Ultra‐Stable Perovskite Quantum Dot Polymer Films

Abstract Cesium lead halide perovskite quantum dots (QDs) exhibit promising potential due to their excellent optoelectronic properties, but the poor stability and limited processability of it are main obstacles for their practical applications. Here, a facile strategy is reported for the synthesis of ultra‐stable perovskite quantum dot polymer films to overcome these bottlenecks, where the QDs are covalently bonded to polymer chain through thiol‐ene click reaction during photopolymerization process. The QD@polymer film exhibits hydrophobicity and excellent underwater photoluminescent (PL) stability over 240 days without PL decay. Notably, the film can maintain 85% of PL intensity even in a strong acid solution (pH 1) over 135 days, a longest endurance time reported so far in harsh conditions. In addition, the film also presents excellent thermal stability, showing reversible on/off switching behavior over 30 heating‐cooling cycles. Integrating the efficient photoluminescence, ultra‐stability, solution‐processability, and photo‐polymerizability, the QD@polymer system demonstrates a highly desired suitability for various applications, including patterned QD arrays and luminescent textiles. Furthermore, a white light emitting device equipped with the prepared QD@polymer as light‐converting layers achieves white emission with color coordinate of (0.34, 0.33) and a 129% color gamut with 99% coverage of the National Television Standard Committee (NTSC) color space.