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Sci Adv. 2019 Nov 8;5(11):eaax7827. doi: 10.1126/sciadv.aax7827. eCollection 2019 Nov.

Thermionic transport across gold-graphene-WSe2 van der Waals heterostructures.

Author information

1
Department of Electrical and Computer Engineering, University of Virginia, Charlottesville, VA 22904, USA.
2
Department of Mechanical and Aerospace Engineering, University of Virginia, Charlottesville, VA 22904, USA.
3
Department of Materials Science and Engineering, University of Virginia, Charlottesville, VA 22904, USA.
4
Department of Physics and Astronomy, University of Toledo, Toledo, OH 43606, USA.
5
Wright Center for Photovoltaic Innovation and Commercialization, University of Toledo, Toledo, OH 43606, USA.

Abstract

Solid-state thermionic devices based on van der Waals structures were proposed for nanoscale thermal to electrical energy conversion and integrated electronic cooling applications. We study thermionic cooling across gold-graphene-WSe2-graphene-gold structures computationally and experimentally. Graphene and WSe2 layers were stacked, followed by deposition of gold contacts. The I-V curve of the structure suggests near-ohmic contact. A hybrid technique that combines thermoreflectance and cooling curve measurements is used to extract the device ZT. The measured Seebeck coefficient, thermal and electrical conductance, and ZT values at room temperatures are in agreement with the theoretical predictions using first-principles calculations combined with real-space Green's function formalism. This work lays the foundation for development of efficient thermionic devices.

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