Length–dependence of conductance in benzothiadiazole molecular wires between graphene nanoribbon electrodes: Effect of conformational changes

Abstract

In this research, we investigated the electronic transport mechanism of benzothiadiazole molecular wires connected to zigzag graphene nanoribbon (zGNR) electrodes on the basis of non-equilibrium Green's functions (NEGF) and density functional theory (DFT). It is obtained that the dynamical rotation of the central molecular wire affects the conjugated electron network along the transport direction and creates two different electronic devices with different electronic properties. First, the planer geometry, (zGNR|(IBT)n|zGNR), with strong coupling of molecular wire and graphene leads which have shown the molecular orbital delocalization over transmission eigenchannels inducing the current transport in such connections. Conformational change of connections is obtained by rotating the central molecular wire with respect to the transport direction creates the second class of electronic devices with low conductance values, (zGNR|(OBT)n|zGNR). The conductance decay constant indicates that non-resonant tunneling dominates the charge transport mechanism in the zGNR|(OBT)n|zGNR, while the zGNR|(IBT)n|zGNR devices have shown lower current attenuation that leads to a much lower decay factor and more conductive nano-connections for longer length of molecular bridge.