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.