Enhanced Homogeneity in Perovskite Photovoltaic Films via Antisolvent Extraction of a Methylamine-Based Gel Precursor

Solution-processed perovskite solar cells (PSCs) are at the forefront of next-generation photovoltaics, exhibiting outstanding photoelectric performance and cost-effective manufacturing. However, the prevalent use of polar aprotic solvents such as <i>N</i>,<i>N</i>-dimethylformamide and dimethyl sulfoxide in the preparation of perovskite precursor solution hinders complete solvent removal during film formation. Their high boiling points and strong coordinating abilities lead to solvated intermediates and heterogeneous perovskite crystal nucleation, particularly in the absence of the antisolvent-assisted crystallization. To address this, we developed a methylamine (MA)-based gel dispersion system that significantly improves the uniformity of perovskite films. By employing ethyl acetate (EA) antisolvent extraction, the gel precursor is extracted from a solution of MAI and PbI₂ in MA ethanol, which is then diluted in pure acetonitrile (ACN) solvent to form a clear perovskite precursor solution. Benefiting from the highly volatile nature of the ACN-based gel perovskite precursor solution and its rich concentration of high-valent PbI_n^2-n coordination compounds, this approach enables the fabrication of high-quality MAPbI₃ perovskite films, yielding PCEs of 21.34% for PSC and 19.77% for a 5 × 5 cm² mini-module. This MA-based gel perovskite precursor strategy offers a promising avenue for potential applications in the scalable manufacture of PSCs.