Article (Scientific journals)
Non-universal Scaling of Thermoelectric Efficiency in 3D and 2D Thermoelectric Semiconductors
Octavian, Kevin; Hasdeo, Eddwi Hesky
2021In Advances in Natural Sciences: Nanoscience and Nanotechnology, 12, p. 015017
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Keywords :
Thermoelectrics
Abstract :
[en] We performed the first-principles calculation on common thermoelectric semiconductors Bi2Te3, Bi2Se3, SiGe, and PbTe in bulk three-dimension (3D) and two-dimension (2D). We found that miniaturization of materials does not generally increase the thermoelectric figure of merit (ZT) according to the Hicks and Dresselhaus (HD) theory. For example, ZT values of 2D PbTe (0.32) and 2D SiGe (0.04) are smaller than their 3D counterparts (0.49 and 0.09, respectively). Meanwhile, the ZT values of 2D Bi2Te3 (0.57) and 2D Bi2Se3 (0.43) are larger than the bulks (0.54 and 0.18, respectively), which agree with HD theory. The HD theory breakdown occurs because the band gap and band flatness of the materials change upon dimensional reduction. We found that flat bands give a larger electrical conductivity (σ) and electronic thermal conductivity (κel) in 3D materials, and smaller values in 2D materials. In all cases, maximum ZT values increase proportionally with the band gap and saturate for the band gap above 10 kBT. The 2D Bi2Te3 and Bi2Se3 obtain a higher ZT due to the flat corrugated bands and narrow peaks in their DOS. Meanwhile, the 2D PbTe violates HD theory due to the flatter bands it exhibits, while 2D SiGe possesses a small gap Dirac-cone band.
Disciplines :
Physics
Author, co-author :
Octavian, Kevin
Hasdeo, Eddwi Hesky  ;  University of Luxembourg > Faculty of Science, Technology and Medicine (FSTM) > Department of Physics and Materials Science (DPHYMS)
External co-authors :
yes
Language :
English
Title :
Non-universal Scaling of Thermoelectric Efficiency in 3D and 2D Thermoelectric Semiconductors
Publication date :
22 March 2021
Journal title :
Advances in Natural Sciences: Nanoscience and Nanotechnology
ISSN :
2043-6262
Publisher :
IOP Publishing, United Kingdom
Volume :
12
Pages :
015017
Peer reviewed :
Peer Reviewed verified by ORBi
Focus Area :
Physics and Materials Science
Available on ORBilu :
since 18 January 2021

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