The Fabrication and Characterization of Single-Component Polymeric White-Light-Emitting Diodes

Authors

  • S. K. Lee,

    1. Center for Advanced Functional Polymers, Department of Chemistry and School of Molecular Science (BK 21), Korea Advanced Institute of Science and Technology, 373-1 Kusong-dong, Yusong-ku, Dae-jeon 305-701, Korea
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  • D.-H. Hwang,

    1. Department of Applied Chemistry, Kumoh National Institute of Technology, Kumi 730-701, Korea
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  • B.-J. Jung,

    1. Center for Advanced Functional Polymers, Department of Chemistry and School of Molecular Science (BK 21), Korea Advanced Institute of Science and Technology, 373-1 Kusong-dong, Yusong-ku, Dae-jeon 305-701, Korea
    2. Present address: Samsung SDI Co., Ltd. 428-5 Gongse-Ri, Giheung-Eup, Yongin-Si, Gyeonggi-Do 449-577, Korea.
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  • N. S. Cho,

    1. Center for Advanced Functional Polymers, Department of Chemistry and School of Molecular Science (BK 21), Korea Advanced Institute of Science and Technology, 373-1 Kusong-dong, Yusong-ku, Dae-jeon 305-701, Korea
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  • J. Lee,

    1. Center for Advanced Functional Polymers, Department of Chemistry and School of Molecular Science (BK 21), Korea Advanced Institute of Science and Technology, 373-1 Kusong-dong, Yusong-ku, Dae-jeon 305-701, Korea
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  • J.-D. Lee,

    1. Department of Applied Chemistry, Kumoh National Institute of Technology, Kumi 730-701, Korea
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  • H.-K. Shim

    1. Center for Advanced Functional Polymers, Department of Chemistry and School of Molecular Science (BK 21), Korea Advanced Institute of Science and Technology, 373-1 Kusong-dong, Yusong-ku, Dae-jeon 305-701, Korea
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  • This work was supported by the Ministry of Commerce, Industry and Energy.

Abstract

By using Ni0-mediated polymerization, we have systematically synthesized a series of fluorene-based copolymers composed of blue-, green-, and red-light-emitting comonomers with a view to producing polymers with white-light emission. 2,7-Dibromo-9,9-dihexylfluorene, {4-(2-[2,5-dibromo-4-{2-(4-diphenylamino-phenyl)-vinyl}-phenyl]-vinyl)-phenyl}-diphenylamine (DTPA), and 2-{2-(2-[4-{bis(4-bromo-phenyl)amino}-phenyl]-vinyl)-6-tert-butyl-pyran-4-ylidene}-malononitrile (TPDCM) were used as the blue-, green-, and red-light-emitting comonomers, respectively. It was found that the emission spectra of the resulting copolymers could easily be tuned by varying their DTPA and TPDCM content. Thus with the appropriate red/green/blue (RGB) unit ratio, we were able to obtain white-light emission from these copolymers. A white-light-emitting diode using the polyfluorene copolymer containing 3 % green-emitting DTPA and 2 % red-emitting TPDCM (PG3R2) with a structure of indium tin oxide/poly(3,4-ethylenedioxythiophene):poly(styrene sulfonic acid)/PG3R2/Ca/Al was found to exhibit a maximum brightness of 820 cd m–2 at 11 V with Commission Internationale de L'Eclairage (CIE) coordinates of (0.33,0.35), which are close to the standard CIE coordinates for white-light emission (0.33,0.33).

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