Charge transport behavior of 1D gold chiral nanojunctions

Abstract

Understanding the process of electron tunneling in chirality-induced single-molecule junctions is imperative for the development of nanoscale switching and artificial nanomotors. Based on the combined non-equilibrium Green's functions formalism and the ground-state density functional theory, we present here the charge transport behavior of chiral gold (7,3) nanowires (NWs) in comparison with various other chiral and achiral 1D gold nanostructures as the principal leads to form stable single-molecule junctions. For σ-saturated alkane chains, we find that the contact potential barriers vary widely with the achiral leads but not with the chiral ones, although a close resemblance exists in the tunneling constants. Lower energy gaps for single-molecule junctions with Au(7,3)NWs ensure better electronic conductance even after allowing for the low thermal loss, due mainly to the close-packed arrangements of atoms with minimum wire tension. Our first-principles quantum transport analysis further suggests that chiral Au(7,3)NWs render higher electronic conductance than chiral gold (5,3) nanotubes (NTs), once bridged by either σ-saturated or π-conjugated molecular moieties. It, however, turns out that asymmetricity in the characteristics of channel formation at the lead-molecule contact remains often associated with chiral Au(7,3)NWs only.