Perovskite nanoparticles Cs4PbBr6 and CsPbBr3: synthesis, analysis and peculiar optical properties

All-inorganic perovskite CsPbBr3 and Cs4PbBr6 nanoparticles are being intensively studied due to their unique properties and wide range of applications; however, however, the nature of their optical properties is not yet fully understood due to the difficulty of synthesis of single-phase nanoparticles. In this article we describe the features of the synthesis of single-phase particles and the results of their chemical and phase analysis. Using data on nanoparticle concentrations, we experimentally determined the absorption coefficient for both phases. It has been shown that nanoparticles of CsPbBr3 and Cs4PbBr6 perovskites exhibit features of such optical characteristics as photoluminescence, optical band gap, including the region of weak absorption (Urbach tail), and action spectrum also. The experimental results can be explained within the framework of existing ideas about the band gap structure for perovskite materials.