Co-sensitization of Organic Dyes for Efficient Dye-Sensitized Solar Cells

Authors

  • Dr. Ming Cheng,

    1. State Key Laboratory of Fine Chemicals, DUT-KTH Joint Education and Research Centre on Molecular Devices, Dalian University of Technology (DUT), 2 Linggong Rd., 116024 Dalian (P.R. China), Fax: (+86) 411-84986250
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  • Prof. Xichuan Yang,

    Corresponding author
    1. State Key Laboratory of Fine Chemicals, DUT-KTH Joint Education and Research Centre on Molecular Devices, Dalian University of Technology (DUT), 2 Linggong Rd., 116024 Dalian (P.R. China), Fax: (+86) 411-84986250
    • State Key Laboratory of Fine Chemicals, DUT-KTH Joint Education and Research Centre on Molecular Devices, Dalian University of Technology (DUT), 2 Linggong Rd., 116024 Dalian (P.R. China), Fax: (+86) 411-84986250
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  • Dr. Jiajia Li,

    1. State Key Laboratory of Fine Chemicals, DUT-KTH Joint Education and Research Centre on Molecular Devices, Dalian University of Technology (DUT), 2 Linggong Rd., 116024 Dalian (P.R. China), Fax: (+86) 411-84986250
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  • Dr. Fuguo Zhang,

    1. State Key Laboratory of Fine Chemicals, DUT-KTH Joint Education and Research Centre on Molecular Devices, Dalian University of Technology (DUT), 2 Linggong Rd., 116024 Dalian (P.R. China), Fax: (+86) 411-84986250
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  • Prof. Licheng Sun

    Corresponding author
    1. State Key Laboratory of Fine Chemicals, DUT-KTH Joint Education and Research Centre on Molecular Devices, Dalian University of Technology (DUT), 2 Linggong Rd., 116024 Dalian (P.R. China), Fax: (+86) 411-84986250
    2. School of Chemical Science and Engineering, Center of Molecular Devices, Department of Chemistry, Royal Institute of Technology (KTH), Teknikringen 42, SE 100 44 Stockholm (Sweden)
    • State Key Laboratory of Fine Chemicals, DUT-KTH Joint Education and Research Centre on Molecular Devices, Dalian University of Technology (DUT), 2 Linggong Rd., 116024 Dalian (P.R. China), Fax: (+86) 411-84986250
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Abstract

Novel cyanine dyes, in which a tetrahydroquinoline derivative is used as an electron donor and 1-butyl-5-carboxy-3, 3-dimethyl-indol-1-ium moiety is used as an electron acceptor and anchoring group, were designed and synthesized for application in dye-sensitized solar cells. The photovoltaic performance of these solar cells depends markedly on the molecular structure of the dyes in terms of the n-hexyl chains and the methoxyl unit. Retardation of charge recombination caused by the introduction of n-hexyl chains resulted in an increase in electron lifetime. As a consequence, an improvement of open-circuit photovoltage (Voc) was achieved. Also, the electron injection efficiencies were improved by the introduction of methoxyl moiety, which led to a higher short-circuit photocurrent density (Jsc). The highest average efficiency of the sensitized devices (η) was 5.6 % (Jsc=13.3 mA cm−2, Voc=606 mV, and fill factor FF=69.1 %) under 100 mW cm−2 (AM 1.5G) solar irradiation. All of these dyes have very high absorption extinction coefficients and strong absorption in a relatively narrow spectrum range (500–650 nm), so one of our organic dyes was explored as a sensitizer in co-sensitized solar cells in combination with the other two other existing organic dyes. Interestingly, a considerably improved photovoltaic performance of 8.2 % (Jsc=20.1 mA cm−2, Voc=597 mV, and FF=68.3 %) was achieved and the device showed a panchromatic response with a high incident photon-to-current conversion efficiency exceeding 85 % in the range of 400–700 nm.

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