NiCo2O4 arrays with a tailored morphology as hole transport layers of perovskite solar cells

Abstract

Inorganic p-type semiconductors have broadly served as hole transport materials (HTLs) in perovskite solar cells (PSCs) in recent years. Among them, NiCo₂O₄ with its excellent conductivity and hole mobility is the emerging candidate for HTLs and is attracting increasing attention. Here, we employ a simple hydrothermal method to fabricate high-quality mesoporous NiCo₂O₄ films as HTLs of PSCs. The study finds that the morphology of NiCo₂O₄ can be regulated from nanosheets (NSs) to nanowires (NWs) as the hydrothermal reaction time increases, and the morphology of NiCo₂O₄ significantly affects the device performance. Specially, the device with NWs achieves a best efficiency of 11.58%, ascribed to the fact that such a one dimension material could provide a straight path for hole extraction/transport. And benefiting from the mesoporous structures of NiCo₂O₄ films, all the devices exhibited a very repeatable and desirable long-term stability. Overall, this work develops alternative NiCo₂O₄ nanostructure-based HTLs and opens up new opportunities in fabricating PSCs.