Nanomorphology of PCDTBT:PC70BM Bulk Heterojunction Solar Cells

Authors

  • Ji Sun Moon,

    1. Center for Polymers and Organic Solids, University of California-Santa Barbara, Santa Barbara, CA, 93106-5090, USA
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  • Jang Jo,

    Corresponding author
    1. Center for Polymers and Organic Solids, University of California-Santa Barbara, Santa Barbara, CA, 93106-5090, USA
    • Center for Polymers and Organic Solids, University of California-Santa Barbara, Santa Barbara, CA, 93106-5090, USA.
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  • Alan J. Heeger

    Corresponding author
    1. Center for Polymers and Organic Solids, University of California-Santa Barbara, Santa Barbara, CA, 93106-5090, USA
    • Center for Polymers and Organic Solids, University of California-Santa Barbara, Santa Barbara, CA, 93106-5090, USA.
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Abstract

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The nanomorphology of a bulk heterojunction (BHJ) material constructed from poly[N - 9′-hepta-decanyl-2,7-carbazole- alt-5,5-(4′,7′-di-2-thienyl-2′,1′,3′-benzothiadiazole)] (PCDTBT):[6,6]-phenyl C70-butyric acid methyl ester (PC70BM) is shown to be laterally oriented, in contrast to the column-like morphology of the similar poly(3-hexyl thiophene):PC60BM. The lateral orientation in the PCDTBT:PC70BM BHJ is not ideal for sweeping charge out at the electrodes. As a result, the power conversion efficiency decreases as the thickness of the BHJ active layer is increased.

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