The major problem identified in carbon-based mixed cation perovskite solar cells (PSCs) is the selection of a suitable solvent for single-step solution-processed perovskite deposition in order to promote their scalable production. Herein we report a detailed study on the selection of appropriate solvent for the one-step deposition of cesium-formamidinium lead iodide (Cs(0.1)FA(0.9)PbI(3)) perovskite via Lewis acid-base adduct approach for fully printable mesoporous PSCs with mesoporous TiO2/ZrO2/C architecture. Highly reproducible Cs(0.1)FA(0.9)PbI(3) solar cells were fabricated via adducts of PbI2 with eco-friendly dimethyl sulfoxide (DMSO). The best cells fabricated with the above approach yielded a photoconversion efficiency (PCE) of 12.33% for a small area device (active area: 0.09 cm(2)) and 10.1% for a large area device (active area 0.7cm(2)). The average power conversion efficiency for 62 PSCs was found to be 10.5% under an AM 1.5G illumination. Finally, the mixed cation perovskite in carbon architecture using the Lewis acid-base adduct approach is remarkably stable, with less than 1% change from the initial PCE after 1800h of storage under dark ambient conditions (25 degrees C, 60-70% RH).