Designing high-performance thermoelectrics in two-dimensional tetradymites
Journal
Nano Energy
Journal Volume
58
Start Page
743
End Page
749
ISSN
22112855
Date Issued
2019
Author(s)
Abstract
The search for new thermoelectric materials has been of great interest in recent years because thermoelectrics offers useful applications in next-generation vehicles that can directly convert waste heat to electricity. Two-dimensional (2D) tetradymites with M 2 X 3 compounds, in which M (Bi) and X (Te, Se, S) are a group-V metal and group-VI anion, respectivety, are theoretically investigated in this study. Their energy bands are characterized by small energy gaps, high group velocities, small effective masses, nonparabolic bands and multi-valleys convergence at near the center of the Brillouin zone, which are favorable conditions for high power factor with the optimum power factor values can be up to 0.20–0.25 W/mK 2 at room temperature. Moreover, the 2D M 2 X 3 contains heavy atomic masses and high polarizability of some chemical bonds, leading to small group velocities of phonons and anharmonic phonon behavior that produce an intrinsic lattice thermal conductivity as low as ?1.5–2.0 W/mK at room temperature. We find that by mixtures of M and X atoms, such as Bi 2 Te 2 Se, the power factor further increases whereas the lattice thermal conductivity decreases. This design gives a high figure of merit of the p-type 2D Bi 2 Te 2 Se from 1.4 to 2.0 at operating temperature within 300?500 K.
Subjects
First-principles Calculation
Multi-valleys Convergence
Thermoelectricity
Two-dimensional Tetradymites
Bismuth Compounds
Bond Strength (chemical)
Calculations
Crystal Lattices
Electric Power Factor
Light Velocity
Phonons
Selenium Compounds
Solid Wastes
Tellurium Compounds
Thermoelectricity
Waste Heat
Anharmonic Phonons
Favorable Conditions
First-principles Calculation
Lattice Thermal Conductivity
Multi-valleys Convergence
Operating Temperature
Thermo-electric Materials
Two Dimensional (2 D)
Thermal Conductivity
SDGs
Publisher
Elsevier Ltd
Type
journal article