Tunable Photoluminescence of LiTaO3: Tb3+, Sm3+ for Dynamic Multimode Optical Anti-Counterfeiting

Currently, static fluorescent anti-counterfeiting technology struggles to cope with the increasingly sophisticated counterfeiting techniques, making the dynamic multimode regulation scheme an urgent necessity. Herein, Tb3+, Sm3+ mono-/co-doped LiTaO3 (LTO) phosphors are prepared by high-temperature solid-state method. Under 254 nm excitation, the emission chromaticity of LTO: Tb3+, Sm3+ is modulated from green to yellow by increasing Sm3+ content due to Tb3+ -> Sm3+ energy transfer. The diverging luminescence thermal stability of LTO: Tb3+ and LTO: Sm3+ is uncovered, which is governed by their distinct vacuum-referenced binding energy (VRBE) levels and charge compensation mechanisms. Based on the time-domain difference between the trap-assisted afterglow of Tb3+ and the photoluminescence of Sm3+, a dynamic anti-counterfeiting pattern that changes from green to orange over time is designed. This work provides a novel material design strategy for time-resolved color signatures and multi-modal dynamic optical encryption.