Anionic Regulation toward Bi 3+ Selective Occupation for Full-Spectrum White Light Emission.

An activator's selective occupation of a host is of great significance for designing high-quality white light-emitting diode phosphors, while achieving a full-spectrum single-phase white light emission phosphor is challenging. In this study, a boron phosphate solid-solution Na 2 Y 2 (BO 3 ) 2- x (PO 4 ) x O:0.005 Bi 3+ (NYB 2- x P x O:0.005 Bi 3+ ) white phosphor was designed by selectively occupying Bi 3+ activators in the mixed anionic groups. The substitutes of the anionic unit (BO 3 ) 3- by the (PO 4 ) 3- unit are supposed to force part of the Bi 3+ ion to enter the Na lattice site, which produces an intense orange-red emission peaked at 590 nm. In parallel, spectral tuning from blue to white light and an internal quantum efficiency of 56.42% was obtained, and the thermal stabile luminescence intensity remains at 94.2% of the initial intensity after four heating-cooling cycles from 30 to 210 °C (luminescent intensity is 83.6% of room temperature (RT) at 150 °C, with excellent thermal stability and recovery performance). Finally, an excellent color rendering index ( Ra = 90.8 and R9 = 85) was demonstrated for white light-emitting diode devices using only an NYB 1.5 P 0.5 O:0.005 Bi 3+ phosphor and a near-ultraviolet (n-UV) 365 nm LED chip. This work delves into the different selective occupancy of Bi 3+ ions and explores a new avenue for the design of phosphors for full-spectrum white light emission.