In Situ Growth of Nickel Oxide Hole-Transport Layer through the Nickel Oleate Route for High-Performance Perovskite Solar Cells

Nickel oxide has become a promising alternative as a hole-transport layer employed in perovskite solar cells (PSCs). However, nickel oxide nanoparticles (NPs) are often necessary to form nickel oxide films, which may cause some microcracks, surface crystal defects, and nonuniformity in the prepared nickel oxide film. In this paper, a strategy is designed to bypass nickel oxide NPs to realize the in situ growth of a uniform nickel oxide film using nickel oleate as the precursor. Therefore, the prepared perovskite solar cells (PSCs) with the structure of FTO/NiO/MAPbI3/PC61BM/Ag exhibit a champion photoelectric conversion efficiency (PCE) up to 16.19%, compared with 11.71 and 9.15% for the prepared and commercial nickel oxide NPs, respectively. It is noted that this champion PCE (16.19%) is higher than those reported in studies on devices with identical structures. Moreover, the average short-circuit current (JSC), open-circuit voltage (VOC), and fill factor (FF) of devices based on the nickel oleate metal strategy are much higher than those prepared from NiO NPs by the sol–gel method (19.46 vs 17.24 mA/cm2, 1.072 vs 1.041 V, and 0.776 vs 0.653, respectively). This work provides a reliable avenue to generate nickel oxide films with increased uniformity and corresponding high-performance PSCs.