Effect of the Conditions of the Synthesis of Mixed CsPbClxBr3–x Perovskite Nanocrystals on Their Optical Properties

Feasibility has been demonstrated for controlling the position of the luminescence maximum in the region 440–510 nm of mixed CsPbCl_xBr_3–x perovskite nanocrystals by changing the initial PbBr₂:PbCl₂ molar ratio of the starting reagents as well as by the choice of the solvent for the post-synthesis treatment. X-ray fluorescence spectroscopy was used to find that the Br^–:Cl^– ratio in the synthesized nanocrystals is lower than the ratio of these ions in the initial reagents. Fourier transform infrared spectroscopy was used to show that postsynthesis treatment in acetone, in contrast to treatment in acetonitrile, promotes the removal of oleylamine, predominantly along with bromide ion, from the surface of the nanocrystals, which leads to a shift in the photoluminescence maximum toward shorter wavelengths and a decrease in the photoluminescence quantum yield. These results hold significance for the development of new combined luminophores derived from perovskite nanocrystals when precise selection of the color characteristics is required.