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 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)@300 K)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.展开更多
基金supported by the National Natural Science Foundation of China(Grant No.21503039)Department of Science and Technology of Liaoning Province(Grant No.2019MS164)+1 种基金Department of Education of Liaoning Province(Grant Nos.LJ2020JCL034,JYTQN2023209)Discipline Innovation Team of Liaoning Technical University(Grant No.LNTU20TD-16)。
文摘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)@300 K)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.
