Issue 15, 2023

High thermoelectric and mechanical performance achieved by a hyperconverged electronic structure and low lattice thermal conductivity in GeTe through CuInTe2 alloying

Abstract

GeTe-based thermoelectric materials have a very high hole carrier concentration (∼1021 cm−3), and thus, improving the figure of merit, ZT, is substantially challenging. In this work, we foremost dope Bi to lower the majority carrier concentration, followed by alloying CuInTe2 to further adjust the hole concentration to an optimal level (0.5–2.0 × 1020 cm−3). This strategy also improves the structural symmetry and leads to hyperconverged valence sub-bands and resonance levels, increasing the effective mass from 1.42 m0 to 1.95 m0. Consequently, a high power factor of ∼23 μW cm−1 K−2 at room temperature and ∼41 μW cm−1 K−2 at 623 K in the (Ge0.93Bi0.05Te0.98)(CuInTe2)0.01 sample is reported. Moreover, the introduced point defects and nano-deposits reduce the lattice thermal conductivity to amorphous levels. As a result, the (Ge0.93Bi0.05Te0.98)(CuInTe2)0.01 sample has a peak ZT value of ∼2.16 at 623 K and an average ZT value of ∼1.42 at 300–773 K. A record high hardness value (∼277 Hv) is achieved. Simultaneous Bi doping and CuInTe2 alloying appear to be an effective strategy for increasing the ZT values of GeTe-based compounds.

Graphical abstract: High thermoelectric and mechanical performance achieved by a hyperconverged electronic structure and low lattice thermal conductivity in GeTe through CuInTe2 alloying

Supplementary files

Article information

Article type
Paper
Submitted
29 Nov 2022
Accepted
20 Feb 2023
First published
21 Feb 2023

J. Mater. Chem. A, 2023,11, 8119-8130

High thermoelectric and mechanical performance achieved by a hyperconverged electronic structure and low lattice thermal conductivity in GeTe through CuInTe2 alloying

H. Kim, S. K. Kihoi, U. S. Shenoy, J. N. Kahiu, D. H. Shin, D. K. Bhat and H. S. Lee, J. Mater. Chem. A, 2023, 11, 8119 DOI: 10.1039/D2TA09280H

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