Unveiling and Balancing the Passivation‐Transport Trade‐Off in Perovskite Solar Cells with Double‐Side Patterned Insulator Contacts

Abstract

Abstract Including an ultrathin insulator interlayer at the perovskite/charge transport interface is a critical strategy for suppressing surface recombination in state‐of‐the‐art perovskite solar cells. However, its further improvement with increased thickness faces a trade‐off due to the exponentially inhibited electrical transport. Here, a patterned insulator contact (PIC) design is presented to overcome this passivation‐transport trade‐off where the conventional ultrathin interlayer is replaced by a thicker counterpart with local openings. Such a PIC is realized using metal fluorides with a high coverage of 80% and a thickness tolerance increased by 3–5. Balancing inhibited transport via local openings is verified by direct observation with local photocurrent mapping. It revealed the atomic passivation mechanism of hydrogen bonding between fluoride ions and perovskite organic cations. It extends the top‐surface passivation to double‐sided passivation and find that LiF‐modified substrate improves the wettability and promotes the out‐of‐plane growth of perovskite. These combined advances and distilled knowledge allow us to achieve power‐conversion‐efficiency (PCE) of 25% (certified 24.95%) in p–i–n perovskite solar cells by simultaneously enhancing the open‐circuit voltage ( V oc ) and the fill factor (FF). The device's reproducibility and operational stability are also improved.