A model for dynamical solvent control of molecular junction electronic properties

TL;DR

This paper introduces a theoretical model incorporating stochastic solvent-molecule interactions to control electron transport in molecular junctions, highlighting the influence of solvent properties on electrical behavior.

Contribution

The paper develops a dynamical solvent-molecule interaction model within non-equilibrium Green's function formalism, accounting for stochastic solvent reorientation effects on molecular junction conductance.

Findings

Solvent viscosity and electrostatic interactions can modulate electrical properties.

Dipole alignment breaks particle-hole symmetry, affecting transport channels.

The model demonstrates control of electron flow via solvent dynamics.

Abstract

Experimental measurements of electron transport properties of molecular junctions are often performed in solvents. Solvent-molecule coupling and physical properties of the solvent can be used as the external stimulus to control electric current through a molecule. In this paper, we propose a model, which includes dynamical effects of solvent-molecule interaction in the non-equilibrium Green's function calculations of electric current. The solvent is considered as a macroscopic dipole moment that reorients stochastically and interacts with the electrons tunnelling through the molecular junction. The Keldysh-Kadanoff-Baym equations for electronic Green's functions are solved in time-domain with subsequent averaging over random realisations of rotational variables using Furutsu-Novikov method for exact closure of infinite hierarchy of stochastic correlation functions. The developed theory requires the use of wide-band approximation as well as classical treatment of solvent degrees of freedom. The theory is applied to a model molecular junction. It is demonstrated that not only electrostatic interaction between molecular junction and solvent but also solvent viscosity can be used to control electrical properties of the junction. Aligning of the rotating dipole moment breaks particle-hole symmetry of the transmission favouring either hole or electron transport channels depending upon the aligning potential.