Cross polarization effect of donor–acceptor group on a potential single‐molecule transistor

Theoretical investigation of the polarization effect on a potential single‐molecule transistor has been studied with density functional theory. 4,4′‐(2‐Amino‐5‐nitro‐1,4‐phenylene)bis(ethyne‐2,1‐diyl) dibenzenethiol (AN‐OPE), containing a donor and an acceptor (D–A) crossed to its oligo(p‐phenylene‐ethynylene) (OPE) backbone, was used as a prototype for this study. Simulation results indicate that AN‐OPE has a higher on/off ratio on conductance than OPE because of the larger polarization along the D–A direction. This high on/off ratio was proved by the 20 times variation in molecular charge, 15 times variation in bond lengths, 49 times variation in polarizability, 9 times variation in the rotation angles, and 13 times variation in the highest occupied molecular orbital–lowest unoccupied molecular orbital gaps under the same gate using B3LYP/6‐31G (d, p). And results imply that conjugated molecules with a cross D–A structure could be a good direction for constructing a better single‐molecule field‐effect transistor. Copyright © 2014 John Wiley & Sons, Ltd.