Effect of Li+, La3+ co-doping on the photoluminescence enhancement of Sr3AlO4F:Sm3+ orange-red-emitting phosphor for white light-emitting diodes

Abstract

A series of Sr3AlO4F:Sm3+, La3+, Li+ orange-red-emitting phosphors were synthesized via a solid-state reaction with charge compensator Li+ co-doping for luminescence enhancement. The X-ray diffraction results demonstrated that all samples were consistent with standard Sr3AlO4F structure belonging to tetragonal phase with I4/mcm space group. The effects of La3+ co-doping and Li+ co-doping on the structure and luminescence properties of Sr3AlO4F:Sm3+ were investigated. The emission spectrum of Sm3+-doped phosphors was composed of several emission peaks at 565 nm (4G5/2→6H5/2), 602 nm (4G5/2→6H7/2) and 650 nm (4G5/2→6H9/2), respectively. After co-doping La3+, the luminescence intensity of Sr3AlO4F:Sm3+, La3+ sample was elevated to 1.46 times of that of Sr3AlO4F:Sm3+ phosphor, which is in consequence of the environmental effect of crystal field around luminescence center. Furthermore, depend on charge compensation effect, the luminescence intensity of Sr3AlO4F:Sm3+, La3+, Li+ phosphor was further enhanced by 1.48 times higher than that of Sr3AlO4F:Sm3+, La3+ phosphor. A w-LEDs device was packaged via coating the as-prepared phosphor on n-UV chip of 395 nm with commercial phosphors. These results indicated that there is a potential application for Sr3AlO4F:Sm3+, La3+, Li+ phosphor as orange-red component in w-LEDs.