Achieving single-phase white light emission by utilizing the sensitization effect of Bi3+ to Eu3+ and Tb3+ in LiY6O5(BO3)3

Abstract

Photoluminescence energy transfer offers an effective strategy for achieving tunable emission colors, including single-phase white light emission. In this study, LiY₆O₅(BO₃)₃ (LYBO) was chosen as the phosphor host and doped with Bi³⁺, Bi³⁺/Eu³⁺ and Bi³⁺/Eu³⁺/Tb³⁺. The high phase purity and crystallinity of the synthesized samples were confirmed via Le Bail fitting of powder X-ray diffraction data. The photoluminescence excitation and emission of Bi³⁺ in LYBO were carefully analyzed. Bi³⁺ exhibited blue light emission corresponding to the ³P₁→¹S₀ transition, and energy transfer from Bi³⁺ to Eu³⁺ enabled color tuning from blue to red in Bi³⁺ and Eu³⁺ co-doped LYBO phosphors. Upon incorporation of green-emitting Tb³⁺, single-phase white light emission was achieved with the composition Li(Y_0.8965Bi_0.01Eu_0.0025Tb_0.1)₆O₅(BO₃)₃, where energy transfer from Bi³⁺ to Tb³⁺ was also observed. When excited by a 310 nm LED chip, the phosphor emitted bright white light. Temperature-dependent photoluminescence studies demonstrated excellent thermal stability, underscoring the material's promise as a white-emitting phosphor for LED applications.