A multicolor‐emitted phosphor for temperature sensing and multimode dynamic anti‐counterfeiting

Abstract The charge carrier capture phosphors for multifunctional integrated applications are gaining popularity these days. The realization of multiple optical properties often requires complex modulation processes, such as multiple ions doping and matrix substitution. Herein, we designed a single‐doped Ba 0.99 Ga 2 O 4 :0.01Bi phosphor with two emission peaks of 500 and 610 nm, both of which have different responses when changing temperatures (298–473 K). Theoretical calculations combined with experimental studies imply that the dopant Bi 3+ ions occupy regular Ba sites and the vacancy‐surrounded Ba sites, which act as luminescence centers. Meanwhile, doping‐induced and defects can operate as traps to store carriers that could be released and migrate toward specific luminescent centers under thermal disturbance. This phosphor shows excellent absolute sensitivity toward optical temperature sensing ( S a = 3.4% K −1 ). We also offered a quadruple anti‐counterfeiting application show based on the multicolor emission behavior of Ba 0.99 Ga 2 O 4 :0.01Bi with photostimulated luminescence at room temperature, different photoluminescent colors at room and high temperatures, as well as afterglow colors from yellow to green. This work stimulates the exploration of modulating the luminescence centers and trap levels to construct multifunctional fluorescent materials.