Density-functional theory study of point defects in Bi2Te3

A scientific challenge in developing thermoelectric materials is to achieve a delicate balance between the thermal and electrical properties of the material. Point defects influence directly the concentration and mobility of both electrical charge carriers (electrons or holes) and thermal energy carriers (phonons). Controlling and varying the type and concentration of point defects provides therefore an important means for improving the thermoelectric properties. Indeed, numerous experimental studies have focused in the past on exploring the properties and nature of point defects. Particularly well suited for studying point defects are computational approaches such as density functional theory (DFT), which can provide direct insight into the electronic and structural properties of the material at the atomic scale. In particular, DFT is well suited to study thermodynamic stability of point defects. In this chapter, we present an overview of the role of point defects for thermoelectric materials and demonstrate an application of DFT for determining the thermodynamic formation energies of various intrinsic point defects in Bi2Te3.