Bio21 - Research Publications

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    Controlled synthesis of poly(3-hexylthiophene) in continuous flow
    Seyler, H ; Subbiah, J ; Jones, DJ ; Holmes, AB ; Wong, WWH (BEILSTEIN-INSTITUT, 2013-07-25)
    There is an increasing demand for organic semiconducting materials with the emergence of organic electronic devices. In particular, large-area devices such as organic thin-film photovoltaics will require significant quantities of materials for device optimization, lifetime testing and commercialization. Sourcing large quantities of materials required for the optimization of large area devices is costly and often impossible to achieve. Continuous-flow synthesis enables straight-forward scale-up of materials compared to conventional batch reactions. In this study, poly(3-hexylthiophene), P3HT, was synthesized in a bench-top continuous-flow reactor. Precise control of the molecular weight was demonstrated for the first time in flow for conjugated polymers by accurate addition of catalyst to the monomer solution. The P3HT samples synthesized in flow showed comparable performance to commercial P3HT samples in bulk heterojunction solar cell devices.
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    Benzotriazole-based donor-acceptor conjugated polymers with a broad absorption in the visible range
    Wong, WWH ; Subbiah, J ; Puniredd, SR ; Pisula, W ; Jones, DJ ; Holmes, AB (ROYAL SOC CHEMISTRY, 2014-02-21)
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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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    Single Isomer of Indene-C70 Bisadduct-Isolation and Performance in Bulk Heterojunction Solar Cells
    Wong, WWH ; Subbiah, J ; White, JM ; Seyler, H ; Zhang, B ; Jones, DJ ; Holmes, AB (AMER CHEMICAL SOC, 2014-02-25)
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    Organic Solar Cells Using a High-Molecular-Weight Benzodithiophene-Benzothiadiazole Copolymer with an Efficiency of 9.4%
    Subbiah, J ; Purushothaman, B ; Chen, M ; Qin, T ; Gao, M ; Vak, D ; Scholes, FH ; Chen, X ; Watkins, SE ; Wilson, GJ ; Holmes, AB ; Wong, WWH ; Jones, DJ (WILEY-V C H VERLAG GMBH, 2015-01-27)
    A high molecular weight donor-acceptor conjugated polymer is synthesized using the Suzuki polycondensation method. Using this polymer, a single-junction bulk-heterojunction solar cell is fabricated giving a power conversion efficiency of 9.4% using a fullerene-modified ZnO interlayer at the cathode contact.
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    Organic Photovoltaic MaterialsDesign, Synthesis and Scale-Up
    Wong, WWH ; Banal, JL ; Geraghty, PB ; Hong, Q ; Zhang, B ; Holmes, AB ; Jones, DJ (WILEY-V C H VERLAG GMBH, 2015-12)
    This account describes the work of our group in the area of organic photovoltaics in the past six years. The emphasis is on our experiences in the development of the organic materials, their characterization, scale-up and application in devices. We share our insight into the relationship between synthetic methods, molecular properties, bulk material properties and device performance.
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    Development of a High-Performance Donor Acceptor Conjugated Polymer: Synergy in Materials and Device Optimization
    Gao, M ; Subbiah, J ; Geraghty, PB ; Chen, M ; Purushothaman, B ; Chen, X ; Qin, T ; Vak, D ; Scholes, FH ; Watkins, SE ; Skidmore, M ; Wilson, GJ ; Holmes, AB ; Jones, DJ ; Wong, WWH (AMER CHEMICAL SOC, 2016-05-24)
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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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    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.