Solvent engineering of scalable deposited wide-bandgap perovskites for efficient monolithic perovskite-organic tandem solar cells

High-quality wide-bandgap perovskite films are a key component in constructing efficient tandem solar cells. Although the efficiency of perovskite tandem devices advances rapidly in recent years, the majority of wide-bandgap perovskite films are deposited by laboratory spin-coating, which greatly hinders their commercial viability. Here, we first show that the widely-used binary solvents (DMF:DMSO) in spin-coating are incapable of producing qualified wide-bandgap perovskite films by scalable methods. It is identified that dense and uniform wide-bandgap thin films can be deposited from single-solvent NMP by blade-coating, which is mainly related to the well-controlled crystallization kinetics enabled by the formation of stable intermediate adduct. Along with a rational passivation by constructing a 2D/3D layered heterojunction, inverted perovskite devices with a bandgap of 1.8 eV deliver a champion efficiency of 18.92 %. On this basis, monolithic perovskite-organic tandem solar cells with an efficient and robust interconnection layer of "SnO2/Au/PEDOT:PSS" are fabricated, yielding a high efficiency of 22.25 % along with an impressive open-circuit voltage of 2.1 V. These results demonstrate an important step toward scalable fabrication of monolithic perovskite-organic tandem solar devices.