The interdependence of electrical parameters has long inhibited the progress of bismuth telluride(Bi_(2)Te3),limiting its widespread application in thermoelectric cooling and power generation.This work investigates th...The interdependence of electrical parameters has long inhibited the progress of bismuth telluride(Bi_(2)Te3),limiting its widespread application in thermoelectric cooling and power generation.This work investigates the n-type Bi_(2)Te_(2.79)Se_(0.21)I_(0.004)(Bi_(2)(Te,Se)_(3),BTS)system with light Zn doping,revealing that Zn addition simultaneously enhances the Seebeck coefficient(S)and electrical conductivity(σ)through the modulation of defect composition and multi-level band regulation.The substitution of Zn atoms at Bi sites enhances S via bandgap(E_(g))widening,band flattening,and band splitting effects,contributing to a competitive power factor(PF)of∼60μW⋅cm^(−1)⋅K^(−2).Additionally,thermal conductivity is maintained at a low level,leading to an extraordinary figure-of-merit(ZT)value of∼1.3 at room temperature.Furthermore,the Bi_(2)Zn_(0.01)Te_(2.79)Se_(0.21)I_(0.004) system demonstrates impressive thermoelectric device performance,with a maximum cooling temperature difference(ΔT_(max))of∼70.0 K at 300 K,rising to∼78.0 K at 323 K and∼85.7 K at 343 K,as well as a maximum conversion efficiency(η_(max))of∼6.2%under aΔT of 200 K.This study clarifies the mechanism of Zn doping and presents a cost-effective strategy for enhancing the performance of n-type BTS thermoelectrics and their devices.展开更多
Thermoelectric(TE)materials,being capable of converting waste heat into electricity,are pivotal for sustainable energy solutions.Among emerging TE materials,organic TE materials,particularly conjugated polymers,are ga...Thermoelectric(TE)materials,being capable of converting waste heat into electricity,are pivotal for sustainable energy solutions.Among emerging TE materials,organic TE materials,particularly conjugated polymers,are gaining prominence due to their unique combination of mechanical flexibility,environmental compatibility,and solution-processable fabrication.A notable candidate in this field is poly(2,5-bis(3-alkylthiophen-2-yl)thieno[3,2-b]thiophene)(PBTTT),a liquid-crystalline conjugated polymer,with high charge carrier mobility and adaptability to melt-processing techniques.Recent advancements have propelled PBTTT’s figure of merit from below 0.1 to a remarkable 1.28 at 368 K,showcasing its potential for practical applications.This review systematically examines strategies to enhance PBTTT’s TE performance through doping(solution,vapor,and anion exchange doping),composite engineering,and aggregation state controlling.Recent key breakthroughs include ion exchange doping for stable charge modulation,multi-heterojunction architectures reducing thermal conductivity,and proton-coupled electron transfer doping for precise Fermi-level tuning.Despite great progress,challenges still persist in enhancing TE conversion efficiency,balancing or decoupling electrical conductivity,Seebeck coefficient and thermal conductivity,and leveraging melt-processing scalability of PBTTT.By bridging fundamental insights with applied research,this work provides a roadmap for advancing PBTTT-based TE materials toward efficient energy harvesting and wearable electronics.展开更多
The accurate characterization of thermoelectric properties at low temperatures is crucial for the development of high-performance thermoelectric cooling devices. While measurement errors of thermoelectric properties a...The accurate characterization of thermoelectric properties at low temperatures is crucial for the development of high-performance thermoelectric cooling devices. While measurement errors of thermoelectric properties at temperatures above room temperature have been extensively discussed, there is a lack of standard measurement protocols and error analyses for low-temperature transport properties. In this study, we present a measurement system capable of characterizing all three key thermoelectric parameters, i.e., Seebeck coefficient, electrical conductivity, and thermal conductivity, for a single sample across a temperature range of 10 K to 300 K. We investigated six representative commercial Bi_(2)Te_(3)-based samples(three N-type and three P-type). Using an error propagation model, we systematically analyzed the measurement uncertainties of the three intrinsic parameters and the resulting thermoelectric figure of merit. Our findings reveal that measurement uncertainties for both N-type and P-type Bi_(2)Te_(3)-based materials can be effectively maintained below 5% in the temperature range of 40 K to 300 K. However, the uncertainties increase to over 10% at lower temperatures, primarily due to the relatively smaller values of electrical resistivity and Seebeck coefficients in this regime. This work establishes foundational data for Bi_(2)Te_(3)-based thermoelectric materials and provides a framework for broader investigations of advanced low-temperature thermoelectrics.展开更多
The development of bionic sensing devices with advanced physiological functionalities has attracted significant attention in flexible electronics.In this study,we innovatively develop an air-stable photo-induced n-typ...The development of bionic sensing devices with advanced physiological functionalities has attracted significant attention in flexible electronics.In this study,we innovatively develop an air-stable photo-induced n-type dopant and a sophisticated photo-induced patterning technology to construct high-resolution joint-free p-n integrated thermoelectric devices.The exceptional stability of the photo-induced n-type dopant,combined with our meticulously engineered joint-free device architecture,results in extremely low temporal and spatial variations.These minimized variations,coupled with superior linearity,position our devices as viable candidates for artificial thermoreceptors capable of sensing external thermal noxious stimuli.By integrating them into a robotic arm with a pain perception system,we demonstrate accurate pain responses to external thermal stimuli.The system accurately discerns pain levels and initiates appropriate protective actions across varying intensities.Our findings present a novel strategy for constructing high-resolution thermoelectric sensing devices toward precise biomimetic thermoreceptors.展开更多
