Cooling molecular electronic junctions by AC current

Preston, Riley J.;Honeychurch, Thomas D.;Kosov, Daniel S.

Abstract

Electronic current flowing in a molecular electronic junction dissipates significant amounts of energy to vibrational degrees of freedom, strain- ing 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 and 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 junc- tion 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.

Journal

Journal of Chemical Physics

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153

ISBN/ISSN

1089-7690

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Publisher

American Institute of Physics

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DOI

10.1063/5.0019178