metal–oxide–semiconductor compatible backplane

    Energy Technology Data Exchange (ETDEWEB)

    Jahnel, M.; Thomschke, M.; Fehse, K.; Vogel, U. [Fraunhofer-Institute for Organische Elektronik, Elektronenstrahl-und Plasmatechnik FEP, 01199 Dresden (Germany); An, J.D.; Park, H. [Konkuk University-Fraunhofer Next Generation Solar Cell Research Center (KFnSC), Konkuk University, 120 Neungdong-ro, Gwangjin-gu, Seoul 143-701 (Korea, Republic of); Leo, K. [Fraunhofer-Institute for Organische Elektronik, Elektronenstrahl-und Plasmatechnik FEP, 01199 Dresden (Germany); Institut für Angewandte Photophysik, Technische Universität Dresden (TUD), 01062 Dresden (Germany); Im, C. [Konkuk University-Fraunhofer Next Generation Solar Cell Research Center (KFnSC), Konkuk University, 120 Neungdong-ro, Gwangjin-gu, Seoul 143-701 (Korea, Republic of)

    2015-10-01

    This paper reports about the integration of polymer-based bulk heterojunction organic photo diodes (OPDs) onto complementary metal–oxide–semiconductor (CMOS) compatible electrode materials. The fabrication and performance of four absorber systems in indium tin oxide-free OPDs for sensing applications have been studied. These are based on the following polymer–fullerene blends: Poly(3-hexylthiophene-2,5-diyl):[6,6]Phenyl C{sub 61} Butyric Acid Methyl Ester and Poly(3-hexylthiophene-2,5 diyl):Di[1,4] methanonaphthaleno [1,2:2′,3′;56,60:2″,3″] [5,6]fullerene-C60-Ih, 1′,1″,4′,4″-tetrahydro-, indene-C60 bisadduct to detect light in the visible range and Poly[[4,8-bis[(2-ethylhexyl)oxy]benzo[1,2-b:4,5-b′]dithiophene-2,6-diyl] [3-fluoro-2-[(2-ethylhexyl)carbonyl] thieno[3,4-b]thiophenediyl

  4. Electron mobilities of n-type organic semiconductors from time-dependent wavepacket diffusion method: pentacenequinone derivatives.

    Science.gov (United States)

    Zhang, WeiWei; Zhong, XinXin; Zhao, Yi

    2012-11-26

    The electron mobilities of two n-type pentacenequinone derivative organic semiconductors, 5,7,12,14-tetraaza-6,13-pentacenequinone (TAPQ5) and 1,4,8,11-tetraaza-6,13-pentacenequinone (TAPQ7), are investigated with use of the methods of electronic structure and quantum dynamics. The electronic structure calculations reveal that the two key parameters for the control of electron transfer, reorganization energy and electronic coupling, are similar for these two isomerization systems, and the charge carriers essentially display one-dimensional transport properties. The mobilities are then calculated by using the time-dependent wavepacket diffusion approach in which the dynamic fluctuations of the electronic couplings are incorporated via their correlation functions obtained from molecular dynamics simulations. The predicted mobility of TAPQ7 crystal is about six times larger than that of TAPQ5 crystal. Most interestingly, Fermi's golden rule predicts the mobilities very close to those from the time-dependent wavepacket diffusion method, even though the electronic couplings are explicitly large enough to make the perturbation theory invalid. The possible reason is analyzed from the dynamic fluctuations.

  5. Integration of near infrared and visible organic photodiodes on a complementary metal–oxide–semiconductor compatible backplane

    International Nuclear Information System (INIS)

    Jahnel, M.; Thomschke, M.; Fehse, K.; Vogel, U.; An, J.D.; Park, H.; Leo, K.; Im, C.

    2015-01-01

    This paper reports about the integration of polymer-based bulk heterojunction organic photo diodes (OPDs) onto complementary metal–oxide–semiconductor (CMOS) compatible electrode materials. The fabrication and performance of four absorber systems in indium tin oxide-free OPDs for sensing applications have been studied. These are based on the following polymer–fullerene blends: Poly(3-hexylthiophene-2,5-diyl):[6,6]Phenyl C_6_1 Butyric Acid Methyl Ester and Poly(3-hexylthiophene-2,5 diyl):Di[1,4] methanonaphthaleno [1,2:2′,3′;56,60:2″,3″] [5,6]fullerene-C60-Ih, 1′,1″,4′,4″-tetrahydro-, indene-C60 bisadduct to detect light in the visible range and Poly[[4,8-bis[(2-ethylhexyl)oxy]benzo[1,2-b:4,5-b′]dithiophene-2,6-diyl] [3-fluoro-2-[(2-ethylhexyl)carbonyl] thieno[3,4-b]thiophenediyl

  6. Self-reflection in a system of excitons and biexcitons in semiconductors

    International Nuclear Information System (INIS)

    Khadzhi, P I; Lyakhomskaya, K D

    1999-01-01

    The characteristic features of the self-reflection of a powerful electromagnetic wave in a system of coherent excitons and biexcitons in semiconductors were investigated as one of the manifestations of the nonlinear optical skin effect. It was found that a monotonically decreasing standing wave with an exponentially falling spatial tail is formed in the surface region of a semiconductor. Under the influence of the field of a powerful pulse, an optically homogeneous medium is converted into one with distributed feedback. The appearance of spatially separated narrow peaks of the refractive index, extinction coefficient, and reflection coefficient is predicted. (nonlinear optical phenomena)

  7. NONLINEAR OPTICAL PHENOMENA: Self-reflection in a system of excitons and biexcitons in semiconductors

    Science.gov (United States)

    Khadzhi, P. I.; Lyakhomskaya, K. D.

    1999-10-01

    The characteristic features of the self-reflection of a powerful electromagnetic wave in a system of coherent excitons and biexcitons in semiconductors were investigated as one of the manifestations of the nonlinear optical skin effect. It was found that a monotonically decreasing standing wave with an exponentially falling spatial tail is formed in the surface region of a semiconductor. Under the influence of the field of a powerful pulse, an optically homogeneous medium is converted into one with distributed feedback. The appearance of spatially separated narrow peaks of the refractive index, extinction coefficient, and reflection coefficient is predicted.

  8. Characteristics of semiconductor bridge (SCB) plasma generated in a micro-electro-mechanical system (MEMS)

    International Nuclear Information System (INIS)

    Kim, Jong-Uk; Park, Chong-Ook; Park, Myung-Il; Kim, Sun-Hwan; Lee, Jung-Bok

    2002-01-01

    Plasma ignition method has been applied in various fields particularly to the rocket propulsion, pyrotechnics, explosives, and to the automotive air-bag system. Ignition method for those applications should be safe and also operate reliably in hostile environments such as; electromagnetic noise, drift voltage, electrostatic background and so on. In the present Letter, a semiconductor bridge (SCB) plasma ignition device was fabricated and its plasma characteristics including the propagation speed of the plasma, plasma size, and plasma temperature were investigated with the aid of the visualization of micro scale plasma (i.e., ≤350 μm), which generated from a micro-electro-mechanical poly-silicon semiconductor bridge (SCB)

  9. Evaluating performance of a pixel array semiconductor SPECT system for small animal imaging

    International Nuclear Information System (INIS)

    Kubo, Naoki; Zhao, Songji; Fujiki, Yutaka

    2005-01-01

    Small animal imaging has recently been focused on basic nuclear medicine. We have designed and built a small animal SPECT imaging system using a semiconductor camera and a newly designed collimator. We assess the performance of this system for small object imaging. We employed an MGC 1500 (Acrorad Co.) camera including a CdTe semiconductor. The pixel size was 1.4 mm/pixel. We designed and produced a parallel-hole collimator with 20-mm hole length. Our SPECT system consisted of a semiconductor camera with the subject holder set on an electric rotating stage controlled by a computer. We compared this system with a conventional small animal SPECT system comprising a SPECT-2000H scanner with four Anger type cameras and pinhole collimators. The count rate linearity for estimation of the scatter was evaluated for a pie-chart phantom containing different concentrations of 99m Tc. We measured the full width half maximum (FWHM) of the 99m Tc SPECT line source along with scatter. The system volume sensitivity was examined using a flood source phantom which was 35 mm long with a 32-mm inside diameter. Additionally, an in vivo myocardial perfusion SPECT study was performed with a rat. With regards to energy resolution, the semiconductor camera (5.6%) was superior to the conventional Anger type camera (9.8%). In the count rate linearity evaluation, the regression lines of the SPECT values were y=0.019x+0.031 (r 2 =0.999) for our system and y=0.018x+0.060 (r 2 =0.997) for the conventional system. Thus, the scatter count using the semiconductor camera was less than that using the conventional camera. FWHMs of our system and the conventional system were 2.9±0.1 and 2.0±0.1 mm, respectively. Moreover, the system volume sensitivity of our system [0.51 kcps/(MBq/ml)/cm] was superior to that of the conventional system [0.44 kcps/(MBq/ml)/cm]. Our system provided clear images of the rat myocardium, sufficient for practical use in small animal imaging. Our SPECT system, utilizing a

  10. Modeling space-charge-limited currents in organic semiconductors: Extracting trap density and mobility

    KAUST Repository

    Dacuña, Javier

    2011-11-28

    We have developed and have applied a mobility edge model that takes drift and diffusion currents to characterize the space-charge-limited current in organic semiconductors into account. The numerical solution of the drift-diffusion equation allows the utilization of asymmetric contacts to describe the built-in potential within the device. The model has been applied to extract information of the distribution of traps from experimental current-voltage measurements of a rubrene single crystal from Krellner showing excellent agreement across several orders of magnitude in the current. Although the two contacts are made of the same metal, an energy offset of 580 meV between them, ascribed to differences in the deposition techniques (lamination vs evaporation) was essential to correctly interpret the shape of the current-voltage characteristics at low voltage. A band mobility of 0.13cm 2V-1s-1 for holes is estimated, which is consistent with transport along the long axis of the orthorhombic unit cell. The total density of traps deeper than 0.1 eV was 2.2×1016cm -3. The sensitivity analysis and error estimation in the obtained parameters show that it is not possible to accurately resolve the shape of the trap distribution for energies deeper than 0.3 eV or shallower than 0.1 eV above the valence-band edge. The total number of traps deeper than 0.3 eV, however, can be estimated. Contact asymmetry and the diffusion component of the current play an important role in the description of the device at low bias and are required to obtain reliable information about the distribution of deep traps. © 2011 American Physical Society.

  11. Amorphous chalcogenide semiconductors for solid state dosimetric systems of high-energetic ionizing radiation

    International Nuclear Information System (INIS)

    Shpotyuk, O.

    1997-01-01

    The application possibilities of amorphous chalcogenide semiconductors use as radiation-sensitive elements of high-energetic (E > 1 MeV) dosimetric systems are analysed. It is shown that investigated materials are characterized by more wide region of registered absorbed doses and low temperature threshold of radiation information bleaching in comparison with well-known analogies based on coloring oxide glasses. (author)

  12. STM and synchrotron radiation studies of prototypical metal/semiconductor systems

    DEFF Research Database (Denmark)

    Lay, G. le; Aristov, V.Y.; Seehofer, L.

    1994-01-01

    Since the origin of surface science noble metal/elemental semiconductor couples have been considered as ''prototypical'' systems. After three decades of research their structural and electronic properties remain an intriguing maze despite recent advances made, especially thanks to the development...

  13. Electrostatic analysis of n-doped SrTiO3 metal-insulator-semiconductor systems

    International Nuclear Information System (INIS)

    Kamerbeek, A. M.; Banerjee, T.; Hueting, R. J. E.

    2015-01-01

    Electron doped SrTiO 3 , a complex-oxide semiconductor, possesses novel electronic properties due to its strong temperature and electric-field dependent permittivity. Due to the high permittivity, metal/n-SrTiO 3 systems show reasonably strong rectification even when SrTiO 3 is degenerately doped. Our experiments show that the insertion of a sub nanometer layer of AlO x in between the metal and n-SrTiO 3 interface leads to a dramatic reduction of the Schottky barrier height (from around 0.90 V to 0.25 V). This reduces the interface resistivity by 4 orders of magnitude. The derived electrostatic analysis of the metal-insulator-semiconductor (n-SrTiO 3 ) system is consistent with this trend. When compared with a Si based MIS system, the change is much larger and mainly governed by the high permittivity of SrTiO 3 . The non-linear permittivity of n-SrTiO 3 leads to unconventional properties such as a temperature dependent surface potential non-existent for semiconductors with linear permittivity such as Si. This allows tuning of the interfacial band alignment, and consequently the Schottky barrier height, in a much more drastic way than in conventional semiconductors

  14. Paramagnetic resonance and electronic conduction in organic semiconductors; Resonance paramagnetique et conduction electroniques dans les semi-conducteurs organiques

    Energy Technology Data Exchange (ETDEWEB)

    Nechtschein, M. [Commissariat a l' energie atomique et aux energies alternatives - CEA, Laboratoire de Resonance Magnetique (France)

    1963-07-01

    As some organic bodies simultaneously display semi-conducting properties and a paramagnetism, this report addresses the study of conduction in organic bodies. The author first briefly recalls how relationships between conductibility and Electron Paramagnetic Resonance (EPR) can be noticed in a specific case (mineral and metallic semiconductors). He discusses published results related to paramagnetism and conductibility in organic bodies. He reviews various categories of organic bodies in which both properties are simultaneously present. He notably addresses radical molecular crystals, non-radical molecular crystals, charge transfer complexes, pyrolyzed coals, and pseudo-ferromagnetic organic structures. He discusses the issue of relationships between conduction (charge transfer by electrons) and ERP (which reveals the existence of non-paired electrons which provide free spins)

  15. 2,6-Bis(benzo[b]thiophen-2-yl-3,7-dipentadecyltetrathienoacene (DBT-TTAR2 as an Alternative of Highly Soluble p-type Organic Semiconductor for Organic Thin Film Transistor (OTFT Application

    Directory of Open Access Journals (Sweden)

    Mery B. Supriadi

    2013-03-01

    Full Text Available A new compound of organic semiconductor based on tetrathienoacene (TTA derivatives, DBT-TTAR2 was synthesized and characterized. The corporation of dibenzo[b,d]thiophene (DBT group and alkyl substituent in both ends of TTA core have a significant effect on their π-π molecular conjugation length, energy gaps value and solubility properties. DBT-TTAR2 is fabricated as p-type organic semiconductor of organic thin film transistor (OTFT by solution process at Industrial Technology Research Institute, Taiwan. A good optical, electrochemical, and thermal properties of DBT-TTAR2 showed that its exhibits a better performance as highly soluble p-type organic semiconductor.

  16. Semiconductor spintronics

    International Nuclear Information System (INIS)

    Fabian, J.; Abiague, A.M.; Ertler, Ch.; Stano, P.; Zutic, I.

    2007-01-01

    Spintronics refers commonly to phenomena in which the spin of electrons in a solid state environment plays the determining role. In a more narrow sense spintronics is an emerging research field of electronics: spintronics devices are based on a spin control of electronics, or on an electrical and optical control of spin of magnetism. While metal spintronics has already found its niche in the computer industry - giant magnetoresistance systems are used as hard disk read heads - semiconductor spintronics is vet demonstrate its full potential. This review presents selected themes of semiconductor spintronics, introducing important concepts in spin transport, spin transport, spin injection. Silsbee-Johnson spin-charge coupling, and spin-dependent tunneling, as well as spin relaxation and spin dynamics. The most fundamental spin-dependent interaction in nonmagnetic semiconductors is spin-orbit coupling. Depending on the crystal symmetries of the material, as well as on the structural properties of semiconductor based heterostructures, the spin-orbit coupling takes on different functional forms, giving a nice playground of effective spin-orbit Hamiltonians. The effective Hamiltonians for the most relevant classes of materials and heterostructures are derived here from realistic electronic band structure descriptions. Most semiconductor device systems are still theoretical concepts, waiting for experimental demonstrations. A review of selected proposed, and a few demonstrated devices is presented, with detailed description of two important classes: magnetic resonant tunnel structures and bipolar magnetic diodes and transistors. In view of the importance of ferromagnetic semiconductor material, a brief discussion of diluted magnetic semiconductors is included. In most cases the presentation is of tutorial style, introducing the essential theoretical formalism at an accessible level, with case-study-like illustrations of actual experimental results, as well as with brief

  17. Magnetoresistance in organic semiconductors: Including pair correlations in the kinetic equations for hopping transport

    Science.gov (United States)

    Shumilin, A. V.; Kabanov, V. V.; Dediu, V. I.

    2018-03-01

    We derive kinetic equations for polaron hopping in organic materials that explicitly take into account the double occupation possibility and pair intersite correlations. The equations include simplified phenomenological spin dynamics and provide a self-consistent framework for the description of the bipolaron mechanism of the organic magnetoresistance. At low applied voltages, the equations can be reduced to those for an effective resistor network that generalizes the Miller-Abrahams network and includes the effect of spin relaxation on the system resistivity. Our theory discloses the close relationship between the organic magnetoresistance and the intersite correlations. Moreover, in the absence of correlations, as in an ordered system with zero Hubbard energy, the magnetoresistance vanishes.

  18. Reduction of Charge Traps and Stability Enhancement in Solution-Processed Organic Field-Effect Transistors Based on a Blended n-Type Semiconductor.

    Science.gov (United States)

    Campos, Antonio; Riera-Galindo, Sergi; Puigdollers, Joaquim; Mas-Torrent, Marta

    2018-05-09

    Solution-processed n-type organic field-effect transistors (OFETs) are essential elements for developing large-area, low-cost, and all organic logic/complementary circuits. Nonetheless, the development of air-stable n-type organic semiconductors (OSCs) lags behind their p-type counterparts. The trapping of electrons at the semiconductor-dielectric interface leads to a lower performance and operational stability. Herein, we report printed small-molecule n-type OFETs based on a blend with a binder polymer, which enhances the device stability due to the improvement of the semiconductor-dielectric interface quality and a self-encapsulation. Both combined effects prevent the fast deterioration of the OSC. Additionally, a complementary metal-oxide semiconductor-like inverter is fabricated depositing p-type and n-type OSCs simultaneously.

  19. Band-engineering of TiO2 as a wide-band gap semiconductor using organic chromophore dyes

    Science.gov (United States)

    Wahyuningsih, S.; Kartini, I.; Ramelan, A. H.; Saputri, L. N. M. Z.; Munawaroh, H.

    2017-07-01

    Bond-engineering as applied to semiconductor materials refers to the manipulation of the energy bands in order to control charge transfer processes in a device. When the device in question is a photoelectrochemical cell, the charges affected by drift become the focus of the study. The ideal band gap of semiconductors for enhancement of photocatalyst activity can be lowered to match with visible light absorption and the location of conduction Band (CB) should be raised to meet the reducing capacity. Otherwise, by the addition of the chromofor organic dyes, the wide-band gab can be influences by interacation resulting between TiO2 surface and the dyes. We have done the impruvisation wide-band gap of TiO2 by the addition of organic chromophore dye, and the addition of transition metal dopand. The TiO2 morphology influence the light absorption as well as the surface modification. The organic chromophore dye was syntesized by formation complexes compound of Co(PAR)(SiPA)(PAR)= 4-(2-piridylazoresorcinol), SiPA = Silyl propil amine). The result showed that the chromophore groups adsorbed onto TiO2 surface can increase the visible light absorption of wide-band gab semiconductor. Initial absorption of a chromophore will affect light penetration into the material surfaces. The use of photonic material as a solar cell shows this phenomenon clearly from the IPCE (incident photon to current conversion efficiency) measurement data. Organic chromophore dyes of Co(PAR)(SiPA) exhibited the long wavelength absorption character compared to the N719 dye (from Dyesol).

  20. Thermodynamics and phase equilibria of ternary systems relevant to contact materials for compound semiconductors

    International Nuclear Information System (INIS)

    Ipser, H.; Richter, K.; Micke, K.

    1997-01-01

    In order to investigate the stability of ohmic contacts to compound semiconductors, it is necessary to know the phase equilibria in the corresponding multi-component systems. We are currently studying the phase equilibria and thermophysical properties of several ternary systems which are of interest in view of the use of nickel, palladium and platinum as contact materials for GaSb and InSb compound semiconductors: Ga-Ni-Sb, In-Ni-Sb, Ga-Pd-Sb and Ga-Pt-Sb. Phase equilibria are investigated by thermal analyses, X-ray powder diffraction methods as well as electron microprobe analysis. Thermodynamic properties are derived from vapour pressure measurements using an isopiestic method. It is planned to combine all information on phase equilibria and thermochemistry for the ternary and the limiting binary systems to perform an optimization of the ternary systems by computer calculations using standard software. (author)

  1. Doping kinetics of organic semiconductors investigated by field-effect transistors

    NARCIS (Netherlands)

    Maddalena, F.; Meijer, E.J.; Asadi, K.; Leeuw, D.M. de; Blom, P.W.M.

