Enhanced Performance in Inverted Polymer Solar Cells with D–π–A-Type Molecular Dye Incorporated on ZnO Buffer Layer

Authors

  • Chang Eun Song,

    1. Department of Materials Science and Engineering, Korea Advanced Institute of Science & Technology (KAIST), Daejeon, 305-701 (Republic of Korea)
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  • Ka Yeon Ryu,

    1. Energy Materials Research Center, Korea Research Institute of Chemical Technology (KRICT), 141 Gajeong-ro, Yuseong-gu, Daejeon, 305-600 (Republic of Korea)
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  • Dr. Seong-Jin Hong,

    1. Energy Materials Research Center, Korea Research Institute of Chemical Technology (KRICT), 141 Gajeong-ro, Yuseong-gu, Daejeon, 305-600 (Republic of Korea)
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  • Dr. Chinna Bathula,

    1. Energy Materials Research Center, Korea Research Institute of Chemical Technology (KRICT), 141 Gajeong-ro, Yuseong-gu, Daejeon, 305-600 (Republic of Korea)
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  • Prof. Sang Kyu Lee,

    1. Energy Materials Research Center, Korea Research Institute of Chemical Technology (KRICT), 141 Gajeong-ro, Yuseong-gu, Daejeon, 305-600 (Republic of Korea)
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  • Prof. Won Suk Shin,

    1. Energy Materials Research Center, Korea Research Institute of Chemical Technology (KRICT), 141 Gajeong-ro, Yuseong-gu, Daejeon, 305-600 (Republic of Korea)
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  • Prof. Jong-Cheol Lee,

    1. Energy Materials Research Center, Korea Research Institute of Chemical Technology (KRICT), 141 Gajeong-ro, Yuseong-gu, Daejeon, 305-600 (Republic of Korea)
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  • Prof. Si Kyung Choi,

    Corresponding author
    1. Department of Materials Science and Engineering, Korea Advanced Institute of Science & Technology (KAIST), Daejeon, 305-701 (Republic of Korea)
    • Si Kyung Choi, Department of Materials Science and Engineering, Korea Advanced Institute of Science & Technology (KAIST), Daejeon, 305-701 (Republic of Korea)

      Sang-Jin Moon, Energy Materials Research Center, Korea Research Institute of Chemical Technology (KRICT), 141 Gajeong-ro, Yuseong-gu, Daejeon, 305-600 (Republic of Korea)

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  • Prof. Joo Hyun Kim,

    1. Department of Polymer Engineering, Pukyong National University, Yongdang-Dong, Nam-Gu, Busan, 608-739 (Republic of Korea)
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  • Prof. Sang-Jin Moon

    Corresponding author
    1. Energy Materials Research Center, Korea Research Institute of Chemical Technology (KRICT), 141 Gajeong-ro, Yuseong-gu, Daejeon, 305-600 (Republic of Korea)
    • Si Kyung Choi, Department of Materials Science and Engineering, Korea Advanced Institute of Science & Technology (KAIST), Daejeon, 305-701 (Republic of Korea)

      Sang-Jin Moon, Energy Materials Research Center, Korea Research Institute of Chemical Technology (KRICT), 141 Gajeong-ro, Yuseong-gu, Daejeon, 305-600 (Republic of Korea)

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Abstract

We report the superior characteristics of a ZnO buffer layer covered with a phenothiazine-based, π-conjugated donor–acceptor (D–π–A)-type organic dye (called “d-ZnO”). The use of this system for the performance enhancement of inverted bulk heterojunction polymer solar cells (PSCs) with the configuration of indium tin oxide/d-ZnO/polymer:PC71BM/MoO3/Ag (PC71BM=[6,6]-phenyl C71 butyric acid methyl ester) is investigated. The layer of organic dyes anchored on the ZnO surface through carboxylate bonding reduces the shunt path on bare ZnO surface and provides better interfacial contacts and energy level alignments between the ZnO layer and the photoactive layer. This phenomenon consequently leads to highly enhanced photovoltaic parameters (fill factor, open-circuit voltage, and short-circuit current density) and power conversion efficiencies (PCEs). Inverted solar cells containing the d-ZnO layer not only revealed about 34 % (PCE: 4.37 %) and 18 % (PCE: 7.11 %) improvement in the PCEs of the representative poly-3(hexylthiophene) (P3HT) and low-band-gap poly{[4,8-bis-(2-ethyl-hexyl-thiophene-5-yl)-benzo[1,2-b:4,5-b’]dithiophene-2,6-diyl]-alt-[2-(2’-ethylhexanoyl)-thieno[3,4-b]thiophen-4,6-diyl]} (PBDTTT-C-T) polymer systems, respectively, but also showed 2–4 times longer device lifetimes than their counterparts without the organic dye layer. These results demonstrate that this simple approach used in inverted PSCs with a metal oxide buffer layer could become a promising procedure to fabricate highly efficient and stable PSCs.

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