Sputtered Nickel Oxide Hole Transporting Layers for Perovskite Solar Cells

Nickel oxide-based hole transporting layers have been widely adopted for the construction of p-i-n-structured perovskite solar cells. So far, various techniques have been explored to successfully build nickel oxide layers, and the sputtering process could be a strong one particularly in view of film uniformity and scalability. In this review, we examined fundamental properties and faced problems of the sputtered nickel oxide films shown in perovskite solar cells. Proposed strategies to overcome the current issues reported in the recent works on perovskite solar cells have been surveyed.