Method for optimizing lead-free perovskite solar cell film

The invention discloses a method for optimizing a lead-free perovskite solar cell thin film, and the method comprises the steps: carrying out the spin coating of a perovskite precursor solution on a hole transmission layer for 50 s during the preparation of an active layer, dispensing a diethyl ether solution doped with chiral mandelic acid after the spin coating is carried out for 12 s, and carrying out the annealing treatment to obtain the active layer; oxygen ions in hydroxy acid molecules in mandelic acid having lone pair electrons and can form coordinate bonds with metal ions to slow down and control the perovskite crystallization process, meanwhile, mandelic acid being a reducing agent and can inhibit oxidation of divalent tin, the crystallinity of the perovskite thin film can be further improved, and the quality of the thin film can be remarkably improved through combination of the two phases; the power conversion efficiency of the tin-based perovskite solar cell is improved; the circularly polarized l