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White Organic Light-Emitting Diodes with Evenly Separated Red, Green, and Blue Colors for Efficiency/Color-Rendition Trade-Off Optimization

Authors

  • Shuming Chen,

    1. Centre for Display Research and Department of Electronic and Computer Engineering, The Hong Kong University of Science & Technology, Clear Water Bay, Kowloon, Hong Kong, P. R. China
    2. Institute of Molecular Functional Materials, Areas of Excellence Scheme, University Grants Committee of HKSAR, P. R. China
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  • Guiping Tan,

    1. Department of Chemistry and Centre for Advanced Luminescence Materials, Hong Kong Baptist University, Waterloo Road, Kowloon Tong, Hong Kong, P. R. China
    2. Institute of Molecular Functional Materials, Areas of Excellence Scheme, University Grants Committee of HKSAR, P. R. China
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  • Wai-Yeung Wong,

    Corresponding author
    1. Department of Chemistry and Centre for Advanced Luminescence Materials, Hong Kong Baptist University, Waterloo Road, Kowloon Tong, Hong Kong, P. R. China
    2. Institute of Molecular Functional Materials, Areas of Excellence Scheme, University Grants Committee of HKSAR, P. R. China
    • Department of Chemistry and Centre for Advanced Luminescence Materials, Hong Kong Baptist University, Waterloo Road, Kowloon Tong, Hong Kong, P. R. China
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  • Hoi-Sing Kwok

    Corresponding author
    1. Centre for Display Research and Department of Electronic and Computer Engineering, The Hong Kong University of Science & Technology, Clear Water Bay, Kowloon, Hong Kong, P. R. China
    2. Institute of Molecular Functional Materials, Areas of Excellence Scheme, University Grants Committee of HKSAR, P. R. China
    • Centre for Display Research and Department of Electronic and Computer Engineering, The Hong Kong University of Science & Technology, Clear Water Bay, Kowloon, Hong Kong, P. R. China.
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Abstract

A novel yellowish-green triplet emitter, bis(5-(trifluoromethyl)-2-p-tolylpyridine) (acetylacetonate)iridium(III) (1), was conveniently synthesized and used in the fabrication of both monochromatic and white organic light-emitting diodes (WOLEDs). At the optimal doping concentration, monochromatic devices based on 1 exhibit a high efficiency of 63 cd A−1 (16.3% and 36.6 lm W−1) at a luminance of 100 cd m−2. By combining 1 with a phosphorescent sky-blue emitter, bis(3,5-difluoro-2-(2-pyridyl)phenyl)-(2-carboxypyridyl)iridium(III) (FIrPic), and a red emitter, bis(2-benzo[b]thiophen-2-yl-pyridine)(acetylacetonate)iridium(III) (Ir(btp)2(acac)), the resulting electrophosphorescent WOLEDs show three evenly separated main peaks and give a high efficiency of 34.2 cd A−1 (13.2% and 18.5 lm W−1) at a luminance of 100 cd m−2. When 1 is mixed with a deep-blue fluorescent emitter, 4,4′-bis(9-ethyl-3-carbazovinylene)-1,1′-biphenyl (BCzVBi), and Ir(btp)2(acac), the resulting hybrid WOLEDs demonstrate a high color-rendering index of 91.2 and CIE coordinates of (0.32, 0.34). The efficient and highly color-pure WOLEDs based on 1 with evenly separated red, green, blue peaks and a high color-rendering index outperform those of the state-of-the-art emitter, fac-tris(2-phenylpyridine)iridium(III) (Ir(ppy)3), and are ideal candidates for display and lighting applications.

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