Defect‐Engineering‐Enabled High‐Efficiency All‐Inorganic Perovskite Solar Cells

The emergence of cesium lead iodide (CsPbI 3 ) perovskite solar cells (PSCs) has generated enormous interest in the photovoltaic research community. However, in general they exhibit low power conversion efficiencies (PCEs) because of the existence of defects. A new all‐inorganic perovskite material, CsPbI 3 :Br:InI 3 , is prepared by defect engineering of CsPbI 3 . This new perovskite retains the same bandgap as CsPbI 3 , while the intrinsic defect concentration is largely suppressed. Moreover, it can be prepared in an extremely high humidity atmosphere and thus a glovebox is not required. By completely eliminating the labile and expensive components in traditional PSCs, the all‐inorganic PSCs based on CsPbI 3 :Br:InI 3 and carbon electrode exhibit PCE and open‐circuit voltage as high as 12.04% and 1.20 V, respectively. More importantly, they demonstrate excellent stability in air for more than two months, while those based on CsPbI 3 can survive only a few days in air. The progress reported represents a major leap for all‐inorganic PSCs and paves the way for their further exploration in order to achieve higher performance.