Low-cost and solution-processed perovskite solar cells have shown great potential for scaling-up mass production. In comparison with the spin coating process for fabricating devices with small areas, the blade coating process is a facile technique for preparing uniform films with large areas. High-efficiency perovskite solar cells have been reported using blade coating, but they were fabricated using the toxic solvent N,N-dimethylformide (DMF) in nitrogen. In this work, we present highly efficient blade-coated perovskite solar cells prepared using a green solvent mixture of γ-butyrolactone (GBL) and dimethyl sulfoxide (DMSO) in an ambient environment. By carefully controlling the interface, morphology, and crystallinity of perovskite films through composition variations and additives, a high power conversion efficiency of 17.02% is achieved in air with 42.4% reduction of standard deviation in performance. The findings in this work resolve the issues of scalability and solvent toxicity; thus, the mass production of perovskite solar cells becomes feasible.

The composite electron transporting layer (ETL) of metal oxide with [6,6]-phenyl-C 61 -butyric acid methyl ester (PCBM) prevents perovskite from metal electrode erosion and increases p−i−n perovskite solar cell (PVSC) stability. Although the oxide exhibits protective function, an additional work function modifier is still needed for good device performance. Usually, complicated multistep synthesis is employed to have a highly crystalline film that increases manufacturing cost and inhibits scalability. We report a facile synthesis of a novel organic-molecule-capped metal oxide nanoparticle film for the composite ETL. The nanoparticle film not only has a dual function of electron transport and protection but also exhibits work function tunability. Solvothermal-prepared SnO 2 nanoparticles are capped with tetrabutylammonium hydroxide (TBAOH) through ligand exchange. The resulting TBAOH−SnO 2 nanoparticles disperse well in ethanol and form a uniform film on PCBM. The power conversion efficiency of the device dramatically increases from 14.91 to 18.77% using this layer because of reduced charge accumulation and aligned band structure. The PVSC thermal stability is significantly enhanced by adopting this layer, which prevents migration of I − and Ag. The ligand exchange method extends to other metal oxides, such as TiO 2 , ITO, and CeO 2 , demonstrating its broad applicability. These results provide a cornerstone for large-scale manufacture of high-performance and stable PVSCs.

Ion migration in organometal halide perovskite solar cell (OHPSC) and crystal structure evolution of organometal halide perovskites (OHPVSKs) in air are considered as one of the critical factors for unstable performance and of the urgent issues for the reliability of OHPSCs. Herein, a novel cation of acetamidinium (Aa+) with stronger coordinated bond with I− than methylammonium is induced into OHPVSK to stabilize its crystal structure. By incorporating Aa+ ions into OHPVSKs, the power conversion efficiency (PCE) of OHPSC without an encapsulation can maintain higher than 75% of its initial PCE after a 200 h humidity (60–80% relative humidity (RH) in air) or a 24 h thermal stress test (85 °C in dry N2). The Aa–MAPbI3 device exhibits an outstanding efficiency of 20.68%, and over 80% of initial PCE is maintained after a 1300 h damp heat as encapsulated. This novel cation can be easily incorporated into OHPVSK via a hot casting process in air with a high environmental tolerance as compared with that from the conventional coating process, which suffers from sophisticated crystallization steps and a strict processing atmosphere. It extends processing windows for OHPVSK fabrication and provides a promising path toward mass production and further commercialization.

Perovskite Solar Cells In article number http://doi.wiley.com/10.1002/solr.202000197, Wei‐Fang Su and co‐workers incorporate a cation of acetamidinium (Aa+) into conventional perovskite layer (MAPbI3). The Aa+ cation effectively hinders the ion migration and enhances the long‐term stability of perovskite solar cells. The champion device achieves 20.68% efficiency. More than 80% of initial power conversion efficiency is maintained after 1300 h of 85°C/85 RH% test as encapsulated.