Pb-based group-IV chalcogenides including Pb Te and Pb Se have been extensively studied as high performance thermoelectric materials during the past few decades.However,the toxicity of Pb inhibits their applications i...Pb-based group-IV chalcogenides including Pb Te and Pb Se have been extensively studied as high performance thermoelectric materials during the past few decades.However,the toxicity of Pb inhibits their applications in vast fields due to the serious harm to the environment.Recently the Pb-free group-IV chalcogenides have become an extensive research subject as promising thermoelectric materials because of their unique thermal and electronic transport properties as well as the enviromentally friendly advantage.This paper briefly summarizes the recent research advances in Sn-,Ge-,and Sichalcogenides thermoelectrics,showing the unexceptionally high thermoelectric performance in Sn Se single crystal,and the significant improvement in thermoelectric performance for those polycrystalline materials by successfully modulating the electronic and thermal transport through using some well-developed strategies including band engineering,nanostructuring and defect engineering.In addition,some important issues for future device applications,including N-type doping and mechanical and chemical stabilities of the new thermoelectrics,are also discussed.展开更多
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
Using the Kane-Mele Hamiltonian, Dirac theory and self-consistent Born approximation, we investigate the effect of dilute charged impurity on the electronic heat capacity and magnetic susceptibility of two-dimensional...Using the Kane-Mele Hamiltonian, Dirac theory and self-consistent Born approximation, we investigate the effect of dilute charged impurity on the electronic heat capacity and magnetic susceptibility of two-dimensional ferromagnetic honeycomb structure of group-Ⅳ elements including silicene, germanene and stanene within the Green's function approach. We also find these quantities in the presence of applied external electric field. Our results show that the silicene(stanene) has the maximum(minimum) heat capacity and magnetic susceptibility at uniform electric fields. From the behavior of theses quantities, the band gap has been changed with impurity concentration, impurity scattering strength and electric field. The analysis on the impurity-dependent magnetic susceptibility curves shows a phase transition from ferromagnetic to paramagnetic and antiferromagnetic phases. Interestingly, electronic heat capacity increases(decreases) with impurity concentration in silicene(germanene and stanene) structure.展开更多
基金Project supported by the National Natural Science Foundation of China(Grant Nos.51472052 and U1601213)
文摘Pb-based group-IV chalcogenides including Pb Te and Pb Se have been extensively studied as high performance thermoelectric materials during the past few decades.However,the toxicity of Pb inhibits their applications in vast fields due to the serious harm to the environment.Recently the Pb-free group-IV chalcogenides have become an extensive research subject as promising thermoelectric materials because of their unique thermal and electronic transport properties as well as the enviromentally friendly advantage.This paper briefly summarizes the recent research advances in Sn-,Ge-,and Sichalcogenides thermoelectrics,showing the unexceptionally high thermoelectric performance in Sn Se single crystal,and the significant improvement in thermoelectric performance for those polycrystalline materials by successfully modulating the electronic and thermal transport through using some well-developed strategies including band engineering,nanostructuring and defect engineering.In addition,some important issues for future device applications,including N-type doping and mechanical and chemical stabilities of the new thermoelectrics,are also discussed.
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.
文摘Using the Kane-Mele Hamiltonian, Dirac theory and self-consistent Born approximation, we investigate the effect of dilute charged impurity on the electronic heat capacity and magnetic susceptibility of two-dimensional ferromagnetic honeycomb structure of group-Ⅳ elements including silicene, germanene and stanene within the Green's function approach. We also find these quantities in the presence of applied external electric field. Our results show that the silicene(stanene) has the maximum(minimum) heat capacity and magnetic susceptibility at uniform electric fields. From the behavior of theses quantities, the band gap has been changed with impurity concentration, impurity scattering strength and electric field. The analysis on the impurity-dependent magnetic susceptibility curves shows a phase transition from ferromagnetic to paramagnetic and antiferromagnetic phases. Interestingly, electronic heat capacity increases(decreases) with impurity concentration in silicene(germanene and stanene) structure.
