Highly efficient and thermally robust phosphor-in-glass ceramic (PiGc) for high-brightness laser-driven lighting

Abstract

How to improve the luminous efficiency (LE) and thermal stability of phosphor conversion materials have always been the focus of high-brightness laser-driven lighting. In this study, we successfully prepared a series of phosphor-in-glass ceramics (PiGc) by conducting a crystallization heat treatment on phosphor-in-glass (PiG) made from LuAG:Ce3+ phosphor and Li2O–Al2O3–SiO2 (LAS) glass via a spark plasma sintering (SPS). Comparing to PiG, the optical and thermal performances of PiGc have been enhanced significantly, including a higher internal quantum effect of 81.2% and lower thermal quenching (it remains 86% at 473k). By precipitating β-spodumene crystals, the coefficient of thermal expansion (CTE) of the PiGc decreased by 15% at 700 °C. Meanwhile, the use of precipitated nanocrystals as 'light-scattering centers' improved luminous efficiency remarkably. Under excitation of 450 nm blue laser with 7.04W/mm2, the LE of the most optimal sample was improved from 209.5 lm/W to 232.2 lm/W. These results indicate that crystallization heat treatment is an effective method for improving the LE and thermal stability of PiG. The PiGc is a highly efficient and thermally robust phosphor conversion materials for high-brightness laser-driven lighting.