Controlling the conductance of molecular wires by defect engineering: a divide et impera approach

Daijiro Nozaki, Horacio M. Pastawski, Gianaurelio Cuniberti

Published 2010-01-27, updated 2010-06-01Version 3

Understanding of charge transport mechanisms in nanoscale structures is essential for the development of molecular electronic devices. Charge transport through 1D molecular systems connected between two contacts is influenced by several parameters such as the electronic structure of the molecule and the presence of disorder and defects. In this work, we have modeled 1D molecular wires connected between electrodes and systematically investigated the influence of both soliton formation and the presence of defects on properties such as the conductance and the density of states. Our numerical calculations have shown that the transport properties are highly sensitive to the position of both solitons and defects. Interestingly, the introduction of a single defect in the molecular wire which divides it into two fragments both consisting of an odd number of sites creates a new conduction channel in the center of the band gap resulting in higher zero-bias conductance than for defect free systems. This phenomenon suggests alternative routes toward engineering molecular wires with enhanced conductance.