Effect of electrode materials on transport properties of asymmetric biphenyl molecular junctions

We analyze the effect of electrode materials Y (Y=Ag, Cu, and Pt) on electronic transport properties of asymmetric biphenyl molecular junctions using first-principles calculations. To introduce coupling asymmetry in these junctions, one end of the biphenyl molecule is terminated by conjugated double thiol (model A) and single thiol (model B) anchoring groups, while the other end is terminated by Cu atom. We reveal that, for Ag and Cu electrode, conjugated double thiol exhibit stronger rectifying performance in contrast to nonconjugated single thiol group. Further, when the molecule is connected to the Pt electrode through single thiol and Cu atom, multifunctional behavior with excellent rectifying performance and clear negative differential resistance (NDR) are observed for the first time. The present results will pave a new roadmap for designing functional molecular devices.