DFT study on electron-transport property of a single-molecule transistor formed by long π-conjugated molecules

The experimental study reported that the single-molecule transistors, in which a π-conjugated highly fused oligosilole derivative with two biphenyl groups is suspended between two Au(111) electrodes, exhibit diode property, negative differential resistance and good switching property. Using RSPACE code, which is DFT calculation code with real-space finite-difference method and Green's function scheme, the electron-transport property of the single-molecule transistor is investigated. We found that the diode property is caused by the adsorption structures of the molecule at electrode surfaces, the negative differential resistance is induced by the asymmetrical structure of the molecule, and the charged state of the molecule is relevant to the switching property of the transistors. We discuss the structural stability and origin of the characteristic transport property of the single-molecule transistor.