State of the Art Review on Thermoelectric Materials

Development of thermoelectric materials with high figure of merit has become the need of the hour for combating environmental problems such as global warming, climate change and for saving limited non renewable natural energy resources such as minerals and oil. The thermoelectric materials have ability to convert waste heat to electrical energy based on Seebeck and Peltier effects. Figure of merit (ZT) of a material is a performance indicator for assessing its ability to produce electricity when exposed to hot gases. Several researchers have reported thermoelectric materials exhibiting ZT greater than one. Greater the value of ZT greater is the generation of electricity. Researchers are striving to improve the value of ZT by adopting different technologies. ZT value approach to 2 or 3 is found to be difficult due to interdependence of thermo electric properties of materials which constitute the figure of merit. At present commercially available thermoelectric materials (Pb-Te, Bi-Te based etc) are toxic, denser and of high cost. Alternate materials such as Mg-based materials are cheaper but have low figure of merit, making these materials unsuitable for wide range of applications. Hence it has become inevitable to develop materials with high figure of merit. Nanotechnology aids to alter well as improve the thermoelectric properties of materials. This review focuses on state of the art on thermoelectric materials and different aspects in their design and development.