Browsing by Author "Su, Ming-Hsin"

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Intramolecular donor-acceptor regioregular poly(3-hexylthiophene)s presenting octylphenanthrenyl-imidazole moieties exhibit enhanced charge transfer for heterojunction solar cell applications
(2008-08-22)
Chang, Yao-Te
;
Hsu, So-Lin
;
Chen, Guan-Yu
;
Su, Ming-Hsin
;
Singh, Thounaojam Avinash
Intramolecular donor-acceptor structures prepared by covalently binding conjugated octylphenanthrenyl-imidazole moieties onto the side chains of regioregular poly(3-hexylthiophene)s exhibit lowered bandgaps and enhanced electron transfer compared to the parent polymer, e.g., conjugation of 90 mol% octylphenanthrenyl-imidazole moieties onto poly(3-hexylthiophene) chains reduces the optical bandgap from 1.91 to 1.80 eV, and the electron transfer probability is at least twice as high as that of pure poly(3-hexylthiophene) when blended with [6,6]-phenyl-C-61-butyric acid methyl ester. The lowered bandgap and the fast charge transfer both contribute to much higher external quantum efficiencies, thus much higher short-circuit current densities for copolymers presenting octylphenanthrenyl-imidazole moieties, relative to those of pure poly(3-hexylthiophene)s. The short-circuit current density of a device prepared from a copolymer presenting 90 mol% octylphenanthrenyl-imidazole moieties is 13.7 mA . cm(-2) which is an increase of 65% compared to the 8.3 mA . cm(-2) observable for a device containing pure poly(3-hexylthiophene). The maximum power conversion efficiency of this particular copolymer is 3.45% which suggest that such copolymers are promising polymeric photovoltaic materials.
Intramolecular Donor-Acceptor Regioregular Poly(hexylphenanthrenyl-imidazole thiophene) Exhibits Enhanced Hole Mobility for Heterojunction Solar Cell Applications
(2009-05-25)
Chang, Yao-Te
;
Hsu, So-Lin
;
Su, Ming-Hsin
;
Wei, Kung-Hwa
;
材料科學與工程學系
PHPIT, a new kind of intramolecular donor-acceptor side-chain-tethered hexyl-phenanthrenyl-imidazole polythiophene, is synthesized. The more balanced electron and hole mobilities and the enhanced visible- and internal-light absorptions in the devices consisting of annealed PHPIT/PCBM blends both contribute to a much higher short-circuit current density, which in turn led to a power conversion efficiency as high as 4.1%.
Inverted heterojunction solar cells incorporating fullerene/polythiophene composite core/shell nanorod arrays
(2010-04-09)
Wang, Hsu-Shen
;
Chen, Shih-Yung
;
Su, Ming-Hsin
;
Wang, Yuh-Lin
;
Wei, Kung-Hwa
We have fabricated inverted heterojunction solar cell devices incorporating [6,6]-phenyl-C(61)-butyric acid methyl ester/poly(3-hexylthiophene) core/shell nanorod arrays by using an anodic alumina oxide template. The internal quantum efficiencies and external quantum efficiencies of these core/shell nanorod inverted solar cells were higher than those of the corresponding conventional inverted bulk heterojunction device. The optimized nanorod array structure had a high hole mobility that was over one order magnitude greater than that of the conventional bulk heterojunction structure, as determined by fitting the dark J-V curves into the space charge limited current model. The more efficient carrier transport of the device incorporating the core/shell nanorod arrays provided it with both a higher short-circuit current density and power conversion efficiency.
Soluble phenanthrenyl-imidazole-presenting regioregular poly (3-octylthiophene) copolymers having tunable bandgaps for solar cell applications
(2007-11-05)
Chang, Yao-Te
;
Hsu, So-Lin
;
Su, Ming-Hsin
;
Wei, Kung-Hwa
;
材料科學與工程學系
We have used Grignard metathesis polymerization to successfully synthesize a series of regioregular polythiophene copolymers that contain electron-withdrawing and conjugated phenanthrenyl-imidazole moieties as side chains. The introduction of the phenanthrenyl-imidazole moieties onto the side chains of the regioregular polythiophenes increased their conjugation lengths and thermal stabilities and altered their bandgap structures. The bandgap energies, determined from the onset of optical absorption, could be tuned from 1.89 eV to 1.77 eV by controlling the number of phenanthrenyl-imidazole moieties in the copolymers. Moreover, the observed quenching in the photoluminescence of these copolymers increases with the number of phenanthrenyl-imidazole moieties in the copolymers, owing to the fast deactivation of the excited state by the electron-transfer reaction. Both the lowered bandgap and fast charge transfer contribute to the much higher external quantum efficiency of the poly (3-octylthiophene)-side-chain-tethered phenanthrenyl-imidazole than that of pure poly(3-octylthiophene), leading to much higher short circuit current density. In particular, the short circuit current densities of the device containing the copolymer having 80 mol % phenanthrenyl-imidazole, P82, improved to 14.2 mA cm(-2) from 8.7 mA cm(-2) for the device of pure poly(3-octylthiophene), P00, an increase of 62 %. In addition, the maximum power conversion efficiency improves to 2.80 % for P82 from 1.22 % for P00 (pure P30T). Therefore, these results indicate that our polymers are promising polymer photovoltaic materials.
Synthesis and Characterization of Donor-Bridge-Acceptor Alternating Copolymers Containing Perylene Diimide Units and Their Application to Photovoltaic Cells
(2010-03-15)
Yuan, Mao-Chuan
;
Su, Ming-Hsin
;
Chiu, Mao-Yuan
;
Wei, Kung-Hwa
;
材料科學與工程學系
We have used Suzuki coupling to prepare a series of alternating copolymers featuring coplanar cyclopentadithiophene and hole-transporting carbazole units. We observed quenching in the photoluminescence spectra of our polymers after incorporating pendent electron-deficient perylene diimide (PDI) moieties on the side chains, indicating more efficient photoinduced electron transfer. Electrochemical measurements revealed that the PDI-containing copolymers displayed reasonable and sufficient offsets of the energy levels of their lowest unoccupied molecular orbitals for efficient charge dissociation. The performance of bulk heterojunction photovoltaic cells incorporating the copolymer/[6,6]-phenyl-C(61)-butyric acid methyl ester blends (1:4, w/w) was optimized when the active layer had a thickness of 70 nm. The photocurrents of the devices were enhanced as a result of the presence of the PDI moieties, thereby leading to improved power conversion efficiencies. (C) 2010 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 48: 1298-1309, 2010