Interface Modification with CuCrO₂ Nanocrystals for Highly Efficient and Stable Planar Perovskite Solar Cells

The interfaces between the absorber and charge transport layers are shown to be critical for the performance of perovskite solar cells (PSCs). PSCs based on the Spiro-OMeTAD hole transport layers generally suffer from the problems of stability and reproducibility. Inorganic hole transport materials CuCrO₂ have good chemical stability and high hole mobility. Herein, we reported the preparation of the delafossite-type CuCrO₂ nanocrystals with a template-etching-calcination method and the incorporation of the as-obtained CuCrO₂ nanocrystals at the perovskite/Spiro-OMeTAD interfaces of planar PSCs to improve the device efficiency and stability. Compared with the traditional hydrothermal method, the template-etching-calcination method used less calcination time to prepare CuCrO₂ nanocrystals. After the CuCrO₂ interface modification, the efficiency of PSCs improved from 18.08% to 20.66%. Additionally, the CuCrO₂-modified PSCs showed good stability by retaining nearly 90% of the initial PCE after being stored in a drybox for 30 days. The template-etching-calcination strategy will pave a new approach for the synthesis of high-performance inorganic hole-transporting materials.