Preparation of Nickel Oxide Nanoflakes for Carrier Extraction and Transport in Perovskite Solar Cells

Low interfacial recombination between the HTL and perovskite absorber is also crucial to the device performance of PSCs. In this work, we developed a three-stage method to prepare NiOx nanoflakes as the HTL in the inverted PSCs.

Due to the addition of the nanoflake layer, the deposited perovskite films with larger grain sizes and fewer boundaries were obtained, implying higher photogenerated current and fill factors in our PSCs. Meanwhile, the downshifted valence band of the NiOx HTL improved hole extraction from the perovskite absorber and open-circuit voltages of PSCs. The optimized device based on the NiOx nanoflakes showed the highest efficiency of 14.21% and a small hysteresis, which outperformed the NiOx thin film as the HTL.