Enhanced red-emitting phosphors through Si4+/Eu3+ co-doping: advancing WLED performance and anti-counterfeiting applications†

The asymmetry of the local environment within host materials plays a critical role in enhancing the emission performance of Eu³⁺ ions. In this study, we introduced a novel Si⁴⁺-doping strategy to optimize the luminous properties of Eu³⁺ ions by promoting asymmetry in the local lattice environment. And then, a series of Si⁴⁺/Eu³⁺ co-doped Sr₃Ga₂Ge₄O₁₄ phosphors were synthesized. Our findings reveal that Si⁴⁺-doping at a concentration of 60 mol% significantly enhances the emission intensity of Eu³⁺ ions in the Sr₃Ga₂Ge₄O₁₄ host by approximately 80%. Also, the internal quantum efficiency increases from 37.80% to 49.04%, alongside a rise in color purity from 87.40% to 99.80%. Utilizing this Sr_2.3Ga₂Ge_1.6Si_2.4O₁₄:0.7Eu³⁺ high-performance red phosphor, we fabricated a white light-emitting diode (WLED) device with natural white light characteristics, achieving CIE coordinates of (0.338, 0.323), a correlated color temperature (CCT) of 5636 K, and a color rendering index (CRI) of R_a = 89.4. Additionally, we developed a high-performance anti-counterfeiting ink using this red phosphor, which adheres uniformly to surfaces with varying roughness and delivers exceptional luminescence effects. This study provides new insights into the development of advanced red-emitting phosphors for applications in lighting and anti-counterfeiting technologies.