Home About us Contact
|
Home About us Contact | ||
|
|
||
Semiconducting Polymer (semiconducting + polymer)
Selected AbstractsCharge Transport in Disordered Organic Materials and Its Relevance to Thin-Film Devices: A Tutorial ReviewADVANCED MATERIALS, Issue 27 2009Nir Tessler Abstract Semiconducting polymers and small molecules form an extremely flexible class of amorphous materials that can be used in a wide range of applications, some of which are display, radio-frequency tags, and solar cells. The rapid progress towards functional devices is occurring despite the lack of sufficient understanding of the physical processes and very little experience in device engineering. This tutorial review aims to provide sufficient intuitive background to draw more researchers to look into the fundamental aspects of device physics and engineering. [source] Enhanced Charge Transportation in Semiconducting Polymer/Insulating Polymer Composites: The Role of an Interpenetrating Bulk InterfaceADVANCED FUNCTIONAL MATERIALS, Issue 11 2010Guanghao Lu Abstract The charge transportation in poly(3-butylthiophene) (P3BT)/insulating polymer composites is studied both microscopically and macroscopically. The increased mobility of free charge carriers, in particular hole mobility, contributes to the enhanced electrical conductivity of this semiconductor/insulator composite. The conductivity origin of the composite, as revealed by conductive-atomic force microscopy (C-AFM), comes mainly from the P3BT network, whose carrier mobility has been improved as a result of reduced activation energy for charge transportation upon forming an interface with the insulating matrix. Both the huge interfacial area and interconnected conductive component are morphologically required for the enhanced electrical property of the composite. An increased size of the P3BT domains, which correspondingly reduces the interfacial area between the two components, ruins the enhancement. This study clarifies the mechanism of the higher electrical properties achieved in a semiconducting polymer upon blending with an insulating polymer, which will further promote the development of these low-cost, easily processable, and environmentally stable composites. [source] Controllable Shifts in Threshold Voltage of Top-Gate Polymer Field-Effect Transistors for Applications in Organic Nano Floating Gate MemoryADVANCED FUNCTIONAL MATERIALS, Issue 2 2010Kang-Jun Baeg Abstract Organic field-effect transistor (FET) memory is an emerging technology with the potential to realize light-weight, low-cost, flexible charge storage media. Here, solution-processed poly[9,9-dioctylfluorenyl-2,7-diyl]-co-(bithiophene)] (F8T2) nano floating gate memory (NFGM) with a top-gate/bottom-contact device configuration is reported. A reversible shift in the threshold voltage (VTh) and reliable memory characteristics was achieved by the incorporation of thin Au nanoparticles (NPs) as charge storage sites for negative charges (electrons) at the interface between polystyrene and cross-linked poly(4-vinylphenol). The F8T2 NFGM showed relatively high field-effect mobility (µFET) (0.02,cm2 V,1 s,1) for an amorphous semiconducting polymer with a large memory window (ca. 30,V), a high on/off ratio (more than 104) during writing and erasing with an operation voltage of 80,V of gate bias in a relatively short timescale (less than 1,s), and a retention time of a few hours. This top-gated polymer NFGM could be used as an organic transistor memory element for organic flash memory. [source] Optically-Pumped Lasing in Hybrid Organic,Inorganic Light-Emitting DiodesADVANCED FUNCTIONAL MATERIALS, Issue 13 2009Myoung Hoon Song Abstract Here, the use of metal oxide layers both for charge transport and injection into an emissive semiconducting polymer and also for the control of the in-plane waveguided optical modes in light-emitting diodes (LEDs) is reported. The high refractive index of zinc oxide is used to confine these modes away from the absorbing electrodes, and include a nano-imprinted grating in the polymer layer to introduce distributed feedback and enhance optical out-coupling. These structures show a large increase in the luminescence efficiency over conventional devices, with photoluminescence efficiency increased by up to 45%. Furthermore, optically-pumped lasing in hybrid oxide polymer LEDs is demonstrated. A tuneable lasing emission is also obtained in a single device structure by employing a graduated thickness of a zinc oxide inter-layer. This demonstrates