OptimizedZTofBi2Te3−GeTecompoun

Abstract

We predict the thermoelectric properties of layered [GeTe] m [Bi 2 Te 3 ] n (GBT) compounds (1 ≤ m ≤ 8, 1 ≤ n ≤ 3), using first-principles-Boltzmann transport calculations of the homogeneous (Bi 2 Te 3 and GeTe) data. The lattice strain and the quantum-confinement effects of compounds evolve the bandgap structures, resulting in asymmetric and large Seebeck coefficient, at high GeTe content.Using semi-empirical calculations of electron scattering rate 1/ ! , dominated by electron-acoustic phonon scattering, we reproduce reported TE properties of GBT compounds. We predict that due to small Seebeck coefficient, the GBT compounds with high n-and p-type doping (~10 20 cm -3 ), do not have high ZT near room temperature. However, we predict that the moderately-doped (~10 19 cm -3 ), p-type GBT compounds have enhanced ZT ≈ 1.4 near room temperature. *

Influence of the stacking sequence on layered-chalcogenide properties: first principles investigation of Pb2Bi2Te5

“…The highest value in the a-axis direction is 4.02 and that in the c-axis direction is 2.26, which are higher than those already reported in literature for other layered chalcogenide compounds (e.g. 1.3 for the Sb 2 Te 3 -GeTe compounds 68 , 1.4 for the Bi 2 Te 3 -GeTe ones 69 and 1.86 for Bi 0.5 Sb 1.5 Te 3 70 ). Despite the lower lattice thermal conductivity of stacking A, its electronic thermal conductivity is much higher than that of stacking B as a result of the metallicity (Figure 5 and 6).…”

The excellent TE performance of photoelectric material CdSe along with a study of Zn(Cd)Se and Zn(Cd)Te based on first-principles

“…Organic materials, especially polymer materials, have been found to be one of the best potential thermoelectric materials on account of their excellent flexibility, easy production, as well as high power factor, 25 but the poor thermal stability and high contact resistance restrict their application in the commercial field. 26 Based on the above, the thermoelectric materials applied in practice are mainly inorganic compounds, such as Na-doped PbTe ( ZT ∼ 2.0 at 773 K), for which the κ L was reduced by adjusting the nanostructure, 7 heavily doped PbSe 27 ( ZT ∼ 2.0 at 1000 K), p-type GBT compounds [GeTe] m [Bi 2 Te 3 ] n 28 ( ZT ∼ 1.4 at 300 K), n-type doped SnSe 29 ( ZT ∼ 2.7 along the a axis) and Cu 2 Se, for which the ZT values were enhanced by doping with 1 mol% indium and a peak value of 2.6 at 850 K was achieved. 30 Additionally, studies by the Ren group and Tritt group 20,31 have recently acquired ZT values of 1.5 in nanostructured Bi 2 Te 3 accompanied with a reduced lattice thermal conductivity, enhanced Seebeck coefficient S and enhanced mobility μ .…”

Thermoelectric Preferred Orientation of (GeTe)0.962(Bi2Te3)0.038

“…One doping compound that can decrease the free carrier concentration is Bi 2 Te 3 . Bi 2 Te 3 is a good dopant, exhibiting a high solubility in GeTe due to its similar crystal structure (rhombohedral). − Crystalline structures in the (GeTe)-(Bi 2 Te 3 ) quasi-binary phase diagram depend on the Bi 2 Te 3 to GeTe ratio. For high amounts of GeTe, the structure becomes rhombohedral, while lower amounts of GeTe result in a cubic structure.…”