First-principles study on photoswitching behavior and negative differential resistance in single molecule junction

We investigate the electronic transport of a photochromic molecule, a 1,2-dithienyl-1,2-dicyanoethene sandwiched between two Au electrodes using first-principles based on non-equilibrium Green's function and density functional theory. This molecule can be reversibly transformed between trans and cis state through irradiation. The calculated current of the cis form is larger than the trans form, indicating an obvious switching behavior in the present device. We discuss the electronic transport properties for cis and trans forms in detail by the transmission spectra and molecular projected self-consistent Hamiltonian states. The observed negative differential resistance effect in the cis form is explained discussing the transmission eigenstates of HOMO energy level. The results suggest that this photochromic molecule can become one of the good candidates for single molecular photoswitching in the future. (C) 2017 Elsevier B.V. All rights reserved.