Tin sulfide (SnS), a low-cost compound from the IV–VI semiconductors, has attracted particular attention due to its great potential for large-scale thermoelectric applications. However, pristine SnS shows a low carrier concentration, which leads to a low thermoelectric performance. In this work, sodium is utilized to substitute Sn to increase the hole concentration and consequently improve the thermoelectric power factor. The resultant Hall carrier concentration up to ∼10¹⁹ cm^–3 is the highest concentration reported so far for this compound. This further leads to the highest thermoelectric figure of merit, zT of 0.65, reported so far in polycrystalline SnS. The temperature-dependent Hall mobility shows a transition of carrier-scattering source from a grain boundary potential below 400 K to acoustic phonons at higher temperatures. The electronic transport properties can be well understood by a single parabolic band (SPB) model, enabling a quantitative guidance for maximizing the thermoelectric power factor. Using the experimental lattice thermal conductivity, a maximal zT of 0.8 at 850 K is expected when the carrier concentration is further increased to ∼1 × 10²⁰ cm^–3, according to the SPB model. This work not only demonstrates SnS as a promising low-cost thermoelectric material but also details the material parameters that fundamentally determine the thermoelectric properties.

中文翻译：

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Na掺杂SnS的热电性质

硫化锡（SnS）是IV-VI半导体中的一种低成本化合物，由于其在大规模热电应用中的巨大潜力而​​备受关注。然而，原始的SnS显示出低的载流子浓度，这导致低的热电性能。在这项工作中，利用钠替代Sn以增加空穴浓度，从而提高热电功率因数。所产生的霍尔载流子浓度高达10 ¹⁹ cm ^–3，是该化合物迄今为止报道的最高浓度。这进一步导致了最高的热电品质因数zT到目前为止，在多晶SnS中报道的Sn为0.65。随温度变化的霍尔迁移率显示出载流子散射源从低于400 K的晶界电势转变为更高温度下的声子。单个抛物线带（SPB）模型可以很好地理解电子传输特性，从而实现定量指导以使热电功率因数最大化。使用实验晶格热导率，当载流子浓度进一步增加到约1×10 ²⁰ cm ^–3时，预期在850 K时的最大zT为0.8，根据SPB模型。这项工作不仅证明SnS是一种有前途的低成本热电材料，而且还详细介绍了从根本上决定热电性能的材料参数。