Bio21 - Research Publications
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ItemThiazolyl substituted benzodithiophene copolymers: synthesis, properties and photovoltaic applications(Royal Society of Chemistry, 2014)Three new conjugated polymers based on 5-decylthiazol-2-yl substituted benzodithiophene have been synthesized by Stille cross-coupling polymerization. 1,3-Dibromo-5-octylthieno[3,4-c]pyrrole-4,6-dione (M1), 2,5-diethylhexyl-3,6-bis(5-bromothiophen-2-yl)pyrrolo[3,4-c]-pyrrole-1,4-dione (M2) and 4,6-dibromo-thieno[3,4-b]thiophene-2-dodecyl carboxylate (M3) were used as acceptor building blocks for the synthesis of conjugated donor-acceptor polymers. The thermal, optical, electrochemical, and photovoltaic properties of the synthesized polymers were studied.
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ItemA molecular nematic liquid crystalline material for high-performance organic photovoltaics(NATURE PUBLISHING GROUP, 2015-01)Solution-processed organic photovoltaic cells (OPVs) hold great promise to enable roll-to-roll printing of environmentally friendly, mechanically flexible and cost-effective photovoltaic devices. Nevertheless, many high-performing systems show best power conversion efficiencies (PCEs) with a thin active layer (thickness is ~100 nm) that is difficult to translate to roll-to-roll processing with high reproducibility. Here we report a new molecular donor, benzodithiophene terthiophene rhodanine (BTR), which exhibits good processability, nematic liquid crystalline behaviour and excellent optoelectronic properties. A maximum PCE of 9.3% is achieved under AM 1.5G solar irradiation, with fill factor reaching 77%, rarely achieved in solution-processed OPVs. Particularly promising is the fact that BTR-based devices with active layer thicknesses up to 400 nm can still afford high fill factor of ~70% and high PCE of ~8%. Together, the results suggest, with better device architectures for longer device lifetime, BTR is an ideal candidate for mass production of OPVs.
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ItemHydrogen bonding in bulk heterojunction solar cells: A case study(NATURE PORTFOLIO, 2014-07-16)Small molecules with dithieno[3,2-b;2',3'-d]thiophene as central building block and octyl cyanoacetate and octyl cyanoacetamide as different terminal building blocks have been designed and synthesized. The amide containing small molecule can form intermolecular hydrogen bonding between N-H...O = C of the amide group. The photovoltaic properties and active layer morphologies of the two molecules in bulk heterojunction solar cells are compared to study the influence of hydrogen bonding on the active layer morphology. New methanofullerene compound containing amide group has also been synthesized and compared with conventional fullerene electron acceptors.
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ItemSynthesis and photovoltaic properties of thieno[3,2-b]thiophenyl substituted benzo[1,2-b:4,5-b ']dithiophene copolymers(ROYAL SOC CHEMISTRY, 2014)A new benzo[1,2-b:4,5-b']dithiophene (BDT) building block with 4,8-disubstitution using 2-(2-ethylhexyl)-3-hexylthieno[3,2-b]thiophene as the substituent has been designed and synthesized. The new building block has been copolymerized with benzothiadiazole (BT) and 5,6-difluorobenzothiadiazole (fBT) by Suzuki and Stille coupling polymerization to synthesize donor-acceptor conjugated polymers. The optical and electrochemical properties of the synthesized copolymers were studied. Bulk heterojunction solar cells were fabricated using the donor-acceptor copolymers in conjunction with PC71BM and exhibited up to 4.20% power conversion efficiency.