Facile and rapid synthesis of high performance perovskite nanocrystals CsPb(X/Br)3 (X=Cl, I) at room temperature

All-inorganic cesium lead halide perovskite nanocrystals (NCs) are promising photoelectric materials for their high photoluminescence quantum yield (PLQY), narrow emission width and tunable optical band gap. Traditionally, the hot injection (HI) method has been utilized to prepare perovskite NCs. However, the HI method requires high temperature, protection under inert gas and other harsh synthetic conditions, which severely hinders large-scale production of these NCs. Herein, we directly synthesized CsPbBr3 perovskite NCs by a modified LARP (ligand-assisted re-precipitation) approach, and then conducted a specific anion exchange reaction with inexpensive, readily available, non-toxic, and non-polluting KX (X = Cl, I) salts aqueous solution to obtain various compositions of CsPbX3 perovskite NCs at room temperature (RT). The obtained RT-NCs have high PLQY and outstanding stability, and their photoluminescence can be precisely regulated across the whole visible region (419-670 nm). The use of inorganic salts for the ion exchange provides an efficient method for the design of various halogenated perovskite NCs and their large-scale synthesis at RT.