Multivalley Band Structure and Phonon-Glass Behavior of TlAgTe

Embargo End Date
2022-02-17

Type
Article

Authors
Shafique, Aamir
Sharma, Sitansh
Sajjad, Muhammad
Schwingenschlögl, Udo

KAUST Department
Computational Physics and Materials Science (CPMS)
Material Science and Engineering Program
Physical Science and Engineering (PSE) Division

Online Publication Date
2021-02-17

Print Publication Date
2021-03-22

Date
2021-02-17

Submitted Date
2020-10-29

Abstract
We show that the extraordinary crystal structure of TlAgTe results in a phonon-glass electron-crystal behavior. The material’s electronic transport properties are evaluated by first-principles calculations and Boltzmann transport theory. We find a multivalley conduction band (n-doping) and low dispersion at the valence band edge (p-doping), which results in a high power factor. Since the mean free path of a large number of phonon modes is found to fall below the Ioffe–Regel limit, semiclassical Boltzmann transport theory cannot describe the phonon transport, but a two-channel model must be applied. The lattice thermal conductivity turns out to be as low as 0.43 W m–1 K–1 because of strong lattice anharmonicity (originating from Tl 6s2 lone pairs) and low group velocities (originating from loose bonding of the Tl atoms), which renders TlAgTe to be a highly promising thermoelectric material.

Citation
Shafique, A., Sharma, S., Sajjad, M., & Schwingenschlögl, U. (2021). Multivalley Band Structure and Phonon-Glass Behavior of TlAgTe. ACS Applied Energy Materials. doi:10.1021/acsaem.0c02684

Acknowledgements
The research reported in this publication was supported by funding from King Abdullah University of Science and Technology (KAUST).

Publisher
American Chemical Society (ACS)

Journal
ACS Applied Energy Materials

DOI
10.1021/acsaem.0c02684

Additional Links
https://pubs.acs.org/doi/10.1021/acsaem.0c02684

Permanent link to this record