Highly luminescent Lead Depleted Cs₄PbBr₆ Nanocrystals via Saponification Synthesis at an Ambient Atmosphere

Lead halide perovskites have proven themselves to be promising materials for applications in optoelectronic devices because of their excellent photophysical properties, however, the synthesis of those nanocrystals has until now, been too complex. Our newly developed saponification approach was employed to synthesize all-inorganic halide perovskites at an ambient atmosphere. We reported the conversion from three-dimensional CsPbBr₃ to lead depleted zero-dimensional Cs₄PbBr₆ nanocrystals by altering the amount of Cs-oleate precursor at a low-temperature synthesis so that the transformation remarkably changes the properties of the nanocrystals. The XRD spectra, TEM images, absorption and photoluminescence spectra have been taken for the systematic study of properties of CsPbBr₃ and Cs₄PbBr₆ nanocrystals. The CsPbBr₃ emitting a strong blue emission (460 nm) and is shifted to the green region (528 nm) for Cs₄PbBr₆, which demonstrates the intrinsic luminescence nature of the Cs₄PbBr₆ nanocrystals. In addition, the lead depleted Cs₄PbBr₆ structure is of great interest that minimizes the chemical instability, and particularly, toxicity issues. These exciting properties offer them an advantage to be used in optoelectronic devices.