A facile method to fabricate high-quality perovskite nanocrystals based on single crystal powder

Although great advancements have been successfully achieved in ligand-assisted reprecipitation strategy (LARP) towards lead halide perovskite nanocrystals (NCs) synthesis, it still remains challenging to develop bright and stable iodide-based perovskite NC via facile LARP. Herein, strikingly bright MAPbI₃ NCs with photoluminescence quantum yield (PLQY) as high as 79% are synthesized via replacing the raw material (MAI and PbI₂) with MAPbI₃ crystal powder during LARP procedure. It has been found that crystal powder derived MAPbI₃ NCs are more iodide-rich compared with that based on raw material, which is favorable to passivate the surface trap state. Accordingly, femtosecond transient absorption spectroscopies and space charge limited current measurements have corroborated that the trap density is much less in crystal powder resulted MAPbI₃ NCs. Further analyses indicate stronger solvation with reduced precursor colloid size has been observed in crystal powder derived precursor solution probably due to the formation of MAPbI₃·DMF. This work has provided a facile but valid method to enhance the photoluminescence of perovskite NC via modulating the beginning precursor solution.