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

Graphical Tb 3+ , Sm 3+ mono-/co- doped LiTaO 3 phosphors are prepared by high-temperature solid-state reaction. Emission color of LiTaO 3 : Tb 3+ , Sm 3+ shifts from green to yellow as Sm 3 ⁺ concentration increases due to energy transfer from Tb 3+ to Sm 3+ . Time-resolved color evolution from green to orange is achieved by combining the trap-assisted afterglow of Tb 3+ and stable photoluminescence of Sm 3+ . 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, Tb 3+ , Sm 3+ mono-/co-doped LiTaO 3 (LTO) phosphors are prepared by high-temperature solid-state method. Under 254 nm excitation, the emission chromaticity of LTO: Tb 3+ , Sm 3+ is modulated from green to yellow by increasing Sm 3+ content due to Tb 3+ → Sm 3+ energy transfer. The diverging luminescence thermal stability of LTO: Tb 3+ and LTO: Sm 3+ 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 Tb 3+ and the photoluminescence of Sm 3+ , 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.