    2010-01-01

    The kinetics of acid doping of the semiconductor regioregular poly-3-hexylthiophene with vaporized chlorosilane have been investigated using field-effect transistors. The dopant density has been derived as a function of temperature and exposure time from the shift in the pinch-off voltage, being the

  2. Effect of Polymer Binders on UV-Responsive Organic Thin-Film Phototransistors with Benzothienobenzothiophene Semiconductor.

    Science.gov (United States)

    Ljubic, Darko; Smithson, Chad S; Wu, Yiliang; Zhu, Shiping

    2016-02-17

    The influence of polymer binders on the UV response of organic thin-film phototransistors (OTF-PTs) is reported. The active channel of the OTF-PTs was fabricated by blending a UV responsive 2,7-dipenty-[1]benzothieno[2,3-b][1]benzothiophene (C5-BTBT) as small molecule semiconductor and a branched unsaturated polyester (B-upe) as dielectric binder (ratio 1:1). To understand the influence of the polymer composition on the photoelectrical properties and UV response of C5-BTBT, control blends were prepared using common dielectric polymers, namely, poly(vinyl acetate) (PVAc), polycarbonate (PC), and polystyrene (PS), for comparison. Thin-film morphology and nanostructure of the C5-BTBT/polymer blends were investigated by means of optical and atomic force microscopy, and powder X-ray diffraction, respectively. Electrical and photoelectrical characteristics of the studied OTF-PTs were evaluated in the dark and under UV illumination with a constant light intensity (P = 3 mW cm(-2), λ = 365 nm), respectively, using two- and three-terminal I-V measurements. Results revealed that the purposely chosen B-upe polymer binder strongly affected the UV response of OTF-PTs. A photocurrent increase of more than 5 orders of magnitude in the subthreshold region was observed with a responsivity as high as 9.7 AW(-1), at VG = 0 V. The photocurrent increase and dramatic shift of VTh,average (∼86 V) were justified by the high number of photogenerated charge carriers upon the high trap density in bulk 8.0 × 10(12) cm(-2) eV(-1) generated by highly dispersed C5-BTBT in B-upe binder. Compared with other devices, the B-upe OTF-PTs had the fastest UV response times (τr1/τr2 = 0.5/6.0) reaching the highest saturated photocurrent (>10(6)), at VG = -5 V and VSD = -60 V. The enhanced UV sensing properties of B-upe based OTF-PTs were attributed to a self-induced thin-film morphology. The enlarged interface facilitated the electron withdrawing/donating functional groups in the polymer chains in

  3. Simultaneous monitoring of singlet and triplet exciton variations in solid organic semiconductors driven by an external static magnetic field

    Energy Technology Data Exchange (ETDEWEB)

    Ding, Baofu, E-mail: b.ding@ecu.edu.au; Alameh, Kamal, E-mail: k.alameh@ecu.edu.au [Electron Science Research Institute, Edith Cowan University, 270 Joondalup Drive, Joondalup, WA 6027 (Australia)

    2014-07-07

    The research field of organic spintronics has remarkably and rapidly become a promising research area for delivering a range of high-performance devices, such as magnetic-field sensors, spin valves, and magnetically modulated organic light emitting devices (OLEDs). Plenty of microscopic physical and chemical models based on exciton or charge interactions have been proposed to explain organic magneto-optoelectronic phenomena. However, the simultaneous observation of singlet- and triplet-exciton variations in an external magnetic field is still unfeasible, preventing a thorough theoretical description of the spin dynamics in organic semiconductors. Here, we show that we can simultaneously observe variations of singlet excitons and triplet excitons in an external magnetic field, by designing an OLED structure employing a singlet-exciton filtering and detection layer in conjunction with a separate triplet-exciton detection layer. This OLED structure enables the observation of a Lorentzian and a non-Lorentzian line-shape magnetoresponse for singlet excitons and triplet excitons, respectively.

  4. Simultaneous monitoring of singlet and triplet exciton variations in solid organic semiconductors driven by an external static magnetic field

    International Nuclear Information System (INIS)

    Ding, Baofu; Alameh, Kamal

    2014-01-01

    The research field of organic spintronics has remarkably and rapidly become a promising research area for delivering a range of high-performance devices, such as magnetic-field sensors, spin valves, and magnetically modulated organic light emitting devices (OLEDs). Plenty of microscopic physical and chemical models based on exciton or charge interactions have been proposed to explain organic magneto-optoelectronic phenomena. However, the simultaneous observation of singlet- and triplet-exciton variations in an external magnetic field is still unfeasible, preventing a thorough theoretical description of the spin dynamics in organic semiconductors. Here, we show that we can simultaneously observe variations of singlet excitons and triplet excitons in an external magnetic field, by designing an OLED structure employing a singlet-exciton filtering and detection layer in conjunction with a separate triplet-exciton detection layer. This OLED structure enables the observation of a Lorentzian and a non-Lorentzian line-shape magnetoresponse for singlet excitons and triplet excitons, respectively.

  5. Impact of Molecular Orientation and Packing Density on Electronic Polarization in the Bulk and at Surfaces of Organic Semiconductors

    KAUST Repository

    Ryno, Sean

    2016-05-16

    The polarizable environment surrounding charge carriers in organic semiconductors impacts the efficiency of the charge transport process. Here, we consider two representative organic semiconductors, tetracene and rubrene, and evaluate their polarization energies in the bulk and at the organic-vacuum interface using a polarizable force field that accounts for induced-dipole and quadrupole interactions. Though both oligoacenes pack in a herringbone motif, the tetraphenyl substituents on the tetracene backbone of rubrene alter greatly the nature of the packing. The resulting change in relative orientations of neighboring molecules is found to reduce the bulk polarization energy of holes in rubrene by some 0.3 eV when compared to tetracene. The consideration of model organic-vacuum interfaces highlights the significant variation in the electrostatic environment for a charge carrier at a surface although the net change in polarization energy is small; interestingly, the environment of a charge even just one layer removed from the surface can be viewed already as representative of the bulk. Overall, it is found that in these herringbone-type layered crystals the polarization energy has a much stronger dependence on the intralayer packing density than interlayer packing density.

  6. Intrinsic spin and momentum relaxation in organic single-crystalline semiconductors probed by ESR and Hall measurements

    Science.gov (United States)

    Tsurumi, Junto; Häusermann, Roger; Watanabe, Shun; Mitsui, Chikahiko; Okamoto, Toshihiro; Matsui, Hiroyuki; Takeya, Jun

    Spin and charge momentum relaxation mechanism has been argued among organic semiconductors with various methods, devices, and materials. However, little is known in organic single-crystalline semiconductors because it has been hard to obtain an ideal organic crystal with an excellent crystallinity and controllability required for accurate measurements. By using more than 1-inch sized single crystals which are fabricated via contentious edge-casting method developed by our group, we have successfully demonstrated a simultaneous determination of spin and momentum relaxation time for gate-induced charges of 3,11-didecyldinaphtho[2,3- d:2',3'- d']benzo[1,2- b:4,5- b']dithiophene, by combining electron spin resonance (ESR) and Hall effect measurements. The obtained temperature dependences of spin and momentum relaxation times are in good agreement in terms of power law with a factor of approximately -2. It is concluded that Elliott-Yafet spin relaxation mechanism can be dominant at room temperature regime (200 - 300 K). Probing characteristic time scales such as spin-lattice, spin-spin, and momentum relaxation times, demonstrated in the present work, would be a powerful tool to elucidate fundamental spin and charge transport mechanisms. We acknowledge the New Energy and Industrial Technology Developing Organization (NEDO) for financial support.

  7. Hybrid artificial photosynthetic systems comprising semiconductors as light harvesters and biomimetic complexes as molecular cocatalysts.

    Science.gov (United States)

    Wen, Fuyu; Li, Can

    2013-11-19

    Solar fuel production through artificial photosynthesis may be a key to generating abundant and clean energy, thus addressing the high energy needs of the world's expanding population. As the crucial components of photosynthesis, the artificial photosynthetic system should be composed of a light harvester (e.g., semiconductor or molecular dye), a reduction cocatalyst (e.g., hydrogenase mimic, noble metal), and an oxidation cocatalyst (e.g., photosystem II mimic for oxygen evolution from water oxidation). Solar fuel production catalyzed by an artificial photosynthetic system starts from the absorption of sunlight by the light harvester, where charge separation takes place, followed by a charge transfer to the reduction and oxidation cocatalysts, where redox reaction processes occur. One of the most challenging problems is to develop an artificial photosynthetic solar fuel production system that is both highly efficient and stable. The assembly of cocatalysts on the semiconductor (light harvester) not only can facilitate the charge separation, but also can lower the activation energy or overpotential for the reactions. An efficient light harvester loaded with suitable reduction and oxidation cocatalysts is the key for high efficiency of artificial photosynthetic systems. In this Account, we describe our strategy of hybrid photocatalysts using semiconductors as light harvesters with biomimetic complexes as molecular cocatalysts to construct efficient and stable artificial photosynthetic systems. We chose semiconductor nanoparticles as light harvesters because of their broad spectral absorption and relatively robust properties compared with a natural photosynthesis system. Using biomimetic complexes as cocatalysts can significantly facilitate charge separation via fast charge transfer from the semiconductor to the molecular cocatalysts and also catalyze the chemical reactions of solar fuel production. The hybrid photocatalysts supply us with a platform to study the

  8. New highly fluorescent biolabels based on II-VI semiconductor hybrid organic-inorganic nanostructures for bioimaging

    International Nuclear Information System (INIS)

    Santos, B.S.; Farias, P.M.A.; Menezes, F.D.; Brasil, A.G.; Fontes, A.; Romao, L.; Amaral, J.O.; Moura-Neto, V.; Tenorio, D.P.L.A.; Cesar, C.L.; Barbosa, L.C.; Ferreira, R.

    2008-01-01

    Semiconductor quantum dots based on II-VI materials may be prepared to develop good biolabeling properties. In this study we present some well-succeeded results related to the preparation, functionalization and bioconjugation of CdY (Y = S, Se and Te) to biological systems (live cells and fixed tissues). These nanostructured materials were prepared using colloidal synthesis in aqueous media resulting nanoparticles with very good optical properties and an excellent resistance to photodegradation

  9. Estimation of carrier mobility at organic semiconductor/insulator interface using an asymmetric capacitive test structure

    Directory of Open Access Journals (Sweden)

    Rajesh Agarwal

    2016-04-01

    Full Text Available Mobility of carriers at the organic/insulator interface is crucial to the performance of organic thin film transistors. The present work describes estimation of mobility using admittance measurements performed on an asymmetric capacitive test structure. Besides the advantage of simplicity, it is shown that at low frequencies, the measured capacitance comes from a large area of channel making the capacitance-voltage characteristics insensitive to contact resistances. 2-D numerical simulation and experimental results obtained with Pentacene/Poly(4-vinyphenol system are presented to illustrate the operation and advantages of the proposed technique.

  10. The optical constants of the organic thin films in the case of xanthats adsorption at the surface of semiconductors minerals

    International Nuclear Information System (INIS)

    Todoran, Radu; Todoran, Daniela

    2008-01-01

    The paper present the determinations of some kinetic parameters that characterize the kinetics of the adsorption phenomenon of some organic xanthate molecule on the surface of some natural semiconductor mineral (galena, sphalerite) in order to understand the inward mechanism of this phenomenon. Among the methods of inquiry that allow kinetics determination in situ the optical ones were chosen relying on the change of the liquid-mineral semiconductor interface, and permitting continuous inquires without disturbing the inward development of the processes. Into the computation, we took into the consideration the physical values which feature the roughness of the solid surface, the diffusion into liquid media and the energetic non-homogeneities of the surface. The R s /R p =f(θ) characteristic helps us to establish the thickness of the adsorbed layer, as well as to determine the optical parameters of the thin film. the experimental results allow us to get some information on the mineral and mineral-solution of xanthate, as well allow us to get some information on the parameters which, in correlation with other proportions experimentally determined - could had as to estimations of the dynamic of the surface of a semiconductor solid body. (Author)

  11. Inspection logistics planning for multi-stage production systems with applications to semiconductor fabrication lines

    Science.gov (United States)

    Chen, Kyle Dakai

    Since the market for semiconductor products has become more lucrative and competitive, research into improving yields for semiconductor fabrication lines has lately received a tremendous amount of attention. One of the most critical tasks in achieving such yield improvements is to plan the in-line inspection sampling efficiently so that any potential yield problems can be detected early and eliminated quickly. We formulate a multi-stage inspection planning model based on configurations in actual semiconductor fabrication lines, specifically taking into account both the capacity constraint and the congestion effects at the inspection station. We propose a new mixed First-Come-First-Serve (FCFS) and Last-Come-First-Serve (LCFS) discipline for serving the inspection samples to expedite the detection of potential yield problems. Employing this mixed FCFS and LCFS discipline, we derive approximate expressions for the queueing delays in yield problem detection time and develop near-optimal algorithms to obtain the inspection logistics planning policies. We also investigate the queueing performance with this mixed type of service discipline under different assumptions and configurations. In addition, we conduct numerical tests and generate managerial insights based on input data from actual semiconductor fabrication lines. To the best of our knowledge, this research is novel in developing, for the first time in the literature, near-optimal results for inspection logistics planning in multi-stage production systems with congestion effects explicitly considered.

  12. Growth Of Organic Semiconductor Thin Films with Multi-Micron Domain Size and Fabrication of Organic Transistors Using a Stencil Nanosieve.

    Science.gov (United States)

    Fesenko, Pavlo; Flauraud, Valentin; Xie, Shenqi; Kang, Enpu; Uemura, Takafumi; Brugger, Jürgen; Genoe, Jan; Heremans, Paul; Rolin, Cédric

    2017-07-19

    To grow small molecule semiconductor thin films with domain size larger than modern-day device sizes, we evaporate the material through a dense array of small apertures, called a stencil nanosieve. The aperture size of 0.5 μm results in low nucleation density, whereas the aperture-to-aperture distance of 0.5 μm provides sufficient crosstalk between neighboring apertures through the diffusion of adsorbed molecules. By integrating the nanosieve in the channel area of a thin-film transistor mask, we show a route for patterning both the organic semiconductor and the metal contacts of thin-film transistors using one mask only and without mask realignment.

  13. Density Functional Theory Simulations of Semiconductors for Photovoltaic Applications: Hybrid Organic-Inorganic Perovskites and III/V Heterostructures

    Directory of Open Access Journals (Sweden)

    Jacky Even

    2014-01-01

    Full Text Available Potentialities of density functional theory (DFT based methodologies are explored for photovoltaic materials through the modeling of the structural and optoelectronic properties of semiconductor hybrid organic-inorganic perovskites and GaAs/GaP heterostructures. They show how the properties of these bulk materials, as well as atomistic relaxations, interfaces, and electronic band-lineups in small heterostructures, can be thoroughly investigated. Some limitations of available standard DFT codes are discussed. Recent improvements able to treat many-body effects or based on density-functional perturbation theory are also reviewed in the context of issues relevant to photovoltaic technologies.

  14. Improvement in semiconductor laser printing using a sacrificial protecting layer for organic thin-film transistors fabrication

    Energy Technology Data Exchange (ETDEWEB)

    Rapp, Ludovic, E-mail: rapp@lp3.univ-mrs.fr [Laboratoire LP3 (Lasers, Plasma et Procedes Photoniques) - UMR 6182 CNRS - Universite de la Mediterranee - Campus de Luminy C917, 13288 Marseille Cedex 09 (France); Cibert, Christophe [Laboratoire LP3 (Lasers, Plasma et Procedes Photoniques) - UMR 6182 CNRS - Universite de la Mediterranee - Campus de Luminy C917, 13288 Marseille Cedex 09 (France); Nenon, Sebastien [CINaM (Centre Interdisciplinaire de Nanoscience de Marseille) - UPR 3118 CNRS - Universite Aix Marseille, Case 913, Campus de Luminy, 13288 Marseille Cedex 09 (France); Alloncle, Anne Patricia [Laboratoire LP3 (Lasers, Plasma et Procedes Photoniques) - UMR 6182 CNRS - Universite de la Mediterranee - Campus de Luminy C917, 13288 Marseille Cedex 09 (France); Nagel, Matthias [Empa, Swiss Federal Laboratories for Materials Testing and Reasearch, Laboratory for Functional Polymers, Uberlandstrasse 129, 8600 Duebendorf (Switzerland); Lippert, Thomas [Paul Scherrer Institut, General Energy Research Department, 5232 Villigen PSI (Switzerland); Videlot-Ackermann, Christine; Fages, Frederic [CINaM (Centre Interdisciplinaire de Nanoscience de Marseille) - UPR 3118 CNRS - Universite Aix Marseille, Case 913, Campus de Luminy, 13288 Marseille Cedex 09 (France); Delaporte, Philippe [Laboratoire LP3 (Lasers, Plasma et Procedes Photoniques) - UMR 6182 CNRS - Universite de la Mediterranee - Campus de Luminy C917, 13288 Marseille Cedex 09 (France)

    2011-04-01

    Laser-induced forward transfer (LIFT) has been used to deposit pixels of an organic semiconductor, distyryl-quaterthiophenes (DS4T). The dynamics of the process have been investigated by shadowgraphic imaging for the nanosecond (ns) and picosecond (ps) regime on a time-scale from the laser iradiation to 1.5 {mu}s. The morphology of the deposit has been studied for different conditions. Intermediate sacrificial layer of gold or triazene polymer has been used to trap the incident radiation. Its role is to protect the layer to be transferred from direct irradiation and to provide a mechanical impulse strong enough to eject the material.

  15. Organizing Systemic Innovation

    NARCIS (Netherlands)

    F.P.H. Jaspers (Ferdinand)

    2009-01-01

    textabstractSystemic innovation refers to product development activities that involve the change of multiple interdependent components. Unlike autonomous innovation, which refers to components that change independently, systemic innovation is for many firms the norm rather than the exception. This

  16. Design strategy for air-stable organic semiconductors applicable to high-performance field-effect transistors

    Directory of Open Access Journals (Sweden)

    Kazuo Takimiya et al

    2007-01-01

    Full Text Available Electronic structure of air-stable, high-performance organic field-effect transistor (OFET material, 2,7-dipheneyl[1]benzothieno[3,2-b]benzothiophene (DPh-BTBT, was discussed based on the molecular orbital calculations. It was suggested that the stability is originated from relatively low-lying HOMO level, despite the fact that the molecule contains highly π-extended aromatic core ([1]benzothieno[3,2-b]benzothiophene, BTBT with four fused aromatic rings like naphthacene. This is rationalized by the consideration that the BTBT core is not isoelectronic with naphthacene but with chrysene, a cata-condensed phene with four benzene rings. It is well known that the acene-type compound is unstable among its structural isomers with the same number of benzene rings. Therefore, polycyclic aromatic compounds possessing the phene-substructure will be good candidates for stable organic semiconductors. Considering synthetic easiness, we suggest that the BTBT-substructure is the molecular structure of choice for developing air-stable organic semiconductors.

  17. High‐Performance Nonvolatile Organic Field‐Effect Transistor Memory Based on Organic Semiconductor Heterostructures of Pentacene/P13/Pentacene as Both Charge Transport and Trapping Layers

    Science.gov (United States)

    Li, Wen; Guo, Fengning; Ling, Haifeng; Zhang, Peng; Wang, Laiyuan; Wu, Dequn

    2017-01-01

    Nonvolatile organic field‐effect transistor (OFET) memory devices based on pentacene/N,N′‐ditridecylperylene‐3,4,9,10‐tetracarboxylic diimide (P13)/pentacene trilayer organic heterostructures have been proposed. The discontinuous n‐type P13 embedded in p‐type pentacene layers can not only provide electrons in the semiconductor layer that facilitates electron trapping process; it also works as charge trapping sites, which is attributed to the quantum well‐like pentacene/P13/pentacene organic heterostructures. The synergistic effects of charge trapping in the discontinuous P13 and the charge‐trapping property of the poly(4‐vinylphenol) (PVP) layer remarkably improve the memory performance. In addition, the trilayer organic heterostructures have also been successfully applied to multilevel and flexible nonvolatile memory devices. The results provide a novel design strategy to achieve high‐performance nonvolatile OFET memory devices and allow potential applications for different combinations of various organic semiconductor materials in OFET memory. PMID:28852619

  18. Mode-Locked Semiconductor Lasers for Optical Communication Systems

    DEFF Research Database (Denmark)

    Yvind, Kresten; Larsson, David; Oxenløwe, Leif Katsuo

    2005-01-01

    We present investigations on 10 and 40 GHz monolithic mode-locked lasers for applications in optical communications systems. New all-active lasers with one to three quantum wells have been designed, fabricated and characterized....

