Transparent Composite Ceramic@aluminum with Ultra‐High Thermal Conductivity for High‐Brightness Laser‐Driven Lighting

Abstract Next‐generation high‐brightness lighting faces a big challenge in developing laser‐drivable color‐converting materials with effective thermal management. Herein, a new material architecture of Al 2 O 3 ‐Y 3 Al 5 O 12 : Ce 3+ (YAG: Ce) transparent composite ceramics coated with Al film (TCC@Al) is proposed. The as‐prepared material shows the highest thermal conductivity (29.3 W m −1 K −1 ) among YAG: Ce‐related transparent ceramics (TC) ever reported owing to the combination role of short‐range thermal conduction of Al 2 O 3 microcrystals and long‐range thermal conduction of Al film. Temperature‐dependent photoluminescence (PL) spectra and femtosecond transient absorption (fs‐TA) spectra evidence the importance of thermal management, whereby the luminescent loss of TCC@Al is only 8.92% at 450 K and is far smaller than TC counterpart (15.86%). Importantly, no obvious luminescence saturation is detected upon 20 W mm −2 blue laser irradiation and the inhomogeneous angular color distribution is suppressed by the scatter of Al 2 O 3 microcrystals, yielding uniform white light with ultra‐high luminous flux (LF) of 4294 lm@20 W mm −2 and luminous efficacy (LE) of 215 lm W −1 . As a consequence, the present TCC@Al‐converted laser‐driven lighting prototype exhibits much better optical performance than the commercial TC‐based one.