Single-molecule junctions with strong molecule-electrode coupling.

We fabricated Au-TTF-Au (tetrathiafulvalene, TTF) and Au-TSF-Au (tetraselenafulvalene, TSF) single-molecule junctions using a nanofabricated mechanically controllable break junction. We found that Au-TSF-Au and Au-TTF-Au single-molecule junctions have one and two stable configurations, respectively, and that the Au-TTF-Au single-molecule conductance is larger than that of Au-TSF-Au. The difference in single-molecule conductances of the two types of junctions originates from the difference in the strength of the molecule-electrode coupling through face-to-face overlapping configurations.