The thermoelectric transport of n-type Bi_(2)Te_(3) heavily depends on grain alignment,causing perfor-mance limitations that severely restrict the demand for low-grade waste heat recovery.Here,the n-type Bi_(2)Te_(2.7...The thermoelectric transport of n-type Bi_(2)Te_(3) heavily depends on grain alignment,causing perfor-mance limitations that severely restrict the demand for low-grade waste heat recovery.Here,the n-type Bi_(2)Te_(2.7)Se_(0.3) material with a certain textured structure is prepared by an innovative rotary swag-ing method.It is found that various defects including Te vacancies,dislocations,and grain boundaries significantly strengthen the phonon scattering.With an obviously suppressed thermal conductivity and well-maintained carrier mobility,the obtained rods extending up to several tens of centimeters achieve a peak ZT of 1.2 at 450 K and an average ZT of 1.0(300-550 K),with Vickers hardness and compressive strength increased to 0.42 GPa and 52.6 MPa,respectively.Moreover,the assembled 17-pair thermoelec-tric module achieves a competitive conversion efficiency of up to 6.3% and a high output power of 0.93 W at a temperature difference of 250 K.This study develops an effective strategy for synergistically en-hancing the thermoelectric and mechanical properties of n-type Bi_(2)(Te,Se)_(3).展开更多
The discovery of band convergence has opened an effective avenue for significantly enhancing thermoelectric performance of SnTe,while alloying CdTe in SnTe is evidenced efficient for improving the valley degeneracy.Ho...The discovery of band convergence has opened an effective avenue for significantly enhancing thermoelectric performance of SnTe,while alloying CdTe in SnTe is evidenced efficient for improving the valley degeneracy.However,the thermoelectric transport properties are limited due to the low solubility of CdTe in SnTe(~3%).Inspired by the improvement of dimensionless figure of merit zT in Cu or Se-doped SnTe,investigating the effect of Cu_(2)Se on the electronic and phonon transport properties of SnTe-CdTe alloys is highly desired.Traditionally,improving the quality factor can trigger an increase of the potential of a compound for higher zT,which is of importance for design of thermoelectric materials.Here,alloyed 3%Cu_(2)Se in SnTe-3%CdTe system enables an increased peak zT,which is attributed by the optimization of electronic performance(~21μW cm^(-1)K^(-2)at 800 K),as well as the decreased lattice thermal conductivity owing to the enhanced mass and strain fluctuations.More importantly,alloying Cu_(2)Se not only improves the quality factor from~0.25 to~0.45,resulting in a higher maximum potential zT,but also effectively preserves the Fermi energy in a relative optimized level.The current findings demonstrate the role of Cu_(2)Se for manipulating thermoelectrics in SnTe.展开更多
Recent theoretical predictions and experimental findings on the transport properties of n-type SnTe have triggered extensive researches on this simple binary compound,despite the realization of n-type SnTe being a gre...Recent theoretical predictions and experimental findings on the transport properties of n-type SnTe have triggered extensive researches on this simple binary compound,despite the realization of n-type SnTe being a great challenge.Herein,Cl as a donor dopant can effectively regulate the position of Fermi level in Sn_(0.6)Pb_(0.4)Te matrix and successfully achieve the n-type transport behavior in SnTe.An outstanding power factor of~14.7μW·cm^(-1)·K^(-2) at 300 K was obtained for Cl-doped Sn_(0.6)Pb_(0.4)Te sample.By combining the experimental analysis with theoretical calculations,the transport properties of n-type SnTe thermoelectrics doped with different halogen dopants(Cl,Br,and I)were then systematically investigated and estimated.The results demonstrated that Br and I had better doping efficiencies compared with Cl,which contributed to the well-optimized carrier concentrations of~1.03×10^(19)and~1.11×10^(19)cm^(-3)at 300 K,respectively.The improved n-type carrier concentrations effectively lead to the significant enhancement on the thermoelectric performance of n-type SnTe.Our study further promoted the experimental progress and deep interpretation of the transport features in n-type SnTe thermoelectrics.The present results could also be crucial for the development of n-type counterparts for SnTe-based thermoelectric devices.展开更多
Based on Peltier effect,Bi_(2)Te_(3)-based alloy is widely used in commercial solid-state refrigeration at room temperature.The mainstream strategies for enhancing room-temperature thermoelectric performance in Bi_(2)...Based on Peltier effect,Bi_(2)Te_(3)-based alloy is widely used in commercial solid-state refrigeration at room temperature.The mainstream strategies for enhancing room-temperature thermoelectric performance in Bi_(2)Te_(3)focus on band and microstructure engineering.However,a clear understanding of the modulation of band structure and scattering through such engineering remains still challenging,because the minority carriers compensate partially the overall transport properties for the narrow-gap Bi_(2)Te_(3)at room temperature(known as the bipolar effect).The purpose of this work is to model the transport properties near and far away from the bipolar effect region for Bi_(2)Te_(3)-based thermoelectric material by a two-band model taking contributions of both majority and minority carriers into account.This is endowed by shifting the Fermi level from the conduction band to the valence band during the modeling.A large amount of data of Bi_(2)Te_(3)-based materials is collected from various studies for the comparison between experimental and predicted properties.The fundamental parameters,such as the density of states effective masses and deformation potential coefficients,of Bi_(2)Te_(3)-based materials are quantified.The analysis can help find out the impact factors(e.g.the mobility ratio between conduction and valence bands)for the improvement of thermoelectric properties for Bi_(2)Te_(3)-based alloys.This work provides a convenient tool for analyzing and predicting the transport performance even in the presence of bipolar effect,which can facilitate the development of the narrow-gap thermoelectric semiconductors.展开更多
This study proposed a strategy for effectively diminishing the carrier concentration in Cu_(2)Te by introducing graphene sheets,Based on thermoelectric property measurements and single parabolic band modeling,the inco...This study proposed a strategy for effectively diminishing the carrier concentration in Cu_(2)Te by introducing graphene sheets,Based on thermoelectric property measurements and single parabolic band modeling,the incorporated graphene effectively reduced the carrier concentration,not only enhancing the thermoelectric performance of the Cu_(2)Te/graphene composite but also substantially improving its figure of merit up to ~1.47 at 1000 K,which is 268% higher than that of pristine Cu_(2)Te,This study gives an insight into the control of carrier concentration and thermoelectric properties in Cu_(2)Te,and it could be extended to other copper chalcogenides for excellent thermoelectrics.展开更多
