Abstract To investigate the thermoelectric properties, we have attempted to tune selenium content in Cu2SnSe3-δ (−0.04 ≤ δ ≤ 0.1) compounds synthesized via the conventional solid-state reaction. Electrical and thermal properties are presented in the low and near room temperature regime (10–350 K). The lowest electrical resistivity is observed for the compound with δ = 0.08. The electron-phonon coupling and the presence of small polarons are experimentally validated from temperature-dependent electrical and thermal transport data. A decrease in the Seebeck coefficient along with carrier concentration is observed, verifying the linear electron band dispersion. A downward shift of the Fermi level deep into the valence band is realized in the case of non-stoichiometric samples, thereby reducing the Seebeck coefficient. A maximum power factor of ~50 μWmK−2 is achieved for the sample with δ = 0.04, which is about twice that of the pristine compound. The highest ZT of ~0.01 is obtained for the compound with δ = 0.08. The observed results suggest that stoichiometry plays a vital role in tuning the thermoelectric properties in the Cu2SnSe3 compound.

中文翻译：

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通过调节 Cu2SnSe3 化合物中的硒含量来增强热电性能

摘要 为了研究热电特性，我们尝试调整通过常规固态反应合成的 Cu2SnSe3-δ (-0.04 ≤ δ ≤ 0.1) 化合物中的硒含量。电学和热学特性在低温和接近室温状态 (10–350 K) 下呈现。对于δ = 0.08 的化合物，观察到最低电阻率。电子-声子耦合和小极化子的存在通过与温度相关的电和热传输数据进行了实验验证。观察到塞贝克系数随载流子浓度的降低，证实了线性电子带色散。在非化学计量样品的情况下，费米能级向下移动到价带深处，从而降低了塞贝克系数。对于 δ = 0.04 的样品，实现了 ~50 μWmK-2 的最大功率因数，大约是原始化合物的两倍。δ = 0.08 的化合物的最高 ZT 为 ~0.01。观察到的结果表明，化学计量在调节 Cu2SnSe3 化合物的热电性能方面起着至关重要的作用。