The Non-Concentration-Quenching Phosphor Ca₃Eu₂B₄O₁₂ for WLED Application

Commercial white LED devices usually suffer from a high color temperature and poor color rendering. Developing a new, efficient, and stable red phosphor is the key to solving this problem. In this work, a series of pure Ca₃Y_2-xB₄O₁₂:xEu³⁺ (0 < x ≤ 2) samples, including the new and fully transitional borate phosphor Ca₃Eu₂B₄O₁₂ (CEBO), have been successfully prepared by solid-state reaction synthesis. CEBO is isostructural with Ca₃Y₂B₄O₁₂ (CYBO), belonging to the orthorhombic system with space group Pnma (No. 62). Under optimal 393 nm excitation, this borate exhibits a strong red emission, peaking at 615 nm, with high color purity. Interestingly, the luminescence of CEBO is relatively higher than that of CYBO:Eu³⁺ phosphors. The quantum yield of this non-concentration-quenching phosphor reaches 95.6%. Furthermore, a warm pc-WLED device has been fabricated by mixing as-prepared CEBO powders and commercial BaMgAl₁₀O₁₇:Eu²⁺ and (Sr, Ba)₂SiO₄:Eu²⁺ phosphors, which exhibits a high color rendering index (Ra = 83.7) along with a color temperature of around 3883 K. The present work indicates that this new borate, with outstanding quantum efficiency and favorable thermal stability, can be used as a red phosphor for application in WLEDs.