Theory-Guided Synthesis of an Eco-Friendly and Low-Cost Copper Based Sulfide Thermoelectric Material

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• 作者：Kan Chen ; Baoli Du ; Nicola Bonini ; Cedric Weber ; Haixue Yan ; Mike J. Reece
• 刊名：Journal of Physical Chemistry C
• 出版年：2016
• 出版时间：December 8, 2016
• 年：2016
• 卷：120
• 期：48
• 页码：27135-27140
• 全文大小：457K
• ISSN：1932-7455

文摘

Cu₃SbS₄ is a copper-based sulfide composed of earth-abundant elements. We present a combined theoretical and experimental study of the thermoelectric properties of Ge-doped Cu₃SbS₄. On the basis of density functional theory, we found that the pristine compound is a semiconductor with a large density-of-state effective mass of ∼2.2 m_e for holes. Ge was predicted to be an effective p-type dopant that only slightly shifts the band structure of Cu₃SbS₄. The power factor was predicted to reach a maximum value with 10–15 mol % Ge-doping on the Sb site (n = (6–9) × 10²⁰ cm^–3) at high temperature (up to 700 K). Theory was used to guide the synthesis of optimally doped Cu₃SbS₄ bulk samples. Experimentally, Cu₃SbS₄ bulk samples were prepared by mechanical alloying and spark plasma sintering. The samples had very fine microstructures, with a grain size of ∼100–300 nm, which contributed to a much lower lattice thermal conductivity than reported in the literature. A maximum power factor of ∼1.08 mW K^–2 m^–1 was achieved with an optimized carrier concentration of ∼4.79 × 10²⁰ cm^–3, which is in good agreement with theoretical prediction, and a zT of ∼0.63 was obtained at 623 K.