Enhanced Hygrothermal Stability of In-Situ-Grown MAPbBr₃ Nanocrystals in Polymer with Suppressed Desorption of Ligands

Currently, the intrinsic instability of organic-inorganichybrid perovskite nanocrystals (PNCs) at high temperature and highhumidity still stands as a big barrier to hinder their potential applicationsin optoelectronic devices. Herein, we report the controllable in-situ-grownPNCs in polyvinylidene fluoride (PVDF) polymer with profoundly enhancedhygrothermal stability. It is found that the introduced tetradecylphosphonicacid (TDPA) ligand enables significantly improved binding to the surfaceof PNCs via a strong covalently coordinated P-O-Pb bond,as evidenced by density functional theory calculations and X-ray photoelectronspectroscopy analyses. Accordingly, such enhanced binding could notonly make efficient passivation of the surface defects of PNCs butalso enable the remarkably suppressed desorption of the ligand fromthe PNCs under high-temperature environments. Consequently, the photoluminescencequantum yield (PL QY) of the as-fabricated MAPbBr(3)-PNCs@PVDFfilm exhibits almost no decay after exposure to air at 333 K over1800 h. Once the temperatures are increased from 293 to 353 K, theirPL intensity can be kept as 88.6% of the initial value, much higherthan that without the TDPA ligand (i.e., 42.4%). Moreover, their PLQY can be maintained above 50% over 1560 h (65 days) under harsh workingconditions of 333 K and 90% humidity. As a proof of concept, the as-assembledwhite light-emitting diodes display a large color gamut of 125% NationalTelevision System Committee standard, suggesting their promising applicationsin backlight devices. Controllablein-situ-grown organic-inorganic hybridperovskite nanocrystals in polymers with profoundly enhanced hygrothermalstability were reported. They exhibited robust stability with almost100% retention of initial PL QY after exposure to air at 333 K for1800 h, and 88.6% of initial PL intensity was retained once the temperaturewas increased from 293 to 353 K. Moreover, their PL QY can be maintainedabove 50% over 1560 h (65 days) under 333 K and 90% humidity conditions.