High‐Performance Inverted Perovskite Solar Cells with Sol–Gel‐Processed Sliver‐Doped NiO_X Hole Transporting Layer

Nickel oxide (NiO X ) has been established as a highly efficient and stable hole‐transporting layer (HTL) in perovskite solar cells (PSCs). However, existing deposition methods for NiO X have been restricted by high‐vacuum processes and fail to address the energy level mismatch at the NiO X /perovskite interface, which has impeded the development of PSCs. Accordingly, we explored the application of NiO X as a hybrid HTL through a sol–gel process, where a NiO X film was pre‐doped with Ag ions, forming a p/p + homojunction in the NiO X ‐based inverted PSCs. This innovative approach offers two synergistic advantages, including the enlargement of the built‐in electric field for facilitating charge separation, optimizing energy level alignment, and charge transfer efficiency at the interface between the perovskite and HTL. Incorporating this hybrid HTL featuring the p/p + homojunction in the inverted PSCs resulted in a high‐power conversion efficiency (PCE) of up to 19.25%, significantly narrowing the efficiency gap compared to traditional n‐i‐p devices. Furthermore, this innovative strategy for the HTL enhanced the environmental stability to 30 days, maintaining 90% of the initial efficiency.