Tetradymite-structured chalcogenides,such as Bi_(2)Te_(3) and Sb_(2)Te_(3),are quasi-two-dimensional(2D)layered compounds,which are significant thermoelectric materials applied near room temperature.The intercalation ...Tetradymite-structured chalcogenides,such as Bi_(2)Te_(3) and Sb_(2)Te_(3),are quasi-two-dimensional(2D)layered compounds,which are significant thermoelectric materials applied near room temperature.The intercalation of vip species in van der Waals(vdW)gap implemented for tunning properties has attracted much attention in recent years.We attempt to insert Ga atoms in the vdW gap between the Te layers in p-type Bi_(0.3)Sb_(1.7)Te_(3)(BST)for further improving thermoelectrics.The vdW-related defects(including extrinsic interstitial and intrinsic defects)induced by Ga intercalation can not only modulate the carrier concentration but also enhance the texture,thereby yielding excellent electrical properties,which are reflected in the power factor PF~4.43 mW·m^(-1)·K^(-2).Furthermore,the intercalation of Ga produces multi-scale lattice imperfections such as point defects,Te precipitations,and nanopores,realizing the low lattice thermal conductivity in BST-Ga samples.Ultimately,a peak zT~1.1 at 373 K is achieved in the BST-1%Ga sample and greatly improved by~22%compared to the pristine BST.The weak bonding of vdW interlayer interaction can boost the synergistic effect for advancing BST-based or other layered thermoelectrics.展开更多
Nonisovalent(GaN)_(1-x)(ZnO)_(x)alloys are more technologically promising than their binary counterparts because of the abruptly reduced band gap.Unfortunately,the lack of two-dimensional(2D)configurations as well as ...Nonisovalent(GaN)_(1-x)(ZnO)_(x)alloys are more technologically promising than their binary counterparts because of the abruptly reduced band gap.Unfortunately,the lack of two-dimensional(2D)configurations as well as complete stoichiometries hinders to further explore the thermal transport,thermoelectrics,and adsorption/permeation.We identify that multilayer(GaN)_(1-x)(ZnO)_(x)stabilize as wurtzite-like Pm-(GaN)_(3)(ZnO)_(1),Pmc2_(1)-(Ga N)_(1)(ZnO)_(1),P3m1-(GaN)_(1)(ZnO)_(2),and haeckelite C2/m-(GaN)_(1)(ZnO)_(3)via structural searches.P3m1-(GaN)_(1)(ZnO)_(2)shares the excellent thermoelectrics with the figure of merit ZT as high as 3.08 at 900 K for the p-type doping due to the ultralow lattice thermal conductivity,which mainly arises from the strong anharmonicity by the interlayer asymmetrical charge distributions.The p–d coupling is prohibited from the group theory in C2/m-(Ga N)_(1)(ZnO)_(3),which thereby results in the anomalous band structure versus Zn O composition.To unveil the adsorption/permeation of H^(+),Na^(+),and OH^(-)ions in AA-stacking configurations,the potential wells and barriers are explored from the Coulomb interaction and the ionic size.Our work is helpful in experimental fabrication of novel optoelectronic and thermoelectric devices by 2D(GaN)_(1-x)(ZnO)_(x)alloys.展开更多
The density junction theory and discrete variation method ( DFT - DVM) was used to study correlation between composition, structure, chemical bond, and property of thermoelectrics of Bi-Sb-Te series. 8 models of Bi20-...The density junction theory and discrete variation method ( DFT - DVM) was used to study correlation between composition, structure, chemical bond, and property of thermoelectrics of Bi-Sb-Te series. 8 models of Bi20-xSbxTe32(x = 0,2,6,8,12,14,18 and 20) were calculated. The results show that there is less difference in the ionic bonds between Te( I)-Bi(Sb) and Te(Ⅱ)-Bi(Sb) , but the covalent bond of Te(Ⅰ)-Bi( Sb ) is stronger than that of Te(Ⅱ)-Bi( Sb ) . The interaction between Te(Ⅰ) and Te(Ⅰ) in different layers is the weakest and the interaction should be Van Der Wools power. The charge of Sb is lower than that of Bi, and the ionic bond of Te-Sb is weaker than that of Te-Bi. The covalent bond of Te-Sb is also weaker than that of Te-Bi. Therefore, the thermoelectric property may be imfiroved by adjusting the electrical conductivity and thermal conductivity through changing the composition in the compounds of Bi-Sb-Te. The calculated results are consistent with the experiments.展开更多
AgCrSe2-based compounds have attracted much attention as an environmentally friendly thermoelectric material in recent years due to the intriguing liquid-like properties.However,the ultra-low carrier concentration and...AgCrSe2-based compounds have attracted much attention as an environmentally friendly thermoelectric material in recent years due to the intriguing liquid-like properties.However,the ultra-low carrier concentration and the high Ag_(Cr)deep-level defects limit the overall thermoelectric performance.Here,we successfully introduced Pb into Ag-deficient Ag_(0.97)CrSe_(2) alloys to tune the carrier concentration across a broad temperature range.The Pb^(2+) as an acceptor dopant preferentially occupies Cr sites,boosting the hole carrier concentration to 1.77×10^(19) cm^(-3) at room temperature.Furthermore,the Pb strongly inhibits the creation of intrinsic Ag_(Cr) defects,weakens the increased thermal excited ionization with the increasing temperature and slowed the rising trend of the carrier concentration.The designed carrier concentration matches the theoretically predicted optimized one over the entire temperature range,leading to a remarkable enhancement in power factor,especially the maximum power factor of ~500 μW·m^(-1)·K^(-2) at 750 K is superior to most previous results.Additionally,the abundant point defects promote phonon scattering,thus reducing the lattice thermal conductivity.As a result,the maximum figure of merit zT(~0.51 at 750 K) is achieved in Ag_(0.97)Cr_(0.995)Pb_(0.005)Se_(2).This work confirms the feasibility of manipulating deep-level defects to achieve temperature-dependent optimal carrier concentration and provides a valuable guidance for other thermoelectric materials.展开更多
The successful deployment of thermoelectric materials necessitates the concurrent development of highperformance p-type and n-type pairs situated within an identical matrix.Nevertheless,limiting by the low dopant solu...The successful deployment of thermoelectric materials necessitates the concurrent development of highperformance p-type and n-type pairs situated within an identical matrix.Nevertheless,limiting by the low dopant solubility,the conventional doping often cannot transfer the Fermi level to the opposite carrier type.Here,the solubility limit of donor dopants was enhanced to achieve n-type GeSe by inducing additional cationic vacancies through raising crystal symmetry.Converting the intrinsic p-type nature of GeSe to n-type poses significant challenges,primarily due to the exceedingly low dopant solubility within its native orthorhombic structure.To overcome this,the In_(2)Te_(3)alloying was initially employed to transition GeSe from orthorhombic to rhombohedral structure,simultaneously generating a large number of Ge vacancies.Following this,the introduction of Pb acts to mitigate the excessive Ge vacancies,steering the material toward a weak p-type character.Crucially,the elevated Ge vacancy concentration serves to extend the solubility limit of Bi donor dopant,which not only promotes the formation of cubic phase,but also enables the p-n type transition.As a result,a peak zT of 0.18 at 773 K was attained for the n-type cubic Ge_(0.55)Bi_(0.2)Pb_(0.2)5Se(In_(2)Te_(3))_(0.1),marking an 18-fold enhancement in comparison with its n-type orthorhombic counterpart.This work attests to the efficacy of introducing vacancies through enhancing crystal symmetry as an effective means to expand dopant solubility,thereby offering valuable insights into the achievement of compatible p-and n-type chalcogenides within the same matrix.展开更多