  19. Assessment of present and future large-scale semiconductor detector systems

    International Nuclear Information System (INIS)

    Spieler, H.G.; Haller, E.E.

    1984-11-01

    The performance of large-scale semiconductor detector systems is assessed with respect to their theoretical potential and to the practical limitations imposed by processing techniques, readout electronics and radiation damage. In addition to devices which detect reaction products directly, the analysis includes photodetectors for scintillator arrays. Beyond present technology we also examine currently evolving structures and techniques which show potential for producing practical devices in the foreseeable future

  20. Amorphous chalcogenide semiconductors for solid state dosimetric systems of high-energetic ionizing radiation

    Energy Technology Data Exchange (ETDEWEB)

    Shpotyuk, O. [Pedagogical University, Czestochowa (Poland)]|[Institute of Materials, Lvov (Ukraine)

    1997-12-31

    The application possibilities of amorphous chalcogenide semiconductors use as radiation-sensitive elements of high-energetic (E > 1 MeV) dosimetric systems are analysed. It is shown that investigated materials are characterized by more wide region of registered absorbed doses and low temperature threshold of radiation information bleaching in comparison with well-known analogies based on coloring oxide glasses. (author). 16 refs, 1 tab.

  1. Accelerated Aging System for Prognostics of Power Semiconductor Devices

    Science.gov (United States)

    Celaya, Jose R.; Vashchenko, Vladislav; Wysocki, Philip; Saha, Sankalita

    2010-01-01

    Prognostics is an engineering discipline that focuses on estimation of the health state of a component and the prediction of its remaining useful life (RUL) before failure. Health state estimation is based on actual conditions and it is fundamental for the prediction of RUL under anticipated future usage. Failure of electronic devices is of great concern as future aircraft will see an increase of electronics to drive and control safety-critical equipment throughout the aircraft. Therefore, development of prognostics solutions for electronics is of key importance. This paper presents an accelerated aging system for gate-controlled power transistors. This system allows for the understanding of the effects of failure mechanisms, and the identification of leading indicators of failure which are essential in the development of physics-based degradation models and RUL prediction. In particular, this system isolates electrical overstress from thermal overstress. Also, this system allows for a precise control of internal temperatures, enabling the exploration of intrinsic failure mechanisms not related to the device packaging. By controlling the temperature within safe operation levels of the device, accelerated aging is induced by electrical overstress only, avoiding the generation of thermal cycles. The temperature is controlled by active thermal-electric units. Several electrical and thermal signals are measured in-situ and recorded for further analysis in the identification of leading indicators of failures. This system, therefore, provides a unique capability in the exploration of different failure mechanisms and the identification of precursors of failure that can be used to provide a health management solution for electronic devices.

  2. Performance characteristics of high resolution semiconductor gamma ray spectrometry system

    International Nuclear Information System (INIS)

    Ko Ko Naing

    1994-05-01

    A high purity germanium (HPGe) gamma-ray detector has been used in Nuclear Research Laboratory, Department of Physics, Yangon University for over fourteen years. Now it is still being used and it is coupled to new peripheral devices, such as spectroscopy amplifier, analog to digital converter and computer fit-in S-100 multichannel analyser. Therefore, it is necessary to determine the important parameters: energy resolution, detecting efficiency and relative efficiency of the system. In the present work, these parameters were obtained by using mixed calibrated source. The results were compared to the data given by the manufacturer. Moreover, the parameters of another γ-ray detecting system NaI(T1) were also determined. In conclusion the results obtained from the above two measurements were compared and discussed

  3. Performance characteristics of high resolution semiconductor gamma ray spectrometry system

    Energy Technology Data Exchange (ETDEWEB)

    Naing, Ko Ko

    1994-05-01

    A high purity germanium (HPGe) gamma-ray detector has been used in Nuclear Research Laboratory, Department of Physics, Yangon University for over fourteen years. Now it is still being used and it is coupled to new peripheral devices, such as spectroscopy amplifier, analog to digital converter and computer fit-in S-100 multichannel analyser. Therefore, it is necessary to determine the important parameters: energy resolution, detecting efficiency and relative efficiency of the system. In the present work, these parameters were obtained by using mixed calibrated source. The results were compared to the data given by the manufacturer. Moreover, the parameters of another {gamma}-ray detecting system NaI(T1) were also determined. In conclusion the results obtained from the above two measurements were compared and discussed

  4. Semiconductor cleaning liquid delivery system and its filter; Handotaiyo seijo yakueki kyokyu system to filter

    Energy Technology Data Exchange (ETDEWEB)

    Saito, T. [Kanto Chemical Co. Inc., Tokyo (Japan); Hayama, H.; Sakka, T. [Nitto Denko Corp., Osaka (Japan)

    1994-11-30

    Most of chemicals used for producing semiconductors are supplied automatically by a chemical delivery system to production devices. This paper explains the current status and the trends of the system. This system supplies the chemicals in the order of a tank lorry, a storage tank, a supply tank, a filter and a production device, and the transfer is performed receiving a supply signal from the supply tank and the production device. The transfer may be done through a dilution equipment. Filters currently used have membrane pore sizes of 0.2 to 0.1 microns as prefilters, and 0.1 to 0.05 microns as final filters. Chemicals used are diverse and can be divided into acid-, alkaline-, and solvent-based groups. Fluorine resin filters are used for acid- and alkaline-resistant applications, and SUS/fluorine resin filters for solvent-resistant applications. Use of large-sized filters of element construction with a membrane area of 1 m{sup 2} class is increasing recently in addition to selection from a performance viewpoint, including particle removing performance. 9 figs., 7 tabs.

  5. Experimental and theoretical evidence of a supercritical-like transition in an organic semiconductor presenting colossal uniaxial negative thermal expansion.

    Science.gov (United States)

    van der Lee, Arie; Roche, Gilles H; Wantz, Guillaume; Moreau, Joël J E; Dautel, Olivier J; Filhol, Jean-Sébastien

    2018-04-28

    Thermal expansion coefficients of most materials are usually small, typically up to 50 parts per million per kelvin, and positive, i.e. materials expand when heated. Some materials show an atypical shrinking behavior in one or more crystallographic directions when heated. Here we show that a high mobility thiophene-based organic semiconductor, BHH-BTBT , has an exceptionally large negative expansion between 95 and 295 K (-216 BTBT , a much studied organic semiconductor with a closely related molecular formula and 3D crystallographic structure. Complete theoretical characterization of BHH-BTBT using ab initio molecular dynamics shows that below ∼200 K two different α and β domains exist of which one is dominant but which dynamically exchange around and above 210 K. A supercritical-like transition from an α dominated phase to a β dominated phase is observed using DSC measurements, UV-VIS spectroscopy, and X-ray diffraction. The origin of the extreme negative and positive thermal expansion is related to steric hindrance between adjacent tilted thiophene units and strongly enhanced by attractive S···S and S···C interactions within the highly anharmonic mixed-domain phase. This material could trigger the tailoring of optoelectronic devices highly sensitive to strain and temperature.

  6. Deposit heterogeneity and the dynamics of the organic semiconductors P3HT and PCBM solution under evaporation

    Science.gov (United States)

    Yu, H. P.; Luo, H.; Liu, T. T.; Jing, G. Y.

    2015-04-01

    The formation of organic semiconductor layer is the key procedure in the manufacture of organic photovoltaic solar cell, in which the natural evaporation of the solvent from the polymer solution plays the essential role for the conversion efficiency. Here, poly(3-hexylthiophene) (P3HT) and fullerene derivative [6,6]-phenyl-C61-butyric acid methyl ester (PCBM), as two types of semiconductor polymers, were selected as the active layer to form the deposit by drying the blend solution drops on the substrate. We explored the influences of droplet size and solute concentration on the homogeneity of the deposit. Additionally, the spatial distribution of molecular chains and grains and the instability of the droplet morphology during the drying were investigated. The results showed that the "coffee-ring" phenomenon occurred forming an annular deposit at the outermost edge and the width of the annular ring increased linearly with the concentration of the P3HT solution, until a saturation plateau is approached. On the other hand, the PCBM deposition presented a circular disk at low concentration, but displayed a sudden instability for an irregular perimeter at a critical concentration and there existed a second critical concentration above which the deposit exhibited the return of the stable circular shape. The results have an instructive impact on the performance of the device and the formation of fine structures during the process of printing, film preparation and painting.

  7. Electrical conductivity, optical properties and mechanical stability of 3, 4, 9, 10-perylenetetracarboxylic dianhidride based organic semiconductor

    Science.gov (United States)

    Pandey, Mayank; Joshi, Girish M.; Deshmukh, Kalim; Nath Ghosh, Narendra; Nambi Raj, N. Arunai

    2015-05-01

    The 3, 4, 9, 10-perylenetetracarboxylic dianhydride (PTCDA) doped polymer films were prepared with Polypyrrole (PPy) and Polyvinyl alcohol (PVA) polymers by solution-casting. The change in structure and chemical composition of samples was identified by XRD and FTIR respectively. The UV-visible spectroscopy demonstrates the optical characteristics and band gap properties of sample. The homogeneous morphology of sample for higher wt% of PTCDA was examined by atomic force microscopy (AFM). The differential scanning calorimetry (DSC) results demonstrate the decrease in melting temperature (Tm) and degree of crystallinity (χc%) of polymeric organic semiconductor. The mechanical property demonstrates the high tensile strength and improved plasticity nature. Impedance spectroscopy was evaluated to determine the conductivity response of polymeric organic semiconductor. The highest DC conductivity (2.08×10-3 S/m) was obtained for 10 wt% of PTCDA at 140 °C. The decrease in activation energy (Ea) represents the non-Debye process and was evaluated from the slope of ln σdc vs. 103/T plot.

  8. Facile synthesis of light harvesting semiconductor bismuth oxychloride nano photo-catalysts for efficient removal of hazardous organic pollutants.

    Directory of Open Access Journals (Sweden)

    Zaki S Seddigi

    Full Text Available In the present work, bismuth oxychloride nanoparticles-a light harvesting semiconductor photocatalyst-were synthesized by a facile hydrolysis route, with sodium bismuthate and hydroxylammonium chloride as the precursor materials. The as-synthesized semiconductor photocatalysts were characterized using X-ray diffraction analysis, Fourier transform infra-red spectroscopy, Raman spectroscopy, Field emission scanning electron microscopy, X-ray photoelectron spectroscopy and Photoluminescence spectroscopy techniques. The crystal structure, morphology, composition, and optical properties of these facile synthesized bismuth oxychloride nanoparticles (BiOCl NPs were compared to those of traditional bismuth oxychloride. In addition, the photocatalytic performance of facile-synthesized BiOCl NPs and traditional BiOCl, as applied to the removal of hazardous organic dyes under visible light illumination, is thoroughly investigated. Our results reveal that facile-synthesized BiOCl NPs display strong UV-Vis light adsorption, improved charge carrier mobility and an inhibited rate of charge carrier recombination, when compared to traditional BiOCl. These enhancements result in an improved photocatalytic degradation rate of hazardous organic dyes under UV-Vis irradiance. For instance, the facile-synthesized BiOCl NPs attained 100% degradation of methylene blue and methyl orange dyes in approximately 30 mins under UV-Vis irradiation, against 55% degradation for traditional BiOCl under similar experimental conditions.

  9. Facile synthesis of light harvesting semiconductor bismuth oxychloride nano photo-catalysts for efficient removal of hazardous organic pollutants.

    Science.gov (United States)

    Seddigi, Zaki S; Gondal, Mohammed A; Baig, Umair; Ahmed, Saleh A; Abdulaziz, M A; Danish, Ekram Y; Khaled, Mazen M; Lais, Abul

    2017-01-01

    In the present work, bismuth oxychloride nanoparticles-a light harvesting semiconductor photocatalyst-were synthesized by a facile hydrolysis route, with sodium bismuthate and hydroxylammonium chloride as the precursor materials. The as-synthesized semiconductor photocatalysts were characterized using X-ray diffraction analysis, Fourier transform infra-red spectroscopy, Raman spectroscopy, Field emission scanning electron microscopy, X-ray photoelectron spectroscopy and Photoluminescence spectroscopy techniques. The crystal structure, morphology, composition, and optical properties of these facile synthesized bismuth oxychloride nanoparticles (BiOCl NPs) were compared to those of traditional bismuth oxychloride. In addition, the photocatalytic performance of facile-synthesized BiOCl NPs and traditional BiOCl, as applied to the removal of hazardous organic dyes under visible light illumination, is thoroughly investigated. Our results reveal that facile-synthesized BiOCl NPs display strong UV-Vis light adsorption, improved charge carrier mobility and an inhibited rate of charge carrier recombination, when compared to traditional BiOCl. These enhancements result in an improved photocatalytic degradation rate of hazardous organic dyes under UV-Vis irradiance. For instance, the facile-synthesized BiOCl NPs attained 100% degradation of methylene blue and methyl orange dyes in approximately 30 mins under UV-Vis irradiation, against 55% degradation for traditional BiOCl under similar experimental conditions.

  10. Study of various n-type organic semiconductors on ultraviolet detective and electroluminescent properties of optoelectronic integrated device

    Science.gov (United States)

    Deng, Chaoxu; Shao, Bingyao; Zhao, Dan; Zhou, Dianli; Yu, Junsheng

    2017-11-01

    Organic optoelectronic integrated device (OID) with both ultraviolet (UV) detective and electroluminescent (EL) properties was fabricated by using a thermally activated delayed fluorescence (TADF) semiconductor of (4s, 6s)-2,4,5,6-tetra(9H-carbazol-9-yl)isophthalonitrile (4CzIPN) as an emitter. The effect of five kinds of n-type organic semiconductors (OSCs) on the enhancement of UV detective and EL properties of OID was systematically studied. The result shows that two orders of magnitude in UV detectivity from 109 to 1011 Jones and 3.3 folds of luminance from 2499 to 8233 cd m-2 could be achieved. The result shows that not only the difference of lowest unoccupied molecular orbital (LUMO) between active layer and OSC but also the variety of electron mobility have a significant effect on the UV detective and EL performance through adjusting electron injection/transport. Additionally, the optimized OSC thickness is beneficial to confine the leaking of holes from the active layer to cathode, leading to the decrease of dark current for high detective performance. This work provides a useful method on broadening OSC material selection and device architecture construction for the realization of high performance OID.

  11. Particle dispersing system and method for testing semiconductor manufacturing equipment

    Science.gov (United States)

    Chandrachood, Madhavi; Ghanayem, Steve G.; Cantwell, Nancy; Rader, Daniel J.; Geller, Anthony S.

    1998-01-01

    The system and method prepare a gas stream comprising particles at a known concentration using a particle disperser for moving particles from a reservoir of particles into a stream of flowing carrier gas. The electrostatic charges on the particles entrained in the carrier gas are then neutralized or otherwise altered, and the resulting particle-laden gas stream is then diluted to provide an acceptable particle concentration. The diluted gas stream is then split into a calibration stream and the desired output stream. The particles in the calibration stream are detected to provide an indication of the actual size distribution and concentration of particles in the output stream that is supplied to a process chamber being analyzed. Particles flowing out of the process chamber within a vacuum pumping system are detected, and the output particle size distribution and concentration are compared with the particle size distribution and concentration of the calibration stream in order to determine the particle transport characteristics of a process chamber, or to determine the number of particles lodged in the process chamber as a function of manufacturing process parameters such as pressure, flowrate, temperature, process chamber geometry, particle size, particle charge, and gas composition.

  12. The Study of an Integrated Rating System for Supplier Quality Performance in the Semiconductor Industry

    Science.gov (United States)

    Lee, Yu-Cheng; Yen, Tieh-Min; Tsai, Chih-Hung

    This study provides an integrated model of Supplier Quality Performance Assesment (SQPA) activity for the semiconductor industry through introducing the ISO 9001 management framework, Importance-Performance Analysis (IPA) Supplier Quality Performance Assesment and Taguchi`s Signal-to-Noise Ratio (S/N) techniques. This integrated model provides a SQPA methodology to create value for all members under mutual cooperation and trust in the supply chain. This method helps organizations build a complete SQPA framework, linking organizational objectives and SQPA activities to optimize rating techniques to promote supplier quality improvement. The techniques used in SQPA activities are easily understood. A case involving a design house is illustrated to show our model.

  13. Diagnosing modern semiconductor processes with the new generation of Atomika TXRF systems

    International Nuclear Information System (INIS)

    Dobler, M.; Jung, M.; Greithanner, S.

    2000-01-01

    Responding to the latest demands in semiconductor process technology, ATOMIKA Instruments has developed a new TXRF surface analyzer generation TXRF 8300/8200W for wafer sizes up to 300 mm. This new tool set provides extended automation features for routine measurements in daily quality control as for unconventional demands in scientific work. The efficiency of the systems is illustrated and compared to the older TXRF 8030W generation. Measurement results gained on usual contaminated wafer surfaces as well as on new semiconductor material substrates are presented and prove the advantages of the improvements and novelties. The possibility to perform an analytical study at thin layers to determine layer thickness and density is demonstrated. A summary of the newest measurement results using these instruments and an outlook for further developments is given. (author)

  14. Prediction of two-dimensional diluted magnetic semiconductors: Doped monolayer MoS2 systems

    KAUST Repository

    Cheng, Yingchun

    2013-03-05

    Using first-principles calculations, we propose a two-dimensional diluted magnetic semiconductor: monolayer MoS2 doped by transition metals. Doping of transition metal atoms from the IIIB to VIB groups results in nonmagnetic states, since the number of valence electrons is smaller or equal to that of Mo. Doping of atoms from the VIIB to IIB groups becomes energetically less and less favorable. Magnetism is observed for Mn, Fe, Co, Zn, Cd, and Hg doping, while for the other dopants from these groups it is suppressed by Jahn-Teller distortions. Analysis of the binding energies and magnetic properties indicates that (Mo,X)S2 (X=Mn, Fe, Co, and Zn) are promising systems to explore two-dimensional diluted magnetic semiconductors.

  15. Large-area formation of self-aligned crystalline domains of organic semiconductors on transistor channels using CONNECT

    Science.gov (United States)

    Park, Steve; Giri, Gaurav; Shaw, Leo; Pitner, Gregory; Ha, Jewook; Koo, Ja Hoon; Gu, Xiaodan; Park, Joonsuk; Lee, Tae Hoon; Nam, Ji Hyun; Hong, Yongtaek; Bao, Zhenan

    2015-01-01

    The electronic properties of solution-processable small-molecule organic semiconductors (OSCs) have rapidly improved in recent years, rendering them highly promising for various low-cost large-area electronic applications. However, practical applications of organic electronics require patterned and precisely registered OSC films within the transistor channel region with uniform electrical properties over a large area, a task that remains a significant challenge. Here, we present a technique termed “controlled OSC nucleation and extension for circuits” (CONNECT), which uses differential surface energy and solution shearing to simultaneously generate patterned and precisely registered OSC thin films within the channel region and with aligned crystalline domains, resulting in low device-to-device variability. We have fabricated transistor density as high as 840 dpi, with a yield of 99%. We have successfully built various logic gates and a 2-bit half-adder circuit, demonstrating the practical applicability of our technique for large-scale circuit fabrication. PMID:25902502

  16. Cardiomyocyte differentiation of embryonic stem cells on the surface of organic semiconductors.

    Science.gov (United States)

    Caserta, Sergio; Barra, Mario; Manganelli, Genesia; Tomaiuolo, Giovanna; Filosa, Stefania; Cassinese, Antonio; Guido, Stefano

    2013-06-25

    Electrically active supports provide new horizons for bio-sensing and artificial organ design. Cell-based electrochemical biosensors can be used as bio-microactuators, applied to the biorobotics. Microchip-based bioassay systems can provide real-time cell analysis for preclinical drug design or for intelligent drug delivery devices. In regenerative medicine, electrically active supports can be used as bio-reactors to monitor cell activity, optimize the stem cell differentiation and control cell and tissue morphology. Biocompatibility and direct interaction of the electrically active surface with the cell surface is a critical aspect of this technology.
 In this work embryonic stem cells (AK7 ES) have been cultivated on the surface of thin films achieved through the evaporation of two aromatic compounds (T6 and PDI-8CN2 ) of particular interest for the fabrication of organic field-effect transistors (OFET). One of the potential advantages offered by the application of OFETs as bio-electronic supports is that they represent a powerful tool for the detection of bio-signals because their electrically active surface is an organic film.
 The cell morphology on T6 and PDI-8CN2 surface shows to be similar to the usual cell appearance, as obtained when standard culture support (petri dish) are employed. Moreover, our experimental results demonstrate that stem cells can be lead to differentiation up to "beating" cardiomyocytes even on these electrically-active organic films.
 This investigation encourages the perspective to develop OFET-based biosensors in order to accurately characterize stem cells during the cardiac differentiation process and eventually increase their differentiation efficiency.

