p-Type CuCrO₂ particulate films as the hole transporting layer for CH₃NH₃PbI₃ perovskite solar cells

CuCrO₂ with a crystal structure of delafossite is a promising material as a transparent conducting oxide. It shows unique properties, for example, wide band gap, good chemical stability, and p-type carrier transporting character. The oxide layers with delafossite structure have been suggested as hole transporting materials for organic-inorganic CH₃NH₃PbI₃ perovskite solar cells. In this study, we fabricated inverted (p-i-n) type planar perovskite solar cells with CuCrO₂ nanoparticles synthesized by the hydrothermal method and their films were formed by spin-coating without any further heat treatment. The champion device gave a 13.1% of power conversion efficiency and CuCrO₂ based devices show improved stability in ambient air compared with the standard PEDOT:PSS based perovskite solar cells.