The structure–property relationship at interfaces is difficult to probe for thermoelectric materials with a complex interfacial microstructure.Designing thermoelectric materials with a simple,structurally-uniform int...The structure–property relationship at interfaces is difficult to probe for thermoelectric materials with a complex interfacial microstructure.Designing thermoelectric materials with a simple,structurally-uniform interface provides a facile way to understand how these interfaces influence the transport properties.Here,we synthesized Bi_(2−x)Sb_(x)Te_(3)(x=0,0.1,0.2,0.4)nanoflakes using a hydrothermal method,and prepared Bi_(2−x)Sb_(x)Te_(3)thin films with predominantly(0001)interfaces by stacking the nanoflakes through spin coating.The influence of the annealing temperature and Sb content on the(0001)interface structure was systematically investigated at atomic scale using aberration-corrected scanning transmission electron microscopy.Annealing and Sb doping facilitate atom diffusion and migration between adjacent nanoflakes along the(0001)interface.As such it enhances interfacial connectivity and improves the electrical transport properties.Interfac reactions create new interfaces that increase the scattering and the Seebeck coefficient.Due to the simultaneous optimization of electrical conductivity and Seebeck coefficient,the maximum power factor of the Bi_(1.8)Sb_(0.2)Te_(3)nanoflake films reaches 1.72 mW m^(−1)K^(−2),which is 43%higher than that of a pure Bi_(2)Te_(3)thin film.展开更多
Solution processability and flexibility still remain major challenges for many thermoelectric(TE)materials,including bismuth telluride(Bi_(2)Te_(3)),a typical and commercially available TE material.Here,we report a ne...Solution processability and flexibility still remain major challenges for many thermoelectric(TE)materials,including bismuth telluride(Bi_(2)Te_(3)),a typical and commercially available TE material.Here,we report a new solutionprocessed method to prepare a flexible film of a Bi_(2)Te_(3)/single-walled carbon nanotube(SWCNT)hybrid,where the dissolved Bi_(2)Te_(3) ion precursors are mixed with dispersed SWCNTs in solution and recrystallized on the SWCNT surfaces to form a“cement-rebar”-like architecture.The hybrid film shows an n-type characteristic,with a stable Seebeck coefficient of^(−1)00.00±1.69μVK^(−1) in air.Furthermore,an extremely low in-plane thermal conductivity of∼0.33Wm^(−1) K^(−1) is achieved at 300 K,and the figure of merit(ZT)reaches 0.47±0.02.In addition,the TE performance is independent of mechanical bending.The unique“cement-rebar”-like architecture is believed to be responsible for the excellent TE performances and the high flexibility.The results provide a new avenue for the fabrication of solution-processable and flexible TE hybrid films and will speed up the applications of flexible electronics and energy conversion.展开更多
The application of high-density and high-performance micro thermoelectric devices is still in its infancy,mainly restricted by the low performance of Bi_(2)Te_(3)-based thick film as well as the limited device inte-gr...The application of high-density and high-performance micro thermoelectric devices is still in its infancy,mainly restricted by the low performance of Bi_(2)Te_(3)-based thick film as well as the limited device inte-gration.In this study,we proposed a dynamic regulation strategy to simultaneously strengthen the thermoelectric and mechanical properties for n-type Bi_(2)Te_(3)-based thick films.The effects of growth temperature and time on thermoelectric properties have been firstly explored.As the thermoelectric properties exhibit consistent degradation with increasing thickness at static growth temperature,an effective rising temperature method is introduced to dynamically regulate the nucleation rate and growing diffusion ability.Thus,the grain refinement with compact texture structure leads to a relatively large carrier mobility(77.1 cm^(2)·V^(-1)·s^(-1))and appropriate concentration(5.25×10^(19)cm^(-3))as well as further 12%improvement of power factor with an average value up to 12.0 mW·cm^(-1)·K^(-2)over a wide temperature ranging from 313 K to 453 K.Furthermore,significant enhancement of mechanical property is also achieved with high elastic modules(56.03 GPa),hardness(0.63 GPa)and large energy dissipation capacity to prevent micro-cracks.This study provides a practical solution with dynamic temperature control to fabricate high-performance Bi_(2)Te_(3) thick films with enhanced mechanical property and pro-cessing feasibility for micro thermoelectric devices.展开更多
