Eco-Friendly SnTe Thermoelectric Materials

Most of the energy that we produce is lost in form of heat due to many indirect processes involved. Thermoelectric material has drawn much attention for centuries, because of the thermoelectric effect which enables direct conversion between thermal and electrical energy. This effect can be used for power generation and refrigeration. However, thermoelectric conversion efficiency is low and mainly limited by the performance of thermoelectric materials. Thermoelectric material, tin telluride (SnTe), is found to be more important because of its low toxicity and environmentally friendly nature.

Professor Zhi-Gang Chen from the University of Southern Queensland in Australia, along with Professor Jin Zou, Dr. Lei Yang and PhD student Raza Moshwan from The University of Queensland, enhanced the performance of SnTe to improve thermoelectric conversion efficiency, which has provided an alternative to toxic PbTe. They highlighted the key strategies to enhance the thermoelectric performance of SnTe materials was through band engineering, carrier concentration optimization, synergistic engineering, and structure design. This research has now been published in the journal, Advanced Functional Materials.

The thermoelectric conversion efficiency is governed by ZT value, which is directly proportional to S²σ and inversely proportional to k. The efficiency can be improved by increasing the electrical conductivity (σ) and Seebeck coefficient (S) while reducing thermal conductivity (k).

The authors found that the ZT value had increased as high as 1.6 through effective structure and band engineering, which was a significant enhancement and competitive with most other thermoelectric materials. They also demonstrated that the S value could be enhanced by increasing the equivalent degenerated valleys of the band structures.

Significant improvements in the thermoelectric material efficiency have been achieved at ZT > 1. However, there is still room to improve the performance to obtain ZT > 2 to implement the usage of SnTe in industry. This study by Australian scientists will enable the development of new methods of power generation and refrigeration on a large scale, thus providing a solution for pollution and the global energy crises.