Combining time-evolving multicolor luminescence with intense afterglow of Na2CaGe2O6: Tb3+/Tb3+, Yb3+ phosphors for dynamic anticounterfeiting

Achieving dynamic optical anticounterfeiting is a significant breakthrough in improving safeguard information security for the easily imitated static photoluminescence (PL). Herein, we report an advanced dynamic optical anticounterfeiting strategy based on Na2CaGe2O6: Tb3+/Tb3+, Yb3+ phosphors combined with time-evolving dynamic multicolor PL and bi-temporal luminescent performance. Interestingly, during the irradiation of ultraviolet lamp, the cross-relaxation effect between Tb3+ ions results in the dynamic variation of PL color of Na2CaGe2O6: Tb3+ from red to green in seconds. Furthermore, the features of persistent luminescence of Na2CaGe2O6: Tb3+ is optimized by the new traps through the co-doping Yb3+ ions. These results provide a more effective method for the design of the novel advanced dynamic anticounterfeiting and information encryption.