Anchor position and donor/acceptor effects on transport properties in fused benzene-substituted oligothiophene molecular device

Utilizing non-equilibrium Greenʹs functions in combination with density-functional theory, the transport properties of molecular devices based on fused benzene-substituted oligothiophenes were explored theoretically. The results show that the positions of anchor group and push–pull substituent groups can affect the conduction properties significantly, and the favorite current direction of the investigated devices can be tuned by applied bias. The first-principle calculations demonstrate that the forward current is favorable under low bias due to the asymmetric shift of transmission peaks of those that are derived from the resonant tunneling through HOMO state, while the asymmetric localization of HOMO states under high bias is beneficial to the reverse current.