Thermoelectric(TE)materials and devices have attracted great attention due to their ability to convert waste heat to electrical power and active cooling.However,the conventional bulk TE materials are inorganic semicon...Thermoelectric(TE)materials and devices have attracted great attention due to their ability to convert waste heat to electrical power and active cooling.However,the conventional bulk TE materials are inorganic semiconductors with inherent brittleness and rigidity.They cannot closely contact curved heat sources and sinks,which limits their application in modern electronics.It remains a big challenge to fabricate high-performance TE materials and devices with good flexibility.Here,we report a flexible TE device comprised of a single wall carbon nanotube(SWCNT)network and(0001)-textured Bi_(2)Te_(3)nanocrystals prepared by a magnetron sputtering technique.The unique Bi_(2)Te_(3)-SWCNT hybrid structure has a TE figure of merit(ZT)value of^0.23 at^330 K.A prototype TE device made of this hybrid gives a maximum output power density of^0.93 m W cm^(-2)under a temperature difference of 25 K at ambient temperature and shows good flexibility under bending.Our results open up a new way to the development of flexible TEs and their application in self-powered portable devices.展开更多
Bi_(2)Te_(3)-based materials are not only the most important and widely used room temperature thermoelectric(TE)materials but are also canonical examples of topological insulators in which the topological surface stat...Bi_(2)Te_(3)-based materials are not only the most important and widely used room temperature thermoelectric(TE)materials but are also canonical examples of topological insulators in which the topological surface states are protected by the time-reversal symmetry.High-performance thin films based on Bi_(2)Te_(3)- have attracted worldwide attention during the past two decades due primarily to their outstanding TE performance as highly efficient TE coolers and as miniature and flexible TE power generators for a variety of electronic devices.Moreover,intriguing topological phenomena,such as the quantum anomalous Hall effect and topological superconductivity discovered in Bi_(2)Te_(3)-based thin films and heterostructures,have shaped research directions in the field of condensed matter physics.In Bi_(2)Te_(3)-based films and heterostructures,delicate control of the carrier transport,film composition,and microstructure are prerequisites for successful device operations as well as for experimental verification of exotic topological phenomena.This review summarizes the recent progress made in atomic defect engineering,carrier tuning,and band engineering down to a nanoscale regime and how it relates to the growth and fabrication of high-quality Bi_(2)Te_(3)-based films.The review also briefly discusses the physical insight into the exciting field of topological phenomena that were so dramatically realized in Bi_(2)Te_(3)-and Bi_(2)Se_(3)‐based structures.It is expected that Bi_(2)Te_(3)-based thin films and heterostructures will play an ever more prominent role as flexible TE devices collecting and converting low-level(body)heat into electricity for numerous electronic applications.It is also likely that such films will continue to be a remarkable platform for the realization of novel topological phenomena.展开更多
Bi_(2)Te_(3)-based alloys are known to have outstanding thermoelectric properties.Although structure–property relations have been studied,still,detailed analysis of the atomic and nano-scale structure of Bi_(2)Te_(3)...Bi_(2)Te_(3)-based alloys are known to have outstanding thermoelectric properties.Although structure–property relations have been studied,still,detailed analysis of the atomic and nano-scale structure of Bi_(2)Te_(3)thin film in relation to their thermoelectric properties remains poorly explored.Herein,highly-textured(HT)and single-crystal-like(SCL)Bi_(2)Te_(3)films have been grown using pulsed laser deposition(PLD)on Si wafer covered with(native or thermal)SiOx and mica substrates.All films are highly textured with c-axis out-of-plane,but the in-plane orientation is random for the films grown on oxide and single-crystal-like for the ones grown on mica.The power factor of the film on thermal oxide is about four times higher(56.8μW·cm^(−1)·K^(−2))than that of the film on mica(12.8μW·cm^(−1)·K^(−2)),which is comparable to the one of the polycrystalline ingot at room temperature(RT).Reduced electron scattering in the textured thin films results in high electrical conductivity,where the SCL film shows the highest conductivity.However,its Seebeck coefficient shows a low value.The measured properties are correlated with the atomic structure details unveiled by scanning transmission electron microscopy.For instance,the high concentration of stacking defects observed in the HT film is considered responsible for the increase of Seebeck coefficient compared to the SCL film.This study demonstrates the influence of nanoscale structural effects on thermoelectric properties,which sheds light on tailoring thermoelectric thin films towards high performance.展开更多
基金supported by the National Natural Science Foundation of China(52272235)supported by the Fundamental Research Funds for the Central Universities(WUT:2021III016GX).
