Multifunctional 0D/2D SnO₂-Mo₂C litchi-pericarp-like ETL to achieve high-efficient perovskite solar cells

Charge transfer and collection is one of the key issues to determine the photovoltaic performance of perovskite solar cells (PSCs). The application of composite electron transport layer (ETL) can overcome the limitations of single material in energy level matching and light utilization, which provides an important candidate technology for the commercialization of PSCs. In this work, the emerging 2D few-layer Mo₂C MXene material is combined with the traditional widely used 0D SnO₂ to form a dense litchi-pericarp-like ETL. Such unique microstructure ETL without any post treatment not only adjusted the crystallization process of perovskite films, but also accelerated the electron extraction and collection process. As a result, PSCs based on this 0D-2D composite ETL achieved a champion power conversion efficiency of 25.44% with improved stability. The proposed material design strategy establishes a viable pathway for engineering high-performance ETLs, with potential applications extending to various optoelectronic devices requiring efficient charge extraction.