Room-temperature quaternary alkylammonium passivation toward morphology-controllable CsPbBr3 nanocrystals with excellent luminescence and stability for white LEDs

Abstract

Colloidal all-inorganic CsPbX3 (X = Cl, Br, I) perovskite nanocrystals (PNCs) have recently shown incomparable superiority and vast application prospects in optoelectronics. However, developing low-cost and high-quality PNCs is the priority on their way to commercialization. Herein, we proposed a room-temperature quaternary alkylammonium (didodecyldimethylammonium bromide, DDAB) passivation strategy without organic polar solvents for synthesizing CsPbBr3 PNCs with controllable morphology via a modified ligand-assisted reprecipitation method. The morphology and size of PNCs were strongly affected by the amount of surface ligands (DDAB and organic acids with different chain lengths), resulting in the shift of emission peak. Benefiting from tight binding of surface ligands, the resulting CsPbBr3 PNCs exhibited bright green emission with near-unit photoluminescence quantum yields (PLQY) and excellent stability against water and air. The ultrafast transient absorption and time-resolved photoluminescence spectra further revealed that the lifetime of trap-assisted non-radiative recombination in PNCs was especially short, which could be attributed to the efficient passivation of surface defect states. Furthermore, light-emitting diodes (LEDs) based on green PNCs showed bright white light emission, and its corresponding color coordinate (0.330, 0.329) was almost consistent with that of the standard white light, which indicated that the as-prepared PNCs had latent practical value in lighting and display technology.