First-principles study of phenyl ethylene oligomers as current-switch

We use a self-consistent method to study the distinct current-switch of 2′-amino-4-ethynylphenyl-4′-ethynylphenyl-5′-nitro-1-benzenethiol, from the first-principles calculations. The switch behavior is in accord with the early experiment [M.A. Reed, J.H. Tour, Sci. Am. 282 (2000) 86]. To further investigate the transport mechanism of the conformational molecular switch, we calculate the switching behavior of p-terphenyl with the rotations of the middle ring as well, the results are consistent with Reed's experiment. We also study the effect of the hydrogen atom substituting one ending sulfur atom on the transport and find that the asymmetry of I–V curves appears and the switch effect still lies in both the positive and negative bias range.