Novel Cyan-Green-Emitting Bi3+-Doped BaScO2F, R+ (R = Na, K, Rb) Perovskite Used for Achieving Full-Visible-Spectrum LED Lighting

Cyan-emitting phosphors are important for near-ultraviolet (NUV) light-emitting diodes (LEDs) to gain high-quality white lighting. In the present work, a Bi³⁺-doped BaScO₂F, R⁺ (R = Na, K, Rb) perovskite, which emits 506 nm cyan-green light under 360 or 415 nm excitation, is obtained via a high-temperature solid-state method for the first time. The obtained perovskite shows improved photoluminescence and thermal stability due to the charge compensation of Na⁺, K⁺, and Rb⁺ co-doping. Its spectral broadening is attributed to two centers Bi (1) and Bi (2), which are caused by the zone-boundary octahedral tilting due to the substitution of Bi³⁺ for the larger Ba²⁺. Employing the blend phosphors of Ba_0.998ScO₂F:0.001Bi³⁺,0.001K⁺ and the commercial BAM:Eu²⁺, YAG:Ce³⁺, and CaAlSiN₃:Eu²⁺, a full-spectrum white LED device with R_a = 96 and CCT = 4434 K was fabricated with a 360 nm NUV chip. Interestingly, a novel strategy is proposed: the cyan-green Ba_0.998ScO₂F:0.001Bi³⁺,0.001K⁺ and orange Sr₃SiO₅:Eu²⁺ phosphors were packaged with a 415 nm NUV chip to produce the white LED with R_a = 85 and CCT = 4811 K.