Thermal Transport through Single-Molecule Junctions

Molecular junctions exhibit a rich and tunable set of thermal transport phenomena. However, the predicted high
thermoelectric efficiencies, phonon quantum interference effects, rectification, and nonlinear heat transport properties of organic
molecules are yet to be verified because suitable experimental techniques have been missing. Here, by combining the break
junction technique with suspended heat-flux sensors with picowatt per Kelvin sensitivity, we measured the thermal and electrical
conductance of single organic molecules at room temperature simultaneously. We used this method to study the thermal
transport properties of two model systems, namely, dithiol-oligo(phenylene ethynylene) and octane dithiol junctions with gold
electrodes. In agreement with our density functional theory and phase-coherent transport calculations, we show that heat
transport across these systems is governed by the phonon mismatch between the molecules and the metallic electrodes. This
work represents the first measurement of thermal transport through single molecules and opens new opportunities for studying
heat management at the nanoscale level.