Inorganic Perovskite Surface Reconfiguration for Stable Inverted Solar Cells with 20.38% Efficiency and Its Application in Tandem Devices

Inorganic perovskite solar cells (IPSCs) have garnered attention in tandem solar cells (TSCs) due to their suitable bandgap and impressive thermal stability. However, the efficiency of inverted IPSCs has been limited by the high trap density on the top surface of inorganic perovskite film. Herein, a method for fabricating efficient IPSCs by reconfiguring the surface properties of CsPbI2.85Br0.15 film with 2‐amino‐5‐bromobenzamide (ABA) is developed. This modification not only exhibits the synergistic coordination of carbonyl (C=O) and amino (NH2) groups with uncoordinated Pb2+, but also the Br fills halide vacancies and suppresses the formation of Pb0, effectively passivating the defective top surface. As a result, a champion efficiency of 20.38%, the highest efficiency reported for inverted IPSCs to date is achieved. Furthermore, the successful fabrication of a p–i–n type monolithic inorganic perovskite/silicon TSCs with an efficiency of 25.31% for the first time is demonstrated. Crucially, the unencapsulated ABA‐treated IPSCs shows enhanced photostability, retaining 80.33% of its initial efficiency after 270 h, and thermal stability (maintain 85.98% of its initial efficiency after 300 h at 65 °C). The unencapsulated ABA‐treated TSCs also retains 92.59% of its initial efficiency after 200 h under continuous illumination in ambient air.