Optimizing the NiO${}_x$/Au interface via postannealing of the all-inorganic CsPbIBr${}_2$ perovskite solar cells for high efficiency

All-inorganic perovskite solar cells (PSCs) have been demonstrated to solve the thermal instability problem of organic-inorganic hybrid PSCs. Therefore, NiO${}_x$ film is prepared by electron beam evaporation as a hole transport layer of all inorganic CsPbIBr${}_2$ PSCs. Then, the postannealing is used to promote the diffusion of NiO${}_x$ into the gold electrode, and enhance interface contact and reducing the electrical resistance of NiO${}_x$/Au. After optimizing NiO${}_x$/Au interface, the devices based on NiO${}_x$ achieved a power conversion efficiency (PCE) of 6.7%. Furthermore, the best all-inorganic CsPbIBr${}_2$ PSC free of encapsulation retains 95% of initial efficiency over 100 h at 85 °C. Herein, an effective postannealing strategy is provided for optimized NiO${}_x$/Au interface to make stable and efficient all-inorganic CsPbIBr${}_2$ PSCs. (© 2021 Wiley-VCH GmbH)