使用第一性原理计算优化 SnSe2 的热电性质,The Journal of Physical Chemistry C

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使用第一性原理计算优化 SnSe2 的热电性质
The Journal of Physical Chemistry C ( IF 3.3 ) Pub Date : 2023-03-31 , DOI: 10.1021/acs.jpcc.2c09137
Sree Sourav Das ₁ , Md. Golam Rosul ₂ , Mona Zebarjadi _{1,

3}

Affiliation

我们提出了一个第一性原理框架来研究 SnSe _{2的电子特性}，一种潜在的良好层状热电材料。我们使用密度泛函理论和玻尔兹曼输运方程在弛豫时间近似下的解，包括电子-声子和电离杂质相互作用来计算热电功率因数，其中使用 PERTUBO 包计算电子-声子散射，改进的 Brooks-Herring 方法是用于模拟电离杂质散射。我们研究了在包含和不包含范德瓦尔斯相互作用的情况下不同载流子浓度下的温度依赖性传输特性。包含范德瓦尔斯相互作用会增加电子-声子散射，但总弛豫时间主要由高浓度水平的电离杂质散射决定。₂作为温度和载流子浓度的函数。优化的功率因数乘以温度发生在载流子浓度为 4 × 10 ¹⁹^cm –3^时，^并在面内方向的 523 K 和 0.185 W m –1 K – 处达到最大值 0.49 W m ^–1 K ^{–1 1}在横向方向上 700 K。最后，使用 Callaway 的模型评估晶格热导率。我们的优化模型显示 950 K 时的最高ZT值为 1.1，这源于 SnSe ₂层的超低热导率。

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Optimization of the Thermoelectric Properties of SnSe2 Using First-Principles Calculations

We present a first-principles framework to study the electronic properties of SnSe₂, a potentially good layered thermoelectric material. We use density functional theory and solutions of the Boltzmann transport equation under relaxation time approximation including electron–phonon and ionized impurity interactions to calculate the thermoelectric power factor where electron–phonon scattering is computed using the PERTUBO package, and the modified Brooks-Herring approach is used to model the ionized impurity scattering. We study the temperature-dependent transport properties at different carrier concentrations with and without the inclusion of van der Waals interactions. The inclusion of van der Waals interactions increases the electron–phonon scattering, but the total relaxation time is mostly dominated by ionized impurity scattering at high concentration levels. We first validate our theory by comparing the results to available experimental data and then optimize the thermoelectric performance of SnSe₂ as a function of temperature and carrier concentration. The optimized power factor times temperature happens at a carrier concentration of 4 × 10¹⁹ cm^–3 and reaches the maximum value of 0.49 W m^–1 K^–1 at 523 K in the in-plane direction and 0.185 W m^–1 K^–1 at 700 K in the cross-plane direction. Finally, the lattice thermal conductivity is evaluated using Callaway’s model. Our optimized model shows the highest ZT value of 1.1 at 950 K originating in the ultralow thermal conductivity across the SnSe₂ layers.

更新日期：2023-03-31

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