Ultra-low lattice thermal conductivity driven high thermoelectric figure of merit in Sb/W co-doped GeTe

Abstract

High thermoelectric performance is a material challenge associated mainly with the manipulation of lattice dynamics to obtain extrinsic phonon transport routes, which can make the lattice thermal conductivity (Îșlat) intrinsically low by introducing multiple scattering mechanisms. The present study shows that the lattice-strain-induced phonon scattering resulting from microstructural distortions in GeTe-based compounds can enable ultralow lattice thermal conductivity. The unusual lattice shrinkage, W interstitials, W nanoprecipitates, and heavy elemental mass, in Ge0.85Sb0.1W0.05Te culminate in an ultralow lattice thermal conductivity of ∌0.2 W m−1 K−1 at 825 K. Microstructural distortions in this Sb/W co-doped GeTe are found to be primarily associated with shorter W–Te bonding owing to the anomalous effect of the higher electronegativity of the W atoms. Furthermore, the increased electrical conductivity (σ) resulting from the enhanced vacancy formation caused by W doping and W interstitials synergistically contributes to optimization of the thermoelectric performance (ZT) to ∌2.93 at 825 K. The thermoelectric efficiency (η) as high as ∌17% has been obtained for a single leg in this composition at an operating temperature of 825 K, with an estimated device ZT value of ∌1.38.

Graphical abstract: Ultra-low lattice thermal conductivity driven high thermoelectric figure of merit in Sb/W co-doped GeTe

Supplementary files

Article information

Article type
Paper
Submitted
31 Jul 2024
Accepted
19 Sep 2024
First published
24 Oct 2024
This article is Open Access
Creative Commons BY license

J. Mater. Chem. A, 2024, Advance Article

Ultra-low lattice thermal conductivity driven high thermoelectric figure of merit in Sb/W co-doped GeTe

K. S. Bayikadi, S. Imam, W. Tee, S. Kavirajan, C. Chang, A. Sabbah, F. Fu, T. Liu, C. Chiang, D. Shukla, C. Wu, L. Chen, M. Chou, K. Chen and R. Sankar, J. Mater. Chem. A, 2024, Advance Article , DOI: 10.1039/D4TA05332J

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