Color tunable emission and energy transfer in LaSi3N5:Ce3+,Tb3+ phosphors for UV white LEDs

Abstract

A series of new blue-green emitting LaSi₃N₅:Ce³⁺,Tb³⁺ phosphors were obtained through a high temperature solid-state method. The crystal structure, photoluminescence properties and energy transfer from Ce³⁺ to Tb³⁺ were investigated. The doped ions Ce³⁺ and Tb³⁺ were confirmed to occupy the same crystallographic sites as La³⁺ using a Rietveld structure refinement method. The emission spectra of these phosphors was composed of a blue emission band attributed to the d–f transition of Ce³⁺, together with several sharp lines ascribed to the emission of Tb³⁺ under UV light excitation. Thus a color tunable emission from blue to green was obtained via controlling the doping concentration of Tb³⁺. In addition, the mechanism of energy transfer, efficiency of energy transfer, chromaticity coordinates and thermal stability of these phosphors were investigated. The results indicated that the Ce³⁺,Tb³⁺ co-activated LaSi₃N₅ phosphors with color-tunable blue-green emission and high quantum efficiency may have potential for UV white LEDs.