Materials Research Lecture

Current thermoelectric technology is based on materials developed some 60 years ago, primarily Bi₂Te₃-based structures for cooling applications and PbTe and Si-Ge alloys for power generation. While being the backbone of extremely reliable devices, the conversion efficiency of these materials is typically no better than 4-5% and this limits their industrial applications. To achieve a greater penetration of the market, novel more efficient thermoelectric materials must be developed. During the past dozen years or so, major efforts worldwide focused on identifying and synthesizing new and more efficient thermoelectric materials intended especially for mid-temperature operations as power generating modules that convert waste industrial heat into electricity. Several promising families of thermoelectric materials have been identified and one of the most prospective are solid solutions based on Mg₂Si_1-xSn_x. Apart from having good conversion efficiency, especially in their n-type forms, the structure consists of readily available and inexpensive chemicals which are also environmentally friendly. I will review the progress made in the past few years and also point out needs and opportunities to enhance the thermoelectric performance of this class of materials further. I will also describe and discuss the advantages and benefits of a recently developed novel synthesis process of compound thermoelectric semiconductors based on controlling highly exothermic chemical reactions.