Novel Orange-Emitting Phosphor Ba2LuGaO5:Bi3+ with High Efficiency and Thermal Robustness Induced by D‑Band Emission

Bi3+-activated phosphors have demonstrated great values in solid-state lighting, biomedicine, and detectors. Low quantum efficiency and unsatisfactory thermal stability are the main reasons that limit the practical application of Bi3+-activated phosphors. In this study, a high-efficiency and stable orange-light-emitting phosphor induced by D-band emission, Ba2LuGaO5:Bi3+, was successfully synthesized by selecting gallate with a highly rigid structure and appropriate cation sites. Under the excitation of near-ultraviolet light, Ba2LuGaO5:Bi3+ emits strong orange light with an internal quantum efficiency of 73% and thermal stability of 80%@150 °C. Based on two possible models of metal-to-metal charge-transfer transition and Bi3+ pairs/clusters, the origin of D-band emission is discussed in detail. According to the crystallographic data and spectroscopy data analysis, the luminescence of Ba2LuGaO5:Bi3+ is generated by the Bi3+ pair/cluster. The results indicate that Ba2LuGaO5:Bi3+ is of great potential in white-light-emitting diodes.