Self‐Assembly Atomic Stacking Transport Layer of 2D Layered Titania for Perovskite Solar Cells with Extended UV Stability

Abstract A novel atomic stacking transporting layer (ASTL) based on 2D atomic sheets of titania (Ti 1− δ O 2 ) is demonstrated in organic–inorganic lead halide perovskite solar cells. The atomically thin ASTL of 2D titania, which is fabricated using a solution‐processed self‐assembly atomic layer‐by‐layer deposition technique, exhibits the unique features of high UV transparency and negligible (or very low) oxygen vacancies, making it a promising electron transporting material in the development of stable and high‐performance perovskite solar cells. In particular, the solution‐processable atomically thin ASTL of 2D titania atomic sheets shows superior inhibition of UV degradation of perovskite solar cell devices, compared to the conventional high‐temperature sintered TiO 2 counterpart, which usually causes the notorious instability of devices under UV irradiation. The discovery opens up a new dimension to utilize the 2D layered materials with a great variety of homostructrual or heterostructural atomic stacking architectures to be integrated with the fabrication of large‐area photovoltaic or optoelectronic devices based on the solution processes.