Switching behavior induced by different substituents of group in single molecular device

Abstract

We investigate the electronic transport properties of photochromic azobenzene-based molecular devices with Au electrodes using non-equilibrium Green’s function and density functional theory. A reversible switching behavior between cis and trans isomerization is found in the device. In addition, the substituent of −NH2 on the right end hydrogen atom of azobenzene molecule reduces the switching ratio of current, consequently the disappearance of switching behavior, while the substituent of −NO2 improves the switching ratio of current. We discuss the different electronic transport induced by different substituents through the transmission spectra, localized density of states, molecular projected self-consistent Hamiltonian and transmission pathways. The observed polarization effect under bias is explained by the evolution of molecular projected self-consistent Hamiltonian of LUMO level. The results indicate that the electron-withdrawing group −NO2 substituting right terminal hydrogen of azobenzene molecule becomes a candidate for improving the performance of molecular device.