Rational Amphiphilic Ligand Engineering Enables Enhanced Stability and Efficiency of CsPbBr₃ Nanocrystals Based Light Emitting Diodes

Metal halide perovskites have shown great potential for lighting. However, their low stability under irradiation/thermal stress and/or ambient storage conditions are critical for light-emitting diodes (LEDs). Among the stabilization strategies, ligand surface modification is effective toward stable perovskites, but the dynamic ligand adsorption/desorption process on the surface is a limiting factor. Herein, a new family of biogenic and amphiphilic capping agents, phosphatidyl-L-serine (Ptd-L-Ser), combining stronger multibinding motifs compared to conventional capping agents has led to superior CsPbBr₃ (CsPbBr₃-Ptd-L-Ser) with significantly enhanced stability upon storage/heating/water, keeping excellent photoluminescence quantum yields of ≈80% over half year. Spectroscopic/theoretical studies reveal that the origin of this behavior is the increased exciton binding energy associated to the versatility of multiple bindings. This results in CsPbBr₃-Ptd-L-Ser nanocrystals-based green-LEDs featuring excellent stabilities of >700 h (20 mA) and >200 h (100 mA) that strongly contrast with the reference devices with pristine CsPbBr₃ nanocrystals (120 h (20 mA) and 27 h (100 mA)). White LEDs (WLEDs) with chromaticity coordinates of (0.34, 0.33) and high luminous efficiency of 76 lm W^–1, keeping stable over weeks, are further demonstrated under continuous operational conditions, thereby suggesting CsPbBr₃-Ptd-L-Ser nanocrystals can be a potential candidate for commercial WLED technology.