A Strategy to Suppress Phonon Transport in Molecular Junctions Using pi-Stacked Systems

Qian Li, Mikkel Strange, Ivan Duchemin, Davide Donadio, Gemma C. Solomon

Research output: Contribution to journalJournal articleResearchpeer-review

Abstract

Molecular junctions are promising candidates for thermoelectric devices due to the potential to tune the electronic and thermal transport properties. However, a high figure of merit is hard to achieve, without reducing the phononic contribution to thermal conductance. Here, we propose a strategy to suppress phonon transport in graphene-based molecular junctions preserving high electronic power factor, using nonbonded pi-stackal systems. Using first-principles calculations, we find that the thermal conductance of pi-stacked systems can be reduced by about 95%, compared with that of a covalently bonded molecular junction. Phonon transmission of pi-stacked systems is largely attenuated in the whole frequency range, and the remaining transmission occurs mainly below 5 THz, where out-of-plane channels dominate. The figure of merit (ZT) of the pi-stacked molecular junction is dramatically enhanced because of the very low phononic thermal conductance, leaving tom for further optimization of the electronic properties.
Original languageEnglish
JournalJournal of Physical Chemistry C
Volume121
Issue number13
Pages (from-to)7175-7182
Number of pages8
ISSN1932-7447
DOIs
Publication statusPublished - 2017

Cite this