  17. Investigations on Substrate Temperature-Induced Growth Modes of Organic Semiconductors at Dielectric/semiconductor Interface and Their Correlation with Threshold Voltage Stability in Organic Field-Effect Transistors.

    Science.gov (United States)

    Padma, Narayanan; Maheshwari, Priya; Bhattacharya, Debarati; Tokas, Raj B; Sen, Shashwati; Honda, Yoshihide; Basu, Saibal; Pujari, Pradeep Kumar; Rao, T V Chandrasekhar

    2016-02-10

    Influence of substrate temperature on growth modes of copper phthalocyanine (CuPc) thin films at the dielectric/semiconductor interface in organic field effect transistors (OFETs) is investigated. Atomic force microscopy (AFM) imaging at the interface reveals a change from 'layer+island' to "island" growth mode with increasing substrate temperatures, further confirmed by probing the buried interfaces using X-ray reflectivity (XRR) and positron annihilation spectroscopic (PAS) techniques. PAS depth profiling provides insight into the details of molecular ordering while positron lifetime measurements reveal the difference in packing modes of CuPc molecules at the interface. XRR measurements show systematic increase in interface width and electron density correlating well with the change from layer + island to coalesced huge 3D islands at higher substrate temperatures. Study demonstrates the usefulness of XRR and PAS techniques to study growth modes at buried interfaces and reveals the influence of growth modes of semiconductor at the interface on hole and electron trap concentrations individually, thereby affecting hysteresis and threshold voltage stability. Minimum hole trapping is correlated to near layer by layer formation close to the interface at 100 °C and maximum to the island formation with large voids between the grains at 225 °C.

  18. Late stage crystallization and healing during spin-coating enhance carrier transport in small-molecule organic semiconductors

    KAUST Repository

    Chou, Kang Wei

    2014-01-01

    Spin-coating is currently the most widely used solution processing method in organic electronics. Here, we report, for the first time, a direct investigation of the formation process of the small-molecule organic semiconductor (OSC) 6,13-bis(triisopropylsilylethynyl) (TIPS)-pentacene during spin-coating in the context of an organic thin film transistor (OTFT) application. The solution thinning and thin film formation were monitored in situ by optical reflectometry and grazing incidence wide angle X-ray scattering, respectively, both of which were performed during spin-coating. We find that OSC thin film formation is akin to a quenching process, marked by a deposition rate of ∼100 nm s-1, nearly three orders of magnitude faster than drop-casting. This is then followed by a more gradual crystallization and healing step which depends upon the spinning speed. We associate this to further crystallization and healing of defects by residency of the residual solvent trapped inside the kinetically trapped film. The residency time of the trapped solvent is extended to several seconds by slowing the rotational speed of the substrate and is credited with improving the carrier mobility by nearly two orders of magnitude. Based on this insight, we deliberately slow down the solvent evaporation further and increase the carrier mobility by an additional order of magnitude. These results demonstrate how spin-coating conditions can be used as a handle over the crystallinity of organic semiconductors otherwise quenched during initial formation only to recrystallize and heal during extended interaction with the trapped solvent. This journal is © the Partner Organisations 2014.

  19. The Effects of Different Electron-Phonon Couplings on the Spectral and Transport Properties of Small Molecule Single-Crystal Organic Semiconductors

    Directory of Open Access Journals (Sweden)

    Carmine Antonio Perroni

    2014-03-01

    Full Text Available Spectral and transport properties of small molecule single-crystal organic semiconductors have been theoretically analyzed focusing on oligoacenes, in particular on the series from naphthalene to rubrene and pentacene, aiming to show that the inclusion of different electron-phonon couplings is of paramount importance to interpret accurately the properties of prototype organic semiconductors. While in the case of rubrene, the coupling between charge carriers and low frequency inter-molecular modes is sufficient for a satisfactory description of spectral and transport properties, the inclusion of electron coupling to both low-frequency inter-molecular and high-frequency intra-molecular vibrational modes is needed to account for the temperature dependence of transport properties in smaller oligoacenes. For rubrene, a very accurate analysis in the relevant experimental configuration has allowed for the clarification of the origin of the temperature-dependent mobility observed in these organic semiconductors. With increasing temperature, the chemical potential moves into the tail of the density of states corresponding to localized states, but this is not enough to drive the system into an insulating state. The mobility along different crystallographic directions has been calculated, including vertex corrections that give rise to a transport lifetime one order of magnitude smaller than the spectral lifetime of the states involved in the transport mechanism. The mobility always exhibits a power-law behavior as a function of temperature, in agreement with experiments in rubrene. In systems gated with polarizable dielectrics, the electron coupling to interface vibrational modes of the gate has to be included in addition to the intrinsic electron-phonon interaction. While the intrinsic bulk electron-phonon interaction affects the behavior of mobility in the coherent regime below room temperature, the coupling with interface modes is dominant for the

  20. Self-Organized Transport System

    Science.gov (United States)

    2009-09-28

    This report presents the findings of the simulation model for a self-organized transport system where traffic lights communicate with neighboring traffic lights and make decisions locally to adapt to traffic conditions in real time. The model is insp...

  1. Diaryl fluorene-Based Shape-Persistent Organic Nano molecular Frameworks via Iterative Friedel-Crafts Protocol toward Multicomponent Organic Semiconductors

    International Nuclear Information System (INIS)

    Zhang, G.W.; Wang, L.; Xie, L.H.; Hou, X.Y.; Liu, Z.D.; Huang, W.; Huang, W.

    2013-01-01

    We describe bottom-up fluorenol approach to create soluble covalent organic nano molecular architectures (ONAs) as potential multicomponent organic semiconductors (MOSs). BPyFBFFA as a typical model of ONAs and MOSs exhibits a persistent chair-shaped geometric structure that consists of hole-transporting tri phenylamine (TPA), high-efficiency ter fluorene, and high-mobility pyrenes. BPyFBFFA was synthesized via the intermediates PyFA and BPyFA with iterative Friedel-Crafts reactions and Suzuki cross-coupling reactions. BPyFBFFA behaves as an efficient blue light-emitter without the low-energy green emission band. Complex diaryl fluorenes (CDAFs) are promising candidates for nano scale covalent organic frameworks and MOSs. Friedel-Crafts protocols offer versatile toolboxes for molecular architects to frame chemistry and materials, nano science, and molecular nano technology as well as molecular manufactures

  2. Hydrogen discharges operating at atmospheric pressure in a semiconductor gas discharge system

    Energy Technology Data Exchange (ETDEWEB)

    Aktas, K; Acar, S; Salamov, B G [Physics Department, Faculty of Arts and Sciences, Gazi University, 06500 Ankara (Turkey)

    2011-08-15

    Analyses of physical processes which initiate electrical breakdown and spatial stabilization of current and control it with a photosensitive cathode in a semiconductor gas discharge system (SGDS) are carried out in a wide pressure range up to atmospheric pressure p, interelectrode distance d and diameter D of the electrode areas of the semiconductor cathode. The study compares the breakdown and stability curves of the gas discharge in the planar SGDS where the discharge gap is filled with hydrogen and air in two cases. The impact of the ionizing component of the discharge plasma on the control of the stable operation of the planar SGDS is also investigated at atmospheric pressure. The loss of stability is primarily due to modification of the semiconductor-cathode properties on the interaction with low-energy hydrogen ions and the formation of a space charge of positive ions in the discharge gap which changes the discharge from Townsend to glow type. The experimental results show that the discharge current in H{sub 2} is more stable than in air. The breakdown voltages are measured for H{sub 2} and air with parallel-plane electrodes, for pressures between 28 and 760 Torr. The effective secondary electron emission (SEE) coefficient is then determined from the breakdown voltage results and compared with the experimental results. The influence of the SEE coefficient is stated in terms of the differences between the experimental breakdown law.

  3. Research and Design on a Product Data Definition System of Semiconductor Packaging Industry

    Science.gov (United States)

    Shi, Jinfei; Ma, Qingyao; Zhou, Yifan; Chen, Ruwen

    2017-12-01

    This paper develops a product data definition (PDD) system for a semiconductor packaging and testing company with independent intellectual property rights. The new PDD system can solve the problems such as, the effective control of production plans, the timely feedback of production processes, and the efficient schedule of resources. Firstly, this paper introduces the general requirements of the PDD system and depicts the operation flow and the data flow of the PDD system. Secondly, the overall design scheme of the PDD system is put forward. After that, the physical data model is developed using the Power Designer15.0 tool, and the database system is built. Finally, the function realization and running effects of the PDD system are analysed. The successful operation of the PDD system can realize the information flow among various production departments of the enterprise to meet the standard of the enterprise manufacturing integration and improve the efficiency of production management.

  4. Optical Resonance of A Three-Level System in Semiconductor Quantum Dots

    Directory of Open Access Journals (Sweden)

    Nguyen Van Hieu

    2017-11-01

    Full Text Available The optical resonance of a three-level system of the strongly correlated electrons in the twolevel semiconductor quantum dot interacting with the linearly polarized monochromatic electromagnetic radiation is studied. With the application of the Green function method the expressions of the state vectors and the energies of the stationary states of the system in the regime of the optical resonance are derived. The Rabi oscillations of the electron populations at different levels as well as the Rabi splitting of the peaks in the photon emission spectra are investigated. PACS numbers: 71.35.-y, 78.55.-m, 78.67.Hc

  5. System tests of radiation hard optical links for the ATLAS semiconductor tracker

    International Nuclear Information System (INIS)

    Charlton, D.G.; Dowell, J.D.; Homer, R.J.; Jovanovic, P.; Kenyon, I.R.; Mahout, G.; Shaylor, H.R.; Wilson, J.A.; Rudge, A.; Fopma, J.; Mandic, I.; Nickerson, R.B.; Shield, P.; Wastie, R.; Weidberg, A.R.; Eek, L.-O.; Go, A.; Lund-Jensen, B.; Pearce, M.; Soederqvist, J.; Morrissey, M.; White, D.J.

    2000-01-01

    A prototype optical data and Timing, Trigger and Control transmission system based on LEDs and PIN-diodes has been constructed. The system would be suitable in terms of radiation hardness and radiation length for use in the ATLAS SemiConductor Tracker. Bit error rate measurements were performed for the data links and for the links distributing the Timing, Trigger and Control data from the counting room to the front-end modules. The effects of cross-talk between the emitters and receivers were investigated. The advantages of using Vertical Cavity Surface Emitting Lasers (VCSELs) instead of LEDs are discussed

  6. Crafting semiconductor organic-inorganic nanocomposites via placing conjugated polymers in intimate contact with nanocrystals for hybrid solar cells

    Energy Technology Data Exchange (ETDEWEB)

    Zhao, Lei; Lin, Zhiqun [School of Materials Science and Engineering, Georgia Institute of Technology, Atlanta, GA (United States)

    2012-08-22

    Semiconductor organic-inorganic hybrid solar cells incorporating conjugated polymers (CPs) and nanocrystals (NCs) offer the potential to deliver efficient energy conversion with low-cost fabrication. The CP-based photovoltaic devices are complimented by an extensive set of advantageous characteristics from CPs and NCs, such as lightweight, flexibility, and solution-processability of CPs, combined with high electron mobility and size-dependent optical properties of NCs. Recent research has witnessed rapid advances in an emerging field of directly tethering CPs on the NC surface to yield an intimately contacted CP-NC nanocomposite possessing a well-defined interface that markedly promotes the dispersion of NCs within the CP matrix, facilitates the photoinduced charge transfer between these two semiconductor components, and provides an effective platform for studying the interfacial charge separation and transport. In this Review, we aim to highlight the recent developments in CP-NC nanocomposite materials, critically examine the viable preparative strategies geared to craft intimate CP-NC nanocomposites and their photovoltaic performance in hybrid solar cells, and finally provide an outlook for future directions of this extraordinarily rich field. (Copyright copyright 2012 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

  7. Double-digest RAD sequencing using Ion Proton semiconductor platform (ddRADseq-ion) with nonmodel organisms.

    Science.gov (United States)

    Recknagel, Hans; Jacobs, Arne; Herzyk, Pawel; Elmer, Kathryn R

    2015-11-01

    Research in evolutionary biology involving nonmodel organisms is rapidly shifting from using traditional molecular markers such as mtDNA and microsatellites to higher throughput SNP genotyping methodologies to address questions in population genetics, phylogenetics and genetic mapping. Restriction site associated DNA sequencing (RAD sequencing or RADseq) has become an established method for SNP genotyping on Illumina sequencing platforms. Here, we developed a protocol and adapters for double-digest RAD sequencing for Ion Torrent (Life Technologies; Ion Proton, Ion PGM) semiconductor sequencing. We sequenced thirteen genomic libraries of three different nonmodel vertebrate species on Ion Proton with PI chips: Arctic charr Salvelinus alpinus, European whitefish Coregonus lavaretus and common lizard Zootoca vivipara. This resulted in ~962 million single-end reads overall and a mean of ~74 million reads per library. We filtered the genomic data using Stacks, a bioinformatic tool to process RAD sequencing data. On average, we obtained ~11,000 polymorphic loci per library of 6-30 individuals. We validate our new method by technical and biological replication, by reconstructing phylogenetic relationships, and using a hybrid genetic cross to track genomic variants. Finally, we discuss the differences between using the different sequencing platforms in the context of RAD sequencing, assessing possible advantages and disadvantages. We show that our protocol can be used for Ion semiconductor sequencing platforms for the rapid and cost-effective generation of variable and reproducible genetic markers. © 2015 John Wiley & Sons Ltd.

  8. Probing Carrier Transport and Structure-Property Relationship of Highly Ordered Organic Semiconductors at the Two-Dimensional Limit.

    Science.gov (United States)

    Zhang, Yuhan; Qiao, Jingsi; Gao, Si; Hu, Fengrui; He, Daowei; Wu, Bing; Yang, Ziyi; Xu, Bingchen; Li, Yun; Shi, Yi; Ji, Wei; Wang, Peng; Wang, Xiaoyong; Xiao, Min; Xu, Hangxun; Xu, Jian-Bin; Wang, Xinran

    2016-01-08

    One of the basic assumptions in organic field-effect transistors, the most fundamental device unit in organic electronics, is that charge transport occurs two dimensionally in the first few molecular layers near the dielectric interface. Although the mobility of bulk organic semiconductors has increased dramatically, direct probing of intrinsic charge transport in the two-dimensional limit has not been possible due to excessive disorders and traps in ultrathin organic thin films. Here, highly ordered single-crystalline mono- to tetralayer pentacene crystals are realized by van der Waals (vdW) epitaxy on hexagonal BN. We find that the charge transport is dominated by hopping in the first conductive layer, but transforms to bandlike in subsequent layers. Such an abrupt phase transition is attributed to strong modulation of the molecular packing by interfacial vdW interactions, as corroborated by quantitative structural characterization and density functional theory calculations. The structural modulation becomes negligible beyond the second conductive layer, leading to a mobility saturation thickness of only ∼3  nm. Highly ordered organic ultrathin films provide a platform for new physics and device structures (such as heterostructures and quantum wells) that are not possible in conventional bulk crystals.

  9. Quantitative analysis of lattice disorder and crystallite size in organic semiconductor thin films

    KAUST Repository

    Rivnay, Jonathan

    2011-07-07

    The crystallite size and cumulative lattice disorder of three prototypical, high-performing organic semiconducting materials are investigated using a Fourier-transform peak shape analysis routine based on the method of Warren and Averbach (WA). A thorough incorporation of error propagation throughout the multistep analysis and a weighted fitting of Fourier-transformed data to the WA model allows for more accurate results than typically obtained and for determination of confidence bounds. We compare results obtained when assuming two types of column-length distributions, and discuss the benefits of each model in terms of simplicity and accuracy. For strongly disordered materials, the determination of a crystallite size is greatly hindered because disorder dominates the coherence length, not finite size. A simple analysis based on trends of peak widths and Lorentzian components of pseudo-Voigt line shapes as a function of diffraction order is also discussed as an approach to more easily and qualitatively assess the amount and type of disorder present in a sample. While applied directly to organic systems, this methodology is general for the accurate deconvolution of crystalline size and lattice disorder for any material investigated with diffraction techniques. © 2011 American Physical Society.

  10. Role of band states and trap states in the electrical properties of organic semiconductors: Hopping versus mobility edge model

    KAUST Repository

    Mehraeen, Shafigh

    2013-05-01

    We compare the merits of a hopping model and a mobility edge model in the description of the effect of charge-carrier concentration on the electrical conductivity, carrier mobility, and Fermi energy of organic semiconductors. We consider the case of a composite electronic density of states (DOS) that consists of a superposition of a Gaussian DOS and an exponential DOS. Using kinetic Monte Carlo simulations, we apply the two models in order to interpret the recent experimental data reported for n-doped C60 films. While both models are capable of reproducing the experimental data very well and yield qualitatively similar characteristic parameters for the density of states, some discrepancies are found at the quantitative level. © 2013 American Physical Society.

  11. Phonon-electron coupling and tunneling effect on charge transport in organic semi-conductor crystals of Cn-BTBT

    Science.gov (United States)

    Zhou, Yecheng; Deng, Wei-Qiao; Zhang, Hao-Li

    2016-09-01

    Cn-[1]benzothieno[3,2-b][1]-benzothiophene (BTBT) crystals show very high hole mobilities in experiments. These high mobilities are beyond existing theory prediction. Here, we employed different quantum chemistry methods to investigate charge transfer in Cn-BTBT crystals and tried to find out the reasons for the underestimation in the theory. It was found that the hopping rate estimated by the Fermi Golden Rule is higher than that of the Marcus theory due to the high temperature approximation and failure at the classic limit. More importantly, molecular dynamics simulations revealed that the phonon induced fluctuation of electronic transfer integral is much larger than the average of the electronic transfer integral itself. Mobilities become higher if simulations implement the phonon-electron coupling. This conclusion indicates that the phonon-electron coupling promotes charge transfer in organic semi-conductors at room temperature.

  12. Investigation of the nature of the unpaired electron states in the organic semiconductor N-methyl-N-ethylmorpholinium-tetracyanoquinodimethane

    DEFF Research Database (Denmark)

    Rice, M. J.; Yartsev, V. M.; Jacobsen, Claus Schelde

    1980-01-01

    The nature of the unpaired electron states in the dimerized phase of the crystalline organic semiconductor N-methyl-N-ethylmorpholinium-tetracyanoquinodimethane [MEM(TCNQ)2] is investigated by the combined means of polarized-optical-reflectance measurements and microscopic theoretical analysis....... It is found that each unpaired electron is localized on a dimeric TCNQ unit, and it is demonstrated that the two-site molecular orbital (MO) which accommodates the unpaired electron involves internal molecular distortion of the dimeric unit. Experimental values are deduced for the intradimer π MO hopping...... integral, the TCNQ monomer ag molecular-vibration frequencies and linear-electron-molecular-vibration coupling constants, and the difference in energy of the slightly nonequivalent TCNQ monomer π MO's. The dimer charge oscillation associated with the extremely weak coupling of the unpaired electron...

  13. Optical conductivity and optical effective mass in a high-mobility organic semiconductor: Implications for the nature of charge transport

    KAUST Repository

    Li, Yuan

    2014-12-03

    We present a multiscale modeling of the infrared optical properties of the rubrene crystal. The results are in very good agreement with the experimental data that point to nonmonotonic features in the optical conductivity spectrum and small optical effective masses. We find that, in the static-disorder approximation, the nonlocal electron-phonon interactions stemming from low-frequency lattice vibrations can decrease the optical effective masses and lead to lighter quasiparticles. On the other hand, the charge-transport and infrared optical properties of the rubrene crystal at room temperature are demonstrated to be governed by localized carriers driven by inherent thermal disorders. Our findings underline that the presence of apparently light carriers in high-mobility organic semiconductors does not necessarily imply bandlike transport.

  14. Optical conductivity and optical effective mass in a high-mobility organic semiconductor: Implications for the nature of charge transport

    KAUST Repository

    Li, Yuan; Yi, Yuanping; Coropceanu, Veaceslav; Bredas, Jean-Luc

    2014-01-01

    We present a multiscale modeling of the infrared optical properties of the rubrene crystal. The results are in very good agreement with the experimental data that point to nonmonotonic features in the optical conductivity spectrum and small optical effective masses. We find that, in the static-disorder approximation, the nonlocal electron-phonon interactions stemming from low-frequency lattice vibrations can decrease the optical effective masses and lead to lighter quasiparticles. On the other hand, the charge-transport and infrared optical properties of the rubrene crystal at room temperature are demonstrated to be governed by localized carriers driven by inherent thermal disorders. Our findings underline that the presence of apparently light carriers in high-mobility organic semiconductors does not necessarily imply bandlike transport.

