Tb-based phosphor BaTb₄Si₃O₁₃:Eu³⁺ with high energy transfer efficiency for white LEDs

The conventional random co-doping of Tb³⁺ and Eu³⁺ leads to spatial separation that severely limits energy transfer efficiency between these ions, which is critical for minimizing non-radiative losses in white LEDs. To address the limitation, we designed BaTb_4-xSi₃O₁₃:xEu³⁺, breaking through the bottleneck by occupying Tb³⁺ sites with Eu³⁺. Rietveld refinement and ionic radius analysis confirmed site occupancy selectivity, enabling 71.59 % Tb³⁺→Eu³⁺ energy transfer efficiency, which is higher than conventional random doping systems. Under 380 nm excitation, the phosphor yielded red emission with CIE coordinates of (0.6153,0.3838) and 86.64 % color purity, and exhibited exceptional thermal stability with 70 % intensity retention at 473 K. Fabricated wLEDs using a NUV chip with commercial blue phosphor, green phosphor, and the developed phosphor produced warm white light with a correlated color temperature of 4519 K and CIE coordinates of (0.3478, 0.3868), achieving a high color rendering index of 87.4. These results demonstrate BaTb₄Si₃O₁₃:Eu³⁺ as a highly promising red phosphor candidate for solid-state lighting applications.