Well-designed sunlight-like Bi3+-activated white-light phosphor for general lighting†

Abstract

Sunlight-like phosphor-converted white-light-emitting diodes (pc-WLEDs) that are capable of offering a healthy light environment have attracted more and more attention. Herein, we report a series of novel single-composition sunlight-like white-light phosphors Ba₂Y₅(BO₃)_5−x(PO₄)_xO₂:0.5%Bi³⁺ (0 ≤ x ≤ 1) that are designed by using heterostructure BO₃–PO₄ polyanion unit substitution strategy. Structural and spectral analysis reveals that partial replacement of triangle plane BO₃ with tetrahedron PO₄ induces lattice contraction and distortion, opening a new Bi³⁺-substitution pathway, enabling Bi³⁺ ions to occupy Ba sites that could not be occupied previously, yielding a new lower-energy emission. With increasing PO₄ content, the lower-energy emission is gradually intensified and red-shifted from cyan-green to yellow, accordingly realizing emission with tunable color, including white-light with high photoluminescence quantum yield of 50–72%. With the optimized white-light phosphor (x = 0.8), as-prepared pc-WLEDs with sunlight-like spectrum behavior present a high color rendering index (Ra = 90.1) and a low correlated color temperature (CCT = 4509.25 K). Impressively, full-time sunlight simulation can be achieved in Ba₂Y₅(BO₃)_4.2(PO₄)_0.8O₂:0.5%Bi³⁺ phosphors by using multiple excitation wavelengths. These results suggest that as-prepared Ba₂Y₅(BO₃)_5−x(PO₄)_xO₂:0.5%Bi³⁺ phosphors present potential applications not only in general lighting but also in anti-counterfeiting fields.