Fluorene-based alternating polymers containing electron-withdrawing bithiazole units: Preparation and device applications

Authors

  • Jaemin Lee,

    1. Department of Chemistry (BK21), Korea Advanced Institute of Science and Technology, 373-1 Guseong-dong, Yuseong-gu, Daejeon 305-701, Korea
    2. Center for Advanced Functional Polymers, Korea Advanced Institute of Science and Technology, 373-1 Guseong-dong, Yuseong-gu, Daejeon 305-701, Korea
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  • Byung-Jun Jung,

    1. Department of Chemistry (BK21), Korea Advanced Institute of Science and Technology, 373-1 Guseong-dong, Yuseong-gu, Daejeon 305-701, Korea
    2. Center for Advanced Functional Polymers, Korea Advanced Institute of Science and Technology, 373-1 Guseong-dong, Yuseong-gu, Daejeon 305-701, Korea
    Current affiliation:
    1. Corporate R&D Center, Samsung SDI, 428-5 Gongsae-ri; Kiheung-eup, Yongin, Kyunggi-do 449-577, Korea
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  • Sang Kyu Lee,

    1. Department of Chemistry (BK21), Korea Advanced Institute of Science and Technology, 373-1 Guseong-dong, Yuseong-gu, Daejeon 305-701, Korea
    2. Center for Advanced Functional Polymers, Korea Advanced Institute of Science and Technology, 373-1 Guseong-dong, Yuseong-gu, Daejeon 305-701, Korea
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  • Jeong-Ik Lee,

    1. Basic Research Laboratory, Electronics and Telecommunications Research Institute, 161 Gajeong-dong, Yuseong-gu, Daejeon 305-350, Korea
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  • Hoon-Je Cho,

    1. Department of Chemistry (BK21), Korea Advanced Institute of Science and Technology, 373-1 Guseong-dong, Yuseong-gu, Daejeon 305-701, Korea
    2. Center for Advanced Functional Polymers, Korea Advanced Institute of Science and Technology, 373-1 Guseong-dong, Yuseong-gu, Daejeon 305-701, Korea
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  • Hong-Ku Shim

    Corresponding author
    1. Department of Chemistry (BK21), Korea Advanced Institute of Science and Technology, 373-1 Guseong-dong, Yuseong-gu, Daejeon 305-701, Korea
    2. Center for Advanced Functional Polymers, Korea Advanced Institute of Science and Technology, 373-1 Guseong-dong, Yuseong-gu, Daejeon 305-701, Korea
    • Center for Advanced Functional Polymers, Korea Advanced Institute of Science and Technology, 373-1 Guseong-dong, Yuseong-gu, Daejeon 305-701, Korea
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Abstract

We report here the synthesis via Suzuki polymerization of two novel alternating polymers containing 9,9-dioctylfluorene and electron-withdrawing 4,4′-dihexyl-2,2′-bithiazole moieties, poly[(4,4′-dihexyl-2,2′-bithiazole-5,5′-diyl)-alt-(9,9-dioctylfluorene-2,7-diyl)] (PHBTzF) and poly[(5,5′-bis(2″-thienyl)-4,4′-dihexyl-2,2′-bithiazole-5″,5″-diyl)-alt-(9,9-dioctylfluorene-2,7-diyl)] (PTHBTzTF), and their application to electronic devices. The ultraviolet–visible absorption maxima of films of PHBTzF and PTHBTzTF were 413 and 471 nm, respectively, and the photoluminescence maxima were 513 and 590 nm, respectively. Cyclic voltammetry experiment showed an improvement in the n-doping stability of the polymers and a reduction of their lowest unoccupied molecular orbital energy levels as a result of bithiazole in the polymers' main chain. The highest occupied molecular orbital energy levels of the polymers were −5.85 eV for PHBTzF and −5.53 eV for PTHBTzTF. Conventional polymeric light-emitting-diode devices were fabricated in the ITO/PEDOT:PSS/polymer/Ca/Al configuration [where ITO is indium tin oxide and PEDOT:PSS is poly(3,4-ethylenedioxythiophene) doped with poly(styrenesulfonic acid)] with the two polymers as emitting layers. The PHBTzF device exhibited a maximum luminance of 210 cd/m2 and a turn-on voltage of 9.4 V, whereas the PTHBTzTF device exhibited a maximum luminance of 1840 cd/m2 and a turn-on voltage of 5.4 V. In addition, a preliminary organic solar-cell device with the ITO/PEDOT:PSS/(PTHBTzTF + C60)/Ca/Al configuration (where C60 is fullerene) was also fabricated. Under 100 mW/cm2 of air mass 1.5 white-light illumination, the device produced an open-circuit voltage of 0.76 V and a short-circuit current of 1.70 mA/cm2. The fill factor of the device was 0.40, and the power conversion efficiency was 0.52%. © 2005 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 43: 1845–1857, 2005

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