Toward the green synthesis of CsPbBr₃ perovskite nanocrystals using ethanol as an antisolvent and cyclodextrin as a ligand

Metal halide perovskite nanocrystals (PNCs) exhibiting excellent optoelectronic properties have been commonly synthesized by the ligand-assisted reprecipitation (LARP) method. However, the application of the LARP method for the large-scale production of PNCs is greatly hindered by the heavy use of the toxic antisolvent toluene and alkylamine ligand. In this study, ethanol was used as the antisolvent to synthesize CsPbBr3 PNCs at room temperature, which was enabled by simply using cyclodextrin (alpha-CD) as the ligand. The proposed method could produce alpha-CD@CsPbBr3 PNCs with a size of 35.0 +/- 0.6 nm, a photoluminescence quantum efficiency of 86.0 +/- 0.1%, and a yield of 33.4 +/- 0.6% (5 batches). In addition, the obtained alpha-CD@CsPbBr3 PNCs could persist for 6 months in ethanol with a loss of luminescence of less than 10%. The effective generation, high reproducibility, and long-term stability of the PNCs were contributed from the strong interaction between alpha-CD and CsPbBr3 and the poor solubility of alpha-CD in ethanol, which resulted in a firm enclosing of CsPbBr3 crystals within alpha-CD molecules. Additionally, the anion exchanges of the alpha-CD@PNCs were rapidly achieved in ethanol by using common salts of KI and NaCl. Using a non-toxic and low-cost antisolvent and ligand, this method is more eco-friendly and economical than ever.