Broadband yellow-emitting LuMgGaO4:Bi3+ phosphor utilizing Bi3+ pairs for full-spectrum WLEDs

Developing near ultraviolet (NUV) excited yellow-emitting phosphors with emission spectrum encompassing cyan light is an inevitable requirement for pursuing full-spectrum high-quality lighting. In this study, a yellow-emitting phosphor, LuMgGaO4:Bi3+, was successfully synthesized through the selection of gallate with facile synthesis, chemical stability, and favorable cationic sites. Under excitation by NUV light, LuMgGaO4:Bi3+ emits yellow light with a significant Stokes shift, low emission energy, and a large full width at half maximum (FWHM), which originates from d-state emission. The origin of excitation and d-state emission is elaborated through crystal structure and spectral data analysis, as well as theoretical calculations grounded on semi-empirical models. The results suggest that the excitation spectrum of LuMgGaO4:Bi3+ is composed of Bi3+ pairs, MMCT, and 1S0→3P1 electron transitions, and the d-state emission of LuMgGaO4:Bi3+ originates from Bi3+ pairs. The packaged WLED lamp can emit warm white light without any cyan or yellow light traps present. The results indicate that LuMgGaO4:Bi3+ phosphor holds immense potential for employment in full-spectrum WLED lighting.