AbstractThis study focuses on improving the quality of MAPbI3‐based perovskite films by adjusting the concentration ratios of the methylammonium iodide (MAI) precursor using a two‐step sequential deposition method. The primary objective is to explore how altering the MAI concentration influences the microstrain, dislocation density, perovskite film quality, and their subsequent impact on the performance of perovskite solar cells. The examined device configuration CdS/MAPbI3/Spiro‐OMeTAD demonstrates impressive power conversion efficiency of 12.05%, Voc of 1.02 V, Jsc of 16.2 mA cm−2, and fill factor of 0.73. X‐ray diffraction and scanning electron microscope analyses show improved crystal quality and surface characteristics with reduced microstrain, dislocation density, larger crystal grains, and minimized pinholes. The investigation of MAPbI3's optical and electrical characteristics provides in‐depth insights, facilitating the optimization of MAI precursor concentrations for improved perovskite film development and enhanced solar cell performance.