NiOx thickness dependent improvement of NiOx/Perovskite interface for inverted planar perovskite solar cells

Sputtered nickel oxide (NiOx) as hole transport layer (HTL) could easily realize the large-area uniformity, as well as reduce the fabrication cost for metal-halide perovskite solar cells (PSCs). However, nonradiative recombination losses at the interface between NiOx and perovskite (PVK) lead to an open-circuit voltage (Voc) deficit, which is an important limiting factor for the improvement of power conversion efficiency (PCE). To address this situation, we report a strategy of improving the energy band matching at the NiOx/PVK interface by the simple thickness control of NiOx. Combined experimental and numerical simulation results indicate that the suitable thickness reduces the valence band barrier at NiOx and PVK interface and expedites the charge carrier collection. We achieved a PCE of 16.1% via an optimized NiOx thickness of PSCs, which is 2.2% and 1.7% absolute higher than that of 10 and 30 nm thickness of NiOx-based PSCs, respectively. Overall, these findings provide critical insights for improved hole transport at the interface between the NiOx and perovskite thin film, and the fabrication of highly efficient, robust, and large-area perovskite optoelectronic devices.