Thermoelectrics is a research area that focuses on the development of high-performance materials for direct thermal and electrical energy conversion in power generation and solid-state cooling.Ever since Ioffe’s infe...Thermoelectrics is a research area that focuses on the development of high-performance materials for direct thermal and electrical energy conversion in power generation and solid-state cooling.Ever since Ioffe’s inference in 1950s that heavily doped semiconductors make the best thermoelectrics,inorganic semiconductors and semimetals have remained the cornerstone of high-performance thermoelectric materials.In this article,we review the recent advances in inorganic material thermoelectrics with special emphases on:(i)the complementary local-global view of material and the roles of configurational entropy and Fermi surface complexity in material screening;(ii)the emerging schemes of resonant bonding,dynamic disorder,“gap”engineering,pudding-mold-shaped bands in material performance enhancement;(iii)a list of promising bulk materials,such as host-vip structures,half-Heusler compounds,silicides,Zintl phases,and incommensurate structures;and(iv)state-of-the-art materials synthesis and fabrication techniques.These advances will facilitate the development of next-generation bulk thermoelectric materials.展开更多
Mg_(3)(Sb,Bi)_(2)-based thermoelectrics(TEs)show promise for near-room-temperature energy conversion and TE-cooling applications.However,further improvements in electrical power factors and figure-of-merits(zTs)are co...Mg_(3)(Sb,Bi)_(2)-based thermoelectrics(TEs)show promise for near-room-temperature energy conversion and TE-cooling applications.However,further improvements in electrical power factors and figure-of-merits(zTs)are constrained by precise Mg-vacancy regulation and elucidation of underlying mechanisms.Herein,we report a novel in-situ Mg-vacancy engineering strategy in Mg_(3)(Sb,Bi)_(2)where excess Mg is generated from local reactions between a selection of specific transition metals and the component anionic element(s)in Mg_(3)(Sb,Bi)_(2)during spark-plasma-sintering.This process effectively refills matrix Mg-vacancies through the subsequent global diffusion of Mg cations in Mg_(3)(Sb,Bi)_(2)lattices.This local-reaction-global-diffusion concept,contrasting with reported mechanisms associated with localized grain-boundary engineering,is elaborated through multiscale investigation.Vacancy-restrained Mg_(3)(Sb,Bi)_(2)demonstrates remarkably enhanced carrier mobility and zTs,achieving record-high power factors.Our fabricated Mg_(3)Sb_(0.5)Bi_(1.5)/MgAgSb and Mg_(3)SbBi/MgAgSb modules achieve record-high dual-output performance with power-density/efficiency values of 1.23 W cm^(−2)/11.7%and 1.05 W cm^(−2)/12.8%,respectively,under a temperature difference(ΔT)of 315 K.The constructed Mg_(3)Sb_(0.5)Bi_(1.5)/Bi_(0.5)Sb_(1.5)Te_(3)and Mg_(3)Sb_(0.75)Bi_(1.25)/Bi_(0.5)Sb_(1.5)Te_(3)Peltier modules deliver competitive coolingΔTmax exceeding 70 and 67 K,respectively,at 303 K.The concept is expected to extend to the defect engineering of other energy materials(e.g.,SnTe and PbSe TEs),TE-interface materials,and metal-semiconductor interfaces with optimized functionalities.展开更多
Thermoelectric materials convert heat directly into electricity and are therefore promising for energy harvesting and environmental applications.Ideal high-performance thermoelectrics combine ultralow lattice thermal ...Thermoelectric materials convert heat directly into electricity and are therefore promising for energy harvesting and environmental applications.Ideal high-performance thermoelectrics combine ultralow lattice thermal conductivity,κL,with high carrier mobility,a paradigm commonly termed phonon-glass electron-crystal.However,strong coupling between electronic and phononic transport complicates simultaneous optimization of these properties.BecauseκL is largely independent of electronic transport,targeted suppression ofκL is an effective route to partially decouple heat and charge transport.This review summarizes recent advances in reducingκL via two complementary approaches:phonon engineering of bulk nanostructured systems and phonon engineering of low-dimensional materials.In bulk systems,κL may be minimized while retaining high electrical conductivity and maximizing the thermoelectric figure of merit ZT by controlling three fundamental phonon parameters:the volumetric specific heat cv,the phonon group velocity vg,and the phonon relaxation timeτ.Low-dimensional architectures,including superlattices,nanowires,and nanocomposites,supply additional levers to suppress lattice heat transport and to tailor the electronic structure.Integrating multiscale and multimodal phononcontrol strategies enables significant reductions inκL without sacrificing electronic performance,thereby advancing the phonon-glass electron-crystal paradigm.展开更多
Bi_(2)Se_(3) has emerged as a promising thermoelectric(TE)material due to its environmentally benign composition and earth-abundant constituents.However,the practical implementation of Bi_(2)Se_(3)-based systems remai...Bi_(2)Se_(3) has emerged as a promising thermoelectric(TE)material due to its environmentally benign composition and earth-abundant constituents.However,the practical implementation of Bi_(2)Se_(3)-based systems remains challenging due to suboptimal TE performance.This study demonstrates the fabrication of c-axis oriented Bi_(2)Se_(3) thin films through pulsed laser deposition,with subsequent selenization treatment significantly enhancing TE performance through dual optimization of carrier concentration and crystallographic alignment.A strategic post-deposition selenization process effectively mitigates selenium vacancies and correspondingly reduces the carrier concentration to 2.0×10^(19) cm^(−3) while improving in-plane carrier mobility.A high power factor(PF)of about 9.5μW·cm^(−1)·K^(−2) is achieved at 475 K in the highly c-axis oriented Bi_(2)Se_(3) thin films selenized for about 60 min,outperforming the reported state-of-the-art Bi_(2)Se_(3) films.Demonstrating practical applicability,an 8-leg planar thin-film device generates an exceptional power density of 441.3μW/cm^(2) under a 25 K temperature gradient,establishing new performance benchmarks for chalcogenide-based microgenerators.These findings provide crucial insights into defect engineering and structural optimization strategies for developing high-performance TE devices compatible with self-powered microelectronic applications.展开更多
