Department of Chemistry, Northwestern University, Evanston, Illinois 60208, USA.
J Am Chem Soc. 2011 Oct 19;133(41):16588-97. doi: 10.1021/ja206380h. Epub 2011 Sep 25.
Thermoelectric heat-to-power generation is an attractive option for robust and environmentally friendly renewable energy production. Historically, the performance of thermoelectric materials has been limited by low efficiencies, related to the thermoelectric figure-of-merit ZT. Nanostructuring thermoelectric materials have shown to enhance ZT primarily via increasing phonon scattering, beneficially reducing lattice thermal conductivity. Conversely, density-of-states (DOS) engineering has also enhanced electronic transport properties. However, successfully joining the two approaches has proved elusive. Herein, we report a thermoelectric materials system whereby we can control both nanostructure formations to effectively reduce thermal conductivity, while concurrently modifying the electronic structure to significantly enhance thermoelectric power factor. We report that the thermoelectric system PbTe-PbS 12% doped with 2% Na produces shape-controlled cubic PbS nanostructures, which help reduce lattice thermal conductivity, while altering the solubility of PbS within the PbTe matrix beneficially modifies the DOS that allow for enhancements in thermoelectric power factor. These concomitant and synergistic effects result in a maximum ZT for 2% Na-doped PbTe-PbS 12% of 1.8 at 800 K.
热电热能到电能的转换是一种有吸引力的选择，可用于稳健且环保的可再生能源生产。从历史上看，热电材料的性能受到低效率的限制，这与热电优值 ZT 有关。研究表明，纳米结构热电材料主要通过增加声子散射来提高 ZT，从而有益地降低晶格热导率。相反，态密度（DOS）工程也增强了电子输运性能。然而，成功地结合这两种方法一直难以实现。在此，我们报告了一种热电材料体系，通过控制纳米结构的形成来有效降低热导率，同时同时修改电子结构以显著提高热电功率因子。我们报告说，PbTe-PbS 12%掺杂 2%Na 的热电系统会产生形状可控的立方 PbS 纳米结构，这有助于降低晶格热导率，而改变 PbS 在 PbTe 基体中的溶解度则会有益地改变 DOS，从而提高热电功率因子。这些伴随和协同的效果使 2%Na 掺杂的 PbTe-PbS 12%在 800K 时的最大 ZT 达到 1.8。
