Trap induction and regulation to enhance long persistent luminescence for information encryption and anti-counterfeiting

The security level of traditional long persistent luminescence (LPL) phosphor with a single adjustable decay time is increasingly insufficient to meet the demands of a rapidly advancing society, resulting in significant losses for individuals and corporations. Therefore, exploring a phosphor with a two-model of adjustable decay time and afterglow color is meaningful for advanced information encryption and anti-counterfeiting. Here, we propose a simple and efficient strategy to regulate the trap type and concentration in high defect tolerance matrix CaGa 4 O 7 (CGO), achieving tunable emission color, afterglow color and decay time. At first, we introduce the rare earth ions Tb 3+ to generate the new defects, and then substitute Ca 2+ with Zn 2+ in CGO:Tb 3+ (CZGO:Tb 3+ ) phosphors to increase the inherent defects concentration, thereby greatly increasing the number of band electrons trapped by the defects and improving their LPL performance. Owing to the lattice distortion, its luminescence performance is increased by 6.09 times. It is worth noting that CZGO:Tb 3+ phosphor has a variety of emission modes over time, so it has great potential in information anti-counterfeiting and encryption applications.