We study the thermal and electronic transport properties as well as the thermoelectric(TE)performance of three two-dimensional(2 D)XI_(2)(X=Ge,Sn,Pb)bilayers using density functional theory and Boltzmann transport the...We study the thermal and electronic transport properties as well as the thermoelectric(TE)performance of three two-dimensional(2 D)XI_(2)(X=Ge,Sn,Pb)bilayers using density functional theory and Boltzmann transport theory.We compared the lattice thermal conductivity,electrical conductivity,Seebeck coefficient,and dimensionless figure of merit(ZT)for the XI_(2)monolayers and bilayers.Our results show that the lattice thermal conductivity at room temperature for the bilayers is as low as~1.1 W·m^(-1)·K^(-1)-1.7 W·m^(-1)·K^(-1),which is about 1.6 times as large as the monolayers for all the three materials.Electronic structure calculations show that all the XI_(2)bilayers are indirect-gap semiconductors with the band gap values between 1.84 eV and 1.96 eV at PBE level,which is similar as the corresponding monolayers.The calculated results of ZT show that the bilayer structures display much less direction-dependent TE efficiency and have much larger n-type ZT values compared with the monolayers.The dramatic difference between the monolayer and bilayer indicates that the inter-layer interaction plays an important role in the TE performance of XI_(2),which provides the tunability on their TE characteristics.展开更多
基金Project supported by the Fundamental Research Fund for the Central Universities and the Zhongying Young Scholar Program of Southeast University。
文摘We study the thermal and electronic transport properties as well as the thermoelectric(TE)performance of three two-dimensional(2 D)XI_(2)(X=Ge,Sn,Pb)bilayers using density functional theory and Boltzmann transport theory.We compared the lattice thermal conductivity,electrical conductivity,Seebeck coefficient,and dimensionless figure of merit(ZT)for the XI_(2)monolayers and bilayers.Our results show that the lattice thermal conductivity at room temperature for the bilayers is as low as~1.1 W·m^(-1)·K^(-1)-1.7 W·m^(-1)·K^(-1),which is about 1.6 times as large as the monolayers for all the three materials.Electronic structure calculations show that all the XI_(2)bilayers are indirect-gap semiconductors with the band gap values between 1.84 eV and 1.96 eV at PBE level,which is similar as the corresponding monolayers.The calculated results of ZT show that the bilayer structures display much less direction-dependent TE efficiency and have much larger n-type ZT values compared with the monolayers.The dramatic difference between the monolayer and bilayer indicates that the inter-layer interaction plays an important role in the TE performance of XI_(2),which provides the tunability on their TE characteristics.
