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Highly Efficient Warm White Organic Light-Emitting Diodes by Triplet Exciton Conversion

Authors

  • Yi-Lu Chang,

    Corresponding author
    1. Department of Materials Science and Engineering, University of Toronto, 184 College St., Toronto, Ontario, M5S 3E4, Canada
    • Department of Materials Science and Engineering, University of Toronto, 184 College St., Toronto, Ontario, M5S 3E4, Canada
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  • Yin Song,

    1. Department of Chemistry, Institute for Optical Science and Center for Quantum Information and Quantum Control University of Toronto, 80 St George Street, Toronto, Ontario, M5S 3H6, Canada
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  • Zhibin Wang,

    1. Department of Materials Science and Engineering, University of Toronto, 184 College St., Toronto, Ontario, M5S 3E4, Canada
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  • Michael G. Helander,

    1. Department of Materials Science and Engineering, University of Toronto, 184 College St., Toronto, Ontario, M5S 3E4, Canada
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  • Jacky Qiu,

    1. Department of Materials Science and Engineering, University of Toronto, 184 College St., Toronto, Ontario, M5S 3E4, Canada
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  • Lily Chai,

    1. Department of Materials Science and Engineering, University of Toronto, 184 College St., Toronto, Ontario, M5S 3E4, Canada
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  • Zhiwei Liu,

    1. Department of Materials Science and Engineering, University of Toronto, 184 College St., Toronto, Ontario, M5S 3E4, Canada
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  • Gregory D. Scholes,

    Corresponding author
    1. Department of Chemistry, Institute for Optical Science and Center for Quantum Information and Quantum Control University of Toronto, 80 St George Street, Toronto, Ontario, M5S 3H6, Canada
    • Department of Chemistry, Institute for Optical Science and Center for Quantum Information and Quantum Control University of Toronto, 80 St George Street, Toronto, Ontario, M5S 3H6, Canada.
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  • Zhenghong Lu

    Corresponding author
    1. Department of Materials Science and Engineering, University of Toronto, 184 College St., Toronto, Ontario, M5S 3E4, Canada
    • Department of Materials Science and Engineering, University of Toronto, 184 College St., Toronto, Ontario, M5S 3E4, Canada
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Abstract

White organic light-emitting diodes (WOLEDs) are currently under intensive research and development worldwide as a new generation light source to replace problematic incandescent bulbs and fluorescent tubes. One of the major challenges facing WOLEDs has been to achieve high energy efficiency and high color rendering index simultaneously to make the technology competitive against other alternative technologies such as inorganic LEDs. Here, an all-phosphor, four-color WOLEDs is presented, employing a novel device design principle utilizing molecular energy transfer or, specifically, triplet exciton conversion within common organic layers in a cascaded emissive zone configuration to achieve exceptional performance: an 24.5% external quantum efficiency (EQE) at 1000 cd/m2 with a color rendering index (CRI) of 81, and an EQE at 5000 cd/m2 of 20.4% with a CRI of 85, using standard phosphors. The EQEs achieved are the highest reported to date among WOLEDs of single or multiple emitters possessing such high CRI, which represents a significant step towards the realization of WOLEDs in solid-state lighting.

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