The optical properties of the CsPbBr3 and Cs4PbBr6 NCs were studied by analyzing the absorption and PL. The absorption was measured by a Jasco V-750 spectrophotometer equipped with an integrated sphere within the 300-800 nm wavelength range. The PL emission spectra for a 320 nm excitation wavelength in the 450-650 nm range were measured with Jasco (FP-8350).