Abstract
Utilizing first-principles calculations and Boltzmann transport theory, the crystal structure, thermal and electronic transport, and thermoelectric (TE) properties of the Sb2Sn2Te6 monolayer are evaluated in the current work. The Sb2Sn2Te6 monolayer is an indirect band gap semiconductor with a band gap of 0.81 eV using the Heyd-Scuseria-Ernzerhof (HSE06) functional in combination with the spin-orbital coupling (SOC) effect. The antibonding states formed by the hybridization of Sb s orbital with Te p orbital near the Fermi level weaken the bonding strength of the Sb-Te bond, leading to significant anharmonicity and low group velocity. Thus, a low lattice thermal conductivity of 2.77 W/m K is achieved for the Sb2Sn2Te6 monolayer at 300 K. The band convergence and multivalley characteristics in the electronic band structure give birth to the enhancements of Seebeck coefficients and carrier mobilities, resulting in a substantial power factor of 76.69 μW/mK2 at 300 K under the carrier concentration of 3.20×1020 cm−3. An optimal figure of merit (ZT) of 2.37 at 900 K for the Sb2Sn2Te6 monolayer is obtained under the carrier concentration of 2.42×1020 cm−3. The present work not only provides fundamental insights into the correlation between the antibonding state, chemical bond and lattice thermal conductivity in Sb2Sn2Te6 monolayer, but also elaborates on the promising prospect of the Sb2Sn2Te6 monolayer in the TE application with high conversion efficiency.
Published Version
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