La3+ tuned Sr3Y2Ge3O12: Dy3+ warm light LEDs phosphor

Phosphor-converted white light-emitting diodes (w-LEDs) have become indispensable for modern lighting and display technologies. However, the development of efficient and thermally robust white phosphors remains a persistent challenge. Here, we report a series of Sr 3 Y 2 Ge 3 O 12 : Dy 3+ garnet-based phosphors that exhibit dual emissions at 480 and 580 nm, enabling cool-white light generation. Co-doping with La 3+ effectively lowers the crystal symmetry and narrows the band gap from 4.67 to 4.56 eV, which enhances the radiative transitions of Dy 3+ . As a result, the emission intensities at 480 and 580 nm bands are boosted by factors of 2.21 and 1.91, respectively. The spectral modification drives a chromaticity shift from cool to warm white light, with correlated color temperature decreasing from 4703 K to 2927 K. Moreover, the modified phosphors exhibit excellent thermal stability (92.51 % at 150 °C) while maintaining high internal quantum efficiency (29.43 %). When integrated with 365 nm excitation chips, the phosphors enable the fabrication of w-LEDs with tunable color temperatures. These findings offer a promising pathway for the design of next-generation high-performance warm w-LEDs.