Graziosi, Patrizio, Li, Zhen and Neophytou, Neophytos (2022) Bipolar conduction asymmetries lead to ultra-high thermoelectric power factor. Applied Physics Letters, 120 (7). 072102. doi:10.1063/5.0076967 ISSN 1077-3118.

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Abstract

Low bandgap thermoelectric materials suffer from bipolar effects at high temperatures, with increased electronic thermal conductivity and reduced Seebeck coefficient, leading to a reduced power factor and a low ZT figure of merit. In this work we show that the presence of strong transport asymmetries between the conduction and valence bands can allow high phonon-limited electronic conductivity at finite Seebeck coefficient values, leading to largely enhanced power factors. The power factors that can be achieved can be significantly larger compared to their maximum unipolar counterparts, allowing for doubling of the ZT figure of merit. We identify this behavior in low-bandgap cases from the half-Heusler material family. Using both advanced electronic Boltzmann transport calculations for realistic material band structures and model parabolic electronic bands, we elaborate on the parameters that determine this effect. We then develop a series of descriptors that can guide machine learning studies in identifying such classes of materials with extraordinary power factors at nearly undoped conditions. For this we test more than 3000 analytical band structures and their features, and more than 120 possible descriptors, to identify the most promising ones that contain: (i) only band structure features for easy identification from material databases and (ii) band structure and transport parameters that provide much higher correlations, but for which parameter availability can be somewhat more scarce.

Item Type:	Journal Article
Subjects:	Q Science > QC Physics T Technology > TK Electrical engineering. Electronics Nuclear engineering
Divisions:	Faculty of Science, Engineering and Medicine > Engineering > Engineering
SWORD Depositor:	Library Publications Router
Library of Congress Subject Headings (LCSH):	Thermoelectricity, Thermoelectric materials, Bipolar integrated circuits
Journal or Publication Title:	Applied Physics Letters
Publisher:	AIP Publishing
ISSN:	1077-3118
Official Date:	14 February 2022
Dates:	Date Event 14 February 2022 Published 18 February 2022 Available 3 February 2022 Accepted
Volume:	120
Number:	7
Article Number:	072102
DOI:	10.1063/5.0076967
Status:	Peer Reviewed
Publication Status:	Published
Reuse Statement (publisher, data, author rights):	This article may be downloaded for personal use only. Any other use requires prior permission of the author and AIP Publishing. This article appeared in Patrizio Graziosi, Zhen Li, and Neophytos Neophytou , "Bipolar conduction asymmetries lead to ultra-high thermoelectric power factor", Appl. Phys. Lett. 120, 072102 (2022) and may be found at https://doi.org/10.1063/5.0076967
Access rights to Published version:	Restricted or Subscription Access
Copyright Holders:	© 2022 Author(s). Published under an exclusive license by AIP Publishing
Date of first compliant deposit:	23 March 2022
Date of first compliant Open Access:	24 March 2022
RIOXX Funder/Project Grant:	Project/Grant ID RIOXX Funder Name Funder ID 788465 H2020 Marie Skłodowska-Curie Actions http://dx.doi.org/10.13039/100010665 678763 European Research Council http://dx.doi.org/10.13039/501100000781 UNSPECIFIED Cineca http://viaf.org/viaf/143321534

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