Interface Reaction Inhibition in Phosphor-in-Silica Glass for High-Performance Laser Illumination
Phosphor-in-glass (PiG) materials are promising color converters for high-power laser illumination, yet suppressing interfacial reactions between phosphor and glass matrix at elevated sintering temperatures remains a critical challenge. Here, we report a Y3Al5O12:Ce3+ (YAG:Ce) phosphor-in-silica glass (PiSG) with high SiO2 content (>85 wt%) fabricated via a Cs2CO3 flux. Incorporation of Cs2O significantly inhibits SiO2-YAG:Ce reactions, preserving internal quantum efficiency (IQE) at 97.7% of pure YAG:Ce, and achieving 88.3% IQE even after calcination at 1400°C for 2 h. In contrast, smaller alkali ions (Li+, Na+) accelerate YAG:Ce decomposition. Mechanistic studies reveal that Cs+ with large ionic radius and weak interaction with oxygen suppresses non-bridging oxygen (NBO) formation, promoting a complete silica network that limits alkali ion diffusion. Leveraging the mixed alkali effect (10% Li2O + 5% Cs2O), the PiSG exhibits enhanced hydrothermal stability, withstanding 200°C treatment for 10 h. A PiG film-sapphire device delivers 3080 lm luminous flux and 213 lm W−1 efficiency under blue laser excitation. These findings establish YAG:Ce-PiSG as a highly promising color-conversion material for high-performance laser illumination.