Room‐Temperature Cross‐Linking Enabled Perovskite Quantum Dots for Long Lifespan Blue Light‐Emitting Diodes

ABSTRACT Ultrasmall perovskite CsPbBr 3 quantum dots (QDs) with blue emission are promising materials for light‐emitting diodes (LEDs). However, achieving room‐temperature synthesis of blue‐emitting CsPbBr 3 QDs with long‐term stability remains a major challenge, hampering their real‐world applications. Herein, we report a novel room‐temperature strategy for synthesizing highly stable, blue‐emitting CsPbBr 3 QDs, achieved with cross‐linked network structures—marking a significant advancement over conventional approaches. Polymer (dimethyl siloxane dimethyl vinyl terminated (PDMS)) cross‐linked by curing agent (dimethyl methyl hydrogen siloxane) offers networks that control the size of CsPbBr 3 QDs around 5 nm. The networks inhibit the fall‐off of ligands from the QD surface, which restrains the agglomeration of QDs and mitigates thermal quenching of light emission. The CsPbBr 3 QDs with a photoluminescence quantum yield (PLQY) of 93% remain monodispersed in solution over 30 days. The QD‐based films retain 95% of their initial PLQY after thermal treatment at 120°C. Blue‐emitting CsPbBr 3 LEDs with an emission of 472 nm and a full‐width at half‐maximum (FWHM) of 23 nm exhibit a peak luminance of 4096 cd m −2 and an excellent operational half‐lifetime ( T 50 ) over 38 h at 100 cd cm −2 , the longest‐lifespan perovskite blue‐quantum‐dot LEDs reported to date.