The group led by Prof. Peng Jiang and Prof. Xinhe Bao from Dalian Institute of Chemical Physics (DICP), Chinese Academy of Sciences (CAS) made an important progress on developing novel thermoelectric materials. The thermoelectric performance of GeSe was enhanced greatly by entropy stabilization of high-symmetry alloys. This work has recently been published in Angew. Chem. Int. Ed. (Angew. Chem. Int. Ed. DOI: 10.1002/anie.201708134)
Thermoelectric technology can realize the direct conversion between heat and electricity, which holds great potential as clean and sustainable energy conversion technology. Although Bi2Te3 and PbTe based thermoelectric materials exhibit high zT, new thermoelectric materials with earth abundant and less toxic elements are required for large-scale applications. Orthorhombic GeSe, a potential environment-friendly thermoelectric material, has been predicted to have good thermoelectric performance theoretically. However, due to the lack of an appropriate method to tune the carrier concentration of GeSe, the maximum zT value of GeSe has only reached 0.2 experimentally.
Herein, by alloying GeSe with AgSbSe2, a new rhombohedral phase is stabilized at room temperature, an example of entropy stabilization of a high symmetry alloy. The thermoelectric properties of GeSe were improved greatly due to the dramatic increase in carrier concentration and effective mass. The zT of GeAg0.2Sb0.2Se1.4 reaches 0.86 at 710 K, which is 18 times higher than that of pristine GeSe and over four times higher than doped orthorhombic GeSe. These results open a new avenue towards developing novel thermoelectric materials through crystal phase engineering by high-entropy alloying strategy.
The theoretical calculations were carried out by Prof. G. Jeffery Snyder from Northwestern University, USA and Prof. Wei Zhuang from Fujian Institute of Research on the Structure of Matter, CAS. The TEM characterization was performed with the assistance of Prof. Binghui Ge from Institute of Physics, CAS. This work was financially supported by Natural Science Foundation of China and DICP. (Text and image by Zhiwei Huang)