Non-equilibrium transport through a disordered molecular nanowire

TL;DR

This paper studies how disorder and electron-vibron interactions affect charge and heat transport in a disordered molecular nanowire under non-equilibrium conditions, revealing that interactions amplify disorder effects.

Contribution

It provides a detailed analysis of the combined impact of disorder and electron-vibron interactions on transport in a strongly localized molecular nanowire using non-equilibrium Green's functions.

Findings

Disorder dominates charge and heat transport at intermediate temperatures.

Electron-vibron interaction enhances the suppression of tunneling caused by disorder.

Transport is significantly affected by the interplay of disorder and vibrational interactions.

Abstract

We investigate the non-equilibrium transport properties of a disordered molecular nanowire. The nanowire is regarded as a quasi-one-dimensional organic crystal composed of self-assembled molecules. One orbital and a single random energy are assigned to each molecule while the intermolecular coupling does not fluctuate. Consequently, electronic states are expected to be spatially localized. We consider the regime of strong localization, namely, the localization length is smaller than the length of the molecular wire. Electron-vibron interaction, taking place in each single molecule, is also taken into account. We investigate the interplay between disorder and electron-vibron interaction in response to either an applied electric bias or a temperature gradient. To this end, we calculate the electric and heat currents when the nanowire is connected to leads, using the Keldysh non-equilibrium Green's function formalism. At intermediate temperature, scattering by disorder dominates both charge and heat transport. We find that the electron-vibron interaction enhances the effect of the disorder on the transport properties due to the exponential suppression of tunneling.