Pristine inorganic nickel oxide as desirable hole transporting material for efficient quasi two-dimensional perovskite solar cells

Abstract

The performance of quasi two-dimensional (Q-2D) perovskite solar cells (PSCs) prepared by hot-casting method is far from satisfactory owing to the inefficient charge transfer inside the film caused by undesirable underlying surface, in which hole transporting material (HTM) plays a critical role in achieving a stable and high performance p-i-n structured Q-2D PSCs. Herein, pristine nickel oxide (NiOx) is prepared by sol-gel method as a desirable HTM to fabricate p-i-n structured Q-2D PSCs. The formation of high-quality perovskite films with less defects and higher crystallinity can be promoted by the NiOx layer with desired wetting surface. Importantly, the NiOx HTM possesses a better energy-level match with post-deposited perovskite film, which largely boosts up the hole extraction efficiency. Consequently, the champion device achieves a remarkable power conversion efficiency (PCE) of 14.85%, which is the best result for inorganic HTM based Q-2D PSCs so far. Furthermore, compared with conventional organic polymer HTM, NiO x HTM possesses better chemical stability and more competitive prices. This work reveals that inorganic HTM with ideal wetting surface could be a superb choice to release the power of Q-2D perovskites for achieving ideal photovoltaic performance. • Pristine NiOx is prepared by sol-gel method with desired wetting surface. • Favorable energy-level match was achieved for NiOx with post-deposited perovskites. • NiOx-based Quasi two-dimensional perovskite solar cell deliver a high PCE of 14.85%.