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Heteroarene-fused π-conjugated main-chain polymers containing 4,7-bis(4-octylthiophen-2-yl)benzo[c][1,2,5]thiadiazole or 2,5-bis(4-octylthiophen-2-yl)thiazolo[5,4-d]thiazole and their application to photovoltaic devices

Authors

  • Tae Wan Lee,

    1. Department of Chemistry, Research Institute for Natural Sciences, Korea University, 5 Anam-dong, Sungbuk-gu, Seoul, 136-701 Korea
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  • Nam Su Kang,

    1. Korea Institute of Science & Technology, Center for Energy Materials Research, 39-1 Hawolkok-dong, Sungbuk-gu, Seoul, 136-791 Korea
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  • Jae Woong Yu,

    Corresponding author
    1. Advanced Materials Engineering for Information and Electronics, Kyung Hee University, 1 Seocheon, Kiheung, Yongin, Kyungki 446-701 Korea
    • Advanced Materials Engineering for Information and Electronics, Kyung Hee University, 1 Seocheon, Kiheung, Yongin, Kyungki 446-701 Korea
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  • Mai Ha Hoang,

    1. Department of Chemistry, Research Institute for Natural Sciences, Korea University, 5 Anam-dong, Sungbuk-gu, Seoul, 136-701 Korea
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  • Kyung Hwan Kim,

    1. Department of Chemistry, Research Institute for Natural Sciences, Korea University, 5 Anam-dong, Sungbuk-gu, Seoul, 136-701 Korea
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  • Jung-Il Jin,

    1. Department of Chemistry, Research Institute for Natural Sciences, Korea University, 5 Anam-dong, Sungbuk-gu, Seoul, 136-701 Korea
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  • Dong Hoon Choi

    Corresponding author
    1. Department of Chemistry, Research Institute for Natural Sciences, Korea University, 5 Anam-dong, Sungbuk-gu, Seoul, 136-701 Korea
    • Department of Chemistry, Research Institute for Natural Sciences, Korea University, 5 Anam-dong, Sungbuk-gu, Seoul, 136-701 Korea
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Abstract

Two conjugated main-chain polymers consisting of heteroarene-fused π-conjuagted donor moiety alternating with 4,7-bis(5-bromo-4-octylthiophen-2-yl)benzo[c][1,2,5]thiadiazole (P1) or 2,5-bis(5-bromo-4-octylthiophen-2-yl) thiazolo[5,4-d]thiazole (P2) units have been synthesized. They are intrinsically amorphous in nature and do not exhibit crystalline melting temperatures during thermal analysis. The effect of the fused rings on the thermal, optical, electrochemical, charge transport, and photovoltaic properties of these polymers has been investigated. The polymer (P1) containing 4,7-bis(5-bromo-4-octylthiophen-2-yl)benzo[c][1,2,5] thiadiazole has a broad absorption extending from 300 to 600 nm with optical bandgaps as low as 2.02 eV. The HOMO levels (5.42 to 5.29 eV) are more sensitive to the choice of acceptor. The polymers were employed to fabricate organic photovoltaic cells with methanofullerene [6,6]-phenyl C71-butyric acid methyl ester (PC71BM). As a result, the polymer solar cell device containing P1 had the best preliminary results with an open-circuit voltage of 0.61 V, a short-circuit current density of 6.19 mA/cm2, and a fill factor of 0.32, offering an overall power conversion efficiency of 1.21%. © 2010 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2010

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