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

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

来源：Journal of Physical Chemistry C, 2017, 121(13): 7175-7182.

DOI：10.1021/acs.jpcc.7b02005

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.

• 出版日期2017-4-6
• 单位中国地震局