Bi3+-activated Sr3SbAl3Ge2O14: dual-site occupancy and broadband cyan emission for WLED spectral compensation

Abstract

Cyan-emitting phosphors are essential for near-ultraviolet LEDs and play a key role in achieving high-quality white light. In this work, a new series of Bi³⁺-doped Sr₃SbAl₃Ge₂O₁₄:xBi³⁺ (0.01 ≤ x ≤ 0.09) phosphors was prepared by a high-temperature solid-state method. The samples can be excited by ultraviolet to violet light and show a broad cyan emission centered at 518 nm (x = 0.03) with a full width at half maximum of 93 nm, indicating broadband luminescence. Analysis of excitation spectra, luminescence decay, and the Van Uitert model suggests that Bi³⁺ ions occupy both Al³⁺ and Sr²⁺ sites, giving rise to the wide cyan emission. The CIE chromaticity coordinates confirm that all compositions emit cyan light, and the optimal sample (x = 0.03) shows coordinates of (0.2271, 0.5026). Combining Sr₃SbAl₃Ge₂O₁₄:Bi³⁺ with commercial phosphors and near-UV LED chips enables the fabrication of white LEDs, demonstrating its potential as a cyan-emitting component for high-performance white light devices.