Disorder and dephasing effect on electron transport through conjugated molecular wires in molecular junctions

TL;DR

This paper investigates how disorder and dephasing influence electron transport in conjugated molecular wires, revealing the transition from tunneling to hopping conduction and providing a model to interpret experimental conductance data.

Contribution

It introduces a density-functional tight-binding approach within the D'Amato-Pastawski model to explicitly study structure-transport relationships under dephasing conditions.

Findings

Reproduced the tunneling-to-hopping transition in molecular wires.

Analyzed the effects of length and thermal fluctuations on conductance.

Provided a new tool for interpreting molecular junction conductance measurements.

Abstract

Understanding electron transport processes in molecular wires connected between contacts is a central focus in the field of molecular electronics. Especially, the dephasing effect causing tunneling-to-hopping transition has great importance from both applicational and fundamental points of view. We analyzed coherent and incoherent electron transmission through conjugated molecular wires by means of density-functional tight-binding theory within the D'Amato-Pastawski model. Our approach can study explicitly the structure/transport relationship in molecular junctions in a dephasing environmental condition using only single dephasing parameter. We investigated the length dependence and the influence of thermal fluctuations on transport and reproduced the well-known tunneling-to-hopping transition. This approach will be a powerful tool for the interpretation of recent conductance measurements of molecular wires.