  15. Effects of Charge-Transfer Excitons on the Photophysics of Organic Semiconductors

    Science.gov (United States)

    Hestand, Nicholas J.

    The field of organic electronics has received considerable attention over the past several years due to the promise of novel electronic materials that are cheap, flexible and light weight. While some devices based on organic materials have already emerged on the market (e.g. organic light emitting diodes), a deeper understanding of the excited states within the condensed phase is necessary both to improve current commercial products and to develop new materials for applications that are currently in the commercial pipeline (e.g. organic photovoltaics, wearable displays, and field effect transistors). To this end, a model for pi-conjugated molecular aggregates and crystals is developed and analyzed. The model considers two types of electronic excitations, namely Frenkel and charge-transfer excitons, both of which play a prominent role in determining the nature of the excited states within tightly-packed organic systems. The former consist of an electron-hole pair bound to the same molecule while in the later the electron and hole are located on different molecules. The model also considers the important nuclear reorganization that occurs when the system switches between electronic states. This is achieved using a Holstein-style Hamiltonian that includes linear vibronic coupling of the electronic states to the nuclear motion associated with the high frequency vinyl-stretching and ring-breathing modes. Analysis of the model reveals spectroscopic signatures of charge-transfer mediated J- and H-aggregation in systems where the photophysical properties are determined primarily by charge-transfer interactions. Importantly, such signatures are found to be sensitive to the relative phase of the intermolecular electron and hole transfer integrals, and the relative energy of the Frenkel and charge-transfer states. When the charge-transfer integrals are in phase and the energy of the charge-transfer state is higher than the Frenkel state, the system exhibits J

  16. Charge transport in organic molecular semiconductors from first principles: The bandlike hole mobility in a naphthalene crystal

    Science.gov (United States)

    Lee, Nien-En; Zhou, Jin-Jian; Agapito, Luis A.; Bernardi, Marco

    2018-03-01

    Predicting charge transport in organic molecular crystals is notoriously challenging. Carrier mobility calculations in organic semiconductors are dominated by quantum chemistry methods based on charge hopping, which are laborious and only moderately accurate. We compute from first principles the electron-phonon scattering and the phonon-limited hole mobility of naphthalene crystal in the framework of ab initio band theory. Our calculations combine GW electronic bandstructures, ab initio electron-phonon scattering, and the Boltzmann transport equation. The calculated hole mobility is in very good agreement with experiment between 100 -300 K , and we can predict its temperature dependence with high accuracy. We show that scattering between intermolecular phonons and holes regulates the mobility, though intramolecular phonons possess the strongest coupling with holes. We revisit the common belief that only rigid molecular motions affect carrier dynamics in organic molecular crystals. Our paper provides a quantitative and rigorous framework to compute charge transport in organic crystals and is a first step toward reconciling band theory and carrier hopping computational methods.

  17. Insight into doping efficiency of organic semiconductors from the analysis of the density of states in n-doped C60 and ZnPc

    Science.gov (United States)

    Gaul, Christopher; Hutsch, Sebastian; Schwarze, Martin; Schellhammer, Karl Sebastian; Bussolotti, Fabio; Kera, Satoshi; Cuniberti, Gianaurelio; Leo, Karl; Ortmann, Frank

    2018-05-01

    Doping plays a crucial role in semiconductor physics, with n-doping being controlled by the ionization energy of the impurity relative to the conduction band edge. In organic semiconductors, efficient doping is dominated by various effects that are currently not well understood. Here, we simulate and experimentally measure, with direct and inverse photoemission spectroscopy, the density of states and the Fermi level position of the prototypical materials C60 and zinc phthalocyanine n-doped with highly efficient benzimidazoline radicals (2-Cyc-DMBI). We study the role of doping-induced gap states, and, in particular, of the difference Δ1 between the electron affinity of the undoped material and the ionization potential of its doped counterpart. We show that this parameter is critical for the generation of free carriers and influences the conductivity of the doped films. Tuning of Δ1 may provide alternative strategies to optimize the electronic properties of organic semiconductors.

  18. Determination of the orbital lineup at reactive organic semiconductor interfaces using photoemission spectroscopy

    International Nuclear Information System (INIS)

    Schlaf, R.; Merritt, C. D.; Picciolo, L. C.; Kafafi, Z. H.

    2001-01-01

    We determined the orbital lineup of the tris (8-hydroxyquinolinato) gallium (Gaq 3 )/Mg interface using combined x-ray and ultraviolet photoemission spectroscopy (XPS and UPS) measurements. The Gaq 3 /Mg system is a prototypical model structure for organic electron/low work function electrode transporting materials interfaces found in organic light emitting diodes (OLED). A Gaq 3 thin film was grown in 15 steps on a previously sputter-cleaned Mg substrate starting at a 1 Aa nominal thickness up to a final thickness of 512 Aa. Before, and in between the growth steps, the sample surface was characterized by XPS and UPS. The results indicate the formation of a reaction layer of about 12 Aa thickness at the Mg interface, which resulted in a 0.96 V interface dipole potential. At Gaq 3 coverages higher than 256 Aa, a strong charging shift occurred in the overlayer related UPS-emission lines, which was identified by measuring the high binding energy cutoff (secondary edge) of both the XP and UP spectra. The several magnitudes different x-ray and ultraviolet source photon intensities allow pinpointing charging shifts with high sensitivity. Due to the low work function of the reacted interface layer, the Gaq 3 electronic states are aligned at a binding energy below the substrate Fermi edge that exceeds the magnitude of the optical gap between the highest occupied and lowest unoccupied molecular orbitals (HOMO and LUMO). This allowed the conclusion that the ground state exciton binding energy of Gaq 3 needs to be larger than 0.43 eV. Based on these considerations, the lowest possible electron injection barrier matching the experimental data was estimated to be 0.15 eV. copyright 2001 American Institute of Physics

  19. High performance organic field-effect transistors with ultra-thin HfO2 gate insulator deposited directly onto the organic semiconductor

    International Nuclear Information System (INIS)

    Ono, S.; Häusermann, R.; Chiba, D.; Shimamura, K.; Ono, T.; Batlogg, B.

    2014-01-01

    We have produced stable organic field-effect transistors (OFETs) with an ultra-thin HfO 2 gate insulator deposited directly on top of rubrene single crystals by atomic layer deposition (ALD). We find that ALD is a gentle deposition process to grow thin films without damaging rubrene single crystals, as results these devices have a negligibly small threshold voltage and are very stable against gate-bias-stress, and the mobility exceeds 1 cm 2 /V s. Moreover, the devices show very little degradation even when kept in air for more than 2 months. These results demonstrate thin HfO 2 layers deposited by ALD to be well suited as high capacitance gate dielectrics in OFETs operating at small gate voltage. In addition, the dielectric layer acts as an effective passivation layer to protect the organic semiconductor

  20. The system of digital-image optical microscope in semiconductor particle detector development

    International Nuclear Information System (INIS)

    Han Lixiang; Li Zhankui; Jin Genming; Wang Zhusheng; Xiao Guoqing

    2009-01-01

    Optical microscopic detection is very important in the process of semiconductor particle detector development. A system of digital-image optical microscope has been constructed with rather low price, which performance is comparable with the moderate-level imports. The system mounts powerful dry objective, and a 2μm resolution could be achieved. Observations with bright and dark field, polarized light,and interference light can be carried out on it. The system have large area on-line monitor,and the photographic device can be controlled by PC. It can be used in the control of defects and contaminations, pattern test, identification of crystal backing, inspection of the smoothness and the flatness of the crystal surface. It can also be used in some precise procedures, such as test, assembly, packaging and repairing. The quality of the bond could be examined by observing the appearance of the bond point and the microscopic structure of the solder. The surface fluctuation can be precisely measured under the microscope with the technology of multi-beam interference. In the article, the application of this system for semiconductor particle detector development has been illustrated, and the construction information has been described in detail. (authors)

  1. Nanostructured pyronin Y thin films as a new organic semiconductor: Linear/nonlinear optics, band gap and dielectric properties

    Energy Technology Data Exchange (ETDEWEB)

    Zahran, H.Y. [Metallurgical Lab.1, Nanoscience Laboratory for Environmental and Bio-medical Applications (NLEBA), Semiconductor Lab., Department of Physics, Faculty of Education, Ain Shams University, Roxy, 11757 Cairo (Egypt); Advanced Functional Materials & Optoelectronic Laboratory (AFMOL), Department of Physics, Faculty of Science, King Khalid University, P.O. Box 9004, Abha (Saudi Arabia); Yahia, I.S., E-mail: dr_isyahia@yahoo.com [Metallurgical Lab.1, Nanoscience Laboratory for Environmental and Bio-medical Applications (NLEBA), Semiconductor Lab., Department of Physics, Faculty of Education, Ain Shams University, Roxy, 11757 Cairo (Egypt); Advanced Functional Materials & Optoelectronic Laboratory (AFMOL), Department of Physics, Faculty of Science, King Khalid University, P.O. Box 9004, Abha (Saudi Arabia); Alamri, F.H. [Advanced Functional Materials & Optoelectronic Laboratory (AFMOL), Department of Physics, Faculty of Science, King Khalid University, P.O. Box 9004, Abha (Saudi Arabia)

    2017-05-15

    Pyronin Y dye (PY) is a kind of xanthene derivatives. Thin films of pyronin Y were deposited onto highly cleaned glass substrates using low-cost/spin coating technique. The structure properties of pyronin Y thin films with different thicknesses were investigated by using X-ray diffraction (XRD) and atomic force microscope (AFM). PY thin films for all the studied thicknesses have an amorphous structure supporting the short range order of the grain size. AFM supports the nanostructure with spherical/clusters morphologies of the investigated thin films. The optical constants of pyronin Y thin films for various thicknesses were studied by using UV–vis–NIR spectrophotometer in the wavelength range 350–2500 nm. The transmittance T(λ), reflectance R(λ) spectral and absorbance (abs(λ)) were obtained for all film thicknesses at room temperature and the normal light incident. These films showed a high transmittance in the wide scale wavelengths. For different thicknesses of the studied thin films, the optical band gaps were determined and their values around 2 eV. Real and imaginary dielectric constants, dissipation factor and the nonlinear optical parameters were calculated in the wavelengths to the range 300–2500 nm. The pyronin Y is a new organic semiconductor with a good optical absorption in UV–vis regions and it is suitable for nonlinear optical applications. - Highlights: • Pyronin Y (PY) nanostructured thin films were deposited by using spin coating technique. • XRD/AFM were used to study the structure of PY films. • The optical band gap was calculated on the basis of Tauc's model. • Linear/nonlinear optical parameters are calculated and interpreted via the applied optical theories. • PY thin films is a new organic semiconductor for its application in optoelectronic devices.

  2. Energy-Saving Benefits of Adiabatic Humidification in the Air Conditioning Systems of Semiconductor Cleanrooms

    Directory of Open Access Journals (Sweden)

    Min-Suk Jo

    2017-11-01

    Full Text Available This paper aimed to evaluate the applicability of adiabatic humidification in the heating, ventilation, and air conditioning (HVAC systems of semiconductor cleanrooms. Accurate temperature and humidity control are essential in semiconductor cleanrooms and high energy consumption steam humidification is commonly used. Therefore, we propose an adiabatic humidification system employing a pressurized water atomizer to reduce the energy consumption. The annual energy consumption of three different HVAC systems were analyzed to evaluate the applicability of adiabatic humidification. The studied cases were as follows: (1 CASE 1: a make-up air unit (MAU with a steam humidifier, a dry cooling coil (DCC, and a fan filter unit (FFU; (2 CASE 2: a MAU with the pressurized water atomizer, a DCC, and a FFU; and (3 CASE 3: a MAU, a DCC, and a FFU, and the pressurized water atomizer installed in the return duct. The energy saving potential of adiabatic humidification over steam humidification has been proved, with savings of 8% and 23% in CASE 2 and CASE 3 compared to CASE 1, respectively. Furthermore, the pressurized water atomizer installed in the return duct exhibits greater energy saving effect than when installed in the MAU.

  3. Synthesis, structural, thermal and optical studies of inorganic-organic hybrid semiconductors, R-PbI4

    Science.gov (United States)

    Pradeesh, K.; Nageswara Rao, K.; Vijaya Prakash, G.

    2013-02-01

    Wide varieties of naturally self-assembled two-dimensional inorganic-organic (IO) hybrid semiconductors, (4-ClC6H4NH3)2PbI4, (C6H9C2H4NH3)2PbI4, (CnH2n+1NH3)2PbI4 (where n = 12, 16, 18), (CnH2n-1NH3)2PbI4 (where n = 3, 4, 5), (C6H5C2H4NH3)2PbI4, NH3(CH2)12NH3PbI4, and (C4H3SC2H4NH3)2PbI4, were fabricated by intercalating structurally diverse organic guest moieties into lead iodide perovskite structure. The crystal packing of all these fabricated IO-hybrids comprises of well-ordered organic and inorganic layers, stacked-up alternately along c-axis. Almost all these hybrids are thermally stable upto 200 °C and show strong room-temperature exciton absorption and photoluminescence features. These strongly confined optical excitons are highly influenced by structural deformation of PbI matrix due to the conformation of organic moiety. A systematic correlation of optical exciton behavior of IO-hybrids with the organic/inorganic layer thicknesses, intercalating organic moieties, and various structural disorders were discussed. This systematic study clearly suggests that the PbI layer crumpling is directly responsible for the tunability of optical exciton energy.

  4. Aggregation of Organic Semiconductors and Its Influence on Carrier Transport and Solar Cell Performance

    KAUST Repository

    Hu, Hanlin

    2017-08-28

    Photovoltaic technology based on solution-processable organic solar cells (OSCs) provides a promising route towards a low-cost strategy to address the sharply increasing energy demands worldwide. However, up to date, the vast majority of solar cell reports have been based on spin-cast BHJ layers. Spin coating is not compatible with high speed and scalable coating processes, such as blade-coating and slot-die coating, which require the nanoscale morphology to be reproduced in scalable coating methods. And tolerance for thicker BHJ films would also facilitate high speed scalable coating. In the first part of this thesis, we investigate how pre-aggregating the conjugated polymer in solution impacts the charge transport in polymer films. We use P3HT in a wide range of molecular weights in different solvents of common use in organic electronics to investigate how they impact the aggregation behavior in the ink and in the solid state. By deliberately disentangling polymer chains via sonication of the solution in the presence of solvophobic driving forces, we show a remarkable ability to tune aggregation, which directly impacts charge transport, as measured in the context of field effect transistors. The second part of this thesis looks at the impact of the solution-coating method and the photovoltaic performance gap when applying modern BHJ inks developed for spin coating to scalable coating methods, namely blade coating. We ascribe this to significant differences in the drying kinetics between the processes. Emulating the drying kinetics of spin-coating was found to result in performance parity as well as morphological parity across several systems, resulting in demonstration of PTB7:PC71BM solar cells with efficiency of 9% and 6.5% PCEs on glass and flexible PET substrates, respectively. The last part of this thesis looks into going beyond performance parity by leveraging the differences of the scalable coating method to enable highly efficient thick solar cells which

  5. The coupling of thermochemistry and phase diagrams for group III-V semiconductor systems. Final report

    Energy Technology Data Exchange (ETDEWEB)

    Anderson, T.J.

    1998-07-21

    The project was directed at linking the thermochemical properties of III-V compound semiconductors systems with the reported phase diagrams. The solid-liquid phase equilibrium problem was formulated and three approaches to calculating the reduced standard state chemical potential were identified and values were calculated. In addition, thermochemical values for critical properties were measured using solid state electrochemical techniques. These values, along with the standard state chemical potentials and other available thermochemical and phase diagram data, were combined with a critical assessment of selected III-V systems. This work was culminated with a comprehensive assessment of all the III-V binary systems. A novel aspect of the experimental part of this project was the demonstration of the use of a liquid encapsulate to measure component activities by a solid state emf technique in liquid III-V systems that exhibit high vapor pressures at the measurement temperature.

  6. The Data Acquisition and Calibration System for the ATLAS Semiconductor Tracker

    CERN Document Server

    Abdesselam, A; Barr, A J; Bell, P; Bernabeu, J; Butterworth, J M; Carter, J R; Carter, A A; Charles, E; Clark, A; Colijn, A P; Costa, M J; Dalmau, J M; Demirkoz, B; Dervan, P J; Donega, M; D'Onifrio, M; Escobar, C; Fasching, D; Ferguson, D P S; Ferrari, P; Ferrère, D; Fuster, J; Gallop, B; García, C; González, S; González-Sevilla, S; Goodrick, M J; Gorisek, A; Greenall, A; Grillo, A A; Hessey, N P; Hill, J C; Jackson, J N; Jared, R C; Johannson, P D C; de Jong, P; Joseph, J; Lacasta, C; Lane, J B; Lester, C G; Limper, M; Lindsay, S W; McKay, R L; Magrath, C A; Mangin-Brinet, M; Martí i García, S; Mellado, B; Meyer, W T; Mikulec, B; Minano, M; Mitsou, V A; Moorhead, G; Morrissey, M; Paganis, E; Palmer, M J; Parker, M A; Pernegger, H; Phillips, A; Phillips, P W; Postranecky, M; Robichaud-Véronneau, A; Robinson, D; Roe, S; Sandaker, H; Sciacca, F; Sfyrla, A; Stanecka, E; Stapnes, S; Stradling, A; Tyndel, M; Tricoli, A; Vickey, T; Vossebeld, J H; Warren, M R M; Weidberg, A R; Wells, P S; Wu, S L

    2008-01-01

    The SemiConductor Tracker (SCT) data acquisition (DAQ) system will calibrate, configure, and control the approximately six million front-end channels of the ATLAS silicon strip detector. It will provide a synchronized bunch-crossing clock to the front-end modules, communicate first-level triggers to the front-end chips, and transfer information about hit strips to the ATLAS high-level trigger system. The system has been used extensively for calibration and quality assurance during SCT barrel and endcap assembly and for performance confirmation tests after transport of the barrels and endcaps to CERN. Operating in data-taking mode, the DAQ has recorded nearly twenty million synchronously-triggered events during commissioning tests including almost a million cosmic ray triggered events. In this paper we describe the components of the data acquisition system, discuss its operation in calibration and data-taking modes and present some detector performance results from these tests.

  7. The data acquisition and calibration system for the ATLAS Semiconductor Tracker

    International Nuclear Information System (INIS)

    Abdesselam, A; Barr, A J; Demirkoez, B; Barber, T; Carter, J R; Bell, P; Bernabeu, J; Costa, M J; Escobar, C; Butterworth, J M; Carter, A A; Dalmau, J M; Charles, E; Fasching, D; Ferguson, D P S; Clark, A; Donega, M; D'Onifrio, M; Colijn, A-P; Dervan, P J

    2008-01-01

    The SemiConductor Tracker (SCT) data acquisition (DAQ) system will calibrate, configure, and control the approximately six million front-end channels of the ATLAS silicon strip detector. It will provide a synchronized bunch-crossing clock to the front-end modules, communicate first-level triggers to the front-end chips, and transfer information about hit strips to the ATLAS high-level trigger system. The system has been used extensively for calibration and quality assurance during SCT barrel and endcap assembly and for performance confirmation tests after transport of the barrels and endcaps to CERN. Operating in data-taking mode, the DAQ has recorded nearly twenty million synchronously-triggered events during commissioning tests including almost a million cosmic ray triggered events. In this paper we describe the components of the data acquisition system, discuss its operation in calibration and data-taking modes and present some detector performance results from these tests

  8. A Furan-Thiophene-Based Quinoidal Compound: A New Class of Solution-Processable High-Performance n-Type Organic Semiconductor.

