Molecular electronics in junctions with energy disorder

TL;DR

This paper studies electron transport in molecular wires with environmental energy fluctuations, revealing broad current distributions and laser-induced ratchet currents due to static disorder.

Contribution

It introduces a model for energy disorder in molecular wires and analyzes the effects of static disorder and laser excitation on transport and current asymmetries.

Findings

Broad current distribution even with small energy variance

Disorder-induced spatial asymmetries lead to ratchet currents under laser excitation

Static disorder significantly affects transport properties in molecular electronics

Abstract

We investigate transport through molecular wires whose energy levels are affected by environmental fluctuations. We assume that the relevant fluctuations are so slow that they, within a tight-binding description, can be described by disordered, Gaussian distributed onsite energies. For long wires, we find that the corresponding current distribution can be rather broad even for a small energy variance. Moreover, we analyse with a Floquet master equation the interplay of laser excitations and static disorder. Then the disorder leads to spatial asymmetries such that the laser diving can induce a ratchet current.