Designing $\pi$-stacked molecular structures to control heat transport through molecular junctions

TL;DR

This paper introduces a molecular design leveraging $$ stacking to control phononic heat transport in molecular junctions, enabling tailored heat dissipation without compromising electrical conduction, relevant for thermoelectric devices.

Contribution

It proposes a novel molecular architecture using $$ stacking to modulate phonon heat conductance independently of electrical conductance, supported by theoretical modeling and first-principles calculations.

Findings

Small coupling between masses can suppress or enhance phonon conductance.

The proposed design is feasible with standard molecular building blocks.

Optimal parameters for heat control are identified through modeling.

Abstract

We propose and analyze a new way of using $\pi$ stacking to design molecular junctions that either enhance or suppress a phononic heat current, but at the same time remain conductors for an electric current. Such functionality is highly desirable in thermoelectric energy converters, as well as in other electronic components where heat dissipation should be minimized or maximized. We suggest a molecular design consisting of two masses coupled to each other with one mass coupled to each lead. By having a small coupling (spring constant) between the masses, it is possible to either reduce, or perhaps more surprisingly enhance the phonon conductance. We investigate a simple model system to identify optimal parameter regimes and then use first principle calculations to extract model parameters for a number of specific molecular realizations, confirming that our proposal can indeed be realized using standard molecular building blocks.