Precursor solution volume-dependent ligand-assisted synthesis of CH^sub 3^NH^sub 3^PbBr^sub 3^ perovskite nanocrystals

Ligand-assisted reprecipitation (LARP) technique is a powerful approach for the synthesis of organometal halide perovskite nanocrystals (PNCs). The morphology and surface property of the formed PNCs which determine their optical properties are ultrasensitive to the synthetic parameters. To guarantee the batch-to-batch reproducibility of PNCs with excellent optical properties, it is of central importance to better understand the factors influencing the formation of PNCs during LARP process. Herein the dual-factor of the amount of perovskite precursor and the polarity of mixture solvent was modified by varying precursor solution volume (PSV) in the LARP system. The concentration, size, surface state and optical properties of the synthesized CH3NH3PbBr3 PNCs as a function of PSV were systematically investigated aiming to understand the influence of the dual-factor on the nucleation and growth of PNCs. Experimental results revealed that few crystal nuclei was generated due to lower amount of precursor at lower PSV, which was favorable for the growth of large perovskite crystals. At the higher PSV, the inhibition of crystal growth with increased amount of precursor was compensated by increasing the polarity of mixture solvent, which led to the dissolution of surface ligands and eventually growth of large perovskite crystals. The obtained results on PSV-dependent synthesis of PNCs will be used as a guide to optimize the synthetic parameters in the LARP process.