Thermoelectric performance of Bi2Sn2Te6 monolayer with ultralow lattice thermal conductivity induced by hybrid bonding properties: A theoretical prediction

• Published in: Science China. Technological sciences 2024-11, Vol.67 (11), p.3381-3393
• Main Authors: Tang, ShuWei, Wang, Hao, Wan, Da, Li, XiaoDong, Guo, WanRong, Zheng, Tuo, Qi, XiuLing, Bai, ShuLin
• Format: Article
• Language: English
• Subjects: Anharmonicity; Bonding strength; Chemical bonds; Crystal lattices; Crystal structure; Dispersion curve analysis; Electron transport; Engineering; Figure of merit; First principles; Group velocity; Gruneisen parameter; Heat conductivity; Heat transfer; Modulus of elasticity; Molecular dynamics; Monolayers; Orbital mechanics; Phonons; Relaxation time; Review; Spin-orbit interactions; Storage modulus; Thermal conductivity; Thermoelectricity; Transport properties; Transport theory; Vibrational spectra
• ISSN: 1674-7321; 1869-1900
• DOI: 10.1007/s11431-024-2783-x

The crystal structure, mechanical stability, phonon dispersion, electronic transport properties and thermoelectric (TE) performance of the Bi 2 Sn 2 Te 6 monolayer are assessed with the first-principles calculations and the Boltzmann transport theory. The Bi 2 Sn 2 Te 6 monolayer is an indirect semiconductor with a band gap of 0.91 eV using the Heyd-Scuseria-Ernzerhof (HSE06) functional in consideration of the spin-orbit coupling (SOC) effect. The Bi 2 Sn 2 Te 6 monolayer is high thermodynamically and mechanically stable by the assessments of elastic modulus, phonon dispersion curves, and ab initio molecular dynamics (AIMD) simulations. The hybrid bonding characteristics are discovered in Bi 2 Sn 2 Te 6 monolayer, which is advantageous for phonon scattering. The antibonding interactions near the Fermi level weaken the chemical bonding and reduce the phonon vibrational frequency. Due to the short phonon relaxation time, strong anharmonic scattering, large Grüneisen parameter, and small phonon group velocity, an ultralow lattice thermal conductivity (0.27 W/(m·K)@300K) is achieved for the Bi 2 Sn 2 Te 6 monolayer. The optimal dimensionless figure of merit ( ZT ) values for the n -type and p -type Bi 2 Sn 2 Te 6 monolayers are 2.68 and 1.63 at 700 K, respectively, associated with a high TE conversion efficiency of 20.01% at the same temperature. Therefore, the Bi 2 Sn 2 Te 6 monolayer emerges as a promising candidate for TE material with high conversion efficiency.