Bi2Se3、Bi2Te3和Sb2Te3纳米膜的电声输运机制及热电性能的调控研究

Thermoelectric materials provide a safe, reliable, environmentally friendly and all solid state power generation and refrigeration, which plays a more and more important role in alleviating energy crisis, environmental pollution and climatic change. Two-dimensional layered nanostructures have become the frontier and hot spot in the field of thermoelectric materials in recent years due to their enhanced thermoelectric properties. But in order to further optimize and improve the thermoelectric properties of two-dimensional layered nanostructures, it is necessary to make a further study on their electron and phonon transport mechanism. Based on our previous studies, this research plan proposes to investigate the electron/phonon transport properties of Bi2Se3, Bi2Te3 and Sb2Te3 nanofilms by combining density functional theory and the Boltzmann transport equation. On the basis of the calculation of electron and phonon structure and relaxation time, the mechanism of the enhancement of the thermoelectric properties is discussed. Through the study of the influence of intrinsic parameters of nanofilms (the film thickness and carrier concentration) and external parameters (the strain and electric field) on the electron/phonon transport properties of Bi2Se3, Bi2Te3 and Sb2Te3 nanofilms, we will explore the regulation of the thermoelectric properties of nanofilms. These studies will deepen our understanding of the thermoelectric transport properties of Bi2Se3, Bi2Te3 and Sb2Te3 nanofilms and provide a theoretical reference for the preparation of high-performance nanostructured thermoelectric materials.

热电材料提供了一种安全可靠、环保和全固态的发电和制冷方式，在解决能源危机、环境污染和气候变化上正扮演越来越重要的角色。二维的层状纳米结构因其具有增强的热电优值而成为近年来热电材料领域研究的前沿和热点，但为了进一步优化并提高其热电性能，需要对其电声输运机制进行更加深入的研究。本项目在前期研究的基础上，提出采用密度泛函理论和玻尔兹曼方程相结合的方法来研究Bi2Se3、Bi2Te3和Sb2Te3纳米膜的电声输运性质，并在对电子和声子结构及驰豫时间进行计算的基础上深入探讨纳米膜的热电优值增强的机制；我们将通过研究纳米膜的内禀参数（如膜厚和载流子浓度）和外部参数（应变和电场）对纳米膜的电声输运性质的影响来探索调控纳米膜热电输运性质的规律。这些研究将加深我们对Bi2Se3、Bi2Te3和Sb2Te3纳米膜热电输运性质的理解，并为制备高性能的纳米热电材料提供理论参考。

热电材料提供了一种安全可靠、环保和全固态的发电和制冷方式，在解决能源危机、环境污染和气候变化上正扮演越来越重要的角色。本项目在前期研究的基础上，采用密度泛函理论和玻尔兹曼方程相结合的方法研究了应变和外电场对Bi2Se3、Bi2Te3和Sb2Te3纳米膜热电性能的调控作用。我们发现应变能够明显改变纳米膜的电子结构，当对纳米膜施加拉伸应变时，随着应变的增加，价带变得更加平坦，带隙变小，而当施加压缩应变时，价带变得更加陡峻，带隙变大。应变对纳米膜导带的影响正好与价带相反。拉伸应变使P型纳米膜的塞贝克增大，这主要是由于拉伸应变增强了纳米膜价带边的态密度。拉伸应变减小纳米膜的声子热导率，而压缩应变增加纳米膜的声子热导率。合适的拉伸应变能增强P型纳米膜的热电性能。外电场对单层纳米膜的影响较小，这主要是由于单层纳米膜对外电场有很强的屏蔽效应。随着膜层的增加，纳米膜对外电场变得越来越敏感。膜层越厚，外电场对纳米膜的调控效果就越明显，这与实验结果是一致的。这些研究能加深我们对纳米膜热电输运性质的理解，并为制备高性能的纳米热电材料提供理论参考。