First-principle study on the conductance of benzene-based molecules with various bonding characteristics

Abstract

Electron transport through benzene-based molecule is the fundamental issue of the electrical properties of graphene and other conjugated π-systems. To improve the device performance of conjugated π-systems, we designed a series of benzene models and analyzed the effect of bonding environments on the molecular conductance of benzene. By combing density functional theory and the non-equilibrium Green’s function method, it is found that the conductance of isolated benzene in a saturated sp3 carbon chain is a little higher than that in a conjugated sp2 oligophenyl chain, due to its lower attenuation with increasing unit number. The intermolecular d-p-π coupling acts as an important positive factor favoring to improve the conductance, whereas the d-p-σ decoupling is a negative factor to reduce the conductance. In conjugated π-systems, the intramolecular π-π conjugation has enhanced by the increasing unit number, which is another positive factor contributing to the high conductivity with long molecular length. These analyses not only help to enrich our knowledge about electron transport through conjugated π-systems, but also guide the design of graphene-based electronic devices.