Cooling molecular electronic junctions by AC current

TL;DR

This paper proposes a method to cool molecular electronic junctions using AC voltage, reducing vibrational temperature by over 40% while maintaining current, thus enhancing stability and lifespan.

Contribution

It introduces a practical AC-driven cooling scheme for molecular junctions, leveraging nonequilibrium Green's functions to analyze vibrational temperature control.

Findings

Achieves over 40% reduction in molecular junction temperature.

Maintains same average current during cooling process.

Provides a theoretical framework for vibrational temperature management.

Abstract

Electronic current flowing in a molecular electronic junction dissipates significant amounts of energy to vibrational degrees of freedom, straining and rupturing chemical bonds and often quickly destroying the integrity of the molecular device. The infamous mechanical instability of molecular electronic junctions critically limits performance, lifespan, and raises questions as to the technological viability of single-molecule electronics. Here we propose a practical scheme for cooling the molecular vibrational temperature via application of an AC voltage over a large, static operational DC voltage bias. Using nonequilibrium Green's functions, we computed the viscosity and diffusion coefficient experienced by nuclei surrounded by a nonequilibrium "sea" of periodically driven, current-carrying electrons. The effective molecular junction temperature is deduced by balancing the viscosity and diffusion coefficients. Our calculations show the opportunity of achieving in excess of 40\% cooling of the molecular junction temperature while maintaining the same average current.