Browsing by Author "Yang, Po-An"

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Benzooxadiazole-based donor/acceptor copolymers imparting bulk-heterojunction solar cells with high open-circuit voltages
(2013-01-08)
Jiang, Jian-Ming
;
Yang, Po-An
;
Lan, Shang-Che
;
Yu, Chia-Ming
;
Wei, Kung-Hwa
In this study we used Suzuki cross-coupling to synthesize three new donor/acceptor copolymers-PFTBO, PAF1130, and PCTBO-featuring soluble alkoxy-modified 2,1,3-benzooxadiazole (BO) moieties as acceptor units and electron-rich building blocks-dialkyl fluorene (F), alkylidene fluorene (AF), and carbazole (C), respectively-as donor units. These polymers, which we characterized using gel permeation chromatography, thermogravimetric analysis, NMR spectroscopy, UV-Vis absorption spectroscopy, and electrochemical cyclic voltammetry, exhibited good solubility, low-lying energy levels for their highest occupied molecular orbitals, excellent thermal stability, and air stability. Using these polymers, we fabricated bulk-heterojunction solar cell devices having the structure indium tin oxide/poly(3,4-ethylenedioxythiophene):polystyrenesulfonate/polymer:[6,6]-phenyl-C-61-butyric acid methyl ester (PC61BM) (1:1, w/w)/Ca/Al. Under AM 1.5G illumination (100 mW cm(-2)), the solar cell incorporating PFTBO exhibited a high value of V-OC of 1.04 V and that based on PCTBO provided a power conversion efficiency of 4.1% without the need for any post treatment. (C) 2012 Elsevier Ltd. All rights reserved.
Crystalline Low-Band Gap Polymers Comprising Thiophene and 2,1,3-Benzooxadiazole Units for Bulk Heterojunction Solar Cells
(2011-12-13)
Jiang, Jian-Ming
;
Yang, Po-An
;
Hsieh, Tsung-Hsuan
;
Wei, Kung-Hwa
;
材料科學與工程學系
We have used Stille coupling polymerization to synthesize a series of new crystalline low band gap conjugated polymers-PTHBO, PBTTBO, and PTTTBO-constituting mainly electron-rich thiophene (TH), 2,2'-bithiophene (BT), and thieno[3,2-b]thiophene (TT) units in conjugation with electron-deficient 2,1,3-benzooxadiazole (BO) moieties. All of these polymers exhibited (i) sufficient energy offsets with respect to those of fullerenes to allow efficient charge transfer and (ii) low-lying highest occupied molecular orbital (HOMO, -5.47 eV). These polymers exhibited excellent thermal stability, high crystallinity, and broad spectral absorptions. As a result, bulk hetero-junction photovoltaic devices derived from these polymers and fullerenes provided open-circuit voltages (V(oc)) as high as 1.02 V. In particular, the photovoltaic device comprising the PTTTBO/PC(61)BM (1:1) blend system and 1,8-diiodooctane (DIO, 0.5 vol %) as an additive exhibited excellent performance, under AM 1.5 G irradiation (100 mW cm(-2)), with a value of V(oc) of 0.85 V, a short-circuit current density (J(sc)) of 11.6 mA cm(-2), a fill factor (FF) of 0.54, and a promising power conversion efficiency (PCE) of 5.3%.
Synthesis, characterization, and photovoltaic properties of a low-bandgap copolymer based on 2,1,3-benzooxadiazole
(2011-01-01)
Jiang, Jian-Ming
;
Yang, Po-An
;
Chen, Hsiu-Cheng
;
Wei, Kung-Hwa
;
材料科學與工程學系
PBDTBO, a conjugated polymer comprising benzo[1,2-b:4,5-b']dithiophene (BDT) and 5,6-bis(octyloxy) benzo[c][1,2,5]-oxadiazole (BO) units, exhibits a deep HOMO energy level of -5.27 eV and excellent solubility. A device incorporating PBDTBO and [6,6]-phenyl-C(61)-butyric acid methyl ester (1 : 1, w/w) exhibited a power conversion efficiency of 5.7%.
