Engineering ultrahigh thermal anisotropy in 2D van der Waals films

ORAL

Abstract

Thermally anisotropic materials, whose thermal conductivity differs depending on the direction of heat conduction, are technologically important for heat management and fundamentally intriguing in terms of their mechanism of heat transport. Previous studies have achieved thermal anisotropy through anisotropic bonding, fabricating heterostructures, and introducing low dimensional defects, giving rise to anisotropic ratios of 1-2 orders of magnitude. Herein we report an ultrahigh thermal anisotropy (~1000 at room temperature) in large-area thin films with tunable thicknesses made by stacking transition metal dichalcogenide (MoS2 or WS2) monolayers. We measure an ultralow cross-plane thermal conductivity comparable to that of air, which can be attributed to interlayer rotation and the lack of lattice order. In the in-plane direction, a high thermal conductivity close to that of the single crystal counterpart is maintained due to the long-range lattice order and grain connectivity in the polycrystalline monolayers. The overall thermal anisotropy ratio in our films is higher than that of any man-made or natural material, demonstrating interlayer structure as a new degree of freedom for engineering thermal anisotropy in matter.

*This work is supported by the AFOSR (FA9550-18-1-0480).

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Presenters

  • Shi En Kim

    • Pritzker School of Molecular Engineering, University of Chicago

Authors

  • Shi En Kim

    • Pritzker School of Molecular Engineering, University of Chicago

  • Joonki Suh

    • School of Materials Science and Engineering, Ulsan National Institute of Science and Technology

  • Akash Rai

    • Department of Materials Science and Engineering, University of Illinois at Urbana-Champaign

  • Fauzia Mujid

    • Department of Chemistry, University of Chicago
    • Pritzker School of Molecular Engineering, University of Chicago

  • Chibeom Park

    • James Franck Institute, University of Chicago

  • Ariana Ray

    • School of Applied and Engineering Physics, Cornell University
    • Physics, Cornell University

  • David Anthony Muller

    • Cornell University
    • School of Applied and Engineering Physics, Cornell University
    • Applied and Engineering Physics, Cornell University
    • School of Applied and Engineering Physics, Cornell University, Ithaca, New York 14853, USA

  • David Cahill

    • Department of Materials Science and Engineering, University of Illinois Urbana Champaign
    • Department of Materials Science and Engineering, University of Illinois at Urbana-Champaign
    • University of Illinois at Urbana-Champaign

  • Jiwoong Park

    • Pritzker School of Molecular Engineering, University of Chicago
    • University of Chicago
    • Department of Chemistry, University of Chicago