The Experts below are selected from a list of 150 Experts worldwide ranked by ideXlab platform
Wen-chang Chen - One of the best experts on this subject based on the ideXlab platform.
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Solvent Effects on Morphology and Electrical Properties of Poly(3-hexylthiophene) Electrospun Nanofibers.
Polymers, 2019Co-Authors: Jung-yao Chen, Chau-hsien Hsu, Yi‐hua Zhang, Qin-cheng Zhang, Chia-ling Chang, Chi-chung Hua, Wen-chang ChenAbstract:Herein, poly(3-hexylthiophene-2,5-diyl) (P3HT) nanofiber-based organic field-effect transistors were successfully prepared by coaxial electrospinning technique with P3HT as the core polymer and poly(methyl methacrylate) (PMMA) as the shell polymer, followed by extraction of PMMA. Three different solvents for the core polymer, including chloroform, chlorobenzene and 1,2,4-trichlorobenzene, were employed to manipulate the morphologies and electrical properties of P3HT electrospun nanofibers. Through the analyses from dynamic light scattering of P3HT solutions, polarized photoluminescence and X-ray diffraction pattern of P3HT electrospun nanofibers, it is revealed that the P3HT electrospun nanofiber prepared from the chloroform system displays a low crystallinity but highly oriented crystalline grains due to the dominant population of Isolated-Chain species in solution that greatly facilitates P3HT Chain stretching during electrospinning. The resulting high charge-carrier mobility of 3.57 × 10−1 cm2·V−1·s−1 and decent mechanical deformation up to a strain of 80% make the P3HT electrospun nanofiber a promising means for fabricating stretchable optoelectronic devices.
Show-an Chen - One of the best experts on this subject based on the ideXlab platform.
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Hole mobility on Isolated Chains of poly(3-hexylthiophene) by microwave conductivity measurement
The Journal of chemical physics, 2009Co-Authors: Ching-yang Liu, Show-an ChenAbstract:We demonstrate a facile method to investigate intrinsic charge mobility on Isolated Chains of conjugated polymers by use of microwave absorption method. Hole carriers are generated on conjugated polymer Chains in dilute solution by doping with the p-type dopants NOSbF6, instead of using excitation sources of pulsed laser and electron beam as reported in the literature. The number of hole carriers can be easily estimated by doping level. Measurements on poly(3-hexylthiophene) in benzene with various doping levels from 0.1% to 3% indicate that the hole mobility can be divided into two ranges. In the doping level 0.1%–0.3%, the hole mobility maintains at the constant level 0.03 cm2/V s, which can be regarded as that on an Isolated Chain since the average number of hole carriers per Chain is only around one. As the doping level is higher than 0.3%, a presence of multiple hole carriers on a Chain occurs, which results in a repulsion of hole carriers and leads to a reduced hole mobility.
Claudio De Rosa - One of the best experts on this subject based on the ideXlab platform.
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Chain conformations of syndiotactic poly(m-methylstyrene) in the crystalline state
Polymer, 2003Co-Authors: Claudio De Rosa, Simona Esposito, Annamaria Buono, Finizia AuriemmaAbstract:A conformational energy analysis of the Isolated Chain of syndiotactic poly(m-methylstyrene) under the constraint of a crystalline field is reported. Two different minimum energy conformations having similar energy have been found; the trans-planar conformation with tcm symmetry and the two-fold helical conformation with s(2/1)2 symmetry, according with the observed polymorphic behavior of this polymer. The calculated Chain axes are in agreement with the experimental axes of 5.1 and 7.9 A found for the different polymorphic forms of syndiotactic poly(m-methylstyrene). However, only a metastable disordered modification (form III) having Chains in trans-planar conformation has been described. This indicates that, even though the trans-planar conformation is, in the Isolated Chain as stable as the helical conformation, the packing of the Chains in helical conformation is probably more efficient than that of the trans-planar Chains.
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Conformational and Packing Energy Calculations for Isotactic Poly(vinylcyclohexane): Crystal Structure of Form I
Macromolecules, 1996Co-Authors: Claudio De Rosa, And Anna Borriello, Paolo CorradiniAbstract:The polymorphic behavior of poly(vinylcyclohexane) is discussed on the basis of conformational energy calculations on an Isolated Chain. The presence of two different modifications is in accordance with the energy minima present in the conformational energy maps. The packing of the Chains in form I is analyzed on the basis of packing energy and structure factor calculations.
Jean-luc Brédas - One of the best experts on this subject based on the ideXlab platform.
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Electronic Evolution of Poly(3,4-ethylenedioxythiophene) (PEDOT): From the Isolated Chain to the Pristine and Heavily Doped Crystals
Journal of the American Chemical Society, 2008Co-Authors: Eung-gun Kim, Jean-luc BrédasAbstract:Poly(3,4-ethylenedioxythiophene) (PEDOT) is the prototypical conjugated polymer used in the doped state as the hole injection/transport layer in organic (opto)electronic devices. Numerous experimental studies have been successful only in drawing a partial microscopic picture of PEDOT due to its complex morphology, which has also hampered application of theoretical approaches. Using density functional theory methods, combined with refined structural models built upon crystallographic data of PEDOT and other substituted polythiophenes, our work seeks to establish a comprehensive understanding of the electronic and geometric structures of PEDOT, as an Isolated Chain and in the pristine and doped bulk phases. We find that ethylenedioxy substitution planarizes the polythiophene backbone but the experimentally observed bandgap reduction is caused mainly by a stronger destabilization of the valence band than the conduction band via donor-type substitution. The calculated crystal of pristine PEDOT has a monoclini...
Jung-yao Chen - One of the best experts on this subject based on the ideXlab platform.
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Solvent Effects on Morphology and Electrical Properties of Poly(3-hexylthiophene) Electrospun Nanofibers.
Polymers, 2019Co-Authors: Jung-yao Chen, Chau-hsien Hsu, Yi‐hua Zhang, Qin-cheng Zhang, Chia-ling Chang, Chi-chung Hua, Wen-chang ChenAbstract:Herein, poly(3-hexylthiophene-2,5-diyl) (P3HT) nanofiber-based organic field-effect transistors were successfully prepared by coaxial electrospinning technique with P3HT as the core polymer and poly(methyl methacrylate) (PMMA) as the shell polymer, followed by extraction of PMMA. Three different solvents for the core polymer, including chloroform, chlorobenzene and 1,2,4-trichlorobenzene, were employed to manipulate the morphologies and electrical properties of P3HT electrospun nanofibers. Through the analyses from dynamic light scattering of P3HT solutions, polarized photoluminescence and X-ray diffraction pattern of P3HT electrospun nanofibers, it is revealed that the P3HT electrospun nanofiber prepared from the chloroform system displays a low crystallinity but highly oriented crystalline grains due to the dominant population of Isolated-Chain species in solution that greatly facilitates P3HT Chain stretching during electrospinning. The resulting high charge-carrier mobility of 3.57 × 10−1 cm2·V−1·s−1 and decent mechanical deformation up to a strain of 80% make the P3HT electrospun nanofiber a promising means for fabricating stretchable optoelectronic devices.
