研究目的
To investigate the electron and phonon transport properties of layered Bi2O2Se and Bi2O2Te using first-principles calculations combined with the Boltzmann transport theory to understand their thermoelectric transport mechanism.
研究成果
The study reveals that both Bi2O2Se and Bi2O2Te are semiconductors with indirect energy gaps and exhibit low lattice thermal conductivities. The p-type doping shows superior thermoelectric performance compared to n-type doping. The lattice thermal conductivity exhibits strong anisotropy, especially for Bi2O2Te. The findings are significant for the optimization of thermoelectric performance in these materials.
研究不足
The study does not consider the effect of nanostructuring on the thermoelectric properties, which could further reduce the lattice thermal conductivity. The relaxation time approximation used in the electronic transport calculations may not capture all scattering mechanisms accurately.
1：Experimental Design and Method Selection:
The study employs first-principles calculations combined with the Boltzmann transport theory to investigate the electron and phonon transport properties. The structural optimization is performed using density functional theory with the projector-augmented-wave pseudopotential and the Perdew–Burke–Ernzerhof exchange correlation functional. The electronic structure and transport properties are calculated using the GGA plus Tran–Blaha modified Becke–Johnson potential, considering spin–orbit coupling. The lattice thermal conductivity is calculated based on the phonon Boltzmann transport equation.
2：Sample Selection and Data Sources:
The study focuses on layered Bi2O2Se and Bi2O2Te compounds, with their structural parameters optimized and compared with experimental values.
3：List of Experimental Equipment and Materials:
The calculations are performed using the VASP software for electronic structure calculations and the ShengBTE package for phonon transport properties. A 4×4×4 supercell is used for calculating the second and third-order force constants.
4：Experimental Procedures and Operational Workflow:
The study involves structural optimization, electronic structure calculation, and phonon transport properties calculation. The electronic transport properties are calculated using the Boltzmann transport theory and the relaxation time approximation as implemented in the BoltzTraP code.
5：Data Analysis Methods:
The Seebeck coefficient and electrical conductivity are analyzed as functions of carrier concentration. The lattice thermal conductivity is analyzed with respect to temperature and phonon mean free path.
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