Sequential Ultrasonic Spray-Coating Planar Three Layers for 1 cm² Active Area Inverted Perovskite Solar Cells

The sequential deposition of a NiO_x hole-transporting layer, one-step CH₃NH₃PbI₃ perovskite absorber, and blended electron-transporting layer that comprises [6,6]-phenyl-C₆₁-butyric acid methyl ester (PCBM) and PNDI(2OD)T2 via automated ultrasonic spray-coating technique is demonstrated in air for planar inverted p–i–n solution-processed perovskite solar cells. Films fabricated via laboratory-sale spin-coating and industrially compatible spray-coating process, respectively, are compared with each other to optimize both the film-coating quality and corresponding device performance. This is validated by the photovoltaic performance of prototype devices with three spray-coated layers with the active area of 1 × 1 cm². The champion cells achieve a power conversion efficiency of 10.09%, which is one of the highest efficiencies obtained from fully spray-processed large-area perovskite solar cells thus far. Furthermore, these results reinforce the feasibility of the spray-coating methodology for the fabrication of multilayers within perovskite solar cells stack and low-cost route toward upscaling the manufacturing alternatives to spin coating.