Thermoelectric materials have a wide range of application because they can be directly used in refrigeration and power generation. And the Bi_(2)Te_(3) stand out because of its excellent thermoelectric performance and...Thermoelectric materials have a wide range of application because they can be directly used in refrigeration and power generation. And the Bi_(2)Te_(3) stand out because of its excellent thermoelectric performance and are used in commercial thermoelectric devices. However, n-type Bi_(2)Te_(3) has seriously hindered the development of Bi_(2)Te_(3)-based thermoelectric devices due to its weak mechanical properties and inferior thermoelectric performance. Therefore, it is urgent to develop a high-performance n-type Bi_(2)Te_(3) polycrystalline. In this work, we employed interstitial Cu and the hot deformation process to optimize the thermoelectric properties of Bi_(2)Te_(2.7)Se_(0.3), and a high-performance thermoelectric module was fabricated based on this material. Our combined theoretical and experimental effort indicates that the interstitial Cu reduce the defect density in the matrix and suppresses the donor-like effect, leading to a lattice plainification effect in the material. In addition, the two-step hot deformation process significantly improves the preferred orientation of the material and boosts the mobility. As a result, a maximum ZT of 1.27 at 373 K and a remarkable high ZT_(ave) of 1.22 across the temperature range of 300–425 K are obtained. The thermoelectric generator(TEG, 7-pair) and thermoelectric cooling(TEC, 127-pair) modules were fabricated with our n-type textured Cu_(0.01)Bi_(2)Te_(2.7)Se_(0.3) coupled with commercial p-type Bi_(2)Te_(3). The TEC module demonstrates superior cooling efficiency compared with the commercial Bi_(2)Te_(3) device, achieving a ΔT of 65 and 83.4 K when the hot end temperature at 300 and 350 K, respectively. In addition, the TEG module attains an impressive conversion efficiency of 6.5% at a ΔT of 225 K, which is almost the highest value among the reported Bi_(2)Te_(3)-based TEG modules.展开更多
Recently,off-centering behavior has been discovered in a series of thermoelectric materials.This behavior indicates that the constituent atoms of the lattice displace from their coordination centers,leading to the loc...Recently,off-centering behavior has been discovered in a series of thermoelectric materials.This behavior indicates that the constituent atoms of the lattice displace from their coordination centers,leading to the locally distorted state and local symmetry breaking,while the material still retains its original crystallographic symmetry.This effect has been proved to be the root cause of ultralow thermal conductivity in off-centering materials,and is considered as an effective tool to regulate the thermal conductivity and improve the thermoelectric performance.Herein,we present a collection of recently discovered off-centering compounds,discuss their electronic origins and local coordination structures,and illuminate the underlying mechanism of the off-centering effect on phonon transport and thermal conductivity.This paper presents a comprehensive view of our current understanding to the off-centering effect,and provides a new idea for designing high performance thermoelectrics.展开更多
Pristine GeTe shows inferior thermoelectric performance around unit due to the large carrier concentration induced by the presence of intrinsic high concentration of Ge vacancy. In this study, we report a thermoelectr...Pristine GeTe shows inferior thermoelectric performance around unit due to the large carrier concentration induced by the presence of intrinsic high concentration of Ge vacancy. In this study, we report a thermoelectric figure of merit ZT of 1.56 at 700 K, realized in Sb-doped GeTe based thermoelectric(TE)materials via combined effect of suppression of intrinsic Ge vacancy and Sb doping. The nonequilibrium nature during melt spinning process plays very important role. For one thing, it promotes the homogeneity in Ge_(1-x)Sb_xTe samples and refines the grain size of the product. Moreover the persistent Ge precipitated as impurity phase in the traditional synthesis process is found to be dissolved back into the GeTe sublattice, accompanying with a drastic suppression of Ge vacancies concentration which in combination with Sb electron doping significantly reduced the inherent carrier concentration in GeTe.Low carrier concentration, approaching the optimum carrier concentration ～3.74 × 10^(-20) cm^(-3) and a high power factor of 4.01 × 10^(-3) W m^(-1)K^(-2) at 750 K are achieved for Ge_(0.98)Sb_(0.02) Te sample. In addition,the enhanced grain boundary phonon scattering by refining the grain size through melt spinning(MS)process, coupled with the intensified alloying phonon scattering via Sb doping leads to low thermal conductivity of 1.53 W m^(-1) K^(-1) at 700 K for Ge_(0.94) Sb_(0.06) Te sample. All those contribute to a high ZT value,representing over 50% improvement in the ZT value compared to the Sb free samples, which provides an alternative way for ultrafast synthesis of high performance GeTe based thermoelectric material.展开更多
