Facial synthesis of highly stable and bright CsPbX 3 (X=Cl, Br, I) perovskite nanocrystals via an anion exchange at the water-oil interface

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 CsPbI 3 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 CsPbI 3 as well as other color-tunable CsPbX 3 NCs with high quantum efficiency at room temperature via an anion exchange at the water-oil interface, in which the as-synthesized pristine CsPbBr 3 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 CsPbI 3 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 CsPbX 3 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.