Novel Eu2+-Activated Yellow-Emitting Sr8MgLu(PO4)(7) Phosphors for White-Light Near-Ultraviolet LEDs

Abstract

An Eu2+-activated Sr8MgLu(PO4)(7) yellow-emitting phosphor was synthesized by a conventional solid state reaction for applications in white-light near-ultraviolet (NUV) light-emitting diodes (LEDs) having excellent color rendering index. Upon excitation at 390 nm, the Sr8MgLu(PO4)(7):Eu2+ phosphor exhibits an asymmetric broad yellow emission centered at 594 nm and the composition-optimized concentration of Eu2+ in Sr8MgLu(PO4)(7):Eu2+ was determined to be 0.5 mol%. The excitation spectrum of this phosphor has a broadband absorption in the 250-450 nrn NUV region, which matches well with NUV chips. A white-light LED, fabricated using a NUV LED 390 nm chip pumped by a blend of yellow-emitting Sr8MgLu(PO4)(7):0.005Eu(2+) and blue-emitting BaMgAl10O17:Eu2+ phosphors, resulted in an excellent color rendering index of 95.4 and Commission International l'Eclairage (CIE) chromaticity coordinates of (0.336, 0.353) at a correlated color temperature of 5354 K. Based on these results, we are currently evaluating the potential application of Sr8MgLu(PO4)(7):Eu2+ as a yellow-emitting near-ultraviolet convertible phosphor.