Temperature-dependent color-tunable persistent luminescence in Ba_0.95Sr_0.05Ga_2-yGd_yO₄:Bi³⁺ phosphor for advanced...

As emerging anti-counterfeiting materials, persistent luminescence (PersL) materials have attracted much attention owing to their particular luminescent properties, including durable luminescence, facile identification, high security and environment-friendly. Especially, exploiting color-tunable dynamic afterglow materials that facilitate the use of advanced technology such as multi-mode dynamic anti-counterfeiting remains of great realistic significance. Herein, a series of Ba_0.95Sr_0.05Ga_2-yGd_yO₄:Bi³⁺ phosphors with tunable photoluminescence and PersL were synthesized by the cationic substitution strategy. The displacement of Ga³⁺ by Gd³⁺ induces an additional blue emission owing to the generation of a new Bi³⁺ luminescence center. The pure white light is realized in Ba_0.942Sr_0.05Ga_1.9Gd_0.1O₄:0.8 %Bi³⁺,0.25 %K⁺ when excited by 325 nm light. Besides, color-tunable emission is triggered by changing the excitation wavelength or temperature. Significantly, excellent room-temperature PersL and dramatically intensified PersL with tunable color output under thermal stimulation are clearly discernible. Such properties result from the existence of multiple Bi³⁺ luminescent centers and traps. These findings open up new ideas to produce color-tunable dynamic PersL materials for advanced anti-counterfeiting, information storage and encryption.