First-principles study on electron transport properties of benzene chain

Abstract

Recently, the studies on nanoscale molecules which operate similarly to the silicon devices such as transistors and switches attract much attention since such molecules enable the further miniaturization of devices. For example, a single-row phenyl chain is expected to be expressed switching function by rotating phenyl rings. In this study, we examined the switching function of 1,4-biphenyldithiol and 4,4'-terphenyldithiol using first-principles electron-transport property calculation. As the results, the electron-transport properties of phenyl chain exhibit two conduction channels, where one channel shows broad peaks and the other represents sharp ones in the transmission traces. Broad peaks are disappeared by rotating phenyl ring with twist angle of 90° where the delocalized π bondings between the phenyl rings are broken. On the other hand, the sharp peaks remain with high conductivity even though the twist angle becomes 90°. This gives rise to increasing of electric power consumption and destabilization of the molecules caused by the off-state leakage current. Therefore, it is necessary to control the contribution of such channels to electron conduction.