Facial synthesis of highly stable and bright CsPbX3 (X=Cl, Br, I) perovskite nanocrystals via an anion exchange at the water-oil interface

Abstract

Cesium lead halide perovskite nanocrystals (NCs) have attracted unprecedented attention owing to their compelling properties for optoelectronic applications. Compared with the classical hot-injection method, the room-temperature (RT) synthetic strategy is more facile and tender, but it is hard to obtain stable CsPbI3 NCs and it usually uses polar solvents that sometimes reduce the stability and properties of NCs. Here, we reported a simple approach to synthesize highly efficient and stable CsPbI3 as well as other color-tunable CsPbX3 NCs with high quantum efficiency at room temperature via an anion exchange at the water-oil interface, in which the as-synthesized pristine CsPbBr3 NCs in toluene were treated in aqueous solutions of HX (X=Cl, Br, and I) and protonated oleylamine (OAm) acted as a carrier. The synthesized CsPbI3 NCs had an emission at 680 nm and even showed excellent colloidal stability after being stored for 32 d. The high efficiency and stability of the obtained CsPbX3 NCs were ascribed to the facts that: (i) the polar reagents were almost removed from the surface of NCs; (ii) the defect-related nonradiative recombination was suppressed efficiently by surface passivation.