Luminescent properties of LiBaPO4:RE (RE = Eu2+, Tb3+, Sm3+) phosphors for white light-emitting diodes

Abstract

Multicolor emitting phosphors LiBaPO4:RE (RE = Eu2+, Tb3+, Sm3+) reported as interesting down-conversion luminescent materials in white light-emitting diodes (w-LEDs) have been prepared by a conventional solid-state reaction. The excitation and emission spectra indicate that these phosphors can be effectively excited by the near-UV light, and emit blue, green, and red light, respectively. The photoluminescence properties, decay times, and Commission Internationale de I’Eclairage (CIE) chromaticity indexes are determined for various concentrations of the activators Eu2+, Tb3+, and Sm3+ in LiBaPO4 host. Furthermore, the temperature-dependent luminescence of these phosphors was investigated. The emission intensities of Tb3+- and Sm3+-doped LiBaPO4 increased unexpectedly with increasing temperature. This interesting phenomenon is proposed to be the result of two ground states in the configurational coordination diagram. The present investigation suggests that LiBaPO4:RE (RE = Eu2+, Tb3+, Sm3+) were potential candidates for application in w-LEDs.