School of Chemistry - 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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    Photophysics and aggregation effects of a triphenylamine-based dye sensitizer on metal-oxide nanoparticles suspended in an ion trap
    Dryza, V ; Nguyen, JL ; Kwon, T-H ; Wong, WWH ; Holmes, AB ; Bieske, EJ (ROYAL SOC CHEMISTRY, 2013-01-01)
    The photophysical behaviour of a triphenylamine-based organic dye sensitizer (Carbz-PAHTDTT) attached to alumina and titania nanoparticles (labelled Carbz-Al and Carbz-Ti, respectively) is examined in the absence and presence of the chenodeoxycholic acid (CDCA) coadsorber. The experiments are conducted in vacuo by suspending the target dye-sensitized nanoparticles within a quadrupole ion trap, where they are probed with laser radiation to obtain emission spectra and time-resolved excited state decay curves. For Carbz-Al, the dye's emission band is blue-shifted and the excited state lifetime is increased upon the coabsorption of CDCA, effects attributed to reduced dye aggregation. Compared to Carbz-Al, the Carbz-Ti excited state lifetimes are significantly shorter due to excited dye molecules injecting electrons into the titania conduction band. For Carbz-Ti, the electron injection quantum yields for the surfaces with CDCA (CDCA : dye = 25 : 1) and without CDCA are estimated to be 0.87 and 0.71, respectively. The gas-phase results demonstrate that Carbz-PAHTDTT dye aggregates are detrimental to the performance of a dye-sensitized solar cell.
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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-C-70 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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    Electroactive and Photoactive Poly[lsoindigo-alt-EDOT] Synthesized Using Direct (Hetero)Arylation Polymerization in Batch and in Continuous Flow
    Grenier, F ; Aich, BR ; Lai, Y-Y ; Guerette, M ; Holmes, AB ; Tao, Y ; Wong, WWH ; Leclerc, M (AMER CHEMICAL SOC, 2015-03-24)
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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, 2015-12-01)
    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, 2015-01-01)
    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.