Executive Summary : | Thermoelectric (TE) technology provides a simple and environmentally responsible way to recover waste heat by converting it to electricity directly and reversibly. Heavy metal-based chalcogenides having a narrow bandgap are ideal for thermoelectric application. PbTe, GeTe, Bi2Te3 are the current state-of-the-art TE materials. Among them, PbTe is the most explored and promising material for practical device applications. However, its usage is limited due to the toxicity of Pb. As a result, much effort has gone into designing TE materials with ultrahigh conversion efficiency over a wide temperature range, while using earth-abundant, environmentally safe, and inexpensive components. GeTe recently emerged as ideal replacement of PbTe. GeTe based TE materials have been promising materials due to their excellent structural, electrical, and thermal properties. However, due to the low Seebeck coefficient (34 μV/K at 300 K) and high thermal conductivity (~ 8 Wm-1K-1 at 300 K) originated from high hole concentration (~10^21 cm-3) leads to maximum zT is 0.8 at 720 K. Recently different strategies are implemented to enhanced the TE performance of the GeTe via electronic structure modulation to improve the power factor as well as the reduction of the lattice thermal conductivity via nanostructuring, point defects, lattice anharmonicity and so on. To explore TE materials in everyday life, we must fabricate TE devices. Thus, investigating GeTe based TE materials for device applications will be a great opportunity and promising in the field of TE research. In this project, a systematic study will be conducted on the GeTe based TE materials to explore the possibility to enhance TE performance, through electronic band structure, microstructure, and phonon transport engineering. |