Stabilized and Operational PbI₂ Precursor Ink for Large-Scale Perovskite Solar Cells via Two-Step Blade-Coating

Perovskite solar cells (PVSCs) have made dramatic progress benefiting by various preparation methods in the past few years. Particularly, a two-step deposition technique has been demonstrated as an efficient, low-cost approach to fabricate large-scale PVSCs. However, these large-scale PVSCs are lagging far behind the state-of-the-art spin-coated counterparts because of the unstabilized nature of PbI₂ precursor ink and the difficulty in complete conversion to crystallized perovskite films. Here, we demonstrate a stabilized and operational trace methylammonium iodide (MAI)–polyurethane (PU)–lead iodide (PbI₂) (MP–PbI₂) precursor ink formulation to fabricate large-scale PVSCs via the blade-coating process. The synergetic effects of trace MAI and PU can regulate the rheological properties of PbI₂ precursor ink and form an oriented intermediate complex, which are beneficial for constructing compact perovskite films with fewer pinholes and defects. Thus, the MP–PbI₂-based PVSCs yield power conversion efficiencies (PCEs) over 19% for a 0.12 cm² device and 11.07% for a 25 cm² solar module. Moreover, flexible PVSC with a PCE of 17.30% has been manufactured using this scalable ink formulation and maintaining over 90% of its original PCE after 6000 bending cycles at the radius of 3 mm. This approach opens up a new precursor engineering for achieving large-scale PVSCs via roll-to-roll technology.