Charge transport through a molecular wire for flexible electronics

Abstract

In the present work we used a system consisting of a molecular wire of multiple thiophene rings bridged between gold electrodes to study the charge transport mechanism, the effect of the tilt angle, the temperature dependence, the atomic configuration of the gold electrodes, the molecule–electrode interaction and the effect of rotation of the molecular wire on the conductance of the studied system. We found that, for shorter molecular lengths, the charge transport can be explained by tunneling, but, as the molecular length increases, it changes to hopping, which is supported by modeling the conductance of the molecular wire with a change in the temperature of the system. The results show that shorter molecular wires exhibit temperature-invariant behavior, and longer molecular wires exhibit highly temperature-variant behavior. The geometrically optimized symmetries of thiophene molecules with even and odd orientation are different, which leads to a difference in the contact configurations between the molecule and the electrodes, and results in a larger coupling parameter for thiophene molecules with even thiophene rings than for thiophene molecules with odd thiophene rings.