Lowering Color Temperature of Y3Al5O12:Ce3+ White Light Emitting Diodes Using Reddish Light-Recycling Filter

Abstract

A wide variation in correlated color temperature (CCT) in Y3Al5O12:Ce3+ (YAG:Ce) phosphor-on-cup white light emitting diodes (LEDs) coated with a single phosphor is realized by employing a tunable short wave pass dichroic filter [denoted as a light-recycling filter (LRF)]. An improved balance among blue, green, and red emission spectra is obtained from the reddish LRF-assisted YAG: Ce white LEDs. The lowest CCT of 3720 K in YAG: Ce single-phosphor-converted white LEDs is observed in the reddish LRF-assisted LEDs, where LEDs have an enhanced luminous efficacy (1.58-fold) and reasonable color rendering index (CRI, Ra > 75). (C) 2009 The Electrochemical Society. [DOI: 10.1149/1.3253619] All rights reserved.