Graphene-Assisted Zwitterionic Conjugated Polycyclic Molecular Interfacial Layer Enables Highly Efficient and Stable Inverted Perovskite Solar Cells

As an effective strategy to achieve high performance and operational stability in perovskite solar cells (PSCs), numerous studies have been conducted to develop efficient charge transporting materials that possess desirable conductivity, carrier mobility, and stability. Among the great number of candidate materials, graphene has attracted significant attention owing to its remarkable optoelectrical properties and stability. Based on these advantages, in this study, a graphene-assisted electron transport layer (ETL) was developed through functionalization with an n-type semiconducting small molecule, perylene diimide amino N -oxide (PDINO), which simultaneously improved the performance and stability of PSCs. The PDINO-functionalized graphene ETL exhibited suitable energy-level alignment with enhanced carrier mobility, thus resulting in an enhanced power conversion efficiency of 21.2% for the inverted structured PSCs. Moreover, through the hydrophobic surface feature and barrier property of graphene and the π–π interaction of PDINO with the underlying layer of PSCs, notably improved operational stability was achieved using the developed functionalized graphene ETL.