School of Chemistry - Research Publications

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    Thiazolyl substituted benzodithiophene copolymers: synthesis, properties and photovoltaic applications
    Xiao, Z ; Subbiah, J ; Sun, K ; Ji, S ; Jones, DJ ; Holmes, AB ; Wong, WWH (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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    A molecular nematic liquid crystalline material for high-performance organic photovoltaics
    Sun, K ; Xiao, Z ; Lu, S ; Zajaczkowski, W ; Pisula, W ; Hanssen, E ; White, JM ; Williamson, RM ; Subbiah, J ; Ouyang, J ; Holmes, AB ; Wong, WWH ; Jones, DJ (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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    Effect of molecular weight on the properties and organic solar cell device performance of a donor-acceptor conjugated polymer
    Xiao, Z ; Sun, K ; Subbiah, J ; Qin, T ; Lu, S ; Purushothaman, B ; Jones, DJ ; Holmes, AB ; Wong, WWH (ROYAL SOC CHEMISTRY, 2015)

    The effect of molecular weight of a conjugated polymer on its photophysical properties and solar cell device performance was investigated.

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    Synthesis and photovoltaic properties of thieno[3,2-b]thiophenyl substituted benzo[1,2-b:4,5-b ']dithiophene copolymers
    Xiao, Z ; Subbiah, J ; Sun, K ; Jones, DJ ; Holmes, AB ; Wong, WWH (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.