- Innovations could improve the conversion of waste heat to energy.
By substituting some of the indium in CuInSe2 with manganese the thermoelectric properties of CuInSe2 have been improved by over two orders of magnitude. Thermoelectric materials work in two ways, by creating either electricity (Seebeck effect) or a temperature gradient (Peltier effect). These improved thermoelectric substances may be key in converting waste heat to energy, for example in automobile engines. Additionally, these materials may prove useful in developing new solid-state refrigerators, due to their advantages of being more compact, portable and environmentally friendly as compared to traditional liquid, ozone-depleting refrigerants. In this work, increased electrical conductivity has been observed in CuInSe2 by adding manganese, thus the thermoelectric figure of merit (ZT) of the material is increased. At the same time, the addition of manganese disrupts the normal atom locations in the material, resulting in a decrease in the thermal conductivity. This is exciting because most often the improvement in one of these properties is at the expense of the other. This work demonstrates that CuInSe2-based systems could be viable thermoelectric materials if the electrical conductivity could be even further enhanced. The improved system would be of interest to the automobile industry, for example, for the purpose of converting waste heat in the internal combustion engine to electricity.
