Low-Temperature Solution-Processed CuCrO₂ Hole-Transporting Layer for Efficient and Photostable Perovskite Solar Cells

Organic–inorganic hybrid perovskite solar cells (PVSCs) have become the front-running photovoltaic technology nowadays and are expected to profoundly impact society in the near future. However, their practical applications are currently hampered by the challenges of realizing high performance and long-term stability simultaneously. Herein, the development of inverted PVSCs is reported based on low temperature solution-processed CuCrO₂ nanocrystals as a hole-transporting layer (HTL), to replace the extensively studied NiO_x counterpart due to its suitable electronic structure and charge carrier transporting properties. A ≈45 nm thick compact CuCrO₂ layer is incorporated into an inverted planar configuration of indium tin oxides (ITO)/c-CuCrO₂/perovskite/[6,6]-phenyl-C61-butyric acid methyl ester (PCBM)/bathocuproine (BCP)/Ag, to result in the high steady-state power conversion efficiency of 19.0% versus 17.1% for the typical low temperature solution-processed NiO_x-based devices. More importantly, the optimized CuCrO₂-based device exhibits a much enhanced photostability than the reference device due to the greater UV light-harvesting of the CuCrO₂ layer, which can efficiently prevent the perovskite film from intense UV light exposure to avoid associated degradation. The results demonstrate the promising potential of CuCrO₂ nanocrystals as an efficient HTL for realizing high-performance and photostable inverted PVSCs.