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Deep Energetic Trap States in Organic Photovoltaic Devices

Authors

  • Christopher G. Shuttle,

    Corresponding author
    1. Materials Department, University of California Santa Barbara, CA 93106, United States
    • Materials Department, University of California Santa Barbara, CA 93106, United States.
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  • Neil D. Treat,

    1. Materials Department, University of California Santa Barbara, CA 93106, United States
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  • Jessica D. Douglas,

    1. Materials Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, CA 94720, and Department of Chemistry, University of California, Berkeley, CA 94720-1460
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  • Jean M. J. Fréchet,

    1. Materials Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, CA 94720, and Department of Chemistry, University of California, Berkeley, CA 94720-1460
    2. King Abdullah University of Science and Technology, Thuwal, Saudi Arabia, 23955-6900
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  • Michael L. Chabinyc

    Corresponding author
    1. Materials Department, University of California Santa Barbara, CA 93106, United States
    • Materials Department, University of California Santa Barbara, CA 93106, United States.
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Abstract

The nature of energetic disorder in organic semiconductors is poorly understood. In photovoltaics, energetic disorder leads to reductions in the open circuit voltage and contributes to other loss processes. In this work, three independent optoelectronic methods were used to determine the long-lived carrier populations in a high efficiency N-alkylthieno[3,4-c]pyrrole-4,6-dione (TPD) based polymer: fullerene solar cell. In the TPD co-polymer, all methods indicate the presence of a long-lived carrier population of ∼ 1015 cm−3 on timescales ≥ 100 μs. Additionally, the behavior of these photovoltaic devices under optical bias is consistent with deep energetic lying trap states. Comparative measurements were also performed on high efficiency poly-3-hexylthiophene (P3HT): fullerene solar cells; however a similar long-lived carrier population was not observed. This observation is consistent with a higher acceptor concentration (doping) in P3HT than in the TPD-based copolymer.

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