the scope for using such architectures to improve the external efficiency of organic semiconductor LEDs, and opens new possibilities for the realization of polymer injection lasers. [source] Infiltrating Semiconducting Polymers into Self-Assembled Mesoporous Titania Films for Photovoltaic Applications,ADVANCED FUNCTIONAL MATERIALS, Issue 4 2003K.M. Coakley Abstract Interpenetrating networks of organic and inorganic semiconductors are attractive for photovoltaic cells because electron transfer between the two semiconductors splits excitons. In this paper we show that films of titania with a uniform distribution of pore sizes can be made using a block copolymer as a structure-directing agent, and that 33,% of the total volume of the film can be filled with a semiconducting polymer. [source] Novel Thiophene-Thiazolothiazole Copolymers for Organic Field-Effect Transistors,ADVANCED MATERIALS, Issue 23 2007I. Osaka A semiconducting polymer bearing the thiazolothiazole moiety in the polythiophene backbone (see figure) is synthesized. The polymer is found to have small bandgap and large ionization potential. Despite the low molecular weight, the polymer exhibited a high field-effect mobility after annealing. A high on/off ratio suggests the polymer possesses high stability against oxygen doping. The polymer device also showed good environmental stability. [source] Efficient Hybrid Solar Cells from Zinc Oxide Nanoparticles and a Conjugated Polymer,ADVANCED MATERIALS, Issue 12 2004ZnO nanoparticles dispersed in a semiconducting polymer form the active layer of a solar cell (see Figure) that is able to convert up to 40,% of the incident photons at 500,nm into electrical current and has a power conversion efficiency of about 1.5,% in sunlight. Manufactured at low temperature using environmentally friendly materials, it represents a new step to ,green electricity'. [source] Synthesis and photophysical properties of a novel semiconducting polymerPOLYMERS FOR ADVANCED TECHNOLOGIES, Issue 1-2 2004Hongmin Huang Abstract An alternating copolymer containing triphenylamine (TPA) and cyano-substituted benzene moieties, TPA-CNPPV was synthesized using the Wittig reaction. The monomers and polymer were characterized by H-NMR, FT-IR and mass spectroscopy (MS). The polymer shows good solubility in common organic solvents and excellent film-forming ability. Thermogravimetric analysis (TGA) demonstrates that the polymer has a degradation temperature (TD) of 600°C; differential scanning calorimetry (DSC) result indicates that the glass transition temperature (Tg) of TPA-CNPPV is 160°C, suggesting high thermal stability. The photophysical properties of the light-emitting material were investigated in both solution and spin-coated film. Photo-isomerization of the polymer was investigated by UV-vis and fluorescence spectra. The interaction between TPA-CNPPV and C60 was studied by fluorescence quenching. Copyright © 2004 John Wiley & Sons, Ltd. [source] Conjugated-Polymer-Based Lateral Heterostructures Defined by High-Resolution PhotolithographyADVANCED FUNCTIONAL MATERIALS, Issue 17 2010Jui-Fen Chang Abstract Solution processing of polymer semiconductors provides a new paradigm for large-area electronics manufacturing on flexible substrates, but it also severely restricts the realization of interesting advanced device architectures, such as lateral heterostructures with defined interfaces, which are easily accessible with inorganic materials using photolithography. This is because polymer semiconductors degrade, swell, or dissolve during conventional photoresist processing. Here a versatile, high-resolution photolithographic method is demonstrated for patterning of polymer semiconductors and exemplify this with high-performance p-type and n-type field-effect transistors (FETs) in both bottom- and top-gate architectures, as well as ambipolar light-emitting field-effect transistors (LEFETs), in which the recombination zone can be pinned at a photolithographically defined lateral heterojunction between two semiconducting polymers. The technique therefore enables the realization of a broad range of novel device architectures while retaining optimum materials performance. [source] Tunable Injection Barrier in Organic Resistive Switches Based on Phase-Separated Ferroelectric,Semiconductor Blends,ADVANCED FUNCTIONAL MATERIALS, Issue 19 2009Kamal Asadi Abstract 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 diodes. Comparison between the on- and off-current of the switching diodes, with the