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Issue 48, 2018
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High thermoelectric performance in complex phosphides enabled by stereochemically active lone pair electrons

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Abstract

We propose a new strategy to design high performance thermoelectric materials with stereochemically active lone pair electrons. This novel concept is experimentally demonstrated in the cluster compounds Ag6Ge10(1−x)Ga10xP12 with x = 0.0, 0.01, 0.03, 0.04. A maximum power factor of 13 μW cm−1 K−2 is achieved after optimizing carrier concentration. Density functional theory calculations reveal that the stereochemically active lone pair electrons from s orbitals of Ge give rise to a peak in the density of states near the valence band maximum, a feature that is beneficial for achieving a high power factor. Experimental results also confirm the theoretically predicted relatively low thermal conductivity of about 1 W m−1 K−1 arising from the rattling vibrations associated with Ag6 clusters, which create low-frequency localized optical phonons in the acoustic region and thus enable strong anharmonic phonon scattering. The highest zT value attained here is 0.65 at 723 K for the x = 0.03 sample, a record high value for polycrystalline phosphide and still with significant potential for optimization.

Graphical abstract: High thermoelectric performance in complex phosphides enabled by stereochemically active lone pair electrons

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Publication details

The article was received on 31 Aug 2018, accepted on 21 Nov 2018 and first published on 22 Nov 2018


Article type: Paper
DOI: 10.1039/C8TA08448C
Citation: J. Mater. Chem. A, 2018,6, 24877-24884
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    High thermoelectric performance in complex phosphides enabled by stereochemically active lone pair electrons

    X. Shen, Y. Xia, G. Wang, F. Zhou, V. Ozolins, X. Lu, G. Wang and X. Zhou, J. Mater. Chem. A, 2018, 6, 24877
    DOI: 10.1039/C8TA08448C

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