Photoconductivity of C60 as an Origin of Bias-Dependent Photocurrent in Organic Photovoltaics

Authors

  • Won-Ik Jeong,

    1. WCU Hybrid Materials Program and Dept. Materials Science and Engineering, Seoul National University, Seoul, 151-744, Republic of Korea
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  • Yang Eun Lee,

    1. WCU Hybrid Materials Program and Dept. Materials Science and Engineering, Seoul National University, Seoul, 151-744, Republic of Korea
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  • Hyun-Sub Shim,

    1. WCU Hybrid Materials Program and Dept. Materials Science and Engineering, Seoul National University, Seoul, 151-744, Republic of Korea
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  • Tae-Min Kim,

    1. WCU Hybrid Materials Program and Dept. Materials Science and Engineering, Seoul National University, Seoul, 151-744, Republic of Korea
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  • Sei-Yong Kim,

    1. WCU Hybrid Materials Program and Dept. Materials Science and Engineering, Seoul National University, Seoul, 151-744, Republic of Korea
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  • Jang-Joo Kim

    Corresponding author
    1. WCU Hybrid Materials Program and Dept. Materials Science and Engineering, Seoul National University, Seoul, 151-744, Republic of Korea
    • WCU Hybrid Materials Program and Dept. Materials Science and Engineering, Seoul National University, Seoul, 151-744, Republic of Korea.
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Abstract

The bulk-ionized photoconductivity of C60 is reported as an origin of the bias-dependent linear change of the photocurrent in copper phthalocyanine (CuPc)/C60 planar heterojunction solar cells, based on the observation of the variation of the bias-dependent photocurrent on excitation wavelengths and the thickness-dependent photocurrent of the C60 layer. A theoretical model, which is a combination of the Braun-Onsager model for the dissociation of excitons at the donor/acceptor interface and the Onsager model for the bulk ionization of excitons in the C60 layer, describes the bias-dependent photocurrent in the devices very well. The bulk-ionized photoconductivity of C60 must generally contribute to the photocurrent in organic photovoltaics, since fullerene and fullerene derivatives are widely used in these devices.

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