Tunable Cold/Warm White Light Obtained via Reversible Phase Transition of Antimony-Doped Indium Chlorides

Metal halides with efficient, stable, and tunable white light emission are ideal for lighting applications, because their emission properties can be effectively optimized through rational doping and precise compositional engineering. However, the synthesis of such materials often requires strict conditions and complex procedures. In this work, we report a phase transition from Sb-doped Cs2InCl5·H2O to Cs2NaInCl6, along with tunable white light emission. Partial substitution of Na+ enables the formation of high-energy multiple emission centers, resulting in efficient white light with an adjustable correlated color temperature ranging from 2500 K to 5000 K under 365 nm excitation. The photoluminescence quantum yield reaches up to 45.24%. Efficient energy transfer among emission centers and the doping concentration of Na+ are critical for achieving high-performance tunable white light. The synthesized Cs2NaxInCl5+x:Sb composite exhibits excellent stability under ultraviolet irradiation and environmental conditions such as oxygen and humidity, even after 200 h of ultraviolet irradiation, the emission spectrum remains stable, with more than 80% of its initial efficiency being preserved. Our results show its potential for advanced lighting applications and provide valuable insight for a desirable emission-tunable metal halide design.