Highly Humidity-Resistant Oxynitride Phosphor BaSi₆N₈O:Ce³⁺ for pc-LEDs

Many phosphor hosts, for example, nitrides and sulfides, often face challenges such as hydrolysis and oxidation, limiting their application in phosphor-converted white light-emitting diodes (pc-LEDs). In this study, we developed a highly humidity-resistant yellow-green-emitting phosphor BaSi₆N₈O:Ce³⁺ (BSNO:Ce³⁺). The DFT calculations revealed a high Debye temperature (Θ_D = 1159 K), indicating a rigid crystal structure that contributes to the photoluminescence thermal quenching resistance of BSNO. Furthermore, we observed a notable positional shift of Ce³⁺ in the BSNO lattice, contributing to an unusual photoluminescence (PL) red shift compared to BSNO:Eu²⁺. Importantly, BSNO:Ce³⁺ exhibited remarkable PL stability under harsh conditions, showing no degradation in water for 10 days and less than 10% intensity loss at elevated temperatures up to 773 K. We constructed a prototype white LED with a high color rendering index (R_a = 92) by combining a 365 nm chip with BSNO:0.03Ce³⁺ and commercial phosphors, demonstrating its potential for advanced pc-LED applications.