Preparation method of bromine-doped iodine bismuth copper semiconductor film

The invention relates to a preparation method of a bromine-doped iodine bismuth copper semiconductor film, which comprises the following steps of: S1, regulating cuprous bromide, cuprous iodide, bismuth iodide and iodine elementary substance according to a chemical proportion that the molar ratio of the cuprous bromide to the cuprous iodide is 0-0.4, the molar ratio of the copper element to the bismuth element is 0.4-1.0, and the molar ratio of the iodine elementary substance to the cuprous iodide is 0-0.4; the mole number of the iodine elementary substance is equal to the sum of cuprous bromide and cuprous iodide; s2, N, N-dimethylformamide (DMF) is used as a solvent, the mixture obtained in the step S1 is dissolved, and an iodine bismuth copper solution with the concentration of 0.4-0.8 M is obtained and serves as a spin-coating precursor solution; s3, coating the precursor solution on a substrate by adopting a spin-coating method; the substrate is a conductive substrate or an insulating substrate with an e