(111)‐Dominated Perovskite Films by Antisolvent Engineering

Abstract Fabricating perovskite films with a dominant crystal orientation is an effective path to realizing quasi‐single‐crystal perovskite film, which can eliminate the fluctuation of the electrical properties in films arising from grain‐to‐grain variations, and improve the performance of perovskite solar cells (PSCs). Perovskite (FAPbI₃) films based on one‐step antisolvent methods usually suffer from chaotic orientations due to the inevitable intermediate phase conversion from intermediates of PbI₂•DMSO, FA₂Pb₃I₈•4DMSO, and δ‐FAPbI₃ to α‐FAPbI₃. Here, a high‐quality perovskite film with (111) preferred orientation ((111)‐α‐FAPbI₃) using a short‐chain isomeric alcohol antisolvent, isopropanol (IPA) or isobutanol (IBA), is reported. The interaction between IPA and PbI₂ leads to a corner‐sharing structure instead of an edge‐sharing PbI₂ octahedron, sidestepping the formation of these intermediates. With the volatilization of IPA, FA⁺ can replace IPA in situ to form α‐FAPbI₃ along the (111) direction. Compared to randomly orientated perovskites, the dominantly (111) orientated perovskite ((111)‐perovskite) exhibits improved carrier mobility, uniform surface potential, suppressed film defects and enhanced photostability. PSCs based on the (111)‐perovskite films show 22% power conversion efficiency and excellent stability, which remains unchanged after 600 h continuous working at maximum power point, and 95% after 2000 h of storage in atmosphere environment.