First-principle study on the electronic transport properties of 1,2-bis(2,4-dimethyl-5-phenyl-3-thienyl)perfluorocyclopentene (a diarylethene) as an optical molecular switch

In this research, the electronic transport of 1,2-bis(2,4-dimethyl-5-phenyl-3-thienyl)perfluorocyclopentene (as a diarylethene) and 2 of its derivatives were investigated by nonequilibrium green's function (NEGF) joined with density functional theory (DFT). Ultraviolet radiation or visible light can convert these optical molecular switches from closed form to open form. Several parameters, including different structural bond lengths and bond angles, the effect of electrode surface (Pt, Au, and Ag), and attachment sites (top, hollow, and bridge), I–V physical appearance, on/off ratios, HOMO–LUMO gaps, and the electron transmission spectra T(E) were studied. The conductivity changed from off state (low conductivity) to on state (high conductivity) as the molecule changes from open form to closed form. The best switching performance is obtained in the Au surface at the hollow site. Calculations show that the substituents –NH2 and –NO2 at R position decrease the switching efficiency.