Solution preparation of CsPbBr3/Cs4PbBr6 polycrystalline composites

Metal halide perovskite is considered as a promising optoelectronic material. Zero-dimensional perovskite Cs4PbBr6 has attracted much attention because of its high stability and bright green luminescence. In this paper, CsPbBr3/Cs4PbBr6 polycrystalline composites were prepared by the solution cooling method and characterized. Powder XRD diffraction shows that the lattice constants of Cs4PbBr6 are a = b = 13.7163 angstrom, c = 17.3109 angstrom. According to UV-Vis diffuse reflectance spectroscopy and the Tauc plot method, the estimated absorption edge energies of CsPbBr3 and Cs4PbBr6 are 2.19eV and 4.14eV, respectively. The first-principles calculations show that CsPbBr3 and Cs4PbBr6 are direct bandgap crystal structures, and the theoretical bandgap values are 1.75 eV and 3.91 eV, respectively. The absorption spectra show that CsPbBr3/Cs4PbBr6 polycrystalline composites have a wider absorption range, from visible light to ultraviolet light, and presents green photoluminescence. In addition, the formation mechanism of CsPbBr3/Cs4PbBr6 polycrystalline composites was also been analyzed.