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.
Commercial photovoltaic technologies follow an empirical inverse scaling law, where the absolute power conversion efficiency (PCE) values drop by ~0.8% when the device area increases by an order of magnitude. Perovskite solar cells (PSCs) have yet to reach this mark; in current literature their PSCs exhibit a ~3.2% (n-i-p structure) and ~2.0% (p-i-n structure) drop in absolute PCE as the device area increases by an order of magnitude. In this work, we explore the underlying reasons for such scaling losses, especially for the p-i-n configuration, and have successfully reduced this scaling loss to ~0.9%. With a comprehensive understanding of the underlying mechanisms, high-quality PSCs with a PCE of 20.3% for 2 cm2 devices and 19.8% for 6.8 cm2 mini-modules were obtained. [Display omitted]
•The interaction between hydrophilic perovskite ink and hydrophobic PTAA surface is studied in detail.•Origins of micro and nano-scale pinholes in MAPbI3 films over PTAA substrates and possibilities to avoid them are provided.•Reproducibility and scalability of perovskite mini-modules exhibiting 19.8% PCE for 6.8 cm2 is achieved.•Using fundamental insights, the scalability losses in PSCs fabricated on a hydrophobic surface are minimized.•Only ~0.9% loss in absolute PCE per order of magnitude change in the active area is achieved.