Rational Buried Interface Engineering of Inorganic NiOx Layer toward Efficient Inverted Perovskite Solar Cells

The power conversion efficiency of inverted perovskite solar cells (PSCs) based on p-i-n structure exceeds 25%, largely owning to the persistent improvement on the quality of heterojunction interface. Nickel oxide (NiOx) of low cost and superior chemical stability is one of the most promising candidates as hole-transport material that is suitable for large-scale fabrication. Meanwhile, the certified efficiency of inorganic NiOx-based inverted PSCs surpasses 25% via improving the poor quality of buried interface contact, which is originated from large offset of valence band energy level, as well as high density of interfacial defects between NiOx hole-transport layer and perovskite film. In this review, the development and progress in buried interface engineering of inorganic NiOx layer are systematically summarized, including strategies on energy level alignment and interfacial defect passivation, which are adopted to promote the better energy level alignment and suppress the defect-assisted nonradiative recombination at interface. On the basis of deeper understanding of buried interface features, some novel materials and methods for interface modification can be rationally designed. Perspectives on future development of efficient and stable large-scale perovskite solar modules and tandem cells are also provided.