3 D NiO Nanowall Hole-Transporting Layer for the Passivation of Interfacial Contact in Inverted Perovskite Solar Cells

Nickel oxide (NiO) materials with excellent stability and favorable energy bands are desirable candidates for hole-selective contact (HSC) of inverted perovskite solar cell (PSC). However, studies that focus on addressing interfacial issues, which are induced by the poor NiO/perovskite contact or other defects, are scarce. In this study, a facile one-step hydrothermal strategy is demonstrated for the development of a 3 D NiO nanowall (NW) film as a promising HSC. The new NiO NWs HSC exhibits a robust and homogenous mesoporous network structure, which improved the NiO/perovskite interface contact, passivated the interfacial defect and improved the quality of the perovskite film. The optimized interface features enabled a power conversion efficiency (PCE) approaching 18 %. A diethanolamine (DEA) interlayer was introduced to further passivate the intrinsic defect of the NiO surface, resulting in better charge transfer with suppressed recombination loss. As a result, the champion PCE of the NiO NWs/DEA-based device was increased to 19.16 % with a high open-circuit voltage (approximate to 1.11 V) and fill factor (>80 %), which is prominent in methylammonium lead iodide-based inverted PSCs. Furthermore, the device exhibited better stability and lower hysteresis behavior than a conventional solution-based NiO nanocrystal device.