Luminescent properties of LiBaPO_4:RE (RE = Eu~(2+), Tb~(3+), Sm~(3+)) phosphors for white light-emitting diodes

摘要

Multicolor emitting phosphors LiBaPO_4:RE (RE = Eu~(2+), Tb~(3+), Sm~(3+)) 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 Eu~(2+), Tb~(3+), and Sm~(3+) in LiBaPO_4 host. Furthermore, the temperature-dependent luminescence of these phosphors was investigated. The emission intensities of Tb~(3+)- and Sm~(3+)-doped LiBaPO_4 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 LiBaPO_4:RE (RE = Eu~(2+), Tb~(3+), Sm~(3+)) were potential candidates for application in w-LEDs.