Length dependence of the thermal conductance of alkane-based single-molecule junctions: An ab-initio study

Motivated by recent experiments, we present here a systematic ab-initio study of the length dependence of the thermal conductance of single-molecule junctions. We make use of a combination of density functional theory with non-equilibrium Green's function techniques to investigate the length de...

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Bibliographic Details
Published in:arXiv.org 2016-11
Main Authors: Klöckner, J C, Bürkle, M, Cuevas, J C, Pauly, F
Format: Article
Language:English
Subjects:
Alkanes
Anchoring
Chains
Coupling (molecular)
Density functional theory
Dependence
Fluorine
Gold
Green's functions
Heat transfer
Hydrogen atoms
Phonons
Polytetrafluoroethylene
Thermal conductivity
Thermal management
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Summary:Motivated by recent experiments, we present here a systematic ab-initio study of the length dependence of the thermal conductance of single-molecule junctions. We make use of a combination of density functional theory with non-equilibrium Green's function techniques to investigate the length dependence of the phonon transport in single alkane chains, contacted with gold electrodes via both thiol and amine anchoring groups. Additionally, we study the effect of the substitution of the hydrogen atoms in the alkane chains by heavier fluorine atoms to form polytetrafluoroethylenes. Our results demonstrate that (i) the room-temperature thermal conductance is fairly length-independent for chains with more than 5 methylene units and (ii) the efficiency of the thermal transport is strongly influenced by the strength of the phononic metal-molecule coupling. Our study sheds new light onto the phonon transport in molecular junctions, and it provides clear guidelines for the design of molecular junctions for thermal management.
ISSN:2331-8422
DOI:10.48550/arxiv.1609.03827