Abstract The photovoltaic performance of perovskite solar cells is extremely dependent on the crystallization and morphology of the perovskite film, which are affected by the deposition method. Here, we demonstrate a simple approach to form a microporous PbI 2 film, with subsequent conversion to a compact, highly crystalline perovskite film. The PbI 2 and corresponding perovskite films were further probed by two-dimensional X-ray diffraction. The resultant perovskite exhibited improved photovoltaic performance under ambient conditions with about 50% humidity. The PbI 2 microporous structure was formed by exchanging residual DMSO with DMF vapor in the PbI 2 film, which facilitated contact with the methylammonium iodide (MAI) solution. The process resulted in the formation of compact, smooth, pinhole-free perovskite films having no residual PbI 2 . Solar cells fabricated using this methodology exhibited power conversion efficiencies over 16% with negligible photocurrent hysteresis.