$zT$-factor enhancement in SnSe: predictions from first principles calculations
$zT$-factor enhancement in SnSe: predictions from first principles calculations
复制标题
DOI：
--
复制
发表时间：
2016-12
期刊：
影响因子：
--
通讯作者：
Robert L. Gonz'alez-Romero;A. Antonelli;J. Mel'endez
中科院分区：
文献类型：
--
作者：
Robert L. Gonz'alez-Romero;A. Antonelli;J. Mel'endez
用第一性原理方法研究了SnSe的电子结构和热电性质。范德华色散修正的加入提高了结构参数与实验的一致性。能带结构和态的投影密度证明了该体系表现出的宏观各向异性。采用了一种新颖的方法来估计电导和热导的化学势和松弛时间。根据该方法，对单晶和多晶的塞贝克系数和导热系数进行了描述，结果与实验数据吻合良好。至于电导率，用温度相关的弛豫时间计算的值与现有的测量值比较好，特别是对单晶，多晶用恒定的弛豫时间更好地描述。最后，计算了SnSe单晶和多晶的优值。我们发现，在某些“理想”载流子浓度下，它表现出最大值，并且可以通过使用高于实验浓度的载流子浓度来显著增强。根据这些发现，提出了在实践中提高绩效的可能策略。
The electronic structure and thermoelectric properties of SnSe are studied by first-principles methods. The inclusion of van der Waals dispersive corrections improves the agreement of structural parameters with experiments. The bands structure and projected density of states justify the macroscopic anisotropy exhibited by this system. An original methodology is used to estimate the chemical potential and the relaxation time for the electrical and thermal conductivities. Following this methodology, the Seebeck coefficient and thermal conductivity for single crystals and polycrystals are described in good agreement with experimental data. As for the electrical conductivity, values calculated with a temperature-dependent relaxation time compare well with available measurements, especially for single crystals, polycrystals are better described by a constant relaxation time. Finally, the figure of merit of SnSe single crystals and polycrystals is calculated. It is found to exhibit a maximum for some "ideal" carrier concentration, and might be noticeably enhanced by using carrier concentrations higher than the experimental ones. From these findings, possible strategies to increase the figure of merit in practise are suggested.