Enhanced Orange-Red Emission in Sr3Ga2Ge4O14:Sm3+ Phosphors via Si4+/K+ Co-Doping for WLED and Anti-counterfeiting

The local crystal-field symmetry within a host material plays a critical role in modulating the luminescence behavior of Sm 3+ ions. In this study, we propose a novel Si 4+ doping strategy to enhance the photoluminescence properties of Sm 3+ in a Sr 3 Ga 2 Ge 4 O 14 host, with the effects proposed to be associated with alterations in the symmetry of the local coordination environment. A series of Si 4+ /Sm 3+ co-doped phosphors was synthesized via solid-state reaction. At an optimal Si 4+ doping level of 50 mol%, the emission intensity of Sm 3+ increased by approximately 40%. Further introduction of K + as a charge compensator considerably improved the internal quantum efficiency from 25.12% to 47.28% and color purity from 96.8% to 99.9%. A prototype WLED using the optimized phosphor exhibited a low CCT (5769 K) and a high CRI ( R a = 87.6), satisfying the requirements for indoor lighting. The phosphor was also incorporated into a PVA-based anti-counterfeiting ink, showing bright, stable, and substrate-independent UV-excited fluorescence. This work provides a feasible doping strategy for developing high-performance orange-red phosphors and demonstrates their potential in high-quality WLED and advanced anti-counterfeiting applications.