Hybrid Molecular Junctions Using Au-S and Au-πBindings

Electrically conductive molecular junctions are highly desirable components for applications in future molecular-scale electronic circuits. Here, we demonstrate an electrically conductive hybrid molecular junction that consists of Au-S and Au-πbindings using a sumanene derivative with three phosphine-sulfide anchoring groups at the periphery of the sumanene backbone. The molecular junction was prepared between the Au electrodes by the scanning tunneling microscopy-based break junction method. The three anchoring groups and the sumanene backbone in the junction form the Au-S chemical bonds and Au-πdirect bonds, respectively. The Au-S chemical binding immobilized the molecule on the Au electrode and provided the high mechanical stability of the junction, while the direct Au-πbinding led to the large metal-molecule electric coupling and high electronic conductance of the molecular junction. This study analyzes the molecular design of the electrically conductive molecular junctions based on the hybrid binding groups.