Thermoelectric Properties of Pnma and Rocksalt SnS and SnSe
Thermoelectric Properties of Pnma and Rocksalt SnS and SnSe
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DOI：
10.3390/solids3010011
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发表时间：
2022-03-01
期刊：
影响因子：
--
通讯作者：
Skelton, Jonathan M.
中科院分区：
文献类型：
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作者：
Pallikara, Ioanna;Flitcroft, Joseph M.;Skelton, Jonathan M.
热电材料将废热转化为电能，是限制全球变暖所需的一揽子技术的一部分。锡硫属化物SnS和SnSe是有前途的候选热电材料，其中正交晶系的SnSe显示出迄今为止报道的最高品质因数Z T。至于其他IV族硫属化物，SnS和SnSe可以在一定条件下形成岩盐相，但这些相的热电性能在很大程度上尚未开发。我们已经应用了一个完全从头建模协议比较的Z T的正交相和岩盐相的SnS和SnSe。从混合密度泛函理论的电子结构被用来计算的三个电输运性质，包括电子弛豫时间的近似模型，和晶格动力学计算进行建模的声子谱和晶格热导率。我们获得了对已充分研究的斜方晶相的Z T的良好估计。预测的岩盐相显示出较大的电导率和类似的塞贝克系数的正交相，导致更高的热电功率因子，但这些被抵消较大的热导率。因此，这些结果激发了对最近发现的基于扭曲岩盐超晶胞的SnS和SnSe的“π-立方”相的进一步研究，以建立它们的热电性能。
Thermoelectric materials convert waste heat to electricity and are part of the package of technologies needed to limit global warming. The tin chalcogenides SnS and SnSe are promising candidate thermoelectrics, with orthorhombic SnSe showing some of the highest figures of merit Z T reported to date. As for other Group IV chalcogenides, SnS and SnSe can form rocksalt phases under certain conditions, but the thermoelectric properties of these phases are largely unexplored. We have applied a fully ab initio modelling protocol to compare the Z T of the orthorhombic and rocksalt phases of SnS and SnSe. Electronic structures from hybrid density-functional theory were used to calculate the three electrical transport properties, including approximate models for the electron relaxation times, and lattice dynamics calculations were performed to model the phonon spectra and lattice thermal conductivities. We obtained good estimates of the Z T of the well-studied orthorhombic phases. The rocksalt phases were predicted to show larger electrical conductivities and similar Seebeck coefficients to the orthorhombic phases, resulting in higher thermoelectric power factors, but these were offset by larger thermal conductivities. These results therefore motivate further investigation of the recently discovered " pi -cubic" phases of SnS and SnSe, which are based on distorted rocksalt supercells, to establish their thermoelectric performance.