Center for Applied Physics and Technology, College of Engineering, Peking University, Beijing 100871, China.
Nanoscale. 2015 Oct 14;7(38):15962-70. doi: 10.1039/c5nr03813h. Epub 2015 Sep 14.
Motivated by the recent study of inspiring thermoelectric properties in bulk SnSe [Zhao et al., Nature, 2014, 508, 373] and the experimental synthesis of SnSe sheets [Chen et al., J. Am. Chem. Soc., 2013, 135, 1213], we have carried out systematic calculations for a single-layered SnSe sheet focusing on its stability, electronic structure and thermoelectric properties by using density functional theory combined with Boltzmann transport theory. We have found that the sheet is dynamically and thermally stable with a band gap of 1.28 eV, and the figure of merit (ZT) reaches 3.27 (2.76) along the armchair (zigzag) direction with optimal n-type carrier concentration, which is enhanced nearly 7 times compared to its bulk counterpart at 700 K due to quantum confinement effect. Furthermore, we designed four types of thermoelectric couples by assembling single-layered SnSe sheets with different transport directions and doping types, and found that their efficiencies are all above 13%, which are higher than those of thermoelectric couples made of commercial bulk Bi2Te3 (7%-8%), suggesting the great potential of single-layered SnSe sheets for heat-electricity conversion.
受近期研究的启发，我们对块状 SnSe 的热电性能进行了研究[Zhao 等人，《自然》，2014 年，508，373]，并对 SnSe 薄片进行了实验合成[Chen 等人，《美国化学会志》，2013 年，135，1213]。我们使用密度泛函理论结合玻尔兹曼输运理论，对单层 SnSe 薄片的稳定性、电子结构和热电性能进行了系统的计算。我们发现，该薄片在动力学和热学上都是稳定的，带隙为 1.28eV，在最佳 n 型载流子浓度下，沿扶手椅（锯齿）方向的品质因数（ZT）达到 3.27（2.76），与 700K 时的体相比，由于量子限制效应，其值提高了近 7 倍。此外，我们通过组装具有不同输运方向和掺杂类型的单层 SnSe 薄片设计了四种类型的热电对，发现它们的效率均高于 13%，高于商用 Bi2Te3 热电对（7%-8%），表明单层 SnSe 薄片在热电转换方面具有巨大的潜力。
