Achieving Anti‐Thermal Quenching Performance of Red Emissions by Synergetic Excitation Wavelength and IVCT State Position

Abstract Thermal quenching of rare earth doped luminescent materials limits their versatile applications in lighting, displays and sensing. Praseodymium ions have attracted particular interest for anti‐thermal quenching studies due to their rich non‐radiative transitions, yet the conditions for achieving anti‐thermal quenching of red emissions in Pr 3+ ‐doped niobates remain poorly understood. In this work, the discrepancy in hypersensitive transitions and luminescence properties is revealed for a series of ANbO 4 : 0.5% Pr 3+ (A = Lu, La, Y, and Sc) phosphors by integrating Judd‐Ofelt (J‐O) theory. The reversible transformation from conventional thermal quenching to pronounced anti‐thermal quenching in Pr 3+ ‐activated niobates through precise control of excitation wavelength and rational engineering of the intervalence charge transfer (IVCT) state are proposed. In particular, the ScNbO 4 : 0.5% Pr 3+ phosphor exhibits clear transition from thermal quenching under 264 nm excitation to anti‐thermal quenching under 275 nm excitation, with the 1 D 2 → 3 H 4 emission intensity at 373 K rising to 118.17% of the initial value at room‐temperature. Notably, the relationship between IVCT state position and the extent of the anti‐thermal quenching offer new insights into pressure dependent luminescence behavior. This work provides valuable design principles for the development of advanced materials in multimodal optical sensor devices, visualization applications, and safety signs.