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

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

doi:10.1021/acs.jpcc.7b02005

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

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

Department of Chemistry

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 π-stacked systems. Using first-principles calculations, we find that the thermal conductance of π-stacked systems can be reduced by about 95%, compared with that of a covalently bonded molecular junction. Phonon transmission of π-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 π-stacked molecular junction is dramatically enhanced because of the very low phononic thermal conductance, leaving room for further optimization of the electronic properties. (Figure Presented).

Original language	English
Journal	The Journal of Physical Chemistry Part C
Volume	121
Issue number	13
Pages (from-to)	7175-7182
Number of pages	8
ISSN	1932-7447
DOIs	https://doi.org/10.1021/acs.jpcc.7b02005
Publication status	Published - 6 Apr 2017

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title = "A Strategy to Suppress Phonon Transport in Molecular Junctions Using pi-Stacked Systems",

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 π-stacked systems. Using first-principles calculations, we find that the thermal conductance of π-stacked systems can be reduced by about 95%, compared with that of a covalently bonded molecular junction. Phonon transmission of π-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 π-stacked molecular junction is dramatically enhanced because of the very low phononic thermal conductance, leaving room for further optimization of the electronic properties. (Figure Presented).",

author = "Qian Li and Mikkel Strange and Ivan Duchemin and Davide Donadio and Solomon, {Gemma C.}",

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doi = "10.1021/acs.jpcc.7b02005",

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TY - JOUR

T1 - A Strategy to Suppress Phonon Transport in Molecular Junctions Using pi-Stacked Systems

AU - Li, Qian

AU - Strange, Mikkel

AU - Duchemin, Ivan

AU - Donadio, Davide

AU - Solomon, Gemma C.

PY - 2017/4/6

Y1 - 2017/4/6

N2 - 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 π-stacked systems. Using first-principles calculations, we find that the thermal conductance of π-stacked systems can be reduced by about 95%, compared with that of a covalently bonded molecular junction. Phonon transmission of π-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 π-stacked molecular junction is dramatically enhanced because of the very low phononic thermal conductance, leaving room for further optimization of the electronic properties. (Figure Presented).

AB - 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 π-stacked systems. Using first-principles calculations, we find that the thermal conductance of π-stacked systems can be reduced by about 95%, compared with that of a covalently bonded molecular junction. Phonon transmission of π-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 π-stacked molecular junction is dramatically enhanced because of the very low phononic thermal conductance, leaving room for further optimization of the electronic properties. (Figure Presented).

U2 - 10.1021/acs.jpcc.7b02005

DO - 10.1021/acs.jpcc.7b02005

M3 - Journal article

SN - 1932-7447

VL - 121

SP - 7175

EP - 7182

JO - The Journal of Physical Chemistry Part C

JF - The Journal of Physical Chemistry Part C

IS - 13

ER -

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

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