Thermoelectric device is a promising next-generation energy solution owing to its capability to transform waste heat into useful electric energy, which can be realized in materials with high electric conductivities and low thermal conductivities. A recently synthesized silicon allotrope of Si₂₄ features highly anisotropic crystal structure with nanometer-sized regular pores. Here, based on first-principles study without any empirical parameter we show that the slightly doped Si₂₄ can provide an order-of-magnitude enhanced thermoelectric figure of merit at room temperature, compared with the cubic diamond phase of silicon. We ascribe the enhancement to the intrinsic nanostructure formed by the nanopore array, which effectively hinders heat conduction while electric conductivity is maintained. This can be a viable option to enhance the thermoelectric figure of merit without further forming an extrinsic nanostructure. In addition, we propose a practical strategy to further diminish the thermal conductivity without affecting electric conductivity by confining rattling guest atoms in the pores.

中文翻译：

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具有本征纳米级多孔结构的新型硅晶体Si _24中增强的热电性能

热电装置具有将废热转化为有用电能的能力，因此是有前途的下一代能源解决方案，可以在具有高电导率和低热导率的材料中实现。最近合成的Si ₂₄硅同素异形体具有高度各向异性的晶体结构，具有纳米尺寸的规则孔。在此，基于没有任何经验参数的第一性原理研究，我们表明轻度掺杂的Si ₂₄与硅的立方金刚石相相比，在室温下可提供数量级增强的热电品质因数。我们归因于由纳米孔阵列形成的固有纳米结构的增强，其在保持导电性的同时有效地阻碍了热传导。这可以是在不进一步形成外在纳米结构的情况下增强热电品质因数的可行选择。另外，我们提出了一种实用的策略，以通过限制孔中的嘎嘎声来宾原子来进一步减小热导率而不影响电导率。