Thermal-responsive dynamic color-tunable persistent luminescence from green to deep red for advanced anti-counterfeiting

Color-tunable persistent luminescent materials that respond to external physical stimuli are fascinating but rarely reported, especially the dynamic ones. In this work, a dynamically color-tunable persistent luminescence by varying the ambient temperature is revealed in an all-inorganic singly-phase Cr³⁺, Mn²⁺ co-doped zinc gallate spinel phosphor. The persistent luminescence shows dramatic color variation from green (∼503 nm) to deep red (∼709 nm) in 350 ∼ 650 K. The application potential of this phosphor for advanced anti-counterfeiting is verified by fabricating several multi-level anti-counterfeiting models, which work under both fluorescence and afterglow modes. Further, by detailed optical investigations and theoretical calculations, two factors are demonstrated to endow the persistent luminescence of the co-doped phosphor with temperature-dependent afterglow colors: the dual-traps electronic structure of the host and the different photoluminescence thermal quenching properties of the Cr³⁺/Mn²⁺ emitters. This work reports the dynamic color-tunable persistent luminescence under different temperatures in Cr³⁺, Mn²⁺ co-doped zinc gallate and provides a new perspective for the design of thermal-responsive dynamic optical materials for the application of advanced anti-counterfeiting.