Coupling efficiency enhancement in organic light-emitting devices using microlens array-theory and experiment |
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Authors: | Huajun Peng Yeuk Lung Ho Xing-Jie Yu Man Wong Hoi-Sing Kwok |
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Affiliation: | Dept. of Electr., Electron. Eng. Hong Kong Univ. of Sci. & Technol., China; |
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Abstract: | Microlens arrays are introduced on glass substrates to improve the out-coupling efficiency of organic light-emitting devices (OLEDs). The microlenses suppress waveguiding loss in the substrate. A theoretical model, based on electromagnetic wave propagation and geometric ray tracing, is developed to simulate the enhancement effects and optimize the structure parameters of the lens pattern. A simple soft-lithography approach is employed to fabricate the microlens array on glass substrates. With the use of an optimized lens pattern, an increase of over 85% in the coupling efficiency of the OLED is expected theoretically. An increase of 70% in the coupling efficiency is achieved experimentally, without detrimental effect to the electrical performance of the OLED. |
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