Interface Engineering of Graphene/CH3NH3PbI3 Heterostructure for Novel p–i–n Structural Perovskites Solar Cells

Functionalized graphene is widely used in various functional devices. Here, we introduce a simple plane capacity model and the density functional theory to investigate the origin of charge transfer in the graphene/CH3NH3PbI3 interface, where graphene can be p-type or n-type doped by combining with different exposed surfaces of CH3NH3PbI3. Our calculations indicate that at the equilibrium distance, the work function of isolated graphene layer should be corrected by adding a value for assessing the charge transfer. After integrating the perovskite film with the functionalized graphene layer, we obtain a van der Waals heterostructure solar cell with a p–i–n configuration, which introduces a built-in electrical field to facilitate the separation and transport of the photogenerated carriers. The new p–i–n junction highlights the interface effect on graphene in solar cell, which offers an avenue to design new photovoltaic devices with high performance.