Electron Transport Characteristics of the Dimeric 1,4-Benzenedithiol Junction

Understanding the electron transport between single molecules connected through weak interaction is of great importance for molecular electronics. In this paper, we report measurements of the conductivity of the dimeric 1,4-benzenedithiol (BDT) junction using the scanning tunneling microscopy (STM)-based current-displacement I(s) method. The conductance was measured to be 6.14 x 10(-6) G(0), a value almost two orders of magnitude lower than that of the monomer BDT junction. In control experiments, the probability of junction formation decreased with the presence of tris(2-chloroethyl) phosphate (TCEP), a reducing reagent for the disulfide bond. According to theoretical computations, the dihedral angle of the S-S bond tends to take a perpendicular conformation. This non-conjugated structure localizes the electron distribution and accounts for the low conductivity of the disulfide linkage.