Synthesis, characterization, and photovoltaic properties of a low-bandgap copolymer based on 2,1,3-benzooxadiazole
(2011-01-01)
Jiang, Jian-Ming
;
Yang, Po-An
;
Chen, Hsiu-Cheng
;
Wei, Kung-Hwa
;
材料科學與工程學系
PBDTBO, a conjugated polymer comprising benzo[1,2-b:4,5-b']dithiophene (BDT) and 5,6-bis(octyloxy) benzo[c][1,2,5]-oxadiazole (BO) units, exhibits a deep HOMO energy level of -5.27 eV and excellent solubility. A device incorporating PBDTBO and [6,6]-phenyl-C(61)-butyric acid methyl ester (1 : 1, w/w) exhibited a power conversion efficiency of 5.7%.
The new low-band gap polymers comprising C-, Si-, or N-bridged dithiophene and alkoxy-modified 2,1,3-benzooxadiazole units for bulk heterojunction solar cells
(2012-10-01)
Jiang, Jian-Ming
;
Yang, Po-An
;
Yu, Chia-Ming
;
Lin, His-Kuei
;
Huang, Kuei-Chun
In this study, we used Stille coupling polymerization to synthesize a series of new low-band gap-conjugated polymersPCyTBO, PCySiTBO, and PCyNTBOcomprising mainly electron-rich C-, Si-, and N-bridged dithiophene units in conjugation with electron-deficient alkoxy-modified 2,1,3-benzooxadiazole moieties. The highest occupied molecular orbital energy levels of these polymers become higher as the electron-donating ability of C-, Si-, or N-bridged dithiophene units increases. These polymers also displayed excellent thermal stability and broad spectral absorptions, with PCySiTBO revealing some crystallinity. As a result, the photovoltaic device incorporating the PCySiTBO/PC71BM (1:1) blend system and 1,8-diiodooctane (2 vol %) as an additive exhibited excellent performance, under AM 1.5 G irradiation (100 mW cm-2), with a value of Voc of 0.64 V, a short-circuit current density of 13.8 mA cm-2, a fill factor of 0.57, and a promising power conversion efficiency of 5.0%. (c) 2012 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2012
Thiophene spacers impart crystallinity and enhance the efficiency of benzotrithiophene-based conjugated polymers for bulk heterojunction photovoltaics
(2013)
Lan, Shang-Che
;
Yang, Po-An
;
Zhu, Meng-Jie
;
Yu, Chia-Min
;
Jiang, Jian-Ming
In this study we synthesized the donor-acceptor conjugated copolymers PBTT4BT and PBTT4BO featuring benzotrithiophene (BTT) units as donors and benzothiadiazole (BT) and benzoxadiazole (BO) units, respectively, as acceptors, linked through 4-dodecylthiophene spacers. The presence of the spacer units enhanced not only the solubility of the synthesized polymers but also their molecular packing in the solid state; both of these polymers exhibited good crystallinity, as evidenced by a d-spacing of 23.8 angstrom in the (100) plane in their X-ray diffraction curves. When we used these synthesized polymers in bulk heterojunction photovoltaic device applications, the optimal device incorporating PBTT4BO/PC61BM as the active layer exhibited a low efficiency of 3.2%, due to the poor solubility of PBTT4BO, whereas the optimal device incorporating the more-soluble PBTT4BT and PC71BM displayed an efficiency of 4.4%, which is substantially 1.5% higher than that for the PBTTBT/PC71BM device, where PBTTBT was formed by copolymerizing BTT and BT units without any spacer. After thermal annealing, the efficiency of the PBTT4BT/PC71BM device improved further to 5.6%, with a V-OC value of 0.72 V, a J(SC) value of 11.58 mA cm(-2) and a fill factor of 67%. The annealed PBTT4BT/PC71BM active layer possessed a nanoscaled network-like morphology with rod-like PBTT4BT domains that were beneficial for charge separation and transport; accordingly, the power conversion efficiency of the annealed PBTT4BT/PC71BM photovoltaic device was enhanced greatly over that of the as-cast PBTT4BT/PC71BM device.