Amine- and Acid-Free Synthesis of Stable CsPbBr₃ Perovskite Nanocrystals

Abstract

Ligands binding to\nall-inorganic lead halide perovskite nanocrystals\n(IPNCs) are easy to detach from the surface through proton exchange,\ncausing severe stability issues in practical applications. Here, we\nhave reported an amine- and acid-free approach for the synthesis of\nCsPbBr₃ IPNC with highly improved photochemical stability.\nThe reaction mechanism follows a trioctylphosphine-mediated surface\npassivation route, which provides a proton-free reaction environment\nto stabilize the ligand capping on the surface of IPNCs. Nuclear magnetic\nresonance, Fourier transform infrared spectroscopy, and X-ray photoelectron\nspectroscopy characterizations reveal that the IPNCs possess a lead-rich\nsurface passivated by carboxylates. The surface capping motif endows\nIPNCs with comprehensively improved stability against air, water,\nlight, and heat. The IPNCs withstand exposure to ethanol in room light\nfor 30 days and show nearly no fluorescent quenching. More importantly,\nthe IPNCs present high resistance to intense light irradiation. Under\ncontinuous irradiation by 10 W/cm² blue light in open air,\nthe lifetime of the IPNCs reaches over 2000 h, catching up the photostability\nof CdSe QDs. The white LEDs based on the IPNCs display a wide color\ngamut of 122% NTSC and luminous efficacy of 71 lm/W.