One-step polymer assisted roll-to-roll gravure-printed perovskite solar cells without using anti-solvent bathing

High-throughput manufacturing of hybrid halide perovskite solar cells is the next challenge before they enter the market. An anti-solvent bath is generally required to control the perovskite film assembly starting from precursors in solution. Although an anti-solvent bath has proven feasible for roll-to-roll deposition, it implies an undoubted increased complexity of the manufacturing line, meaning enhanced costs for the process itself and anti-solvent disposal. Here, we take advantage of the use of a starch polymer as a rheological modifier in perovskite precursor solutions to avoid the anti-solvent bath. Starch allows for control of the perovskite growth process in one step and reach of required viscosities for gravure-printing technique with ∼50% less of the raw precursor materials. This combined with simplified processing conditions are expected to drastically lower the costs of perovskite material production. We demonstrate that this approach can be upscaled to roll-to-roll gravure printing of flexible solar cells, reaching a maximum power conversion efficiency close to 10%.