Peculiarities of the optical properties of organometallic perovskites with variable content of iodine and bromine

We have studied the optical properties of thin films of organometallic halide perovskites with variable content of iodine and bromine, which were obtained by two-stage deposition from solution. The results are indicative of an increased contribution of excitons to light absorption at the bandgap edge in bromine-containing perovskites as compared to the iodine-containing ones. The possibilities of using perovskites with preset halogen composition in cascade solar cells are discussed.