First-principles Study of Electron Transport Through Oligoacenes

The electronic transport properties of oligoacenes sandwiched between two Au(III) surfaces with serial and parrallel configurations were investigeted by using a fully self-consistent nonequilibrium Green's function method combined with density functional calculations. This theoretical results show that the conductivity of oligoacenes with both sandwiched configurations at low bias voltage is mainly determined by the tail of the transmission peak from the perturbed highest occupied molecular orbital. When the molecular length increases, the zero-bias voltage conductance G(0) of oligoacenes with serial configuration neither follows Magoga's exponential law nor displays the even-odd oscillation effect, while the G(0) of the oligoacenes sandwiched with parallel configuration monotonically increases. The reduction of energy gaps, the alignment of the Fermi level, and the spatial distribution of the perturbed molecular orbitals are used to self-consistently explore the transport mechanism through oligoacenes.