Thermoelectric properties of topological insulators have traditionally been examined in the context of their metallic surface states.However,recent studies have begun to unveil intriguing thermoelectric effects emergi...Thermoelectric properties of topological insulators have traditionally been examined in the context of their metallic surface states.However,recent studies have begun to unveil intriguing thermoelectric effects emerging from the bulk electronic states of topological insulators,which have largely been overlooked in the past.Charge transport phenomena through the bulk are especially important under typical operating conditions of thermoelectric devices,necessitating a comprehensive review of both surface and bulk transport in topological insulators.Here,we review thermoelectric properties that are uniquely observed in topological insulators,placing special emphasis on unconventional phenomena emerging from bulk states.We demonstrate that unusual thermoelectric effects arising from bulk states,such as band inversion-driven warping,can be discerned in experiments through a simple analysis of the weighted mobility.We believe that there is still plenty to uncover within the bulk of topological insulators,yet our current understanding can already inspire new strategies for designing and discovering new materials for next-generation thermoelectrics.展开更多
To date,extensive efforts have been devoted to designing new conjugated polymers with long alkyl or ethylene glycol sidechains.However,these sidechains are insulators,limiting further performance enhancement in doped ...To date,extensive efforts have been devoted to designing new conjugated polymers with long alkyl or ethylene glycol sidechains.However,these sidechains are insulators,limiting further performance enhancement in doped conjugated polymers.Moreover,the most widely used chlorinated solvents are toxic,limiting the practical applications of many conjugated polymers.Here,we report a water/alcohol processable n-type conjugated polymer P(Py2FT),featuring side chain-free cationic backbones.P(Py2FT)exhibits a high n-type electrical conductivity of up to 28.1 S cm^(−1)and a high thermoelectric power factor of up to 28.7μWm^(−1)K^(−2),comparable to some conventional n-type conjugated polymers reported recently.More importantly,cationic polymers display tight molecular packings and interesting enhanced backbone planarity after n-doping,which,we envision,provides a new research direction to address the sidechain issue in conventional conjugated polymers.Our work demonstrates that sidechain-free cationic polymers have great potential for green-solvent-processed heavily doped organic electronics.展开更多
基金supported by the National Key Research and Development Program of China (Grant No.2024YFA1210400)the National Science Fund for Distinguished Young Scholars (Grant No.52525101)+3 种基金the National Natural Science Foundation of China (Grant Nos.52450001 and 22409014)the International Cooperation and Exchange of the National Natural Science Foundation of China (Grant No.52411540237)the Tencent Xplorer Prizethe support of the National High-Level Talent Special Support Programs—Young Talents。
文摘The interdependence of electrical parameters has long inhibited the progress of bismuth telluride(Bi_(2)Te3),limiting its widespread application in thermoelectric cooling and power generation.This work investigates the n-type Bi_(2)Te_(2.79)Se_(0.21)I_(0.004)(Bi_(2)(Te,Se)_(3),BTS)system with light Zn doping,revealing that Zn addition simultaneously enhances the Seebeck coefficient(S)and electrical conductivity(σ)through the modulation of defect composition and multi-level band regulation.The substitution of Zn atoms at Bi sites enhances S via bandgap(E_(g))widening,band flattening,and band splitting effects,contributing to a competitive power factor(PF)of∼60μW⋅cm^(−1)⋅K^(−2).Additionally,thermal conductivity is maintained at a low level,leading to an extraordinary figure-of-merit(ZT)value of∼1.3 at room temperature.Furthermore,the Bi_(2)Zn_(0.01)Te_(2.79)Se_(0.21)I_(0.004) system demonstrates impressive thermoelectric device performance,with a maximum cooling temperature difference(ΔT_(max))of∼70.0 K at 300 K,rising to∼78.0 K at 323 K and∼85.7 K at 343 K,as well as a maximum conversion efficiency(η_(max))of∼6.2%under aΔT of 200 K.This study clarifies the mechanism of Zn doping and presents a cost-effective strategy for enhancing the performance of n-type BTS thermoelectrics and their devices.
基金financial support by Guangdong Basic and Applied Basic Research Foundation(2025A1515012415)National Natural Science Foundation of China(52242305)the Stable Support Project of Shenzhen(Project No.20231122125728001).
文摘Thermoelectric(TE)materials,being capable of converting waste heat into electricity,are pivotal for sustainable energy solutions.Among emerging TE materials,organic TE materials,particularly conjugated polymers,are gaining prominence due to their unique combination of mechanical flexibility,environmental compatibility,and solution-processable fabrication.A notable candidate in this field is poly(2,5-bis(3-alkylthiophen-2-yl)thieno[3,2-b]thiophene)(PBTTT),a liquid-crystalline conjugated polymer,with high charge carrier mobility and adaptability to melt-processing techniques.Recent advancements have propelled PBTTT’s figure of merit from below 0.1 to a remarkable 1.28 at 368 K,showcasing its potential for practical applications.This review systematically examines strategies to enhance PBTTT’s TE performance through doping(solution,vapor,and anion exchange doping),composite engineering,and aggregation state controlling.Recent key breakthroughs include ion exchange doping for stable charge modulation,multi-heterojunction architectures reducing thermal conductivity,and proton-coupled electron transfer doping for precise Fermi-level tuning.Despite great progress,challenges still persist in enhancing TE conversion efficiency,balancing or decoupling electrical conductivity,Seebeck coefficient and thermal conductivity,and leveraging melt-processing scalability of PBTTT.By bridging fundamental insights with applied research,this work provides a roadmap for advancing PBTTT-based TE materials toward efficient energy harvesting and wearable electronics.
