Using Low‐Cost Additive to Improve Perovskite Crystallization for Efficient Solar Cells

In the two‐step sequential deposition, the reaction of PbI 2 and organic halides for conversion to perovskite is crucial for achieving high‐performance perovskite solar cells, which heavily depends on the morphology of the PbI 2 film. The highly structured and dense PbI 2 film is not conducive to the diffusion of organic halides in the planar heterojunction. To solve this problem, acetone is introduced into the PbI 2 precursor as the regulator of the film morphology. The addition of acetone weakens the interaction between dimethyl sulfoxide and PbI 2 , leading to the appropriate morphology of PbI 2 film. Therefore, PbI 2 can react with organic halides and convert to perovskite more efficiently. The high‐quality FA 1− x MA x PbI 3 perovskite film with reduced defect density is achieved. The device delivers an outstanding power conversion efficiency enhancement with a low‐cost additive.