One-step synthesis of colloidal CH₃NH₃PbBr₃ nanoplatelets via chlorobenzene to realize nonsolvent crystallization

Ligand-assisted reprecipitation (LARP) is a convenient and low-cost method to synthesize perovskite nanoplatelets (NPLs) with great optoelectronic properties. However, it still suffers from delicate purification and passivation. Here, we report the synthesis of perovskite NPLs via a simple one-step method through using chlorobenzene as poor solvent. These as-prepared NPLs exhibit good lateral-size homogeneity and emission wavelength tunability. Controlled experiment indicates that compared to the commonly used toluene, chlorobenzene is advantaged to enhance photoluminescence quantum yield (PLQY) and decay time of the perovskite NPLs. Raman spectra, x-ray photoelectron spectroscopy and energy dispersive spectra have shown that it is the passivation of chlorine atoms which suppresses nonradiative recombination and enhances PLQY. These results demonstrate that chlorobenzene is an alternative poor solvent to realize both the simplification of the LARP technique and the passivation of perovskite NPLs.