Bidirectional Energy Transfer and Luminescent Properties of Tb3+/Yb3+ Doped Csla(Moo4)2 Phosphors

Abstract

A series of CsLa(MoO4)2:Tb3+/Yb3+ phosphors were prepared using the high-temperature solid-state method, and their dual-mode luminescence was successfully achieved. The down-conversion green luminescence properties of CsLa(MoO4)2:5%Tb3+, x%Yb3+ (x = 0, 1, 2, 3, 4) under ultraviolet excitation were studied, and the energy transfer behavior from Tb3+ to Yb3+ was investigated. The energy transfer mechanism was determined to be a quadrupole-quadrupole interaction. As the doping concentration of Yb3+ increased, the fluorescence lifetime of Tb3+ gradually decreased, and its emission intensity showed an almost linear decline. Under near-infrared excitation, the obtained CsLa(MoO4)2:5%Tb3+, x%Yb3+ (x = 1, 2, 3, 4) shows bright green up-conversion emission due to the energy transfer from Yb3+ to Tb3+. The up-conversion luminescence mechanism is a two-photon process based on the relationship between emission intensity and laser pumping power. Besides, the temperature-dependent fluorescence test results demonstrated that CsLa(MoO4)2:Tb3+/Yb3+ phosphors exhibited good thermal stability. Based on the dual-stimulus response characteristics, a novel anti-counterfeiting pattern was designed. The synthesized CsLa(MoO4)2:Tb3+/Yb3+ phosphors demonstrated significant research value in the fields of lighting, display and advanced anti-counterfeiting technology.

Keywords: lanthanide ions doping, down/upconversion luminescence, bidirectional energy transfer, anti-counterfeiting