Zhang Tian, Chang Jing, Su Wei, Zhou Xiao-Lin, Jia Xiao
School of Physics and Electronic Engineering, Sichuan Normal University, Chengdu 610066, People's Republic of China.
Nanotechnology. 2020 Nov 27;31(48):485704. doi: 10.1088/1361-6528/abafd8.
Motivated by interesting physical and chemical properties created by doping and topological quantum state, we perform the density functional theory and the Boltzmann transport equation to systematically investigate the geometric structures, stabilities, electronic structures, thermal conductivities and thermoelectric properties for Sb and its oxidations (SbO and SbO). The predicted lattice thermal conductivity (k ) of Sb is 11.6 nW K at 300 K, but it would fall drastically when introducing O atoms. This is mainly attributed to the strong anharmonic interactions by adding O atoms, and few contributions are from the decreasing phonon group velocities caused by the compressed phonon spectrum. SbO has been proven as a topological insulator with a relatively large topological band gap (E ) ∼ 0.156 eV, and meanwhile its carrier mobilities (345.78 cm/Vs for electrons) and scattering time (44.27 × 10 s for electrons) are also rather high among all 2D materials, exhibiting the excellent thermoelectric performance. The calculated maximum thermoelectric figure of merit ([Formula: see text]) of the three Sb films for optimum n-type doping are close to each other at 300 K, but with an increasing temperature, the [Formula: see text] of Sb for optimum n-type doping climbs quickly and can reach up to 0.73 at 700 K, which is far higher than others. More interestingly, the [Formula: see text] of SbO can be increased sharply at 300 K after considering spin-orbit coupling (SOC): 0.50 for optimum p-type doping and 0.41 for optimum n-type doping. However, only the tiny changes in the [Formula: see text] of Sb can be found before and after considering SOC. Our research reveals how the doping and the topological quantum state affect thermoelectric performances, providing reference to design and search high [Formula: see text] thermoelectric materials in future.
受掺杂和拓扑量子态所产生的有趣物理和化学性质的驱动，我们运用密度泛函理论和玻尔兹曼输运方程，系统地研究了锑及其氧化物（SbO和SbO）的几何结构、稳定性、电子结构、热导率和热电性能。预测的锑在300 K时的晶格热导率（k ）为11.6 nW K，但引入氧原子后会急剧下降。这主要归因于添加氧原子导致的强非谐相互作用，而声子群速度因声子谱压缩而降低所起的作用较小。SbO已被证明是一种具有相对较大拓扑带隙（E ）约为0.156 eV的拓扑绝缘体，同时其载流子迁移率（电子为345.78 cm²/Vs）和散射时间（电子为44.27×10⁻¹² s）在所有二维材料中也相当高，展现出优异的热电性能。计算得出的三种锑薄膜在最佳n型掺杂下的最大热电优值（[公式：见原文]）在300 K时彼此接近，但随着温度升高，最佳n型掺杂的锑的[公式：见原文]迅速攀升，在700 K时可达0.73，远高于其他材料。更有趣的是，考虑自旋轨道耦合（SOC）后，SbO在300 K时的[公式：见原文]可大幅提高：最佳p型掺杂时为0.50，最佳n型掺杂时为0.41。然而，考虑SOC前后，锑的[公式：见原文]仅发现微小变化。我们的研究揭示了掺杂和拓扑量子态如何影响热电性能，为未来设计和寻找高[公式：见原文]热电材料提供了参考。
