Efficient and Stable Self-Passivation Perovskite Solar Cells Prepared in Ambient Air Based on an Antisolvent-Free Method

Solution processable perovskite solar cells (PSCs) are one of the most promising candidates for commercialization. However, the perovskite film preparation method is limited by the mandatory antisolvent process under an inert gas atmosphere which significantly influenced its mass production. In this study, we developed a perovskite film preparation without the requirement of antisolvent dripping in air. We employed various solvents to prepare perovskite films and studied their influence on perovskite nucleation and morphology for the respective solvents. Among them, the perovskite prepared using dimethylacetamide (DMAc), which has low solubility and high interaction with PbI2, demonstrated a highly crystalline perovskite black phase without antisolvent dripping. Furthermore, we found that the perovskite concentration played an important role in the perovskite film quality, where the high concentration DMAc-based perovskite produced a smooth and dense perovskite film by the antisolvent-free method in air. PSCs fabricated using this technique delivered a champion power conversion efficiency (PCE) of 20.1%. At the same time, the best device prepared by the blade-coated method also got 18% PCE. Moreover, the unencapsulated devices exhibited excellent stability, which retained more than 90% of their initial efficiency after 47 days in air. This work provides a facile and cost-effective method toward a controllable fabrication of high-performance antisolvent-free MAPbI3-based solar cells.