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Issue 44, 2017
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Cobalt-doping in Cu2SnS3: enhanced thermoelectric performance by synergy of phase transition and band structure modification

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Abstract

Mohite-type ternary sulfide Cu2SnS3, which has been intensively studied in the photovoltaic field, has recently attracted much attention as an outstanding p-type eco-friendly thermoelectric material. In the present work, significant synergistic effects of d-orbital-unfilled transition metal (Co) doping on the crystal structure and electrical/thermal properties of Cu2SnS3 are reported. Crystal structure evolution with Co doping, involving not only monoclinic to cubic and tetragonal transitions but also the formation of a hierarchical architecture (Cu–S nano-precipitates, metal and S vacancies, and even nano-scaled stacking faults), is related to bond softening and intensified phonon scattering. Thus, an ultralow lattice thermal conductivity of 0.90 W m−1 K−1 at 323 K to 0.33 W m−1 K−1 at 723 K was obtained. Moreover, an increased effective mass is derived from the contribution of the Co 3d states to the inherent Cu 3d and S 3p states in the valence band, leading to a remarkable power factor (0.94 mW m−1 K−2, x = 0.20 at 723 K) with optimal doping. As a result, the high ZT of ∼0.85 at 723 K elevates the modified Cu2SnS3 to the level of state-of-the-art mid-temperature eco-friendly sulfide thermoelectric materials.

Graphical abstract: Cobalt-doping in Cu2SnS3: enhanced thermoelectric performance by synergy of phase transition and band structure modification

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Publication details

The article was received on 13 Aug 2017, accepted on 25 Sep 2017 and first published on 25 Sep 2017


Article type: Paper
DOI: 10.1039/C7TA07140J
Citation: J. Mater. Chem. A, 2017,5, 23267-23275
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    Cobalt-doping in Cu2SnS3: enhanced thermoelectric performance by synergy of phase transition and band structure modification

    H. Zhao, X. Xu, C. Li, R. Tian, R. Zhang, R. Huang, Y. Lyu, D. Li, X. Hu, L. Pan and Y. Wang, J. Mater. Chem. A, 2017, 5, 23267
    DOI: 10.1039/C7TA07140J

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