Spray pyrolysis prepared yellow to red color tunable Sr1-xCaxSe:Eu2+ phosphors for white LED

Abstract

The spherical and submicron size of Sr1-xCaxSe:Eu2+ phosphors were successfully prepared by ultrasonic spray pyrolysis. The phosphors adopted a cubic structure, and the replacement of Sr2+ with Ca2+ decreased the lattice parameter. The Sr1-xCaxSe:Eu2+ showed broad and strong excitation under 420-460nm blue light, and the emission band could be tuned from 565 to 607nm by increasing the Ca2+ ratio in the host lattice. In addition, the doping of Zn2+ into Sr2+ or Ca2+ enhanced the emission intensity with a small red shift due to the change in crystal field strength and nephelauxetic effects. The warm and high CRI of white LED was achieved using blue LED pumped with blending phosphors of 612nm emitting Ca0.98Zn0.02Se:Eu2+ and 565nm emitting YAG. The correlated color temperatures and CRI were 4719.2K, and 86.3, respectively, and an acceptable color variation was also observed at operating currents ranging from 20 to 70mA. (c) 2012 Optical Society of America