基金supported by the National Natural Science Foundation of China (Grant No. 52172259)the National Key Research and Development Program of China (Grant Nos. 2021YFA0718700 and 2022YFB3803900)the Fundamental Research Funds for the Inner Mongolia Normal University (Grant No. 2022JBTD008)。
文摘The accurate characterization of thermoelectric properties at low temperatures is crucial for the development of high-performance thermoelectric cooling devices. While measurement errors of thermoelectric properties at temperatures above room temperature have been extensively discussed, there is a lack of standard measurement protocols and error analyses for low-temperature transport properties. In this study, we present a measurement system capable of characterizing all three key thermoelectric parameters, i.e., Seebeck coefficient, electrical conductivity, and thermal conductivity, for a single sample across a temperature range of 10 K to 300 K. We investigated six representative commercial Bi_(2)Te_(3)-based samples(three N-type and three P-type). Using an error propagation model, we systematically analyzed the measurement uncertainties of the three intrinsic parameters and the resulting thermoelectric figure of merit. Our findings reveal that measurement uncertainties for both N-type and P-type Bi_(2)Te_(3)-based materials can be effectively maintained below 5% in the temperature range of 40 K to 300 K. However, the uncertainties increase to over 10% at lower temperatures, primarily due to the relatively smaller values of electrical resistivity and Seebeck coefficients in this regime. This work establishes foundational data for Bi_(2)Te_(3)-based thermoelectric materials and provides a framework for broader investigations of advanced low-temperature thermoelectrics.
基金the Guangdong Basic and Applied Basic Research Foundation(Nos.2022A1515110432,2025A1515012050)National Natural Science Foundation of China(No.52242305)。
文摘The development of bionic sensing devices with advanced physiological functionalities has attracted significant attention in flexible electronics.In this study,we innovatively develop an air-stable photo-induced n-type dopant and a sophisticated photo-induced patterning technology to construct high-resolution joint-free p-n integrated thermoelectric devices.The exceptional stability of the photo-induced n-type dopant,combined with our meticulously engineered joint-free device architecture,results in extremely low temporal and spatial variations.These minimized variations,coupled with superior linearity,position our devices as viable candidates for artificial thermoreceptors capable of sensing external thermal noxious stimuli.By integrating them into a robotic arm with a pain perception system,we demonstrate accurate pain responses to external thermal stimuli.The system accurately discerns pain levels and initiates appropriate protective actions across varying intensities.Our findings present a novel strategy for constructing high-resolution thermoelectric sensing devices toward precise biomimetic thermoreceptors.
基金supported by the National Natural Science Foundation of China(grant no.U21A2079)the China Post-doctoral Science Foundation(grant no.2024M753342)+3 种基金the Post-doctoral Fellowship Program of CPSF(grant no.GZB20230786)the Ningbo International Cooperation Project(grant no.2023H002)the Ningbo Science&Technology Project(grant no.2023A-160-B)the Ningbo Science&Technology Innovation 2025 Major Project(grant no.2022Z187).
文摘The thermoelectric transport of n-type Bi_(2)Te_(3) heavily depends on grain alignment,causing perfor-mance limitations that severely restrict the demand for low-grade waste heat recovery.Here,the n-type Bi_(2)Te_(2.7)Se_(0.3) material with a certain textured structure is prepared by an innovative rotary swag-ing method.It is found that various defects including Te vacancies,dislocations,and grain boundaries significantly strengthen the phonon scattering.With an obviously suppressed thermal conductivity and well-maintained carrier mobility,the obtained rods extending up to several tens of centimeters achieve a peak ZT of 1.2 at 450 K and an average ZT of 1.0(300-550 K),with Vickers hardness and compressive strength increased to 0.42 GPa and 52.6 MPa,respectively.Moreover,the assembled 17-pair thermoelec-tric module achieves a competitive conversion efficiency of up to 6.3% and a high output power of 0.93 W at a temperature difference of 250 K.This study develops an effective strategy for synergistically en-hancing the thermoelectric and mechanical properties of n-type Bi_(2)(Te,Se)_(3).
基金financially supported by the National Key Research and Development Program of China(Grant No.2018YFA0702100)the Joint Funds of the National Natural Science Foundation(NNSF)of China+4 种基金the Chinese Academy of Sciences’Large-Scale Scientific Facility(Grant No.U1932106)the NNSF of China(Grant No.51771126)the Nuclear Power Technology Innovation Center(NPTIC)of China(Grant No.HG2020065)Sichuan University Innovation Research Program of China(Grant No.2020SCUNL112)the World First-Class University Construction Funding of China。
文摘The discovery of band convergence has opened an effective avenue for significantly enhancing thermoelectric performance of SnTe,while alloying CdTe in SnTe is evidenced efficient for improving the valley degeneracy.However,the thermoelectric transport properties are limited due to the low solubility of CdTe in SnTe(~3%).Inspired by the improvement of dimensionless figure of merit zT in Cu or Se-doped SnTe,investigating the effect of Cu_(2)Se on the electronic and phonon transport properties of SnTe-CdTe alloys is highly desired.Traditionally,improving the quality factor can trigger an increase of the potential of a compound for higher zT,which is of importance for design of thermoelectric materials.Here,alloyed 3%Cu_(2)Se in SnTe-3%CdTe system enables an increased peak zT,which is attributed by the optimization of electronic performance(~21μW cm^(-1)K^(-2)at 800 K),as well as the decreased lattice thermal conductivity owing to the enhanced mass and strain fluctuations.More importantly,alloying Cu_(2)Se not only improves the quality factor from~0.25 to~0.45,resulting in a higher maximum potential zT,but also effectively preserves the Fermi energy in a relative optimized level.The current findings demonstrate the role of Cu_(2)Se for manipulating thermoelectrics in SnTe.
