Effects of phosphor distribution and step-index remote configuration on the performance of white light-emitting diodes

Chung Hao Chiang, Hung Yi Tsai, Ting Shi Zhan, Han Yu Lin, Ying Chien Fang, Sheng Yuan Chu

Research output: Contribution to journalArticle

29 Citations (Scopus)

Abstract

Phosphor-converted white light-emitting diodes (pc-WLEDs) are fabricated by combining CaSi2O2N2:Eu2+ and Ca2Si5N8:Eu2+ phosphors with a blue chip. Experimental results demonstrate that placing the red phosphor layer above the yellow one (Y down/R up) yields the highest luminous efficiency, making it the preferable phosphor distribution for pc-WLEDs rather than Y up/R down. This finding suggests that the extent of overlap between the emission spectrum of short-emission-wavelength phosphors and the excitation spectrum of long-emissionwavelength phosphors and their luminous efficacy of radiation should be taken into account simultaneously when studying the optical characteristics of pc-WLEDs. Compared to common pc-WLEDs with silicone gel as the remote layer, the proposed step-index remote configuration exhibits superior luminous efficiency because of reduced total internal reflection and Fresnel loss.

Original languageEnglish
Pages (from-to)2830-2833
Number of pages4
JournalOptics Letters
Volume40
Issue number12
DOIs
Publication statusPublished - 2015 Jan 1

All Science Journal Classification (ASJC) codes

  • Atomic and Molecular Physics, and Optics

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