Good thermoelectric performance is being sought to face major problems related to energy, especially in the concern of the usage of energy on environmental impact. In this work, we investigate the underlying mechanism to enhance the thermoelectric performance of bismuth selenide (Bi₂Se₃) by employing density functional theory (DFT) followed by the Boltzmann transport equation under relaxation time approximation. The structural, electronic, and thermoelectric properties were calculated and analyzed. From the analysis of combined results of thermoelectric properties and electronic properties as the function of the Fermi level, we found that the power factor of Bi₂Se₃ is improved by increasing electrical conductivity that contributed by the large density of states and light effective mass of charge carriers. The figure of merit, on the other hand, is enhanced by increasing Seebeck coefficient that contributed by heavy effective mass and decreasing thermal conductivity that contributed by low density of states. We also found that both power factor and figure of merit can be improved through n-type doping at 300 K and p-type doping at higher temperature (400 K and 500 K).

中文翻译：

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基于密度泛函理论的Bi 2 Se 3热电性能增强机理

人们正在寻求良好的热电性能来面对与能源有关的主要问题，尤其是在能源使用对环境的影响方面。在这项工作中，我们通过采用弛豫时间近似下的密度泛函理论（DFT）和玻尔兹曼输运方程，研究了提高硒化铋（Bi ₂ Se ₃）热电性能的潜在机理。计算，分析了结构，电子和热电性能。通过分析热电性能和电子性能作为费米能级的函数的综合结果，我们发现Bi ₂ Se ₃的功率因数通过增加电导率可以改善这种导电性，这是由于态密度大和载流子的轻有效质量所致。另一方面，通过增加有效质量增加的塞贝克系数和降低态密度导致的热导率来提高品质因数。我们还发现，功率因数和品质因数都可以通过在300 K下进行n型掺杂和在较高温度下（400 K和500 K）进行p型掺杂来改善。