Abstract Despite impressive power conversion efficiencies (PCEs) reported for lab-scale perovskite solar cells (PSCs), obtaining large-area devices with similar performance remains challenging. Fundamentally, this can largely be attributed to a polarity mismatch between the perovskite-precursor solution and the underlying hydrophobic contact materials, resulting in perovskite films of insufficient quality for scaled devices. Specifically, for p-i-n devices, the commonly used DMF/DMSO co-solvent has a significant polarity mismatch with its underlying hole-transporting layer, PTAA. Here, the role of MAPbI3•solvent adduct interaction with the PTAA surface towards the formation of micro- and nano-scale pinholes is elucidated in detail. Replacing DMSO with NMP in the co-solvent system changes the binding energy profoundly, enabling uniform and dense films over large areas. The PCE of DMF/NMP ink-based devices drops slightly with increasing active device area, from 21.5% (0.1 cm2) to 19.8% (6.8 cm2), in comparison with conventional DMF/DMSO ink. This work opens a pathway towards the scalability of solution-processed perovskite optoelectronic devices.