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

Abstract

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.