Interfacial-engineering enhanced performance and stability of ZnO nanowire-based perovskite solar cells.

Perovskite solar cells (PSCs) have attracted extensive attention due to their convenient fabrication and excellent photoelectric characteristics. The highest power conversion efficiency (PCE) of over 25 % has been realized. However, ZnO as electron transport layer (ETL) based PSCs exhibit inferior PCE and stability because of the mismatched energy-band and undesirable interfacial recombination. Here, we introduce a thin layer of SnO2 nanocrystals to construct an interfacial engineering with gradient energy band and interfacial passivation via a facile wet chemical process at a low temperature. The best PCE obtained in this study reaches 18.36 %, and the stability is substantially improved and maintains a PCE of almost 100 % over 500 h. The low-temperature fabrication process facilitates the future application of ZnO/SnO2-based PSCs in flexible and stretchable electronics.