Effect of different substitution position on the switching behavior in single-molecule device with carbon nanotube electrodes

Abstract

We investigate the electronic transport properties of dihydroazulene (DHA) and vinylheptafulvene (VHF) molecule sandwiched between two carbon nanotubes using density functional theory and non-equilibrium Green’s function. The device displays significantly switching behavior between DHA and VHF isomerizations. It is found the different substitution position of F in the molecule influences the switching ratio of device, which is analyzed by transmission spectra and molecular projected self-consistent Hamiltonian. The observed negative differential resistance effect is explained by transmission spectra and transmission eigenstates of transmission peak in the bias window. The observed reverse of current in VHF form in which two H atoms on the right side of the benzene ring of the molecule are replaced by F is explained by transmission spectra and molecule-electrode coupling with the varied bias. The results suggest that the reasonable substitution position of molecule may improve the switching ratio, displaying a potential application in future molecular circuit.