Unconventional Route to Oxygen‐Vacancy‐Enabled Highly Efficient Electron Extraction and Transport in Perovskite Solar Cells

The ability to effectively transfer photoexcited electrons and holes is an important endeavor toward achieving high-efficiency solar energy conversion. Now, a simple yet robust acid-treatment strategy is used to judiciously create an amorphous TiO2 buffer layer intimately situated on the anatase TiO2 surface as an electron-transport layer (ETL) for efficient electron transport. The facile acid treatment is capable of weakening the bonding of zigzag octahedral chains in anatase TiO2 , thereby shortening staggered octahedron chains to form an amorphous buffer layer on the anatase TiO2 surface. Such amorphous TiO2 -coated ETL possesses an increased electron density owing to the presence of oxygen vacancies, leading to efficient electron transfer from perovskite to TiO2 . Compared to pristine TiO2 -based devices, the perovskite solar cells (PSCs) with acid-treated TiO2 ETL exhibit an enhanced short-circuit current and power conversion efficiency.