Charge correlations in polaron hopping through molecules

TL;DR

This paper develops an exact diagrammatic theory to analyze charge correlations in polaron hopping through molecules, revealing significant effects on transport properties and I-V characteristics in DNA sequences.

Contribution

It introduces a diagrammatic approach that exactly accounts for many-particle correlations in incoherent polaron transport, improving upon mean-field approximations.

Findings

Correlations qualitatively alter I-V characteristics.

Second-order expansion captures essential correlation effects.

Transport properties of DNA sequences are significantly affected.

Abstract

In many organic molecules the strong coupling of excess charges to vibrational modes leads to the formation of polarons, i.e., a localized state of a charge carrier and a molecular deformation. Incoherent hopping of polarons along the molecule is the dominant mechanism of transport at room temperature. We study the far-from-equilibrium situation where, due to the applied bias, the induced number of charge carriers on the molecule is high enough such that charge correlations become relevant. We develop a diagrammatic theory that exactly accounts for all many-particle correlations functions for incoherent transport through a finite system. We compute the transport properties of short sequences of DNA by expanding the diagrammatic theory up to second order in the hopping parameters. The correlations qualitatively modify the I-V characteristics as compared to those approaches where correlations are dealt with in a mean-field type approximation only.