Self-reduction triggered color tuning of Eu3+-doped aluminosilicate glass for solid-state white illumination

Abstract

Rare earth-doped transparent glass, boasting high transmittance and excellent luminescent properties, holds great potential in the field of all-inorganic solid-state white illumination. Currently reported single-structure solid-state white lighting usually has the problems of low color rendering index (CRI) and high correlated color temperature (CCT) due to the lacking of red light emission. In this work, a novel single-structure MgO–Al₂O₃–SiO₂–Eu₂O₃ (MAS: Eu) glass with color tuning was prepared by the simple glass melting process. Interestingly, the prepared Eu³⁺-doped aluminosilicate glass possessed a unique capability to achieve color emission under different excitation wavelengths. The reason for this was attributed to the good self-reduction capability of the MAS glass, which effectively reduced Eu³⁺ to Eu²⁺ under an air atmosphere. Meanwhile, only by regulating the Eu³⁺ doping concentration, the MAS glass also achieved a tunable emission from blue to white to red light under 380 nm excitation. The acquisition of white light was realized through the multispectral emission of blue–green light emitted by Eu²⁺ and orange–red light emitted by Eu³⁺. Remarkably, the single-structure MAS glass doped with 8 wt.% Eu³⁺ successfully achieved high-quality white light and high thermal stability, exhibiting a high CRI of 86, a low CCT of 2761 K, good chromaticity parameters of (0.407 and 0.3192), and the emission intensity at 423 K remains above 86.35% that of room temperature. Meanwhile, the doped Eu³⁺ exceeded 12 wt.%, without any observable concentration quenching. Moreover, the MAS: Eu glass showed a high transmittance of 90 and a moderate thermal conductivity of 1.45 W/mK (epoxy resin ∼0.17 W/mK). These results would dramatically inspire the development of high-quality solid-state white lighting applications.