Abstract
We investigate the effects of the refractive index of the encapsulant on the light-extraction efficiency (LEE) of light-emitting diodes (LEDs) for GaN LEDs (n ≈ 2.5) and AlGaInP LEDs (n ≈ 3.0). For non-absorbing rectangular parallelepiped LED chips, as the refractive index of the encapsulant increases, the LEE first increases quasi-linearly, then increases sub-linearly, and finally a saturation is reached. Furthermore, LEDs with a dual-layer graded-refractive-index (GRIN) encapsulant (n encapsulant1 = 1.57 and n encapsulant2 = 1.41) is fabricated through a two-step curing process. We demonstrate that such an LED further enhances the LEE by reducing Fresnel reflection loss at the encapsulant/air interface by 35% compared with an LED encapsulated with a single-layer encapsulant (n encapsulant = 1.57).
©2011 Optical Society of America
Full Article | PDF ArticleMore Like This
Joong-Yeon Cho, Kyeong-Jae Byeon, and Heon Lee
Opt. Lett. 36(16) 3203-3205 (2011)
Xingjian Yu, Linyi Xiang, Shuling Zhou, Naiqi Pei, and Xiaobing Luo
Appl. Opt. 60(2) 306-311 (2021)
Shuang-Chao Chung, Pei-Chen Ho, Dun-Ru Li, Tsung-Xian Lee, Tsung-Hsun Yang, and Ching-Cherng Sun
Opt. Express 23(11) A640-A649 (2015)