Ba3LuGa2O7.5:Bi3+ phosphors with potential application in full-spectrum WLEDs and temperature sensing

Abstract

In this work, a series of novel, broadband, cyan-green emitting Ba₃LuGa₂O_7.5:Bi³⁺ phosphors are prepared to bridge the cyan gap through a simple high-temperature solid-state reaction method. Their crystal structures, morphologies, luminescent properties, temperature-dependent emission spectra, temperature-dependent lifetime decay curves and quantum efficiencies were investigated in detail. Upon 351 nm excitation, the phosphor presents cyan-green emission with the main peak located at 500 nm, corresponding to the ³P₁–¹S₀ transition of Bi³⁺ ions. The emission intensity of BLGO:0.02Bi³⁺ phosphors is greatly enhanced when introducing a suitable flux. The value of external quantum efficiency is advanced from 9.43% to 30.93%. According to the luminescence intensity and thermal quenching properties of the phosphor, the potential applications of BLGO:Bi³⁺ in the two fields of WLEDs and optical temperature sensing were explored. Since the excitation band of the phosphor can match well with that of the near-ultraviolet chip, combined with commercial phosphors, the BLGO:0.02Bi³⁺ phosphor is employed to obtain a full-spectrum WLED device with a higher color rendering index (CRI, Ra = 93.5), and a lower correlated color temperature (CCT, 4523 K). In the temperature range of 293 to 498 K, the relative sensitivities S_r and S are calculated to reach the maximum value of 2.05% K⁻¹ and 2.21% K⁻¹, respectively. These results indicated that the prepared BLGO:Bi³⁺ phosphors have potential application prospects as full-spectrum WLEDs and in temperature sensing.