    Science.gov (United States)

    Xiong, Yu; Tao, Jingwei; Wang, Ruihao; Qiao, Xiaolan; Yang, Xiaodi; Wang, Deliang; Wu, Hongzhuo; Li, Hongxiang

    2016-07-01

    The furan-thiophene-based quinoidal organic semiconductor, TFT-CN, is designed and synthesized. TFT-CN displays a high electron mobility of 7.7 cm(2) V(-1) s(-1) , two orders of magnitude higher than the corresponding thiophene-based derivative. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  9. Effect of titanium oxide-polystyrene nanocomposite dielectrics on morphology and thin film transistor performance for organic and polymeric semiconductors

    Energy Technology Data Exchange (ETDEWEB)

    Della Pelle, Andrea M. [LGS Innovations, 15 Vreeland Rd., Florham Park, NJ 07932 (United States); Department of Chemistry, University of Massachusetts Amherst, 710 N. Pleasant St. Amherst, MA 01003 (United States); Maliakal, Ashok, E-mail: maliakal@lgsinnovations.com [LGS Innovations, 15 Vreeland Rd., Florham Park, NJ 07932 (United States); Sidorenko, Alexander [Department of Chemistry and Biochemistry, University of the Sciences, 600 South 43rd St., Philadelphia, PA 191034 (United States); Thayumanavan, S. [Department of Chemistry, University of Massachusetts Amherst, 710 N. Pleasant St. Amherst, MA 01003 (United States)

    2012-07-31

    Previous studies have shown that organic thin film transistors with pentacene deposited on gate dielectrics composed of a blend of high K titanium oxide-polystyrene core-shell nanocomposite (TiO{sub 2}-PS) with polystyrene (PS) perform with an order of magnitude increase in saturation mobility for TiO{sub 2}-PS (K = 8) as compared to PS devices (K = 2.5). The current study finds that this performance enhancement can be translated to alternative small single crystal organics such as {alpha}-sexithiophene ({alpha}-6T) (enhancement factor for field effect mobility ranging from 30-100 Multiplication-Sign higher on TiO{sub 2}-PS/PS blended dielectrics as compared to homogenous PS dielectrics). Interestingly however, in the case of semicrystalline polymers such as (poly-3-hexylthiophene) P3HT, this dramatic enhancement is not observed, possibly due to the difference in processing conditions used to fabricate these devices (film transfer as opposed to thermal evaporation). The morphology for {alpha}-sexithiophene ({alpha}-6T) grown by thermal evaporation on TiO{sub 2}-PS/PS blended dielectrics parallels that observed in pentacene devices. Smaller grain size is observed for films grown on dielectrics with higher TiO{sub 2}-PS content. In the case of poly(3-hexylthiophene) (P3HT) devices, constructed via film transfer, morphological differences exist for the P3HT on different substrates, as discerned by atomic force microscopy studies. However, these devices only exhibit a modest (2 Multiplication-Sign ) increase in mobility with increasing TiO{sub 2}-PS content in the films. After annealing of the transferred P3HT thin film transistor (TFT) devices, no appreciable enhancement in mobility is observed across the different blended dielectrics. Overall the results support the hypothesis that nucleation rate is responsible for changes in film morphology and device performance in thermally evaporated small molecule crystalline organic semiconductor TFTs. The increased nucleation

  10. Effect of titanium oxide–polystyrene nanocomposite dielectrics on morphology and thin film transistor performance for organic and polymeric semiconductors

    International Nuclear Information System (INIS)

    Della Pelle, Andrea M.; Maliakal, Ashok; Sidorenko, Alexander; Thayumanavan, S.

    2012-01-01

    Previous studies have shown that organic thin film transistors with pentacene deposited on gate dielectrics composed of a blend of high K titanium oxide–polystyrene core–shell nanocomposite (TiO 2 –PS) with polystyrene (PS) perform with an order of magnitude increase in saturation mobility for TiO 2 –PS (K = 8) as compared to PS devices (K = 2.5). The current study finds that this performance enhancement can be translated to alternative small single crystal organics such as α-sexithiophene (α-6T) (enhancement factor for field effect mobility ranging from 30-100× higher on TiO 2 –PS/PS blended dielectrics as compared to homogenous PS dielectrics). Interestingly however, in the case of semicrystalline polymers such as (poly-3-hexylthiophene) P3HT, this dramatic enhancement is not observed, possibly due to the difference in processing conditions used to fabricate these devices (film transfer as opposed to thermal evaporation). The morphology for α-sexithiophene (α-6T) grown by thermal evaporation on TiO 2 –PS/PS blended dielectrics parallels that observed in pentacene devices. Smaller grain size is observed for films grown on dielectrics with higher TiO 2 –PS content. In the case of poly(3-hexylthiophene) (P3HT) devices, constructed via film transfer, morphological differences exist for the P3HT on different substrates, as discerned by atomic force microscopy studies. However, these devices only exhibit a modest (2×) increase in mobility with increasing TiO 2 –PS content in the films. After annealing of the transferred P3HT thin film transistor (TFT) devices, no appreciable enhancement in mobility is observed across the different blended dielectrics. Overall the results support the hypothesis that nucleation rate is responsible for changes in film morphology and device performance in thermally evaporated small molecule crystalline organic semiconductor TFTs. The increased nucleation rate produces organic polycrystalline films with small grain

  11. High-performance semiconductors based on oligocarbazole–thiophene derivatives for solution-fabricated organic field-effect transistors

    Energy Technology Data Exchange (ETDEWEB)

    Chang, Gung-Pei; Hsieh, Kuo-Huang, E-mail: khhsieh@ntu.edu.tw

    2013-01-01

    A series of oligocarbazole–thiophenes based on a constant conjugate backbone (carbazole–bithiophene–carbazole) with various n-alkyl chain lengths was prepared for application to organic field-effect transistors (OFETs). The lengths of the n-alkyl substitutions attached on 9-position of carbazole moieties were methyl (CCzT2), hexyl (C6CzT2), dodecyl (C12CzT2), and octadecyl (C18CzT2), called CxCzT2. Variations of n-alkyl chain lengths are proposed to figure out the optimization of OFET performance via solution fabrication of the active layer. Before fabricating OFET devices, the thermal, optical, and electrochemical properties of CxCzT2 were fully characterized with thermogravimetric analysis, differential scanning calorimetry, ultraviolet–visible spectroscopy, and cyclic voltammetry to realize the relationships of the structure to the properties. After fabricating CxCzT2 on Si/SiO{sub 2} substrates via solution casting, the thin film morphologies were also studied with polarizing optical microscopy, atomic force microscopy, and X-ray diffraction to investigate the structural relationship to OFET performance. A higher hole mobility was observed with C12CzT2 (3.6 × 10{sup −2} cm{sup 2} V{sup −1} s{sup −1}) due to its liquid crystal properties, and the hole mobility could be further improved to 1.2 × 10{sup −1} cm{sup 2} V{sup −1} s{sup −1} by the introduction of a phenyl-self-assembled monolayer on the Si/SiO{sub 2} substrates. The excellent OFET performances of C12CzT2 by solution–fabrication could be considered as a promising candidate for high-end OFET application. - Highlights: ► These oligomeric semiconductors were synthesized rapidly. ► The thermal, optical, and electrochemical properties were fully investigated. ► The liquid crystal properties can be obtained via alkyl chain length adjustment. ► These oligomeric semiconductors can be solution-fabricated. ► One of these oligomeric semiconductors yields high field-effect hole

  12. Synthesis of Conjugated Small Molecules and Polymers by a Palladium Catalyzed Cyclopentannulation Strategy: Towards New Organic Semiconductors

    Science.gov (United States)

    Bheemireddy, Sambasiva Reddy

    The utility of conjugated small molecules and polymers as organic semiconductors have seen a tremendous growth in research and development in academia as well as industry because of their processability and flexibility advantages in comparison to inorganic semiconductors. The extensive research over the years has produced a large number of p-type (hole conducting) and n-type (electron conducting) semiconductors that can be used to construct organic electronic devices. Of these materials, p-type semiconductors are more established and extensively studied because of the ease of preparation as well as their better general stability in comparison to n-type materials. Despite recent research into the development of n-type materials, fullerene (C60 and C 70) and its derivatives are still the predominant materials used as electron acceptors for OPV applications. By taking advantage of the electron accepting behavior of cyclopenta[hi]aceanthrylene fragment of C70, we have designed and synthesized new materials based on cyclopenta-fused polycyclic aromatic hydrocarbons (CP-PAHs). By using a newly developed palladium catalyzed cyclopentannulation methodology, 1,2,6,7- tetraarylcyclopenta[hi]aceanthrylenes were prepared by treating diarylethynylenes with 9,10-dibromoanthracene. Scholl cyclodehydrogenation was used to close the externally fused aryl groups to provide access to contorted 2,7,13,18- tetraalkoxytetrabenzo[f,h,r,t]rubicenes. The contortion provides access to more soluble materials than their planar counterparts but still ii allows significant pi-pi stacking between molecules. Using a modified palladium catalyzed cyclopentannulation polymerization followed by a cyclodehydrogenation reaction, a nonconventional synthesis of CP-PAH embedded ladder polymers was also achieved. These ladder polymers possess broad UV-Vis absorptions and narrow optical gaps of 1.17-1.29 eV. The synthesis of new donor-acceptor copolymers incorporating electron accepting 1,2,6,7- tetra(4

  13. Engineering interfacial properties of organic semiconductors through soft-contact lamination and surface functionalization

    Science.gov (United States)

    Shu, Andrew Leo

    Organic electronics is a topic of interest due to its potential for low temperature and solution processing for large area and flexible applications. Examples of organic electronic devices are already available on the market; however these are, in general, still rather expensive. In order to fully realize inexpensive and efficient organic electronics, the properties of organic films need to be understood and strategies developed to take advantage of these properties to improve device performance. This work focuses on two strategies that can be used to control charge transport at interfaces with active organic semiconducting thin films. These strategies are studied and verified with a range of photoemission spectroscopy, surface probe microscopy, and electrical measurements. Vacuum evaporated molecular organic devices have long used layer stacking of different materials as a method of dividing roles in a device and modifying energy level alignment to improve device performance and efficiency. Applying this type of architecture for solution-processed devices, on the other hand, is nontrivial, as an issue of removal of or mixing with underlying layers arises. We present and examine here soft-contact lamination as a viable technique for depositing solution-processed multilayer structures. The energetics at homojunctions of a couple of air-stable polymers is investigated. Charge transport is then compared between a two-layer film and a single-layer film of equivalent thicknesses. The interface formed by soft-contact lamination is found to be transparent with respect to electronic charge carriers. We also propose a technique for modifying electronic level alignment at active organic-organic heterojunctions using dipolar self-assembled monolayers (SAM). An ultra-thin metal oxide is first deposited via a gentle low temperature chemical vapor deposition as an adhesion layer for the SAM. The deposition is shown to be successful for a variety of organic films. A series of

  14. Transport phenomena and kinetic theory applications to gases, semiconductors, photons, and biological systems

    CERN Document Server

    Gabetta, Ester

    2007-01-01

    The study of kinetic equations related to gases, semiconductors, photons, traffic flow, and other systems has developed rapidly in recent years because of its role as a mathematical tool in many applications in areas such as engineering, meteorology, biology, chemistry, materials science, nanotechnology, and pharmacy. Written by leading specialists in their respective fields, this book presents an overview of recent developments in the field of mathematical kinetic theory with a focus on modeling complex systems, emphasizing both mathematical properties and their physical meaning. The overall presentation covers not only modeling aspects and qualitative analysis of mathematical problems, but also inverse problems, which lead to a detailed assessment of models in connection with their applications, and to computational problems, which lead to an effective link of models to the analysis of real-world systems. "Transport Phenomena and Kinetic Theory" is an excellent self-study reference for graduate students, re...

  15. System and method of modulating electrical signals using photoconductive wide bandgap semiconductors as variable resistors

    Science.gov (United States)

    Harris, John Richardson; Caporaso, George J; Sampayan, Stephen E

    2013-10-22

    A system and method for producing modulated electrical signals. The system uses a variable resistor having a photoconductive wide bandgap semiconductor material construction whose conduction response to changes in amplitude of incident radiation is substantially linear throughout a non-saturation region to enable operation in non-avalanche mode. The system also includes a modulated radiation source, such as a modulated laser, for producing amplitude-modulated radiation with which to direct upon the variable resistor and modulate its conduction response. A voltage source and an output port, are both operably connected to the variable resistor so that an electrical signal may be produced at the output port by way of the variable resistor, either generated by activation of the variable resistor or propagating through the variable resistor. In this manner, the electrical signal is modulated by the variable resistor so as to have a waveform substantially similar to the amplitude-modulated radiation.

  16. Aggregation of Organic Semiconductors and Its Influence on Carrier Transport and Solar Cell Performance

    KAUST Repository

    Hu, Hanlin

    2017-01-01

    Photovoltaic technology based on solution-processable organic solar cells (OSCs) provides a promising route towards a low-cost strategy to address the sharply increasing energy demands worldwide. However, up to date, the vast majority of solar cell

  17. Iron Intercalation in Covalent-Organic Frameworks: A Promising Approach for Semiconductors

    OpenAIRE

    Pakhira, Srimanta; Lucht, Kevin P.; Mendoza-Cortes, Jose L.

    2017-01-01

    Covalent-organic frameworks (COFs) are intriguing platforms for designing functional molecular materials. Here, we present a computational study based on van der Waals dispersion-corrected hybrid density functional theory (DFT-D) to design boroxine-linked and triazine-linked COFs intercalated with Fe. Keeping the original $P-6m2$ symmetry of the pristine COF (COF-Fe-0), we have computationally designed seven new COFs by intercalating Fe atoms between two organic layers. The equilibrium struct...

  18. Tris(2-(1 H -pyrazol-1-yl)pyridine)cobalt(III) as p-Type Dopant for Organic Semiconductors and Its Application in Highly Efficient Solid-State Dye-Sensitized Solar Cells

    KAUST Repository

    Burschka, Julian; Dualeh, Amalie; Kessler, Florian; Baranoff, Etienne; Cevey-Ha, Ngoc-Lê ; Yi, Chenyi; Nazeeruddin, Mohammad K.; Grä tzel, Michael

    2011-01-01

    Chemical doping is an important strategy to alter the charge-transport properties of both molecular and polymeric organic semiconductors that find widespread application in organic electronic devices. We report on the use of a new class of Co

  19. Employee Reward Systems in Organizations

    Directory of Open Access Journals (Sweden)

    Došenović Dragana

    2016-06-01

    Full Text Available Employee rewarding is one of the activities of human resource management concerning the management of money, goods and services that employees receive from their employer in exchange for their work. Given that a properly designed reward system is one of the conditions for a stable business, successful performance of work activities and the achievement of set objectives in each organization, the basic theme of this paper is the employee reward system, with a special focus on different elements of it. The purpose of this paper is to describe the role and significance of the observed system and to draw attention to its role in employee’s motivation.

  20. One-dimensional self-confinement promotes polymorph selection in large-area organic semiconductor thin films

    KAUST Repository

    Giri, Gaurav; Li, Ruipeng; Smilgies, Detlef Matthias; Li, Erqiang; Diao, Ying; Lenn, Kristina M.; Chiu, Melanie; Lin, Debora W.; Allen, Ranulfo A.; Reinspach, Julia A.; Mannsfeld, Stefan C B; Thoroddsen, Sigurdur T; Clancy, Paulette; Bao, Zhenan; Amassian, Aram

    2014-01-01

    A crystal's structure has significant impact on its resulting biological, physical, optical and electronic properties. In organic electronics, 6,13(bis-triisopropylsilylethynyl)pentacene (TIPS-pentacene), a small-molecule organic semiconductor, adopts metastable polymorphs possessing significantly faster charge transport than the equilibrium crystal when deposited using the solution-shearing method. Here, we use a combination of high-speed polarized optical microscopy, in situ microbeam grazing incidence wide-angle X-ray-scattering and molecular simulations to understand the mechanism behind formation of metastable TIPS-pentacene polymorphs. We observe that thin-film crystallization occurs first at the air-solution interface, and nanoscale vertical spatial confinement of the solution results in formation of metastable polymorphs, a one-dimensional and large-area analogy to crystallization of polymorphs in nanoporous matrices. We demonstrate that metastable polymorphism can be tuned with unprecedented control and produced over large areas by either varying physical confinement conditions or by tuning energetic conditions during crystallization through use of solvent molecules of various sizes. © 2014 Macmillan Publishers Limited.

  1. One-dimensional self-confinement promotes polymorph selection in large-area organic semiconductor thin films.

    Science.gov (United States)

    Giri, Gaurav; Li, Ruipeng; Smilgies, Detlef-M; Li, Er Qiang; Diao, Ying; Lenn, Kristina M; Chiu, Melanie; Lin, Debora W; Allen, Ranulfo; Reinspach, Julia; Mannsfeld, Stefan C B; Thoroddsen, Sigurdur T; Clancy, Paulette; Bao, Zhenan; Amassian, Aram

    2014-04-16

    A crystal's structure has significant impact on its resulting biological, physical, optical and electronic properties. In organic electronics, 6,13(bis-triisopropylsilylethynyl)pentacene (TIPS-pentacene), a small-molecule organic semiconductor, adopts metastable polymorphs possessing significantly faster charge transport than the equilibrium crystal when deposited using the solution-shearing method. Here, we use a combination of high-speed polarized optical microscopy, in situ microbeam grazing incidence wide-angle X-ray-scattering and molecular simulations to understand the mechanism behind formation of metastable TIPS-pentacene polymorphs. We observe that thin-film crystallization occurs first at the air-solution interface, and nanoscale vertical spatial confinement of the solution results in formation of metastable polymorphs, a one-dimensional and large-area analogy to crystallization of polymorphs in nanoporous matrices. We demonstrate that metastable polymorphism can be tuned with unprecedented control and produced over large areas by either varying physical confinement conditions or by tuning energetic conditions during crystallization through use of solvent molecules of various sizes.

  2. One-dimensional self-confinement promotes polymorph selection in large-area organic semiconductor thin films

    KAUST Repository

    Giri, Gaurav

    2014-04-16

    A crystal\\'s structure has significant impact on its resulting biological, physical, optical and electronic properties. In organic electronics, 6,13(bis-triisopropylsilylethynyl)pentacene (TIPS-pentacene), a small-molecule organic semiconductor, adopts metastable polymorphs possessing significantly faster charge transport than the equilibrium crystal when deposited using the solution-shearing method. Here, we use a combination of high-speed polarized optical microscopy, in situ microbeam grazing incidence wide-angle X-ray-scattering and molecular simulations to understand the mechanism behind formation of metastable TIPS-pentacene polymorphs. We observe that thin-film crystallization occurs first at the air-solution interface, and nanoscale vertical spatial confinement of the solution results in formation of metastable polymorphs, a one-dimensional and large-area analogy to crystallization of polymorphs in nanoporous matrices. We demonstrate that metastable polymorphism can be tuned with unprecedented control and produced over large areas by either varying physical confinement conditions or by tuning energetic conditions during crystallization through use of solvent molecules of various sizes. © 2014 Macmillan Publishers Limited.

  3. Advancing semiconductor-electrocatalyst systems: application of surface transformation films and nanosphere lithography.

    Science.gov (United States)

    Brinkert, Katharina; Richter, Matthias H; Akay, Ömer; Giersig, Michael; Fountaine, Katherine T; Lewerenz, Hans-Joachim

    2018-05-24

    Photoelectrochemical (PEC) cells offer the possibility of carbon-neutral solar fuel production through artificial photosynthesis. The pursued design involves technologically advanced III-V semiconductor absorbers coupled via an interfacial film to an electrocatalyst layer. These systems have been prepared by in situ surface transformations in electrochemical environments. High activity nanostructured electrocatalysts are required for an efficiently operating cell, optimized in their optical and electrical properties. We demonstrate that shadow nanosphere lithography (SNL) is an auspicious tool to systematically create three-dimensional electrocatalyst nanostructures on the semiconductor photoelectrode through controlling their morphology and optical properties. First results are demonstrated by means of the photoelectrochemical production of hydrogen on p-type InP photocathodes where hitherto applied photoelectrodeposition and SNL-deposited Rh electrocatalysts are compared based on their J-V and spectroscopic behavior. We show that smaller polystyrene particle masks achieve higher defect nanostructures of rhodium on the photoelectrode which leads to a higher catalytic activity and larger short circuit currents. Structural analyses including HRSEM and the analysis of the photoelectrode surface composition by using photoelectron spectroscopy support and complement the photoelectrochemical observations. The optical performance is further compared to theoretical models of the nanostructured photoelectrodes on light scattering and propagation.

  4. A bio-inspired memory device based on interfacing Physarum polycephalum with an organic semiconductor

    Directory of Open Access Journals (Sweden)

    Agostino Romeo

    2015-01-01

    Full Text Available The development of devices able to detect and record ion fluxes is a crucial point in order to understand the mechanisms that regulate communication and life of organisms. Here, we take advantage of the combined electronic and ionic conduction properties of a conducting polymer to develop a hybrid organic/living device with a three-terminal configuration, using the Physarum polycephalum Cell (PPC slime mould as a living bio-electrolyte. An over-oxidation process induces a conductivity switch in the polymer, due to the ionic flux taking place at the PPC/polymer interface. This behaviour endows a current-depending memory effect to the device.

  5. A bio-inspired memory device based on interfacing Physarum polycephalum with an organic semiconductor

    Energy Technology Data Exchange (ETDEWEB)

    Romeo, Agostino; Dimonte, Alice; Tarabella, Giuseppe; D’Angelo, Pasquale, E-mail: dangelo@imem.cnr.it, E-mail: iannotta@imem.cnr.it; Erokhin, Victor; Iannotta, Salvatore, E-mail: dangelo@imem.cnr.it, E-mail: iannotta@imem.cnr.it [IMEM-CNR, Institute of Materials for Electronics and Magnetism-National Research Council, Parma 43124 (Italy)

    2015-01-01

    The development of devices able to detect and record ion fluxes is a crucial point in order to understand the mechanisms that regulate communication and life of organisms. Here, we take advantage of the combined electronic and ionic conduction properties of a conducting polymer to develop a hybrid organic/living device with a three-terminal configuration, using the Physarum polycephalum Cell (PPC) slime mould as a living bio-electrolyte. An over-oxidation process induces a conductivity switch in the polymer, due to the ionic flux taking place at the PPC/polymer interface. This behaviour endows a current-depending memory effect to the device.

