Thermoelectric and Plasmonic Properties of Metal Nanoparticles Linked by Conductive Molecular Bridges

Abstract

Thermoelectric and plasmonic properties of systems comprising small golden nanoparticles (NPs) linked by narrow conductive polymer bridges are studied using the original hybrid quantum‐classical model. The bridges are considered here to be either conjugated polyacetylene, polypyrrole, or polythiophene chain molecules terminated by thiol groups. The parameters required for the model are obtained using density functional theory and density functional tight‐binding simulations. Charge‐transfer plasmons in the considered dumbbell structures are found to possess frequency in the infrared region for all considered molecular linkers. The appearance of plasmon vibrations and the existence of charge flow through the conductive molecule, with manifestation of quantum properties, are confirmed using frequency‐dependent polarizability calculations implemented in the coupled perturbed Kohn–Sham method. To study the thermoelectric properties of the 1D periodical systems, a universal equation for the Seebeck coefficient is derived. The phonon part of the thermal conductivity for the periodical – system is calculated by the classical molecular dynamics. The thermoelectric figure of merit ZT is calculated by considering the electrical quantum conductivity of the systems in the ballistic regime. It is shown that for nanoparticles connected by polyacetylene, polypyrrole, or polythiophene chains at T = 300 K, the ZT value is {0.08;0.45;0.40}, respectively.