Reducing the cyan-cavity: Lu2MAl4SiO12:Ce3+ (M = Mg, Ca, Sr and Ba) phosphor-in-glass film towards full-spectrum laser-driven lighting

Abstract

For the emerging laser-driven phosphor-converted lighting technology, the shortage of cyan-emitting laser phosphors has led to a “cyan cavity” issue that greatly impedes reproduction of the true color of objects under illumination. Herein, a new kind of cyan-green-emitting Lu₂MAl₄SiO₁₂:Ce³⁺ (LMAS:Ce³⁺, M = Mg, Ca, Sr and Ba) phosphor-in-glass film (PiGF) sintered on sapphire plate (SP) was developed to reduce the cyan cavity. Microstructural studies demonstrate the intactness of LMAS:Ce³⁺ phosphor particles during co-sintering with glass and the tight bonding of the film on the SP substrate. A comparative study was performed on a LMAS:Ce³⁺ PiGF-on-SP composite to reveal the relationship between local coordination environment adjusted by M²⁺ and spectroscopic properties, as well as the key influencing factors that determine different luminescence saturation behaviors upon exposure to blue laser. LBaAS:Ce³⁺ PiGF outperforms its counterparts, showing a high internal quantum efficiency (IQE) of 86%, narrowed cyan gap down to 21 nm, and good resistivity to thermal quenching. The introduction of a photonic crystal film and phosphor wheel is able to further enhance the luminescence performance with the luminous flux (LF) increasing to 1140 lm@11 W mm⁻² and 1280 lm@22 W mm⁻², respectively. Finally, a high-color-quality full-spectrum-emitting lighting source was constructed and its potential application for indoor laser-driven lighting was demonstrated.