current measured for semiconductor-only diodes reveals that the switching occurs between bulk-limited, i.e., space-charge-limited, and injection-limited current transport. By deliberately varying the HOMO energy of the semiconductor and the work-function of the metal electrode, it is demonstrated that injection barriers up to 1.6,eV can be surmounted by the ferroelectric polarization yielding on/off current modulations of more than five orders of magnitude. The exponential dependence of the current modulation with a slope of 0.25,eV/decade is rationalized by the magnitude of the injection barrier. [source] A Nitrogen Dioxide Sensor Based on an Organic Transistor Constructed from Amorphous Semiconducting Polymers,ADVANCED MATERIALS, Issue 22 2007A. Das Organic field effect transistors based on amorphous semiconducting polymers are used as highly effective sensors for the detection of low concentrations of NO2. The figure shows the experimental setup used to detect the toxic odor. The threshold voltage rather than the charge carrier mobility is seen to be greatly modified by exposure to NO2. [source] Cover Picture: Multilayer Polymer Light-Emitting Diodes: White-Light Emission with High Efficiency (Adv. Mater.ADVANCED MATERIALS, Issue 17 200517/2005) Abstract White-light-emitting polymer diodes can be fabricated by solution processing using a blend of luminescent semiconducting polymers and organometallic complexes as the emission layer, and water-soluble (or ethanol-soluble) polymers and/or small molecules as the hole-injection/transport layer (HIL/HTL) and the electron injection/transport layer (EIL/ETL), as reported on p.,2053 by Gong, Bazan, Heeger and co-workers. Illumination-quality light is obtained from these multilayer, high-performance devices, with stable CIE coordinates, color temperatures, and high color-rendering indices all close to those of "pure" white light. The cover illustration envisages the incorporation of the fabrication technique with low-cost manufacturing technology in order to produce large areas of high-quality white light. [source] Synthesis and properties of phenothiazylene vinylene-based polymers: New organic semiconductors for field-effect transistors and solar cellsJOURNAL OF POLYMER SCIENCE (IN TWO SECTIONS), Issue 3 2010Seon-Kyoung Son Abstract A series of new phenothiazylene vinylene-based semiconducting polymers, poly[3,7-(4,-dodecyloxyphenyl)phenothiazylene vinylene] (P1), poly[3,7-(4,-dodecyloxyphenyl)phenothiazylene vinylene- alt -1,4-phenylene vinylene] (P2), and poly[3,7-(4,-dodecyloxyphenyl)phenothiazylene vinylene- alt -2,5-thienylene vinylene] (P3), have been synthesized via a Horner-Emmons reaction. FTIR and 1H NMR spectroscopies confirmed that the configurations of the vinylene groups in the polymers were all - trans (E). The weight-averaged molecular weights (Mw) of P1, P2, and P3 were found to be 27,000, 22,000, and 29,000, with polydispersity indices of 1.91, 2.05, and 2.25, respectively. The thermograms for P1, P2, and P3 each contained only a broad glass transition, at 129, 167, and 155 °C, respectively, without the observation of melting features. UV,visible absorption spectra of the polymers showed two strong absorption bands in the ranges 315,370 nm and 450,500 nm, which arose from absorptions of the phenothiazine segments and the conjugated main chains. Solution-processed field-effect transistors fabricated from these polymers showed p -type organic thin-film transistor characteristics. The field-effect mobilities of P1, P2, and P3 were measured to be 1.0 × 10,4, 3.6 × 10,5, and 1.0 × 10,3 cm2 V,1 s,1, respectively, and the on/off ratios were in the order of 102 for P1 and P2, and 103 for P3. Atomic force microscopy and X-ray diffraction analysis of thin films of the polymers show that they have amorphous structures. A photovoltaic device in which a P3/PC71BM (1/5) blend film was used as the active layer exhibited an open-circuit voltage (VOC) of 0.42 V, a short circuit current (JSC) of 5.17 mA cm,2, a fill factor of 0.35, and a power conversion efficiency of 0.76% under AM 1.5 G (100 mW cm,2) illumination. © 2009 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 48: 635,646, 2010 [source] Charge-carrier mobilities in disordered semiconducting polymers: effects of carrier density and electric fieldPHYSICA STATUS SOLIDI (C) - CURRENT TOPICS IN SOLID STATE PHYSICS, Issue 2 2006K.D. Meisel The cover picture of this issue of physica status solidi (c) has been taken from the article [1]. [source] | ||||||||||