Enhanced Stability of Cyan CsPb(Br/Cl) ₃ Perovskite Nanocrystals via Ligand Crosslinking for Underwater Wireless Optical Communication

ABSTRACT Underwater wireless optical communication (UWOC) has emerged as a potential technology for high‐speed data transmission in aquatic environments. Since cyan light (490–500 nm) exhibits the lowest attenuation in seawater, developing high‐efficiency and stable cyan emitters is crucial for UWOC systems. Herein, cyan CsPb(Br/Cl) 3 perovskite nanocrystals (NCs) with excellent stability are synthesized by replacing the native ligands with a multifunctional ligand, ethylene glycol dimethacrylate (EGDMA). The carbonyl groups of EGDMA can coordinate with undercoordinated Pb 2+ ions via lone pair electrons, effectively passivating surface defects and enhancing the photoluminescence quantum yield of the NCs. Meanwhile, the C═C double bonds enable photo‐crosslinking under 365 nm UV light, resulting in a dense polymeric network on the NC surface that significantly improves their overall stability. Finally, the application of these cross‐linked NCs for UWOC is demonstrated, achieving a high −3 dB bandwidth of 2.7 MHz underwater and enabling real‐time data transmission in a UWOC system.