  6. A method for the combined measurement of volatile and condensable organic AMC in semiconductor applications

    Science.gov (United States)

    Miller, Charles M.; Zaloga, Emily C.; Lobert, Jürgen M.

    2014-04-01

    Monitoring airborne molecular contamination (AMC) at the parts per trillion (ppt) level in cleanroom environments, scanner applications and compressed gas lines is essential for processes, equipment and yield-control. For the operation of EUV tools, in particular, volatile organic contamination is known to have as much impact as condensable organic compounds, which requires a suitable sampling and measurement methodology. Some of the current industry standards use sample traps comprised of porous 2,6-diphenylene-oxide polymer resin, such as Tenax®, for measuring volatile organic (6 C atoms, about toluene and higher) AMC. Inherent problems associated with these traps are a number of artifacts and chemical reactions that reduce accuracy of reported organic AMC concentrations. The break-down of the polymeric material forms false positive artifacts when used in the presence of reactive gases, such as nitrous acid and ozone, which attack and degrade the polymer to form detectable AMC. Most importantly, these traps have poor capture efficiency for volatile organic compounds (VOC). To address the disadvantages of polymer-based sample traps, we developed a method based on carbonaceous, multi-layered adsorbent traps to replace the 2,6-diphenylene-oxide polymer resin sample trap type. Along with the new trap's ability to retain volatile organics, the trap was found to provide artifact-free results. With industry trends towards detecting more contaminants while continuously reducing required reporting limits for those compounds, artifact-free and accurate detection of AMC is needed at the parts per quadrillion (ppq) level. The proposed, multi-layered trap substantially increases laboratory productivity and reduces cost by eliminating the need to analyze condensable and volatile organic compounds in two separate methods. In our studies, even some organic compounds with six C-atoms, that are part of exposure tool OEM requirements, were not effectively retained by polymeric

  7. Direct deposition of inorganic–organic hybrid semiconductors and their template-assisted microstructures

    International Nuclear Information System (INIS)

    Dwivedi, V.K.; Baumberg, J.J.; Prakash, G. Vijaya

    2013-01-01

    A straight-forward method is developed to deposit a new class of self-organized inorganic–organic (IO) hybrid, (C 12 H 25 NH 3 ) 2 PbI 4 . These IO hybrid structures are stacked-up as natural multiple quantum well structures and exhibit strong room-temperature exciton emission and other multifunctional features. Here it is successfully demonstrated that these materials can be directly carved into 2D photonic structures from the inexpensive template-assisted electrochemical deposition followed by solution processing. The applicability of this method for many such varieties of IO-hybrids is also explored. By appropriately controlling the deposition conditions and the self-assembly templates, target structures are developed for new-generation low-cost photonic devices. -- Highlights: ► New fabrication methodology for self-organized inorganic–organic hybrids. ► Strongly confined exciton emission and photoconductive properties. ► Simple bottom-up fabrication for device applications.

  8. Controlling morphology and molecular order of solution-processed organic semiconductors for transistors

    NARCIS (Netherlands)

    Li, X.

    2012-01-01

    As a potential low-cost alternative to traditional amorphous-silicon based devices, organic field-effect transistors (OFETs) are expected to be incorporated into all-plastic integrated circuits and flexible display backplanes. More recently, breakthroughs have been made in the performance of OFETs

  9. Influence of the semiconductor oxidation potential on the operational stability of organic field-effect transistors

    NARCIS (Netherlands)

    Sharma, A.; Mathijssen, S.G.J.; Bobbert, P.A.; Leeuw, de D.M.

    2011-01-01

    During prolonged application of a gate bias, organic field-effect transistors show a gradual shift of the threshold voltage towards the applied gate bias voltage. The shift follows a stretched-exponential time dependence governed by a relaxation time. Here, we show that a thermodynamic analysis

  10. Fermi level pinning by integer charge transfer at electrode-organic semiconductor interfaces

    NARCIS (Netherlands)

    Bokdam, Menno; Cakir, Deniz; Brocks, G.

    2011-01-01

    The atomic structure of interfaces between conducting electrodes and molecular organic materials varies considerably. Yet experiments show that pinning of the Fermi level, which is observed at such interfaces, does not depend upon the structural details. In this letter, we develop a general model to

  11. Transcending Organization in Temporary Systems

    DEFF Research Database (Denmark)

    Stjerne, Iben Sandal

    in temporary systems that lack stability and formal order. It advances our understanding of transcending organization in creative industries by adopting a practice based perspective. Empirically, the dissertation presents an in-depth study of the Danish film industry, which is an extreme case of a project...... film workers with different functional roles and six months of ethnographic study of film projects in the Danish film industry, in particular delving into the film project Antboy and its sequels....

  12. Electronic properties and chemistry of metal / organic semiconductor/ S-GaAs(100) heterosructures

    Energy Technology Data Exchange (ETDEWEB)

    Gavrila, G.N.

    2005-10-21

    in the framework of this thesis three perylene derivates are applied as interlayers in metal/organic layer/S-GaAs(100) heterostructures. The aim of this thesis is to prove the influence of different chemical end-groups on the electronic and chemical properties of the interfaces, as well as the molecular orientation in the organic layers. The molecules 3,4,9,10-perylene tetracarbonic acid dianhydride (PTCDA), 3,4,9,10-perylene tetracarbonic acid diimide (PTCDI), and dimethyl-3,4,9,10-perylene tetracarbonic acid diimide (DiMe-PTCDI) were evaporated by organic molecular beam deposition (OMBD) in the ultrahigh vacuum on sulfur-passivated GaAs(001):2 x 1 substrates. Surface-sensitive characterization procedures as photoemission spectroscopy (PES), inverse photoemission spectroscopy (IPES), and near-edge X-ray fine-structure measurements (NEXAFS) were applied for the characterization. Theoretical calculations by means of the density-functional methods were performed, in order to allow an assignment of different components in core-level spectra. The NEXAFS spectra allow a precise determination of the molecule orientation in relation to the substrate. So it can be proved that a small change of chemical end-groups for instance in DiMe-PTCDI compared with PTCDI causes a dramatic change of the molecule orientation. The valence-band spectra of DiMe-PTCDI show an energetic dispersion of 0.2 eV, which can be assigned to a {pi}-orbital overlap and covers the formation of valence bands. The energy-level fitting to the organic-layer/S-GaAs interface as well as the transport band gap of PTCDI, DiMe-PTCDI, and PTCDA were deteminde by means of PES and IPES. The electronic, chemical, and structural properties of metal/organic-layer interfaces were studied by means of core-level spectroscopy and NEXAFS. Mg reacts strongly with the end-groups of PTCDA AND ptcdi, while the In atoms contribute to a charge-transfer process with the perylene cores of all three molecules, whereby the

  13. Nonlinear Transport in Organic Thin Film Transistors with Soluble Small Molecule Semiconductor.

    Science.gov (United States)

    Kim, Hyeok; Song, Dong-Seok; Kwon, Jin-Hyuk; Jung, Ji-Hoon; Kim, Do-Kyung; Kim, SeonMin; Kang, In Man; Park, Jonghoo; Tae, Heung-Sik; Battaglini, Nicolas; Lang, Philippe; Horowitz, Gilles; Bae, Jin-Hyuk

    2016-03-01

    Nonlinear transport is intensively explained through Poole-Frenkel (PF) transport mechanism in organic thin film transistors with solution-processed small molecules, which is, 6,13-bis(triisopropylsilylethynyl) (TIPS) pentacene. We outline a detailed electrical study that identifies the source to drain field dependent mobility. Devices with diverse channel lengths enable the extensive exhibition of field dependent mobility due to thermal activation of carriers among traps.

  14. Designing small molecule polyaromatic p- and n-type semiconductor materials for organic electronics

    KAUST Repository

    Collis, Gavin E.

    2015-12-22

    By combining computational aided design with synthetic chemistry, we are able to identify core 2D polyaromatic small molecule templates with the necessary optoelectronic properties for p- and n-type materials. By judicious selection of the functional groups, we can tune the physical properties of the material making them amenable to solution and vacuum deposition. In addition to solubility, we observe that the functional group can influence the thin film molecular packing. By developing structure-property relationships (SPRs) for these families of compounds we observe that some compounds are better suited for use in organic solar cells, while others, varying only slightly in structure, are favoured in organic field effect transistor devices. We also find that the processing conditions can have a dramatic impact on molecular packing (i.e. 1D vs 2D polymorphism) and charge mobility; this has implications for material and device long term stability. We have developed small molecule p- and n-type materials for organic solar cells with efficiencies exceeding 2%. Subtle variations in the functional groups of these materials produces p- and ntype materials with mobilities higher than 0.3 cm2/Vs. We are also interested in using our SPR approach to develop materials for sensor and bioelectronic applications.

  15. X-ray radiation damage of organic semiconductor thin films during grazing incidence diffraction experiments

    Energy Technology Data Exchange (ETDEWEB)

    Neuhold, A., E-mail: alfred.neuhold@tugraz.at [Institute of Solid State Physics, Graz University of Technology, Graz (Austria); Novak, J.; Flesch, H.-G.; Moser, A.; Djuric, T. [Institute of Solid State Physics, Graz University of Technology, Graz (Austria); Grodd, L.; Grigorian, S.; Pietsch, U. [Institute of Physics, University Siegen (Germany); Resel, R. [Institute of Solid State Physics, Graz University of Technology, Graz (Austria)

    2012-08-01

    Since modern synchrotrons with highly intense X-ray beams are in use to investigate organic materials, the stability of soft matter materials during beam exposure is a crucial issue. Grazing incidence X-ray diffraction and specular X-ray reflectivity measurements were performed on thin films of organic semiconducting materials, like poly(3-hexylthiophene) (P3HT), sexithiophene and pentacene. These films were irradiated with an average flux density between 10{sup 15} and 10{sup 16} photons/(s mm{sup 2}) and evidenced a different stability in synchrotron X-ray radiation. The semi-crystalline P3HT showed a clear intensity decrease of the 1 0 0 Bragg peak and 0 2 0 Bragg peak compared to the rather stable diffraction features of the molecular crystals sexithiophene and pentacene. The difference in synchrotron X-ray radiation stability is explained by the interaction of the X-ray beam with the individual chemical components in the molecules as well as by the different crystallinities of the materials. Furthermore, the semi-crystalline P3HT film exhibited an increase of film thickness after irradiation and the surface roughness slightly decreased. To summarize, this study shows a strong influence of synchrotron X-ray radiation to specific organic thin films like e.g. P3HT, while others like pentacene and sexithiophene are observed as quite stable.

  16. Semiconductor statistics

    CERN Document Server

    Blakemore, J S

    1987-01-01

    In-depth exploration of the implications of carrier populations and Fermi energies examines distribution of electrons in energy bands and impurity levels of semiconductors. Also: kinetics of semiconductors containing excess carriers, particularly in terms of trapping, excitation, and recombination.

  17. Spin diffusion in the Mn2+ ion system of II-VI diluted magnetic semiconductor heterostructures

    Science.gov (United States)

    Maksimov, A. A.; Yakovlev, D. R.; Debus, J.; Tartakovskii, I. I.; Waag, A.; Karczewski, G.; Wojtowicz, T.; Kossut, J.; Bayer, M.

    2010-07-01

    The magnetization dynamics in diluted magnetic semiconductor heterostructures based on (Zn,Mn)Se and (Cd,Mn)Te were studied optically and simulated numerically. In samples with inhomogeneous magnetic ion distribution, these dynamics are contributed by spin-lattice relaxation and spin diffusion in the Mn spin system. A spin-diffusion coefficient of 7×10-8cm2/s was evaluated for Zn0.99Mn0.01Se from comparison of experiment and theory. Calculations of the exciton giant Zeeman splitting and the magnetization dynamics in ordered alloys and digitally grown parabolic quantum wells show perfect agreement with the experimental data. In both structure types, spin diffusion contributes essentially to the magnetization dynamics.

  18. Hybrid composites of monodisperse pi-conjugated rodlike organic compounds and semiconductor quantum particles

    DEFF Research Database (Denmark)

    Hensel, V.; Godt, A.; Popovitz-Biro, R.

    2002-01-01

    Composite materials of quantum particles (Q-particles) arranged in layers within crystalline powders of pi-conjugated, rodlike dicarboxylic acids are reported. The synthesis of the composites, either as three-dimensional crystals or as thin films at the air-water interface, comprises a two...... analysis of the solids and grazing incidence X-ray diffraction analysis of the films on water. 2) Topotactic solid/gas reaction of these salts with H2S to convert the metal ions into Q-particles of CdS or PbS embedded in the organic matrix that consists of the acids 6(H) and 8(H). These hybrid materials...

  19. Nanostructured Silver Substrates With Stable and Universal SERS Properties: Application to Organic Molecules and Semiconductor Nanoparticles

    Directory of Open Access Journals (Sweden)

    Waurisch C

    2009-01-01

    Full Text Available Abstract Nanostructured silver films have been prepared by thermal deposition on silicon, and their properties as SERS substrates investigated. The optimal conditions of the post-growth annealing of the substrates were established. Atomic force microscopy study revealed that the silver films with relatively dense and homogeneous arrays of 60–80-nm high pyramidal nanoislands are the most efficient for SERS of both organic dye and inorganic nanoparticles analytes. The noticeable enhancement of the Raman signal from colloidal nanoparticles with the help of silver island films is reported for the first time.

  20. Semiconductor physics

    CERN Document Server

    Böer, Karl W

    2018-01-01

    This handbook gives a complete survey of the important topics and results in semiconductor physics. It addresses every fundamental principle and most research topics and areas of application in the field of semiconductor physics. Comprehensive information is provided on crystalline bulk and low-dimensional as well as amporphous semiconductors, including optical, transport, and dynamic properties.

  1. Spectroscopic fingerprints for charge localization in the organic semiconductor (DOEO)4[HgBr4]·TCE

    Science.gov (United States)

    Koplak, Oksana V.; Chernenkaya, Alisa; Medjanik, Katerina; Brambilla, Alberto; Gloskovskii, Andrei; Calloni, Alberto; Elmers, Hans-Joachim; Schönhense, Gerd; Ciccacci, Franco; Morgunov, Roman B.

    2015-05-01

    Changes of the electronic structure accompanied by charge localization and a transition to an antiferromagnetic ground state were observed in the organic semiconductor (DOEO)4[HgBr4]·TCE. Localization starts in the temperature region of about 150 K and the antiferromagnetic state occurs below 60 K. The magnetic moment of the crystal contains contributions of inclusions (droplets), and individual paramagnetic centers formed by localized holes and free charge carriers at 2 K. Two types of inclusions of 100-400 nm and 2-5 nm sizes were revealed by transmission electron microscopy. Studying the temperature- and angular dependence of electron spin resonance (ESR) spectra revealed fingerprints of antiferromagnetic contributions as well as paramagnetic resonance spectra of individual localized charge carriers. The results point on coexistence of antiferromagnetic long and short range order as evident from a second ESR line. Photoelectron spectroscopy in the VUV, soft and hard X-ray range shows temperature-dependent effects upon crossing the critical temperatures around 60 K and 150 K. The substantially different probing depths of soft and hard X-ray photoelectron spectroscopy yield information on the surface termination. The combined investigation using complementary methods at the same sample reveals the close relation of changes in the transport properties and in the energy distribution of electronic states.

  2. Inverse spin Hall effect from pulsed spin current in organic semiconductors with tunable spin-orbit coupling.

    Science.gov (United States)

    Sun, Dali; van Schooten, Kipp J; Kavand, Marzieh; Malissa, Hans; Zhang, Chuang; Groesbeck, Matthew; Boehme, Christoph; Valy Vardeny, Z

    2016-08-01

    Exploration of spin currents in organic semiconductors (OSECs) induced by resonant microwave absorption in ferromagnetic substrates is appealing for potential spintronics applications. Owing to the inherently weak spin-orbit coupling (SOC) of OSECs, their inverse spin Hall effect (ISHE) response is very subtle; limited by the microwave power applicable under continuous-wave (cw) excitation. Here we introduce a novel approach for generating significant ISHE signals in OSECs using pulsed ferromagnetic resonance, where the ISHE is two to three orders of magnitude larger compared to cw excitation. This strong ISHE enables us to investigate a variety of OSECs ranging from π-conjugated polymers with strong SOC that contain intrachain platinum atoms, to weak SOC polymers, to C60 films, where the SOC is predominantly caused by the curvature of the molecule's surface. The pulsed-ISHE technique offers a robust route for efficient injection and detection schemes of spin currents at room temperature, and paves the way for spin orbitronics in plastic materials.

  3. Avoiding bias effects in NMR experiments for heteronuclear dipole-dipole coupling determinations: principles and application to organic semiconductor materials.

    Science.gov (United States)

    Kurz, Ricardo; Cobo, Marcio Fernando; de Azevedo, Eduardo Ribeiro; Sommer, Michael; Wicklein, André; Thelakkat, Mukundan; Hempel, Günter; Saalwächter, Kay

    2013-09-16

    Carbon-proton dipole-dipole couplings between bonded atoms represent a popular probe of molecular dynamics in soft materials or biomolecules. Their site-resolved determination, for example, by using the popular DIPSHIFT experiment, can be challenged by spectral overlap with nonbonded carbon atoms. The problem can be solved by using very short cross-polarization (CP) contact times, however, the measured modulation curves then deviate strongly from the theoretically predicted shape, which is caused by the dependence of the CP efficiency on the orientation of the CH vector, leading to an anisotropic magnetization distribution even for isotropic samples. Herein, we present a detailed demonstration and explanation of this problem, as well as providing a solution. We combine DIPSHIFT experiments with the rotor-directed exchange of orientations (RODEO) method, and modifications of it, to redistribute the magnetization and obtain undistorted modulation curves. Our strategy is general in that it can also be applied to other types of experiments for heteronuclear dipole-dipole coupling determinations that rely on dipolar polarization transfer. It is demonstrated with perylene-bisimide-based organic semiconductor materials, as an example, in which measurements of dynamic order parameters reveal correlations of the molecular dynamics with the phase structure and functional properties. Copyright © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  4. Effect of temperature and humidity on electrical properties of organic semiconductor orange dye films deposited from solution

    International Nuclear Information System (INIS)

    Karimov, K.S.; Babadzhanov, A.; Turaeva, M.A.; Marupov, R.; Ahmed, M.M.; Khalid, F.A.; Khan, M.N.; Zakaullah, Kh.; Moiz, S.A.

    2003-01-01

    In this study the effect of temperature and humidity on electrical properties of organic semiconductor orange dye (OD) have been examined. Thin films of OD (C/sub 17/H/sub 17/N/sub 5/O/sub 2/) were deposited from 10 wt. % aqueous solution on gold and conductive glass (SnO/sub 2/) substrates. The films were grown at room temperature under normal gravity conditions, i.e., 1 g and in a spin coater up to an angular speed of 1000 RPM. Two different types of structures: surface Ga/OD/Au and sandwich AVOD/SnO/sub 2/ were fabricated and their DC and low frequency AC characteristics were evaluated for the temperature range 30-70 deg. C at ambient humidity of 50-80 %. It was observed that the sandwich structure of OD films show rectification behavior whilst the conductivity of all devices are temperature and humidity dependent. Observed room temperature activation energy for OD films was 0.30 eV which showed an increase up to 0.51 eV as a function of temperature. It was found that certain sandwich structures are more sensitive to humidity than others and the observed resistance to humidity ratio for Au/OD/Au was 5.4 whereas for Au/OD/Ga samples it was 5.0. (author)

  5. Hybrid Organic-Inorganic Perovskites: Structural Diversity and Opportunities for Semiconductor Design

    Science.gov (United States)

    Mitzi, David

    Photovoltaic (PV) devices based on three-dimensional perovskites, (Cs, MA, FA)Pb(I, Br)3 (MA =methylammonium, FA =formamidinium), have attracted substantial recent interest, because of the unprecedented rise in power conversion efficiency to values above 20%, which in turn is made possible by the near ideal band gap, strong optical absorption, high carrier mobilities, long minority carrier lifetimes, and relatively benign defects and grain boundaries for the absorbers. Some of the same properties that render these materials near-ideal for PV, also make them attractive for LED and other optoelectronic applications. Despite the high levels of device performance, the incorporation of the heavy metal lead, coupled with issues of device stability and electrical hysteresis pose challenges for commercializing these exciting technologies. This talk will provide a perspective on and discuss recent advances related to the broader perovskite family, focusing on the extraordinary structural/chemical diversity, including ability to control structural/electronic dimensionality, substitute on the organic cation, metal or halogen sites, and prospects of multi-functionality arising from separately engineered organic/inorganic structural components (e.g., see). Further exploration within this perovskite structural and chemical space offers exciting opportunities for future energy and electronic materials design. This work has been financially supported by the Office of Energy Efficiency and Renewable Energy (EERE), U.S. Dept. of Energy, under Award Number DE-EE0006712.