基金supported by the National Science Fund for Distinguished Young Scholars (51925101)the National Natural Science Foundation of China (52250090,52371208,52002042,51772012,51571007,and 12374023)+3 种基金Beijing Natural Science Foundation (JO18004)the 111 Project (B17002)the support from the Tencent Xplorer Prizepartially supported by the EPIC facility of Northwestern University’s NUANCE Center。
文摘Thermoelectric materials have a wide range of application because they can be directly used in refrigeration and power generation. And the Bi_(2)Te_(3) stand out because of its excellent thermoelectric performance and are used in commercial thermoelectric devices. However, n-type Bi_(2)Te_(3) has seriously hindered the development of Bi_(2)Te_(3)-based thermoelectric devices due to its weak mechanical properties and inferior thermoelectric performance. Therefore, it is urgent to develop a high-performance n-type Bi_(2)Te_(3) polycrystalline. In this work, we employed interstitial Cu and the hot deformation process to optimize the thermoelectric properties of Bi_(2)Te_(2.7)Se_(0.3), and a high-performance thermoelectric module was fabricated based on this material. Our combined theoretical and experimental effort indicates that the interstitial Cu reduce the defect density in the matrix and suppresses the donor-like effect, leading to a lattice plainification effect in the material. In addition, the two-step hot deformation process significantly improves the preferred orientation of the material and boosts the mobility. As a result, a maximum ZT of 1.27 at 373 K and a remarkable high ZT_(ave) of 1.22 across the temperature range of 300–425 K are obtained. The thermoelectric generator(TEG, 7-pair) and thermoelectric cooling(TEC, 127-pair) modules were fabricated with our n-type textured Cu_(0.01)Bi_(2)Te_(2.7)Se_(0.3) coupled with commercial p-type Bi_(2)Te_(3). The TEC module demonstrates superior cooling efficiency compared with the commercial Bi_(2)Te_(3) device, achieving a ΔT of 65 and 83.4 K when the hot end temperature at 300 and 350 K, respectively. In addition, the TEG module attains an impressive conversion efficiency of 6.5% at a ΔT of 225 K, which is almost the highest value among the reported Bi_(2)Te_(3)-based TEG modules.
基金supported by National Natural Science Foundation of China(52250090,52371208,51571007,51772012)the Beijing Natural Science Foundation(JQ18004),111 Project(B17002)L D Z appreciates the National Science Fund for Distinguished Young Scholars(51925101).
文摘Recently,off-centering behavior has been discovered in a series of thermoelectric materials.This behavior indicates that the constituent atoms of the lattice displace from their coordination centers,leading to the locally distorted state and local symmetry breaking,while the material still retains its original crystallographic symmetry.This effect has been proved to be the root cause of ultralow thermal conductivity in off-centering materials,and is considered as an effective tool to regulate the thermal conductivity and improve the thermoelectric performance.Herein,we present a collection of recently discovered off-centering compounds,discuss their electronic origins and local coordination structures,and illuminate the underlying mechanism of the off-centering effect on phonon transport and thermal conductivity.This paper presents a comprehensive view of our current understanding to the off-centering effect,and provides a new idea for designing high performance thermoelectrics.
基金supported by the National Natural Science Foundation of China(51402222,51521001,and 51632006)the 111 Project of China(B07040)
文摘Pristine GeTe shows inferior thermoelectric performance around unit due to the large carrier concentration induced by the presence of intrinsic high concentration of Ge vacancy. In this study, we report a thermoelectric figure of merit ZT of 1.56 at 700 K, realized in Sb-doped GeTe based thermoelectric(TE)materials via combined effect of suppression of intrinsic Ge vacancy and Sb doping. The nonequilibrium nature during melt spinning process plays very important role. For one thing, it promotes the homogeneity in Ge_(1-x)Sb_xTe samples and refines the grain size of the product. Moreover the persistent Ge precipitated as impurity phase in the traditional synthesis process is found to be dissolved back into the GeTe sublattice, accompanying with a drastic suppression of Ge vacancies concentration which in combination with Sb electron doping significantly reduced the inherent carrier concentration in GeTe.Low carrier concentration, approaching the optimum carrier concentration ～3.74 × 10^(-20) cm^(-3) and a high power factor of 4.01 × 10^(-3) W m^(-1)K^(-2) at 750 K are achieved for Ge_(0.98)Sb_(0.02) Te sample. In addition,the enhanced grain boundary phonon scattering by refining the grain size through melt spinning(MS)process, coupled with the intensified alloying phonon scattering via Sb doping leads to low thermal conductivity of 1.53 W m^(-1) K^(-1) at 700 K for Ge_(0.94) Sb_(0.06) Te sample. All those contribute to a high ZT value,representing over 50% improvement in the ZT value compared to the Sb free samples, which provides an alternative way for ultrafast synthesis of high performance GeTe based thermoelectric material.
基金financially supported by the National Key Research and Development Program of China (2018YFB0703600)the National Natural Science Foundation of China (51772232)+1 种基金the 111 Project of China (B07040)Wuhan Frontier Project on Applied Research Foundation (2019010701011405)
