First-principles electronic structure and its relation to thermoelectric properties of Bi2Te3 -: art. no. 085112

The electronic structure of Bi2Te3. which is a major constituent of the best thermoelectric material operating at room temperature, was calculated by using the first principles full-potential linearized-augmented-planewave method with spin-orbit interaction included by a second variational method. A search of the whole Brillouin zone shows that the band edges are located off the symmetry lines, with locations that are in accord with the phenomenological six-band model. In doped Bi2Te3. Fermi surfaces near the band edges show a nonparabolic behavior. At a high doping concentration, the Fermi surfaces display elongated features, i.e., a knifelike Fermi surface for the valence band and spoonlike Fermi surfaces for the conduction band. which can be attributed to the layered structure of Bi2Te3. The effect of the anisotropic electronic structure combined with a low lattice thermal conductivity of Bi2Te3 gives a large figure of merit.