Time‐Dependent Dynamic Multicolor Afterglow and Multimode Luminescence Thermometry of Lanthanide‐Doped Gallate

ABSTRACT Long‐persistent luminescence materials show strong potential for optical anti‐counterfeiting and luminescent thermometry, yet achieving multimode dynamic anti‐counterfeiting and high‐resolution temperature sensing within a single host remains challenging. Here, we establish theoretical models of host reference binding energy (HRBE) and vacuum reference binding energy (VRBE) for SrGa 2 O 4 , which predict that Sm 3+ and Tb 3+ doping introduces electron and hole traps at 0.60 and 1.51 eV, respectively. Guided by these predictions, we synthesize single‐doped SrGa 2 O 4 :Ln 3+ phosphors that exhibit dynamic fluorescence and time‐dependent multicolor afterglow under continuous excitation. Thermoluminescence spectra confirm that the trap distributions agree with the HRBE–VRBE model. Under 254 nm excitation, emissions evolve from red or green to blue and reverse upon cessation of irradiation. This behavior is attributed to differences in carrier capture and release between deep Ln 3+ ‐related traps and shallow host‐derived traps. Moreover, the distinct thermal‐quenching behaviors of the [GaO 4 ] 2− and Ln 3+ centers enable dual‐mode optical thermometry based on fluorescence intensity ratio and International Commission on Illumination (CIE) chromaticity. In CIE mode, SrGa 2 O 4 :Sm 3+ and SrGa 2 O 4 :Tb 3+ show maximum relative sensitivities ( S r ) of 3.06% and 1.34% K −1 , respectively. These findings demonstrate the potential of SrGa 2 O 4 :Ln 3+ phosphors as multifunctional materials for advanced optical thermometry and dynamic anti‐counterfeiting.