Influence of Molecular Structure on Contact Interaction between Thiophene Anchoring Group and Au Electrode

In this Article, the single molecular junctions of thiophene-based molecules are measured by scanning tunneling microscopy break junction (STM-BJ) in ambient air. While the benzo[1,2-b:4,5-b′]dithiophene (1) and 2,6-dibromobenzo[1,2-b:4,5-b′]dithiophene (2) give out histograms with well-defined peaks corresponding to the molecular junction, thieno[3,2-b]thiophene (3) does not show a peak for the molecular junction. The disappearance of peak may contribute to the weak interaction between thiophene and Au. DFT calculation results demonstrate the weak interaction for 3 contacting Au as compared to 1 and 2. Interestingly, the step probability for molecular junction follows the order of binding interaction between thiophene and Au showing 1 > 2 > 3. The current results reveal the influence of molecular structure on contact interaction between anchoring group and electrode, which can help to understand the electron transport of the single molecular junction.