Recent Progress on Formamidinium‐Dominated Perovskite Photovoltaics

Abstract Organic–inorganic hybrid perovskite materials have attracted widespread attention in the photovoltaic field. The best‐certified perovskite single‐junction photovoltaics have achieved an impressive power conversion efficiency of 25.5%. Particularly, formamidinium lead triiodide (FAPbI 3 ) perovskite material has been considered to be one of the most promising materials for fabricating highly efficient single‐junction solar cells due to its suitable bandgap (1.43 eV). However, the metastable α‐FAPbI 3 perovskite phase, which can spontaneously transform into the undesirable δ phase, limits their further applications. Accordingly, stabilizing the α phase and achieving high‐quality films are keys for achieving high‐efficiency and long‐term operational perovskite photovoltaics. In this review, strategies for stabilization of α‐FAPbI 3 are discussed in detail, and the corresponding thermodynamic mechanisms are also summarized. Moreover, the methods to eliminate defects and improve carrier transport are thoroughly reviewed, which is important for achieving high‐performance photovoltaic devices with outstanding long‐term operational stability. Finally, possible the future research directions of FAPbI 3 photovoltaics toward commercialization are discussed.