In recent years, perovskite solar cells (PSCs) have been regarded as core competitors in the next generation of photovoltaic technology due to their high efficiency, low cost, and tunable bandgap. Among them, FAPbBr₃ perovskite has attracted attention due to its wide bandgap characteristics (~2.23 eV) and high wet heat stability, but its photovoltaic performance is limited by problems such as poor crystal quality, high defect density, and severe carrier recombination. To enhance the performance of FAPbBr₃ perovskite solar cells, this study successfully fabricated devices with an FTO/TiO₂/FAPbBr₃-MACl/C structure by incorporating methylammonium chloride (MACl) into the precursor solution. The effect of MACl mass fraction in the MACl-FABr methanol solution on the crystallization kinetics and film morphology of FAPbBr₃ was systematically investigated. Results indicate that MACl acts as an effective crystallization modulator, facilitating the formation of larger and more uniform grains and producing a compact, pinhole-free film with complete substrate coverage. This structural optimization significantly improved the crystallinity of the perovskite layer, thereby effectively suppressing defect-assisted charge recombination and laying a critical material foundation for enhancing the device's power conversion efficiency.The devices were fabricated using a thin-film deposition process: a TiO₂ electron transport layer was first deposited onto cleaned FTO substrates via treatment with a TiCl₄ aqueous solution. A two-step spin-coating procedure was then applied to deposit PbBr₂ and FABr solutions sequentially, followed by annealing at 150 °C to form the FAPbBr₃ perovskite layer. Finally, a low-temperature carbon paste was screen-printed as the counter electrode and cured. The morphological, structural, and photophysical properties of the films were thoroughly characterized using Scanning Electron Microscopy (SEM), X-ray Diffraction (XRD), UV-visible Spectroscopy (UV-vis), steady-state and time-resolved photoluminescence spectroscopy, and current density-voltage (J-V) measurements. These analyses confirmed that the fabricated devices exhibit high-quality film formation and promising photovoltaic performance. Research shows that when the MACl doping concentration is 10%, an optimal device was fabricated, achieving a record open-circuit voltage (V_OC) of 1.62 V, a short-circuit current density (J_SC) of 8.21 mA∙cm^-2, a fill factor (FF) of 83.73%, and a resulting power conversion efficiency (PCE) of 11.14%, which represents the highest level in the field of FAPbBr₃ devices, outperforming all previously reported data of the same category.

Key words: FAPbBr₃ perovskite solar cells, MACl additive, all-bromide perovskite, two-step solution spin coating, additive engineering