Simultaneously enhanced photoluminescence and persistent luminescence in SrLaAlO4: Tb type layered perovskite via Gd3+ codoping

Abstract

Gd³⁺ co-doping is effective to enhance the photoluminescence of rare earth activators in various host due to energy transfer, however, it is rarely reported via such strategy to regulate persistent luminescence properties. In this work, Gd³⁺ was co-doped into the SrLaAlO₄: Tb persistent luminescence phosphors, and it is found that the photoluminescence and persistent luminescence of the products can be simultaneously improved. The results indicate that as the doping concentration of Gd³⁺ increases, the particle diameters increase which contributes the increased luminescence. Additionally, an energy transfer process from Gd³⁺ to Tb³⁺ ions was observed, which enhances the emission of Tb³⁺ ions. Furthermore, the persistent luminescence properties of the synthesized phosphors were improved. When the UV light source is turned off, the persistent luminescence of SrLaAlO₄: 0.03Tb³⁺, xGd³⁺ (x = 0.00–0.97) can last for more than 2 h, which is 100 % enhanced compared to SrLaAlO₄: 0.03Tb³⁺. The trap distribution of SrLaAlO₄: 0.03Tb³⁺, xGd³⁺ (x = 0.00–0.97) phosphors was analyzed by thermoluminescence. It is found that after the substitution of La³⁺ with Gd³⁺, the trap position shifted towards higher temperatures and the trap concentration increased. The initial intensity of the persistent luminescence was also enhanced after Gd³⁺ co-doping. Based on the experimental findings, the luminescence and persistent luminescence mechanism of SrLaAlO₄: 0.03Tb³⁺, xGd³⁺ (x = 0.00–0.97) phosphors were described and discussed.