Current rectification in mono-and bilayer nanographenes with different edges

Graphene nanomaterials are actively used in electronics and materials science as elements of electric circuits and both structural and storage components. Their unique structure and electronic properties allow for a wide variety of applications (i.e., electron and thermal conductivity, ion transport, ion storage, and electric-current rectification). In this work, we investigate the electric-current-rectifying properties of mono-and bilayer two-terminal nanographene devices with the nonequilibrium Green's function method combined with density functional theory. The diode-like properties are achieved by control of the nanoribbons' edges. The sequential combination of armchair and zigzag domains leads to nanographene junctions with asymmetric current-voltage characteristics. The rectifying properties of the asymmetric armchair-zigzag carbon materials are derived from the nonequilibrium Green's function theory. The electric-current rectification is explained by the interaction of the external electric field induced between the electrodes with the localized electronic states within the junction. The model is applied on cyclophane molecules and bilayer nanographenes for which one of the layers consists of the armchair-edge nanoribbon, and the second layer consists of the zigzag-edge nanoribbon. Owing to the interlayer π-π stacking, the cyclophane and bilayer nanographene junctions show higher rectification ratios compared to the monolayer junctions. The proposed devices consist of nanographenes and polycyclic aromatic hydrocarbons, and the diode-like properties are obtained without heteroatom doping. The investigated carbon materials are promising candidates for current control elements in nanoelectronics.