Large rectification ratio induced by nitrogen (boron) doping in graphene nanoribbon electrodes for OPE junctions

• Rectifying property is modulated by nitrogen and boron dopings.
• Rectifying properties depend closely on position and kind of dopant.
• A molecular diode with well rectifying behavior is presented.

Using nonequilibrium Green's function method combined with density functional theory, we present electronic transport properties for a molecular device constructed by an oligomeric phenylene ethynylenes (OPE) molecule between two zigzag-edge graphene nanoribbon (zGNR) electrodes. Nitrogen and boron dopants are introduced into one electrode, which makes the molecular junctions to have obvious rectifying behaviors. The conductance properties are closely related to the position and the kind of impurity atoms in electrodes. Moreover, the I–VI–V curve of the junction, which is boron doping at the edge, displays unidirectional features in the studied bias region, and large rectification ratios up to 103 are obtained. The mechanism of the performance is analyzed in terms of transmission spectra combined with molecular projected self-consistent Hamiltonian and electrode band structures under different bias voltages. Symmetry analyses of the Bloch wave functions of the corresponding subbands and the frontier molecular orbitals are also applied to reveal the rectifying behavior.