文摘The structure–property relationship at interfaces is difficult to probe for thermoelectric materials with a complex interfacial microstructure.Designing thermoelectric materials with a simple,structurally-uniform interface provides a facile way to understand how these interfaces influence the transport properties.Here,we synthesized Bi_(2−x)Sb_(x)Te_(3)(x=0,0.1,0.2,0.4)nanoflakes using a hydrothermal method,and prepared Bi_(2−x)Sb_(x)Te_(3)thin films with predominantly(0001)interfaces by stacking the nanoflakes through spin coating.The influence of the annealing temperature and Sb content on the(0001)interface structure was systematically investigated at atomic scale using aberration-corrected scanning transmission electron microscopy.Annealing and Sb doping facilitate atom diffusion and migration between adjacent nanoflakes along the(0001)interface.As such it enhances interfacial connectivity and improves the electrical transport properties.Interfac reactions create new interfaces that increase the scattering and the Seebeck coefficient.Due to the simultaneous optimization of electrical conductivity and Seebeck coefficient,the maximum power factor of the Bi_(1.8)Sb_(0.2)Te_(3)nanoflake films reaches 1.72 mW m^(−1)K^(−2),which is 43%higher than that of a pure Bi_(2)Te_(3)thin film.
基金We thank the National Natural Science Foundation of China(No.51973122)for financial support.
文摘Solution processability and flexibility still remain major challenges for many thermoelectric(TE)materials,including bismuth telluride(Bi_(2)Te_(3)),a typical and commercially available TE material.Here,we report a new solutionprocessed method to prepare a flexible film of a Bi_(2)Te_(3)/single-walled carbon nanotube(SWCNT)hybrid,where the dissolved Bi_(2)Te_(3) ion precursors are mixed with dispersed SWCNTs in solution and recrystallized on the SWCNT surfaces to form a“cement-rebar”-like architecture.The hybrid film shows an n-type characteristic,with a stable Seebeck coefficient of^(−1)00.00±1.69μVK^(−1) in air.Furthermore,an extremely low in-plane thermal conductivity of∼0.33Wm^(−1) K^(−1) is achieved at 300 K,and the figure of merit(ZT)reaches 0.47±0.02.In addition,the TE performance is independent of mechanical bending.The unique“cement-rebar”-like architecture is believed to be responsible for the excellent TE performances and the high flexibility.The results provide a new avenue for the fabrication of solution-processable and flexible TE hybrid films and will speed up the applications of flexible electronics and energy conversion.
基金supported by the National Key R&D Program of China(Grant No.2018YFA0702100)the National Natural Science Foundation of China(Grant No.U21A2079)+1 种基金the Beijing Natural Science Foundation(Grant No.2182032),the Zhejiang Provincial Key R&D Program of China(Grant Nos.2021C05002 and 2021C01026)the Leading Innovative and Entrepreneur Team Introduction Program of Zhejiang(2020R01007).
文摘The application of high-density and high-performance micro thermoelectric devices is still in its infancy,mainly restricted by the low performance of Bi_(2)Te_(3)-based thick film as well as the limited device inte-gration.In this study,we proposed a dynamic regulation strategy to simultaneously strengthen the thermoelectric and mechanical properties for n-type Bi_(2)Te_(3)-based thick films.The effects of growth temperature and time on thermoelectric properties have been firstly explored.As the thermoelectric properties exhibit consistent degradation with increasing thickness at static growth temperature,an effective rising temperature method is introduced to dynamically regulate the nucleation rate and growing diffusion ability.Thus,the grain refinement with compact texture structure leads to a relatively large carrier mobility(77.1 cm^(2)·V^(-1)·s^(-1))and appropriate concentration(5.25×10^(19)cm^(-3))as well as further 12%improvement of power factor with an average value up to 12.0 mW·cm^(-1)·K^(-2)over a wide temperature ranging from 313 K to 453 K.Furthermore,significant enhancement of mechanical property is also achieved with high elastic modules(56.03 GPa),hardness(0.63 GPa)and large energy dissipation capacity to prevent micro-cracks.This study provides a practical solution with dynamic temperature control to fabricate high-performance Bi_(2)Te_(3) thick films with enhanced mechanical property and pro-cessing feasibility for micro thermoelectric devices.
