Organometallic halide perovskites have received significant attention due to their promising optoelectronic properties, particularly in photovoltaics. The formation process of perovskite films is crucial in determining their structural and functional characteristics. In this study, the effects of methylamine vapour treatment and vacuum annealing on enhancing the crystallinity, morphology and structural integrity of perovskite films are examined. Methylammonium lead iodide (MAPI)–based perovskite films are investigated, with a focus on their crystallographic structure, vibrational modes and their correlation with device performance. Power conversion efficiencies (PCEs) of 19.5% and 18.6% have been achieved using one-step and two-step processes, respectively. The influence of trap states, film homogeneity and interfacial properties has been analysed through capacitance, photoluminescence and electroluminescence measurements, with recombination behaviour linked to crystallographic properties. These findings provide valuable insights into the role of processing techniques in the rejuvenation of perovskite solar cells. Additionally, they offer guidance for optimising fabrication strategies to improve film quality, device performance, stability and long-term reliability.
