The electronic transport properties and switching mechanism of singlephotochromic diarylethene derivatives sandwiched between two gold surfaces withclosed and open configurations are investigated by a fully self-consistentnonequilibrium Green's function method combined with density functional theory.The calculated transmission spectra of two configurations are strikinglydistinctive. The open form lacks any significant transmission peak within awide energy window, while the closed structure has two significant transmissionpeaks on the both sides of the Fermi level. The electronic transport propertiesof the molecular junction with closed structure under a small bias voltage aremainly determined by the tail of the transmission peak contributed unusually bythe perturbed lowest perturbed unoccupied molecular orbital. The calculatedon-off ratio of currents between the closed and open configurations is abouttwo orders of magnitude, which reproduces the essential features of theexperimental measured results. Moreover, we find that the switching behaviorwithin a wide bias voltage window is extremely robust to both substituting F orS for H or O and varying end anchoring atoms from S to Se and Te.
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