Solvent Engineering for Intermediates Phase, All-Ambient-Air-Processed in Organic–Inorganic Hybrid Perovskite Solar Cells

Intermediate phase is considered an important aspect to deeply understand the crystallization procedure in the growth of high-quality perovskite layers by an anti-solvent technique. However, the moisture influence on the intermediate phase formation is not clear in air conditions as yet. In this work, pure (FA0.2MA1.8)Pb3X8(DMSO·DMF) intermediate phase was obtained in as-prepared perovskite film by spin-coating the precursor of co-solvent (DMSO and DMF) in an ambient air (RH20–30%). Moreover, the appropriate quantity of ethyl acetate (C4H8O2, EA) also controls the formation of pure intermediate phase. The uniform and homogeneous perovskite film was obtained after annealing this intermediate film. Therefore, the best power conversion efficiency (PCE) of perovskite solar cells (PSCs) is 16.24% with an average PCE of 15.53%, of which almost 86% of its initial PCE was preserved after 30 days in air conditions. Besides, the steady-state output efficiency ups to 15.38% under continuous illumination. In addition, the PCE of large area device (100 mm2) reaches 11.11% with a little hysteresis effect. This work would give an orientation for PSCs production at the commercial level, which could lower the cost of fabricating the high efficiency PSCs.