High color rendering white light-emitting-diode illuminator using the red-emitting Eu2+-activated CaZnOS phosphors excited by blue LED

Abstract

A red phosphor CaZnOS:Eu2+ was synthesized by solid state reaction and has been evaluated as a candidate for white LEDs. For this material, the XRD, PL, PL excitation (PLE) and diffuse reflection spectra have also been investigated. CaZnOS:Eu2+ reveals a broad absorption band and good color purity. By utilizing a mixture of red-emitting CaZnOS:Eu2+, green-emitting (Ba,Sr)(2)SiO4:Eu2+ and yellow-emitting Y3Al5O12:Ce3+ as light converters, an intense white InGaN-based blue-LED (similar to 460 nm) was fabricated to exhibit a high color-rendering index Ra of 85 at a correlated color temperature of 4870 K. Based on the results, we are currently evaluating the potential application of CaZnOS:Eu2+ as a red-emitting blue-chip convertible phosphor. (c) 2010 Optical Society of America