(Invited) Phosphor-in-Glass Luminescent Materials for Solid State Laser Lighting

Abstract

Laser-based solid state lighting is superior to the LED-based counterpart in terms of much high input power and lumens, which requires phosphors to be more thermally stable and less luminescence saturation under high-density laser irradiations. To minimize thermal quenching and luminescence saturation of phosphors, a revolutionary method is to apply phosphor-in-glass or ceramic phosphors rather than phosphor-in-silicone (polymer binder) in remote-phosphor technologies because bulk luminescent materials have higher thermal conductivity and less degradation than phosphor/silicone mixtures. In this work, we will report the preparation and optical properties of nitride phosphor-in-glass luminescent materials. The nitride phosphor (β-sialon:Eu2+) was co-fired with the glass frit in the system of ZnO-B2O3-Ba2O3-Al2O3 at 630-650oC. No interfacial reaction occurred during the co-firing. The quantum efficiency and transmittance of the phosphor-in-glass luminescent materials were greatly affected by the phosphor concentration, firing temperature and holding time. Upon the blue laser irradiation, a linear relationship between the luminous flux and the incident laser power was observed when the flux density was below 0.7 W/mm2. A serious luminescence saturation was seen when a high flux density was applied. The saturation was perhaps due to the extremely low concentration and relatively longer decay time of Eu2+. This phosphor-in-glass luminescent materials could be used for low-power solid state laser lighting.