Parameters Influencing Charge Separation in Solid-State Dye-Sensitized Solar Cells Using Novel Hole Conductors

Authors

  • J. E. Kroeze,

    1. Centre for Electronic Materials and Devices, Imperial College London, London SW7 2AY, UK
    2. Present address: Molecular Materials and Nanosystems, Laboratory of Macromolecular and Organic Chemistry, Eindhoven University of Technology, PO Box 513, 5600 MB Eindhoven, The Netherlands
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  • N. Hirata,

    1. Centre for Electronic Materials and Devices, Imperial College London, London SW7 2AY, UK
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  • L. Schmidt-Mende,

    1. Laboratory for Photonics and Interfaces, Institute of Chemical Science and Engineering, Swiss Federal Institute of Technology, 1015 Lausanne, Switzerland
    2. Present address: Department of Materials Science and Metallurgy, University of Cambridge, Pembroke Street, Cambridge CB2 3QZ, UK
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  • C. Orizu,

    1. Merck Chemicals Limited, Manchester Technical Centre, P.O. Box 42 Hexagon House, Blackley, Manchester M9 8ZS, UK
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  • S. D. Ogier,

    1. Merck Chemicals Limited, Manchester Technical Centre, P.O. Box 42 Hexagon House, Blackley, Manchester M9 8ZS, UK
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  • K. Carr,

    1. Merck Chemicals Limited, Manchester Technical Centre, P.O. Box 42 Hexagon House, Blackley, Manchester M9 8ZS, UK
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  • M. Grätzel,

    1. Laboratory for Photonics and Interfaces, Institute of Chemical Science and Engineering, Swiss Federal Institute of Technology, 1015 Lausanne, Switzerland
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  • J. R. Durrant

    1. Centre for Electronic Materials and Devices, Imperial College London, London SW7 2AY, UK
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  • We acknowledge the Commission of the European Community (Project Molycell Contract No. 502783) for their financial assistance, Henry Snaith and Saif Haque for helpful discussions and Li Xiaoe for assistance in TiO2 film preparation.

Abstract

Solid-state dye-sensitized solar cells employing a solid organic hole-transport material (HTM) are currently under intensive investigation, since they offer a number of practical advantages over liquid-electrolyte junction devices. Of particular importance to the design of such devices is the control of interfacial charge transfer. In this paper, the factors that determine the yield of hole transfer at the dye/HTM interface and its correlation with solid-state-cell performance are identified. To this end, a series of novel triarylamine type oligomers, varying in molecular weight and mobility, are studied. Transient absorption spectroscopy is used to determine hole-transfer yields and pore-penetration characteristics. No correlation between hole mobility and cell performance is observed. However, it is found that the photocurrent is directly proportional to the hole-transfer yield. This hole-transfer yield depends on the extent of pore penetration in the dye-sensitized film as well as on the thermodynamic driving force ΔGdye–HTM for interfacial charge transfer. Future design of alternative solid-state HTMs should focus on the optimization of pore-filling properties and the control of interfacial energetics rather than on increasing material hole mobilities.

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