Addressing the Challenges in Designing of Efficient Thermoelectric Materials

Abstract

Thermoelectric materials offer applications in conversion of waste heat to useful electrical energy and are promising sources of renewable energy. To use a material efficiently in thermoelectric application it is necessary to have high figure of merit (ZT). The task of increasing ZT is challenging because of the competing relation between electrical conductivity, thermopower, and thermal conductivity. For enhancing ZT of a thermoelectric material, it is necessary to have a good understanding of its electronic structure as well as transport properties. The goal of the present work is to develop an understanding of the thermoelectric properties of selected materials and address some of the fundamental challenges for achieving enhanced performance in these materials. In this thesis, I have employed density functional theory based calculations combined with Boltzmann transport theory, to study electronic structures, and electronic and thermal transport properties of several promising class of thermoelectric materials, including the transition metal silicides (FeSi2, CrSi2), Zintl compounds, sulphide (Bi2S3), intermetallics and transition metal dichacogenides (MX2 (M = Zr, Hf and X = S, Se), and MoS2). Based on the comprehensive study of electronic and thermoelectric properties we conclude that different strategies are required to improve the ZT of different class of materials. Our findings provide a better understanding of materials properties and can be generalized to other materials as well