基金supported by the National Natural Science Foundation of China(No.52002042)the National Postdoctoral Program for Innovative Talents(No.BX20200028)+3 种基金the National Key Research and Development Program of China(No.2018YFA0702100)China Postdoctoral Science Foundation(No.2021M690280)the Natural Science Foundation of Chongqing,China(No.cstc2019jcyj-msxmX0554)the support from the National Science Fund for Distinguished Young Scholars(No.51925101)。
文摘Recent theoretical predictions and experimental findings on the transport properties of n-type SnTe have triggered extensive researches on this simple binary compound,despite the realization of n-type SnTe being a great challenge.Herein,Cl as a donor dopant can effectively regulate the position of Fermi level in Sn_(0.6)Pb_(0.4)Te matrix and successfully achieve the n-type transport behavior in SnTe.An outstanding power factor of~14.7μW·cm^(-1)·K^(-2) at 300 K was obtained for Cl-doped Sn_(0.6)Pb_(0.4)Te sample.By combining the experimental analysis with theoretical calculations,the transport properties of n-type SnTe thermoelectrics doped with different halogen dopants(Cl,Br,and I)were then systematically investigated and estimated.The results demonstrated that Br and I had better doping efficiencies compared with Cl,which contributed to the well-optimized carrier concentrations of~1.03×10^(19)and~1.11×10^(19)cm^(-3)at 300 K,respectively.The improved n-type carrier concentrations effectively lead to the significant enhancement on the thermoelectric performance of n-type SnTe.Our study further promoted the experimental progress and deep interpretation of the transport features in n-type SnTe thermoelectrics.The present results could also be crucial for the development of n-type counterparts for SnTe-based thermoelectric devices.
基金National Natural Science Foundation of China(T2125008,92263108,92163203,52102292,52003198)Shanghai Rising-Star Program(23QA1409300)Innovation Program of Shanghai Municipal Education Commission(2021-01-07-00-07-E00096)。
文摘Based on Peltier effect,Bi_(2)Te_(3)-based alloy is widely used in commercial solid-state refrigeration at room temperature.The mainstream strategies for enhancing room-temperature thermoelectric performance in Bi_(2)Te_(3)focus on band and microstructure engineering.However,a clear understanding of the modulation of band structure and scattering through such engineering remains still challenging,because the minority carriers compensate partially the overall transport properties for the narrow-gap Bi_(2)Te_(3)at room temperature(known as the bipolar effect).The purpose of this work is to model the transport properties near and far away from the bipolar effect region for Bi_(2)Te_(3)-based thermoelectric material by a two-band model taking contributions of both majority and minority carriers into account.This is endowed by shifting the Fermi level from the conduction band to the valence band during the modeling.A large amount of data of Bi_(2)Te_(3)-based materials is collected from various studies for the comparison between experimental and predicted properties.The fundamental parameters,such as the density of states effective masses and deformation potential coefficients,of Bi_(2)Te_(3)-based materials are quantified.The analysis can help find out the impact factors(e.g.the mobility ratio between conduction and valence bands)for the improvement of thermoelectric properties for Bi_(2)Te_(3)-based alloys.This work provides a convenient tool for analyzing and predicting the transport performance even in the presence of bipolar effect,which can facilitate the development of the narrow-gap thermoelectric semiconductors.
基金supported by the MSIT(Ministry of Science and ICT),Korea,under the ITRC(Information Technology Research Center)support program supervised by the IITP(Institute of Information&Communications Technology Planning&Evaluation)(ⅡTP-2020-2020-0-01655)funded and conducted under the Competency Development Program for Industry Specialists of the Korean Ministry of Trade,Industry and Energy(MOTIE),operated by Korea Institute for Advancement of Technology(KIAT)(No.P0012453,Next-generation Display Expert Training Project for Innovation Process and Equipment,Materials Engineers)。
文摘This study proposed a strategy for effectively diminishing the carrier concentration in Cu_(2)Te by introducing graphene sheets,Based on thermoelectric property measurements and single parabolic band modeling,the incorporated graphene effectively reduced the carrier concentration,not only enhancing the thermoelectric performance of the Cu_(2)Te/graphene composite but also substantially improving its figure of merit up to ~1.47 at 1000 K,which is 268% higher than that of pristine Cu_(2)Te,This study gives an insight into the control of carrier concentration and thermoelectric properties in Cu_(2)Te,and it could be extended to other copper chalcogenides for excellent thermoelectrics.
基金Project supported by the National Key Research and Development Program of China(Grant Nos.2022YFB3803900 and 2018YFA0702100)the Joint Funds of the National Natural Science Foundation of China and the Chinese Academy of Sciences’Large-Scale Scientific Facility(Grant No.U1932106)the Sichuan University Innovation Research Program of China(Grant No.2020SCUNL112)。
文摘Tetradymite-structured chalcogenides,such as Bi_(2)Te_(3) and Sb_(2)Te_(3),are quasi-two-dimensional(2D)layered compounds,which are significant thermoelectric materials applied near room temperature.The intercalation of vip species in van der Waals(vdW)gap implemented for tunning properties has attracted much attention in recent years.We attempt to insert Ga atoms in the vdW gap between the Te layers in p-type Bi_(0.3)Sb_(1.7)Te_(3)(BST)for further improving thermoelectrics.The vdW-related defects(including extrinsic interstitial and intrinsic defects)induced by Ga intercalation can not only modulate the carrier concentration but also enhance the texture,thereby yielding excellent electrical properties,which are reflected in the power factor PF~4.43 mW·m^(-1)·K^(-2).Furthermore,the intercalation of Ga produces multi-scale lattice imperfections such as point defects,Te precipitations,and nanopores,realizing the low lattice thermal conductivity in BST-Ga samples.Ultimately,a peak zT~1.1 at 373 K is achieved in the BST-1%Ga sample and greatly improved by~22%compared to the pristine BST.The weak bonding of vdW interlayer interaction can boost the synergistic effect for advancing BST-based or other layered thermoelectrics.
