Chapter 6: Recent Trends in 2D Nanomaterial Composites as Charge Transporting Layers, Electrodes, and Additives in Active Layers in Organic and Perovskite Solar Cells

Two-dimensional materials are a new class of materials for energy applications because of their tunable bandgap, and economical and solution-processable nature. The power conversion efficiencies of organic and perovskite solar cells are increasing dramatically, owing to the utilization of various nanomaterials and large-scale fabrication processes. Hence, utilization of 2D materials in organic and perovskite solar cells is an advantageous option due to their tunable electronic structure, high mobility, and high optical transparency. In order to further increase the power conversion efficiency, 2D nanomaterials could be applied as hole (HTL) and electron transport layers (ETL) for organic and perovskite solar cells. The tunable band structure and the enhanced charge transfer mechanism in 2D nanomaterials could boost the performance of the solar cell. Hence, this chapter focuses on integration of 2D nanomaterials, such as graphene, transition metal dichalcogenides, and MXenes, in organic and perovskite solar cells, as HTLs or ETLs. The fundamental processes as well as stability and lifetime of 2D nanomaterials incorporated in solar cells are also discussed. Furthermore, the chapter highlights recent advances and the future potential of 2D nanomaterial-based solar cells towards high performance, flexibility, and high stability.