A novel reverse rectifying effects and negative differential resistance in asymmetric X-biphenyl-X (X=Pt, Pd, Pb) molecular junctions

We investigate the electronic transport properties of asymmetric biphenyl systems for X-electrodes (X=Pt, Pd, Pb) using non-equilibrium Green׳s function approach combined with density functional theory. The asymmetry in such systems is constructed by coupling biphenyl molecule to Pt, Pd, Pb electrode materials through dithiocarboxylate anchoring group on the left side and thiol group on the right side. Interestingly, novel reverse rectifying behaviors are observed for Pt and Pd electrode case. This is due to stronger d-orbital characteristics of Pt and Pd electrodes which produces intense transmission peak near the Fermi level. However, negative differential resistance is realized in case of Pb electrode. These observed distinct features for different electrodes are important for next generation nanoscale devices.