Temperature-dependent color-tunable persistent luminescence in BaSrGaGdO:Bi phosphor for advanced anti-counterfeiting.

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 BaSrGaGdO:Bi phosphors with tunable photoluminescence and PersL were synthesized by the cationic substitution strategy. The displacement of Ga by Gd induces an additional blue emission owing to the generation of a new Bi luminescence center. The pure white light is realized in BaSrGaGdO:0.8 %Bi,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 Bi 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.