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Issue 43, 2019
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Strain induced valley degeneracy: a route to the enhancement of thermoelectric properties of monolayer WS2

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Abstract

Two-dimensional transition metal dichalcogenides show great potential as promising thermoelectric materials due to their lower dimensionality, the unique density of states and quantum confinement of carriers. Here the effects of mechanical strain on the thermoelectric performances of monolayer WS2 have been investigated using density functional theory associated with semiclassical Boltzmann transport theory. The variation of the Seebeck coefficient and band gap with applied strain has followed the same type of trend. For n-type material the relaxation time scaled power factor (S2σ/τ) increases by the application of compressive strain whereas for p-type material it increases with the application of tensile strain due to valley degeneracy. A 77% increase in the power factor has been observed for the n-type material by the application of uniaxial compressive strain. A decrease in lattice thermal conductivity with the increase in temperature causes an almost 40% increase in ZT product under applied uniaxial compressive strain. From the study, it is observed that uniaxial compressive strain is more effective among all types of strain to enhance the thermoelectric performance of monolayer WS2. Such strain induced enhancement of thermoelectric properties in monolayer WS2 could open a new window for the fabrication of high-quality thermoelectric devices.

Graphical abstract: Strain induced valley degeneracy: a route to the enhancement of thermoelectric properties of monolayer WS2

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Publication details

The article was received on 14 Jun 2019, accepted on 05 Aug 2019 and first published on 13 Aug 2019


Article type: Paper
DOI: 10.1039/C9RA04470A
RSC Adv., 2019,9, 25216-25224
  • Open access: Creative Commons BY-NC license
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    Strain induced valley degeneracy: a route to the enhancement of thermoelectric properties of monolayer WS2

    J. Bera and S. Sahu, RSC Adv., 2019, 9, 25216
    DOI: 10.1039/C9RA04470A

    This article is licensed under a Creative Commons Attribution-NonCommercial 3.0 Unported Licence. Material from this article can be used in other publications provided that the correct acknowledgement is given with the reproduced material and it is not used for commercial purposes.

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