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AlGaInP Red LEDs with Hollow Hemispherical Polystyrene Arrays
Wen-Ching Cheng1, Shih-Yung Huang2, Yi-Jiun Chen3
1Graduate Institute of Precision Engineering, National Chung Hsing University, Taichung, 402, Taiwan, R.O.C.
Abstract:
A hollow hemispherical polystyrene (HHPS) was fabricated to reduce total internal reflection in AlGaInP-based LEDs. At an injection current of 350 mA, the external quantum efficiencies of LED-I, LED-II, LED-III, and LED-IV are 20.92%, 24.65%, 27.28%, and 33.77% and the wall-plug efficiencies are 17.11%, 20%, 22.5%, and 27.33%, respectively. The enhanced performance is attributed to the light output power enhancement through the surface roughness, microlens-liked PS hemisphere, and scatter-liked HHPS array. In this paper, the rigorous coupled wave analysis (RCWA) numerical method was also conducted to demonstrate the HHPS array effectively enlarge the effective light cone.
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