Ultra‐Stable CsPbBr3@Y2O3 Translucent Ceramic with a Record‐High Thermal Conductivity for Laser‐Driven Applications

Abstract Phosphor‐in‐ceramics (PiCs) have emerged as a promising approach to improve the thermal and moisture resistance of phosphors. For halide perovskites, the assembly of PiCs has been highly difficult because of their tendency to decompose even at low temperature (≈200 °C). In this work, a translucent CsPbBr 3 @Y 2 O 3 (CPB@Y 2 O 3 ) quantum dots‐in‐ceramic (QiC) is fabricated that preserves the optoelectronic properties of CsPbBr 3 nanocrystals (NCs), demonstrates superb environmental stability, and exhibits a record‐high thermal conductivity (8.7 W m −1 K −1 at 25 °C). An in situ template‐assisted reaction is employed to ensure a persistent confinement of CsPbBr 3 NCs throughout the sintering process. An oxygen‐induced photoluminescent (PL) modulation is conducted to obtain highly emissive sintering precursor (SP). As a result, a prototype laser‐driven projection system, using CPB@Y 2 O 3 QiC‐K 2 SiF 6 : Mn 4+ (KSF) phosphorin‐glass film (PiGF) as light source, achieved a high luminous flux of 225 lm and an ultra‐wide color gamut of 174% compared to commercial LED projectors without the need of heat sinks. Moreover, the CPB@Y 2 O 3 QiC is successfully applied for laser‐driven visible light communication (VLC), realizing a high modulation bandwidth of 38.7 MHz and an ultrafast data transmission speed of 167 Mbps. Both applications represent the state‐of‐art device performance for the CsPbBr 3 ‐based materials reported so far.