Efficient perovskite solar mini-modules fabricated via bar-coating using 2-methoxyethanol-based formamidinium lead tri-iodide precursor solution

In small-area perovskite solar cells, efficiencies of >25% have been achieved using an antisolvent dripping technique; however, it is not applicable for coatings on an industrial scale. Currently, large-area devices based on scalable perovskite coatings still show a very large gap with small-area devices. This means that a uniform perovskite coating and defect control on large-area devices are not as secure as they are on small devices. Here, we report the deposition of dense and uniform perovskite films using an air-knife-assisted bar-coating employing a perovskite [(FAPbI3)0.95(MAPbBr3)0.05] precursor solution dissolved in 2-methoxyethanol. A pinhole-free and homogeneous surface morphology was achieved by adding n-cyclohexyl-2-pyrrolidone to ensure a balance between rapid nucleation and slowed crystal growth in the precursor solution. By applying surface passivation with acetylcholine bromide and laser etching to thin layers, mini-modules with an aperture area of 31 cm2 were fabricated, attaining an efficiency of >20% (17.53% in the efficiency certified by a quasi-steady-state protocol).