Acid-mediated phase transition synthesis of stable nanocrystals for high-power LED backlights.

Abstract

Perovskite nanocrystals (PNCs) have excellent optical and optoelectronic properties, but their intrinsic instability hampers their practical applications. Herein, stable CsPbBr3 nanocrystals (NCs) are fabricated with triethylaluminium (TMA, a Lewis acid) and hydrobromic acid by the co-assisted transformation of Cs4PbBr6 NCs. TMA forms a cross-linked alumina (AlOx) encapsulation layer on the nanocrystal surface to suppress the deformation and ion migration. The introduction of hydrobromic acid acts as a binding ligand, and the acidified reaction environment provides conditions for the water-triggered phase transformation of Cs4PbBr6 NCs into CsPbBr3 NCs. The synergistic effect of TMA and hydrobromic acid improves the stability of CsPbBr3 NCs. The obtained CsPbBr3 NC film maintains a high photoluminescence (PL) intensity after immersion in water. When stored in the atmosphere for over 30 days, the PL intensity of the CsPbBr3 NC film hardly decreases. The proposed acid co-assisted phase transformation strategy provides a new avenue for the stabilization of PNCs which exhibits wider application prospects in backlight displays.