A Blue-Light-Emitting Polymer with a Rigid Backbone for Enhanced Color Stability

Authors

  • S. H. Park,

    1. Heeger Center for Advanced Materials (HCAM), Department of Materials Science & Engineering, Gwangju Institute of Science and Technology (GIST), Gwangju 500-712 (South Korea)
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  • Y. Jin,

    1. Department of Chemistry, Pusan National University, Busan 609-735 (South Korea)
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  • J. Y. Kim,

    1. Heeger Center for Advanced Materials (HCAM), Department of Materials Science & Engineering, Gwangju Institute of Science and Technology (GIST), Gwangju 500-712 (South Korea)
    2. Center for Polymers and Organic Solids, University of California at Santa Barbara, Santa Barbara, CA 93106 (USA)
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  • S. H. Kim,

    1. Heeger Center for Advanced Materials (HCAM), Department of Materials Science & Engineering, Gwangju Institute of Science and Technology (GIST), Gwangju 500-712 (South Korea)
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  • J. Kim,

    1. Department of Chemistry, Pusan National University, Busan 609-735 (South Korea)
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  • H. Suh,

    1. Department of Chemistry, Pusan National University, Busan 609-735 (South Korea)
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  • K. Lee

    1. Heeger Center for Advanced Materials (HCAM), Department of Materials Science & Engineering, Gwangju Institute of Science and Technology (GIST), Gwangju 500-712 (South Korea)
    2. Center for Polymers and Organic Solids, University of California at Santa Barbara, Santa Barbara, CA 93106 (USA)
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  • We thank Prof. Alan J. Heeger for fruitful discussion and comments. The research was supported by the International Cooperation Research Program of the Ministry of Science & Technology of Korea (Global Research Laboratory Program, M6-0605-00-0005).

Abstract

Despite the promising expectations of poly(fluorene) (PF)-type materials as efficient blue-light-emitting polymers, the devices based on these materials are not yet fully utilized. Under prolonged operation of the devices, the PF-type materials undergo degradation with the appearance of a long-range emission around 2.2–2.3 eV. As a consequence, the emissive color changes from blue to green with a decrease in the device efficiency. Here, an innovative approach that leads to a new blue-emitting polymer with remarkable color stability is reported. By modifying the chemical structure of PF to inhibit the formation of keto defects, it is demonstrated that the devices exhibit excellent color stability. This new blue-emitting polymer, poly(2,6-(4,4-bis(2-ethylhexyl)-4H-cyclopenta-[def]phenanthrene)) (PCPP), emits a stabilized, efficient blue electroluminescence without exhibiting any peak in the long-wavelength region even after prolonged operation of the devices in air.

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