Synergistic Effect of Surface p‐Doping and Passivation Improves the Efficiency, Stability, and Reduces Lead Leakage in All‐Inorganic CsPbIBr₂‐Based Perovskite Solar Cells

Abstract Wide‐bandgap inorganic cesium lead halide CsPbIBr₂ is a popular optoelectronic material that researchers are interested in because of the character that balances the power conversion efficiency and stability of solar cells. It also has great potential in semitransparent solar cells, indoor photovoltaics, and as a subcell for tandem solar cells. Although CsPbIBr₂‐based devices have achieved good performance, the open‐circuit voltage (V_oc) of CsPbIBr₂‐based perovskite solar cells (PSCs) is still lower, and it is critical to further reduce large energy losses (E_loss). Herein, a strategy is proposed for achieving surface p‐type doping for CsPbIBr₂‐based perovskite for the first time, using 1,5‐Diaminopentane dihydroiodide at the perovskite surface to improve hole extraction efficiency. Meanwhile, the adjusted energy levels reduce E_loss and improve V_oc of the CsPbIBr₂ PSCs. Furthermore, the Cs‐ and Br‐vacancies at the interface are filled, reducing structural disorder and defect states and thus improving the quality of the perovskite film. As a result, the target device achieves a high efficiency of 11.02% with a V_oc of 1.33 V, which is among the best values. In addition to the improved performance, the stability of the target device under various conditions is enhanced, and the lead leakage is effectively suppressed.