24.64%-efficiency MA-free perovskite solar cell with Voc of 1.19 V enabled by a hinge-type fluorine-rich complex

High density of defects at interface severely affects the performance of perovskite solar cells (PSCs). Herein, cobalt (II) hexafluoro-2,4-pentanedionat (CoFAc), a hinge-type fluorine-rich complex, is introduced onto the surface of formamidinium cesium lead iodide (FACsPbI${}_3$) film to address the issues of perovskite/Spiro-OMeTAD interface. The existence of CoFAc passivates both organic cation and halide anion vacancies by establishing powerful hydrogen bonds with HC(NH${}_2$)${}_2$${}^{+}$ (FA${}^{+}$) and strong ionic bonds with Pb${}^{2+}$ in perovskite films. In addition, CoFAc serves as a connecting link to enhance interfacial hole-transport kinetics via interacting with Spiro-OMeTAD. Consequently, FACsPbI${}_3$ PSCs with CoFAc modification display a champion power conversion efficiency (PCE) of 24.64% with a charming open-circuit voltage (V${}_{OC}$) of 1.191 V, which is the record V${}_{OC}$ among all the reported organic-inorganic hybrid PSCs with TiO${}_2$ as electron transport layer. Furthermore, CoFAc-modified devices exhibit an outstanding long-term stability, which can maintain 95% of their initial PCEs after exposure to ambient atmosphere for 1500 h without any encapsulation. (© 2022 Wiley‐VCH GmbH)