  6. Co-evaporation of fluoropolymer additives for improved thermal stability of organic semiconductors

    Science.gov (United States)

    Price, Jared S.; Wang, Baomin; Grede, Alex J.; Shen, Yufei; Giebink, Noel C.

    2017-08-01

    Reliability remains an ongoing challenge for organic light emitting diodes (OLEDs) as they expand in the marketplace. The ability to withstand operation and storage at elevated temperature is particularly important in this context, not only because of the inverse dependence of OLED lifetime on temperature, but also because high thermal stability is fundamentally important for high power/brightness operation as well as applications such as automotive lighting, where interior car temperatures often exceed the ambient by 50 °C or more. Here, we present a strategy to significantly increase the thermal stability of small molecule OLEDs by co-depositing an amorphous fluoropolymer, Teflon AF, to prevent catastrophic failure at elevated temperatures. Using this approach, we demonstrate that the thermal breakdown limit of common hole transport materials can be increased from typical temperatures of ˜100 °C to more than 200 °C while simultaneously improving their electrical transport properties. Similar thermal stability enhancements are demonstrated in simple bilayer OLEDs. These results point toward a general approach to engineer morphologically-stable organic electronic devices that are capable of operating or being stored in extreme thermal environments.

  7. Influence of Molecular Shape on Molecular Orientation and Stability of Vapor-Deposited Organic Semiconductors

    Science.gov (United States)

    Walters, Diane M.; Johnson, Noah D.; Ediger, M. D.

    Physical vapor deposition is commonly used to prepare active layers in organic electronics. Recently, it has been shown that molecular orientation and packing can be tuned by changing the substrate temperature during deposition, while still producing macroscopically homogeneous films. These amorphous materials can be highly anisotropic when prepared with low substrate temperatures, and they can exhibit exceptional kinetic stability; films retain their favorable packing when heated to high temperatures. Here, we study the influence of molecular shape on molecular orientation and stability. We investigate disc-shaped molecules, such as TCTA and m-MTDATA, nearly spherical molecules, such as Alq3, and linear molecules covering a broad range of aspect ratios, such as p-TTP and BSB-Cz. Disc-shaped molecules have preferential horizontal orientation when deposited at low substrate temperatures, and their orientation can be tuned by changing the substrate temperature. Alq3 forms stable, amorphous films that are optically isotropic when vapor deposited over a broad range of substrate temperatures. This work may guide the choice of material and deposition conditions for vapor-deposited films used in organic electronics and allow for more efficient devices to be fabricated.

  8. A Customized Metal Oxide Semiconductor-Based Gas Sensor Array for Onion Quality Evaluation: System Development and Characterization

    Directory of Open Access Journals (Sweden)

    Tharun Konduru

    2015-01-01

    Full Text Available A gas sensor array, consisting of seven Metal Oxide Semiconductor (MOS sensors that are sensitive to a wide range of organic volatile compounds was developed to detect rotten onions during storage. These MOS sensors were enclosed in a specially designed Teflon chamber equipped with a gas delivery system to pump volatiles from the onion samples into the chamber. The electronic circuit mainly comprised a microcontroller, non-volatile memory chip, and trickle-charge real time clock chip, serial communication chip, and parallel LCD panel. User preferences are communicated with the on-board microcontroller through a graphical user interface developed using LabVIEW. The developed gas sensor array was characterized and the discrimination potential was tested by exposing it to three different concentrations of acetone (ketone, acetonitrile (nitrile, ethyl acetate (ester, and ethanol (alcohol. The gas sensor array could differentiate the four chemicals of same concentrations and different concentrations within the chemical with significant difference. Experiment results also showed that the system was able to discriminate two concentrations (196 and 1964 ppm of methlypropyl sulfide and two concentrations (145 and 1452 ppm of 2-nonanone, two key volatile compounds emitted by rotten onions. As a proof of concept, the gas sensor array was able to achieve 89% correct classification of sour skin infected onions. The customized low-cost gas sensor array could be a useful tool to detect onion postharvest diseases in storage.

  9. Absorption and scattering effects by silver nanoparticles near the interface of organic/inorganic semiconductor tandem films

    International Nuclear Information System (INIS)

    Nemes, Coleen T.; Vijapurapu, Divya K.; Petoukhoff, Christopher E.; Cheung, Gary Z.; O’Carroll, Deirdre M.

    2013-01-01

    nanoparticles placed near an organic/inorganic interface can be employed for light management in tandem or hybrid organic/inorganic thin-film semiconductor configurations for solar energy harvesting applications or light detection applications

  10. Accurate on-chip measurement of the Seebeck coefficient of high mobility small molecule organic semiconductors

    Science.gov (United States)

    Warwick, C. N.; Venkateshvaran, D.; Sirringhaus, H.

    2015-09-01

    We present measurements of the Seebeck coefficient in two high mobility organic small molecules, 2,7-dioctyl[1]benzothieno[3,2-b][1]benzothiophene (C8-BTBT) and 2,9-didecyl-dinaphtho[2,3-b:2',3'-f]thieno[3,2-b]thiophene (C10-DNTT). The measurements are performed in a field effect transistor structure with high field effect mobilities of approximately 3 cm2/V s. This allows us to observe both the charge concentration and temperature dependence of the Seebeck coefficient. We find a strong logarithmic dependence upon charge concentration and a temperature dependence within the measurement uncertainty. Despite performing the measurements on highly polycrystalline evaporated films, we see an agreement in the Seebeck coefficient with modelled values from Shi et al. [Chem. Mater. 26, 2669 (2014)] at high charge concentrations. We attribute deviations from the model at lower charge concentrations to charge trapping.

  11. Effects of graphene defect on electronic structures of its interface with organic semiconductor

    Energy Technology Data Exchange (ETDEWEB)

    Yang, Qing-Dan; Wang, Chundong; Mo, Hin-Wai; Lo, Ming-Fai; Yuen, Muk Fung; Ng, Tsz-Wai, E-mail: tszwaing@cityu.edu.hk, E-mail: apcslee@cityu.edu.hk; Zhang, Wen-Jun; Lee, Chun-Sing, E-mail: tszwaing@cityu.edu.hk, E-mail: apcslee@cityu.edu.hk [Department of Physics and Materials Science, Center of Super-Diamond and Advanced Films (COSDAF), City University of Hong Kong (Hong Kong); Dou, Wei-Dong [Department of Physics and Materials Science, Center of Super-Diamond and Advanced Films (COSDAF), City University of Hong Kong (Hong Kong); Physics Department, Shaoxing University, Shaoxing 312000 (China); Tsang, Sai-Wing [Department of Physics and Materials Science, City University of Hong Kong (Hong Kong)

    2015-03-30

    Electronic structures of copper hexadecafluorophthalocyanine (F{sub 16}CuPc)/graphene with different defect density were studied with ultra-violet photoelectron spectroscopy. We showed that the charge transfer interaction and charge flow direction can be interestingly tuned by controlling the defect density of graphene through time-controlled H{sub 2} plasma treatment. By increasing the treatment time of H{sub 2} plasma from 30 s to 5 min, both the interface surface dipole and the electron transporting barrier at F{sub 16}CuPc/graphene interface are significantly reduced from 0.86 to 0.56 eV and 0.71 to 0.29 eV, respectively. These results suggested that graphene's defect control is a simple approach for tuning electronic properties of organic/graphene interfaces.

  12. Ultrafast Electron Transfer at Organic Semiconductor Interfaces: Importance of Molecular Orientation

    KAUST Repository

    Ayzner, Alexander L.

    2015-01-02

    © 2014 American Chemical Society. Much is known about the rate of photoexcited charge generation in at organic donor/acceptor (D/A) heterojunctions overaged over all relative arrangements. However, there has been very little experimental work investigating how the photoexcited electron transfer (ET) rate depends on the precise relative molecular orientation between D and A in thin solid films. This is the question that we address in this work. We find that the ET rate depends strongly on the relative molecular arrangement: The interface where the model donor compound copper phthalocyanine is oriented face-on with respect to the fullerene C60 acceptor yields a rate that is approximately 4 times faster than that of the edge-on oriented interface. Our results suggest that the D/A electronic coupling is significantly enhanced in the face-on case, which agrees well with theoretical predictions, underscoring the importance of controlling the relative interfacial molecular orientation.

  13. Accurate on-chip measurement of the Seebeck coefficient of high mobility small molecule organic semiconductors

    Directory of Open Access Journals (Sweden)

    C. N. Warwick

    2015-09-01

    Full Text Available We present measurements of the Seebeck coefficient in two high mobility organic small molecules, 2,7-dioctyl[1]benzothieno[3,2-b][1]benzothiophene (C8-BTBT and 2,9-didecyl-dinaphtho[2,3-b:2′,3′-f]thieno[3,2-b]thiophene (C10-DNTT. The measurements are performed in a field effect transistor structure with high field effect mobilities of approximately 3 cm2/V s. This allows us to observe both the charge concentration and temperature dependence of the Seebeck coefficient. We find a strong logarithmic dependence upon charge concentration and a temperature dependence within the measurement uncertainty. Despite performing the measurements on highly polycrystalline evaporated films, we see an agreement in the Seebeck coefficient with modelled values from Shi et al. [Chem. Mater. 26, 2669 (2014] at high charge concentrations. We attribute deviations from the model at lower charge concentrations to charge trapping.

  14. Photoelectrical stimulation of neuronal cells by an organic semiconductor-electrolyte Interface

    DEFF Research Database (Denmark)

    Abdullaeva, Oliya S.; Schulz, Matthias; Balzer, Frank

    2016-01-01

    As a step toward the realization of neuroprosthetics for vision restoration, we follow an electrophysiological patch-clamp approach to study the fundamental photoelectrical stimulation mechanism of neuronal model cells by an organic semiconductor–electrolyte interface. Our photoactive layer...... consisting of an anilino-squaraine donor blended with a fullerene acceptor is supporting the growth of the neuronal model cell line (N2A cells) without an adhesion layer on it and is not impairing cell viability. The transient photocurrent signal upon illumination from the semiconductor–electrolyte layer....... Furthermore, we characterize the morphology of the semiconductor–electrolyte interface by atomic force microscopy and study the stability of the interface in dark and under illuminated conditions....

  15. Ultrafast Electron Transfer at Organic Semiconductor Interfaces: Importance of Molecular Orientation

    KAUST Repository

    Ayzner, Alexander L.; Nordlund, Dennis; Kim, Do-Hwan; Bao, Zhenan; Toney, Michael F.

    2015-01-01

    © 2014 American Chemical Society. Much is known about the rate of photoexcited charge generation in at organic donor/acceptor (D/A) heterojunctions overaged over all relative arrangements. However, there has been very little experimental work investigating how the photoexcited electron transfer (ET) rate depends on the precise relative molecular orientation between D and A in thin solid films. This is the question that we address in this work. We find that the ET rate depends strongly on the relative molecular arrangement: The interface where the model donor compound copper phthalocyanine is oriented face-on with respect to the fullerene C60 acceptor yields a rate that is approximately 4 times faster than that of the edge-on oriented interface. Our results suggest that the D/A electronic coupling is significantly enhanced in the face-on case, which agrees well with theoretical predictions, underscoring the importance of controlling the relative interfacial molecular orientation.

  16. Use of the Wilkinson catalyst for the ortho-C-H heteroarylation of aromatic amines: facile access to highly extended π-conjugated heteroacenes for organic semiconductors.

    Science.gov (United States)

    Huang, Yumin; Wu, Di; Huang, Jingsheng; Guo, Qiang; Li, Juan; You, Jingsong

    2014-11-03

    An unprecedented catalytic system composed of the Wilkinson catalyst [Rh(PPh3)3Cl] and CF3COOH enabled the highly regioselective cross-coupling of aromatic amines with a variety of heteroarenes through dual C-H bond cleavage. This protocol provided a facile and rapid route from readily available substrates to (2-aminophenyl)heteroaryl compounds, which may be conveniently transformed into highly extended π-conjugated heteroacenes. The experimental studies and calculations showed that thianaphtheno[3,2-b]indoles have large HOMO-LUMO energy gaps and low-lying HOMO levels, and could therefore potentially be high-performance organic semiconductors. Herein we report the first use of a rhodium(I) catalyst for oxidative C-H/C-H coupling reactions. The current innovative catalyst system is much less expensive than [RhCp*Cl2]2/AgSbF6 and could open the door for the application of this approach to other types of C-H activation processes. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  17. Thermal Gradient During Vacuum-Deposition Dramatically Enhances Charge Transport in Organic Semiconductors: Toward High-Performance N-Type Organic Field-Effect Transistors.

    Science.gov (United States)

    Kim, Joo-Hyun; Han, Singu; Jeong, Heejeong; Jang, Hayeong; Baek, Seolhee; Hu, Junbeom; Lee, Myungkyun; Choi, Byungwoo; Lee, Hwa Sung

    2017-03-22

    A thermal gradient distribution was applied to a substrate during the growth of a vacuum-deposited n-type organic semiconductor (OSC) film prepared from N,N'-bis(2-ethylhexyl)-1,7-dicyanoperylene-3,4:9,10-bis(dicarboxyimide) (PDI-CN2), and the electrical performances of the films deployed in organic field-effect transistors (OFETs) were characterized. The temperature gradient at the surface was controlled by tilting the substrate, which varied the temperature one-dimensionally between the heated bottom substrate and the cooled upper substrate. The vacuum-deposited OSC molecules diffused and rearranged on the surface according to the substrate temperature gradient, producing directional crystalline and grain structures in the PDI-CN2 film. The morphological and crystalline structures of the PDI-CN2 thin films grown under a vertical temperature gradient were dramatically enhanced, comparing with the structures obtained from either uniformly heated films or films prepared under a horizontally applied temperature gradient. The field effect mobilities of the PDI-CN2-FETs prepared using the vertically applied temperature gradient were as high as 0.59 cm 2 V -1 s -1 , more than a factor of 2 higher than the mobility of 0.25 cm 2 V -1 s -1 submitted to conventional thermal annealing and the mobility of 0.29 cm 2 V -1 s -1 from the horizontally applied temperature gradient.

  18. Laser printed organic semiconductor PQT-12 for bottom-gate organic thin-film transistors: Fabrication and characterization

    Energy Technology Data Exchange (ETDEWEB)

    Makrygianni, M. [National Technical University of Athens, Physics Department, Iroon Polytehneiou 9, 15780 Zografou (Greece); National Technical University of Athens, Electrical and Computer Engineering Department, Iroon Polytehneiou 9, 15780 Zografou (Greece); Ainsebaa, A. [Ecole Nationale Supérieure des Mines de Saint-Etienne, Department of Flexible Electronics, CMP-EMSE, MOC, 13541 Gardanne (France); Nagel, M. [EMPA Swiss Federal Lab. for Materials Science and Technology, Laboratory for Functional Polymers, Überlandstrasse 129, 8600 Dubendorf (Switzerland); Sanaur, S. [Ecole Nationale Supérieure des Mines de Saint-Etienne, Department of Flexible Electronics, CMP-EMSE, MOC, 13541 Gardanne (France); Raptis, Y.S. [National Technical University of Athens, Physics Department, Iroon Polytehneiou 9, 15780 Zografou (Greece); Zergioti, I., E-mail: zergioti@central.ntua.gr [National Technical University of Athens, Physics Department, Iroon Polytehneiou 9, 15780 Zografou (Greece); Tsamakis, D. [National Technical University of Athens, Electrical and Computer Engineering Department, Iroon Polytehneiou 9, 15780 Zografou (Greece)

    2016-12-30

    Highlights: • Smooth printing of semiconducting π-conjugated polymer patterns for BG-BC OTFTs. • Well-ordering of PQT-12 when diluted in a high-boiling-point solvent yielding good interface properties. • No significant change in polymer chain orientation observed between LIFT printed patterns. • Reliable solid phase printing technique for thin, organic large area electronics applications, in a well-defined manner. - Abstract: In this work, we report on the effect of laser printed Poly (3,3‴-didodecyl quarter thiophene) on its optical, structural and electrical properties for bottom-gate/bottom-contact organic thin-film transistors applications. This semiconducting π-conjugated polymer was solution-deposited (spin-coated) on a donor substrate and transferred by means of solid phase laser-induced forward transfer (LIFT) technique on SiO{sub 2}/Si receiver substrates to form the active material. This article presents a detailed study of the electrical properties of the fabricated transistors by measuring the parasitic resistances for gold (Au) and platinum (Pt) as source-drain electrodes, for optimizing OTFTs in terms of contacts. In addition, X-ray diffraction patterns revealed that it is possible to control the polymer microstructure through the choice of solvent. Also, no significant change in polymer chain orientation was observed between two printed patterns at 90 and 130 mJ/cm{sup 2} as confirmed by Raman spectra. The results demonstrate hole mobility values of (2.6 ± 1.3) × 10{sup −2} cm{sup 2}/Vs, and lower parasitic resistance for dielectric surface roughness around 1.2 nm and Pt electrodes. Higher performances are correlated to i) the well-ordering of PQT-12 surface when a high-boiling-point solvent is used and ii) the less limitating Pt source/drain electrodes. This analytical study proves that solid phase LIFT printing is a reliable technology for the fabrication of thin, organic large area electronics in a well-defined manner.

  19. Laser printed organic semiconductor PQT-12 for bottom-gate organic thin-film transistors: Fabrication and characterization

    International Nuclear Information System (INIS)

    Makrygianni, M.; Ainsebaa, A.; Nagel, M.; Sanaur, S.; Raptis, Y.S.; Zergioti, I.; Tsamakis, D.

    2016-01-01

    Highlights: • Smooth printing of semiconducting π-conjugated polymer patterns for BG-BC OTFTs. • Well-ordering of PQT-12 when diluted in a high-boiling-point solvent yielding good interface properties. • No significant change in polymer chain orientation observed between LIFT printed patterns. • Reliable solid phase printing technique for thin, organic large area electronics applications, in a well-defined manner. - Abstract: In this work, we report on the effect of laser printed Poly (3,3‴-didodecyl quarter thiophene) on its optical, structural and electrical properties for bottom-gate/bottom-contact organic thin-film transistors applications. This semiconducting π-conjugated polymer was solution-deposited (spin-coated) on a donor substrate and transferred by means of solid phase laser-induced forward transfer (LIFT) technique on SiO_2/Si receiver substrates to form the active material. This article presents a detailed study of the electrical properties of the fabricated transistors by measuring the parasitic resistances for gold (Au) and platinum (Pt) as source-drain electrodes, for optimizing OTFTs in terms of contacts. In addition, X-ray diffraction patterns revealed that it is possible to control the polymer microstructure through the choice of solvent. Also, no significant change in polymer chain orientation was observed between two printed patterns at 90 and 130 mJ/cm"2 as confirmed by Raman spectra. The results demonstrate hole mobility values of (2.6 ± 1.3) × 10"−"2 cm"2/Vs, and lower parasitic resistance for dielectric surface roughness around 1.2 nm and Pt electrodes. Higher performances are correlated to i) the well-ordering of PQT-12 surface when a high-boiling-point solvent is used and ii) the less limitating Pt source/drain electrodes. This analytical study proves that solid phase LIFT printing is a reliable technology for the fabrication of thin, organic large area electronics in a well-defined manner.

  20. Physical effects of DCNQI derivatives doping as an N type organic semiconductor in organic photovoltaic cell performance.

    Science.gov (United States)

    Lee, Joo Hyung; Oh, Se Young

    2014-08-01

    In the previous work, we have reported that organic photovoltaic (OPV) cells using DMDCNQI as an n-type second dopant material showed a high power conversion efficiency (PCE). In the present work, we have synthesized a novel DHDCNQI with long alkyl chains to improve the compatibility between the DHDCNQI dopant molecule and host P3HT polymer. We have fabricated OPV cells consisting of ITO/PEDOT:PSS/P3HT:PCBM:DHDCNQI/Al. We have investigated the characteristics of theses OPV cells using DCNQI derivative dopants from the measurements of the incident photon-to-current collection efficiency and photocurrent. The OPV cell using 3 wt% DHDCNQI exhibited a high PCE of 3.29% due to the high charge separation efficiency, good compatibility and low trap site effect.