Sputtered PbI2 with Post‐Processing for Perovskite Solar Cells

Conformal deposition of perovskite films on textured silicon surfaces using a dry process is crucial for producing high‐performance perovskite/silicon tandem solar cells. Herein, a radio frequency magnetron sputtering process is used with a PbI 2 target to deposit precursor films. Iodination, thermal annealing, and dimethyl sulfoxide treatment are employed as posttreatment processes to improve the stoichiometry, crystallinity, and surface morphology of the PbI 2 precursor. The precursor films are converted into perovskite using direct contact conversion process, and the interfacial and bulk properties are enhanced by methylamine vapor annealing to fabricate perovskite solar cells with a power conversion efficiency of 12.2%. Also, 18.3% efficiency is confirmed at a wider voltage sweep range, which suggests that further efficiency improvement is possible by removing defects inside the perovskite. Finally, uniform perovskite films are conformally deposited on a 25 cm 2 textured silicon surface. With such high‐efficiency potential and conformality, the method of sputtering PbI 2 can open a new way to fabricate perovskite/silicon tandem solar cells.