Eu3+-activated CsBSi2O6 red phosphor with high color purity and thermal stability for warm white LEDs

In this paper, a novel CsBSi₂O₆:xEu³⁺(1 % ≤ x ≤ 9 %) red phosphor is successfully synthesized through the high-temperature solid-state process, featuring a tetragonal zeolite-like structure. The phosphor exhibits a dominant red emission peak at 617 nm under 392 nm ultraviolet excitation, attributed to the ⁵D₀→⁷F₂ electric dipole transition of Eu³⁺ ions, confirming their occupation of non-centrosymmetric sites in the host lattice. Optimal luminescence intensity is achieved at 7 % Eu³⁺ doping, beyond which concentration quenching occurred via static mechanisms driven by dipole–dipole interactions (critical transfer distance R_c ≈ 14.39 Å), with 79 % color purity (CIE: 0.5825, 0.4103) and 80.38 % intensity retention at 140 °C. Integrated into WLEDs with NUV chips, it achieves warm white light (CCT = 4910 K). This work presents that CsBSi₂O₆: Eu³⁺ is a cost-effective, highly thermally stable red phosphor and has great practical application potential in fields such as display technology and lighting equipment.