Rate-equation calculations of the current flow through two-site molecular device and DNA-based junction

TL;DR

This paper uses rate-equation calculations to analyze current flow in two-site molecular devices and DNA junctions, revealing effects like rectification, saturation, and conductance shifts related to structure, coupling, and temperature.

Contribution

It introduces a rate-equation approach to study incoherent current in molecular and DNA junctions, highlighting phenomena not extensively covered before.

Findings

Structural asymmetry causes rectification, which can be neutralized by contact coupling asymmetry.

High-voltage current saturation is independent of coupling and temperature, with inverse square distance dependence for short chains.

Lower temperature shifts conductance peaks to higher voltages.

Abstract

Here we present the calculations of incoherent current flowing through the two-site molecular device as well as the DNA-based junction within the rate-equation approach. Few interesting phenomena are discussed in detail. Structural asymmetry of two-site molecule results in rectification effect, which can be neutralized by asymmetric voltage drop at the molecule-metal contacts due to coupling asymmetry. The results received for poly(dG)-poly(dC) DNA molecule reveal the coupling- and temperature-independent saturation effect of the current at high voltages, where for short chains we establish the inverse square distance dependence. Besides, we document the shift of the conductance peak in the direction to higher voltages due to the temperature decrease.