Thermoelectric properties of graphene/boron nitride heterostructures

Using density functional theory combined with a Green's function scattering approach, we examine the thermoelectric properties of hetero-nanoribbons formed from alternating lengths of graphene and boron nitride. In such structures, the boron nitride acts as a tunnel barrier, which weakly couple...

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Bibliographic Details
Published in:arXiv.org 2015-10
Main Authors: Algharagholy, L A, Al-Galiby, Q, Marhoon, H A, Sadeghi, H, Abduljalil, H M, Lambert, C J
Format: Article
Language:English
Subjects:
Adsorbates
Boron
Boron nitride
Density functional theory
Doping
Electrons
Figure of merit
Graphene
Green's functions
Heterostructures
Silicones
Thermal conductivity
Thermoelectricity
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Summary:Using density functional theory combined with a Green's function scattering approach, we examine the thermoelectric properties of hetero-nanoribbons formed from alternating lengths of graphene and boron nitride. In such structures, the boron nitride acts as a tunnel barrier, which weakly couples states in the graphene, to form mini-bands . In un-doped nanoribbons, the mini bands are symmetrically positioned relative to the Fermi energy and do not enhance thermoelectric performance significantly. In contrast, when the ribbons are doped by electron donating or electron accepting adsorbates, the thermopower S and electronic figure of merit are enhanced and either positive or negative thermopowers can be obtained. In the most favourable case, doping with the electron donor tetrathiafulvalene (TTF) increases the room-temperature thermopower to -284 {\mu}v/K and doping by the electron acceptor tetracyanoethylene (TCNE) increases S to 210 {\mu}v/K. After including both electron and phonon contributions to the thermal conductance, figures of merit ZT up to of order 0.9 are obtained.
ISSN:2331-8422