TY - JOUR

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

AU - Li, Qian

AU - Strange, Mikkel

AU - Duchemin, Ivan

AU - Donadio, Davide

AU - Solomon, Gemma C.

PY - 2017

Y1 - 2017

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

AN - SCOPUS:85019686303

VL - 121

SP - 7175

EP - 7182

JO - The Journal of Physical Chemistry Part C

JF - The Journal of Physical Chemistry Part C

SN - 1932-7447

IS - 13

ER -