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Issue 36, 2017
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Performance optimization and single parabolic band behavior of thermoelectric MnTe

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Abstract

Semiconducting MnTe has long been considered a potential thermoelectric material for p-type conduction. However, its low carrier concentration limits its peak thermoelectric performance, zT, which is only ∼0.6. In this study, Na and Ag are found to enable a significant increase in hole concentration from ∼1019 cm−3 in pristine MnTe to ∼1021 cm−3 in the doped samples, leading to an effective enhancement in power factor in the entire temperature range investigated. Moreover, doping simultaneously introduces additional phonon scattering by point defects and secondary phases, leading to a reduction in lattice thermal conductivity, as low as ∼0.6 W m−1 K−1, approaching the amorphous limit. The synergic effects of carrier concentration optimization and lattice thermal conductivity reduction realize a peak zT as high as 1.0, which is one of the highest reported thus far for this thermoelectric material. The broad carrier concentration achieved in this study enables a reasonable assessment of the electronic transport properties of MnTe, which reveals effective single parabolic band behavior with dominant carrier scattering by acoustic phonons. It is further expected, according to the model, that a peak zT up to 1.1 could be achieved once the lattice thermal conductivity is further reduced. Moreover, the valence band structure strongly suggests the probability of a well-improved zT through a further band engineering approach due to the existence of low-lying bands with large valley degeneracies. This study not only demonstrates that MnTe is a promising thermoelectric material, but also provides guidance for its further optimization.

Graphical abstract: Performance optimization and single parabolic band behavior of thermoelectric MnTe

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Publication details

The article was received on 04 Jun 2017, accepted on 13 Aug 2017 and first published on 14 Aug 2017


Article type: Paper
DOI: 10.1039/C7TA04842D
Citation: J. Mater. Chem. A, 2017,5, 19143-19150
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    Performance optimization and single parabolic band behavior of thermoelectric MnTe

    Y. Xu, W. Li, C. Wang, J. Li, Z. Chen, S. Lin, Y. Chen and Y. Pei, J. Mater. Chem. A, 2017, 5, 19143
    DOI: 10.1039/C7TA04842D

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