Enhanced Light Out-Coupling of Organic Light-Emitting Diodes: Spontaneously Formed Nanofacet-Structured MgO as a Refractive Index Modulation Layer

Authors

  • Kihyon Hong,

    1. Department of Materials Science and Engineering, Division of Advanced Materials Science, Pohang University of Science and Technology (POSTECH), Pohang 790–784 (Republic of Korea)
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  • Hak Ki Yu,

    1. Department of Materials Science and Engineering, Division of Advanced Materials Science, Pohang University of Science and Technology (POSTECH), Pohang 790–784 (Republic of Korea)
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  • Ilhwan Lee,

    1. Department of Materials Science and Engineering, Division of Advanced Materials Science, Pohang University of Science and Technology (POSTECH), Pohang 790–784 (Republic of Korea)
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  • Kisoo Kim,

    1. Department of Materials Science and Engineering, Division of Advanced Materials Science, Pohang University of Science and Technology (POSTECH), Pohang 790–784 (Republic of Korea)
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  • Sungjun Kim,

    1. Department of Materials Science and Engineering, Division of Advanced Materials Science, Pohang University of Science and Technology (POSTECH), Pohang 790–784 (Republic of Korea)
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  • Jong-Lam Lee

    Corresponding author
    1. Department of Materials Science and Engineering, Division of Advanced Materials Science, Pohang University of Science and Technology (POSTECH), Pohang 790–784 (Republic of Korea)
    • Department of Materials Science and Engineering, Division of Advanced Materials Science, Pohang University of Science and Technology (POSTECH), Pohang 790–784 (Republic of Korea).
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Abstract

original image

The light out-coupling efficiency of OLEDs is enhanced by the use of a refractive index modulation layer (RIML) with MgO nanofacet structure (see figure) that can be formed without an additional lithographic or patterning processes. Increases in luminance and power efficiency of up to 19% and 34.7%, respectively, are demonstrated. Low out-coupling efficiency is one of the main limitations to highly efficient OLEDs, so overcoming it would allow substantial improvements.

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