基金financially supported by the Ministry of Science and Technology of China(Nos.2017YFA0700702,2016YFA0200102,and 2019QY(Y)0501)the National Natural Science Foundation of China(Nos.51571193,51402310,and 51625203)Shenyang National Laboratory for Materials Science Foundation and the Science Foundation for The Excellent Youth Scholars of Liaoning Province of China(No.2019-YQ-08)。
文摘Thermoelectric(TE)materials and devices have attracted great attention due to their ability to convert waste heat to electrical power and active cooling.However,the conventional bulk TE materials are inorganic semiconductors with inherent brittleness and rigidity.They cannot closely contact curved heat sources and sinks,which limits their application in modern electronics.It remains a big challenge to fabricate high-performance TE materials and devices with good flexibility.Here,we report a flexible TE device comprised of a single wall carbon nanotube(SWCNT)network and(0001)-textured Bi_(2)Te_(3)nanocrystals prepared by a magnetron sputtering technique.The unique Bi_(2)Te_(3)-SWCNT hybrid structure has a TE figure of merit(ZT)value of^0.23 at^330 K.A prototype TE device made of this hybrid gives a maximum output power density of^0.93 m W cm^(-2)under a temperature difference of 25 K at ambient temperature and shows good flexibility under bending.Our results open up a new way to the development of flexible TEs and their application in self-powered portable devices.
基金This study was supported by the Natural Science Foun-dation of China(Grant No.51632006,51521001 and 91963120)National Key Research and Development Program of China(Grant No.2019YFA0704900)Wuhan Frontier Project on Applied Research Foundation(Grant No.2019010701011405).
文摘Bi_(2)Te_(3)-based materials are not only the most important and widely used room temperature thermoelectric(TE)materials but are also canonical examples of topological insulators in which the topological surface states are protected by the time-reversal symmetry.High-performance thin films based on Bi_(2)Te_(3)- have attracted worldwide attention during the past two decades due primarily to their outstanding TE performance as highly efficient TE coolers and as miniature and flexible TE power generators for a variety of electronic devices.Moreover,intriguing topological phenomena,such as the quantum anomalous Hall effect and topological superconductivity discovered in Bi_(2)Te_(3)-based thin films and heterostructures,have shaped research directions in the field of condensed matter physics.In Bi_(2)Te_(3)-based films and heterostructures,delicate control of the carrier transport,film composition,and microstructure are prerequisites for successful device operations as well as for experimental verification of exotic topological phenomena.This review summarizes the recent progress made in atomic defect engineering,carrier tuning,and band engineering down to a nanoscale regime and how it relates to the growth and fabrication of high-quality Bi_(2)Te_(3)-based films.The review also briefly discusses the physical insight into the exciting field of topological phenomena that were so dramatically realized in Bi_(2)Te_(3)-and Bi_(2)Se_(3)‐based structures.It is expected that Bi_(2)Te_(3)-based thin films and heterostructures will play an ever more prominent role as flexible TE devices collecting and converting low-level(body)heat into electricity for numerous electronic applications.It is also likely that such films will continue to be a remarkable platform for the realization of novel topological phenomena.
基金the China Scholarship Council,in particular for Heng Zhang’s scholarship(No.201706890019).
文摘Bi_(2)Te_(3)-based alloys are known to have outstanding thermoelectric properties.Although structure–property relations have been studied,still,detailed analysis of the atomic and nano-scale structure of Bi_(2)Te_(3)thin film in relation to their thermoelectric properties remains poorly explored.Herein,highly-textured(HT)and single-crystal-like(SCL)Bi_(2)Te_(3)films have been grown using pulsed laser deposition(PLD)on Si wafer covered with(native or thermal)SiOx and mica substrates.All films are highly textured with c-axis out-of-plane,but the in-plane orientation is random for the films grown on oxide and single-crystal-like for the ones grown on mica.The power factor of the film on thermal oxide is about four times higher(56.8μW·cm^(−1)·K^(−2))than that of the film on mica(12.8μW·cm^(−1)·K^(−2)),which is comparable to the one of the polycrystalline ingot at room temperature(RT).Reduced electron scattering in the textured thin films results in high electrical conductivity,where the SCL film shows the highest conductivity.However,its Seebeck coefficient shows a low value.The measured properties are correlated with the atomic structure details unveiled by scanning transmission electron microscopy.For instance,the high concentration of stacking defects observed in the HT film is considered responsible for the increase of Seebeck coefficient compared to the SCL film.This study demonstrates the influence of nanoscale structural effects on thermoelectric properties,which sheds light on tailoring thermoelectric thin films towards high performance.
