Issue 42, 2023

Thermoelectric properties of Pnma and R3m GeS and GeSe

Abstract

With ∼60% of global energy lost as heat, technologies such as thermoelectric generators (TEGs) are an important route to enhancing the efficiency of energy-intensive processes. Optimising thermoelectric (TE) materials requires balancing a set of interdependent physical properties to meet efficiency, cost and sustainability requirements, and is a complex materials-design challenge. In this study, we demonstrate a fully first-principles modelling approach to calculating the properties and thermoelectric figure of merit ZT and apply it to the orthorhombic and rhombohedral phases of GeS and GeSe. While p-doped Pnma GeS and GeSe do not match the performance of the Sn analogues, due to a smaller electrical conductivity σ and larger lattice thermal conductivity κlatt, we predict a large ZTmax = 2.12 for n-doped Pnma GeSe at 900 K, which would make it a good match for p-type SnSe in a thermoelectric couple. Moreover, with n-type doping the σ is largest along the layering direction and aligns with the minimum κlatt, and a much larger ZTmax > 3 could potentially be accessible with control over the growth direction. We also predict that p-doped R3m GeS and GeSe can achieve an industrially-viable ZT > 1, through a high σ counterbalanced by a large thermal conductivity, and experiments indicate this can be further improved by alloying. Our results therefore strongly motivate further study of the under-explored Ge chalcogenides as prospective TEs, with a particular focus on strategies for n-doping the Pnma phases.

Graphical abstract: Thermoelectric properties of Pnma and R3m GeS and GeSe

Supplementary files

Article information

Article type
Paper
Submitted
17 Aug 2023
Accepted
09 Oct 2023
First published
10 Oct 2023
This article is Open Access
Creative Commons BY license

J. Mater. Chem. C, 2023,11, 14833-14847

Thermoelectric properties of Pnma and R3m GeS and GeSe

M. Zhang, J. M. Flitcroft, S. K. Guillemot and J. M. Skelton, J. Mater. Chem. C, 2023, 11, 14833 DOI: 10.1039/D3TC02938G

This article is licensed under a Creative Commons Attribution 3.0 Unported Licence. You can use material from this article in other publications without requesting further permissions from the RSC, provided that the correct acknowledgement is given.

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