基金the National Natural Science Foundation of China(Grant No.11774416)the Fundamental Research Funds for the Central Universities(Grant Nos.2017XKZD08 and 2015XKMS081)+1 种基金the Postgraduate Research&Practice Innovation Program of Jiangsu Province,China(Grant No.KYCX202039)the Assistance Program for Future Outstanding Talents of China University of Mining and Technology(Grant No.2020WLJCRCZL063)。
文摘Nonisovalent(GaN)_(1-x)(ZnO)_(x)alloys are more technologically promising than their binary counterparts because of the abruptly reduced band gap.Unfortunately,the lack of two-dimensional(2D)configurations as well as complete stoichiometries hinders to further explore the thermal transport,thermoelectrics,and adsorption/permeation.We identify that multilayer(GaN)_(1-x)(ZnO)_(x)stabilize as wurtzite-like Pm-(GaN)_(3)(ZnO)_(1),Pmc2_(1)-(Ga N)_(1)(ZnO)_(1),P3m1-(GaN)_(1)(ZnO)_(2),and haeckelite C2/m-(GaN)_(1)(ZnO)_(3)via structural searches.P3m1-(GaN)_(1)(ZnO)_(2)shares the excellent thermoelectrics with the figure of merit ZT as high as 3.08 at 900 K for the p-type doping due to the ultralow lattice thermal conductivity,which mainly arises from the strong anharmonicity by the interlayer asymmetrical charge distributions.The p–d coupling is prohibited from the group theory in C2/m-(Ga N)_(1)(ZnO)_(3),which thereby results in the anomalous band structure versus Zn O composition.To unveil the adsorption/permeation of H^(+),Na^(+),and OH^(-)ions in AA-stacking configurations,the potential wells and barriers are explored from the Coulomb interaction and the ionic size.Our work is helpful in experimental fabrication of novel optoelectronic and thermoelectric devices by 2D(GaN)_(1-x)(ZnO)_(x)alloys.
基金Funded by Open Foundation of State Key Laboratory of Ad-vanced Technology for Materials Synthesis and Processing, Wuhan University of Technology.
文摘The density junction theory and discrete variation method ( DFT - DVM) was used to study correlation between composition, structure, chemical bond, and property of thermoelectrics of Bi-Sb-Te series. 8 models of Bi20-xSbxTe32(x = 0,2,6,8,12,14,18 and 20) were calculated. The results show that there is less difference in the ionic bonds between Te( I)-Bi(Sb) and Te(Ⅱ)-Bi(Sb) , but the covalent bond of Te(Ⅰ)-Bi( Sb ) is stronger than that of Te(Ⅱ)-Bi( Sb ) . The interaction between Te(Ⅰ) and Te(Ⅰ) in different layers is the weakest and the interaction should be Van Der Wools power. The charge of Sb is lower than that of Bi, and the ionic bond of Te-Sb is weaker than that of Te-Bi. The covalent bond of Te-Sb is also weaker than that of Te-Bi. Therefore, the thermoelectric property may be imfiroved by adjusting the electrical conductivity and thermal conductivity through changing the composition in the compounds of Bi-Sb-Te. The calculated results are consistent with the experiments.
基金Project supported by the National Key Research and Development Program of China (Grant Nos. 2018YFA0702100and 2022YFB3803900)the Joint Funds of the National Natural Science Foundation of China and the Chinese Academy of Sciences (CAS)’ Large-Scale Scientific Facility (Grant No. U1932106)the Sichuan University Innovation Research Program of China (Grant No. 2020SCUNL112)。
文摘AgCrSe2-based compounds have attracted much attention as an environmentally friendly thermoelectric material in recent years due to the intriguing liquid-like properties.However,the ultra-low carrier concentration and the high Ag_(Cr)deep-level defects limit the overall thermoelectric performance.Here,we successfully introduced Pb into Ag-deficient Ag_(0.97)CrSe_(2) alloys to tune the carrier concentration across a broad temperature range.The Pb^(2+) as an acceptor dopant preferentially occupies Cr sites,boosting the hole carrier concentration to 1.77×10^(19) cm^(-3) at room temperature.Furthermore,the Pb strongly inhibits the creation of intrinsic Ag_(Cr) defects,weakens the increased thermal excited ionization with the increasing temperature and slowed the rising trend of the carrier concentration.The designed carrier concentration matches the theoretically predicted optimized one over the entire temperature range,leading to a remarkable enhancement in power factor,especially the maximum power factor of ~500 μW·m^(-1)·K^(-2) at 750 K is superior to most previous results.Additionally,the abundant point defects promote phonon scattering,thus reducing the lattice thermal conductivity.As a result,the maximum figure of merit zT(~0.51 at 750 K) is achieved in Ag_(0.97)Cr_(0.995)Pb_(0.005)Se_(2).This work confirms the feasibility of manipulating deep-level defects to achieve temperature-dependent optimal carrier concentration and provides a valuable guidance for other thermoelectric materials.
基金financially supported by the National Key R&D Program of China(No.2021YFB1507403)the National Natural Science Foundation of China(No.52071218)+1 种基金Shenzhen Science and Technology Innovation Commission(No.JCYJ20230808105700001)Shenzhen University 2035 Program for Excellent Research(No.00000218)。
文摘The successful deployment of thermoelectric materials necessitates the concurrent development of highperformance p-type and n-type pairs situated within an identical matrix.Nevertheless,limiting by the low dopant solubility,the conventional doping often cannot transfer the Fermi level to the opposite carrier type.Here,the solubility limit of donor dopants was enhanced to achieve n-type GeSe by inducing additional cationic vacancies through raising crystal symmetry.Converting the intrinsic p-type nature of GeSe to n-type poses significant challenges,primarily due to the exceedingly low dopant solubility within its native orthorhombic structure.To overcome this,the In_(2)Te_(3)alloying was initially employed to transition GeSe from orthorhombic to rhombohedral structure,simultaneously generating a large number of Ge vacancies.Following this,the introduction of Pb acts to mitigate the excessive Ge vacancies,steering the material toward a weak p-type character.Crucially,the elevated Ge vacancy concentration serves to extend the solubility limit of Bi donor dopant,which not only promotes the formation of cubic phase,but also enables the p-n type transition.As a result,a peak zT of 0.18 at 773 K was attained for the n-type cubic Ge_(0.55)Bi_(0.2)Pb_(0.2)5Se(In_(2)Te_(3))_(0.1),marking an 18-fold enhancement in comparison with its n-type orthorhombic counterpart.This work attests to the efficacy of introducing vacancies through enhancing crystal symmetry as an effective means to expand dopant solubility,thereby offering valuable insights into the achievement of compatible p-and n-type chalcogenides within the same matrix.
基金supported by the National Key Research and Development Program of China(2017YFF0204706)the Program of Introducing Talents and Discipline Innovation to Universities 2017(X2017004)。
文摘Thermoelectrics is a research area that focuses on the development of high-performance materials for direct thermal and electrical energy conversion in power generation and solid-state cooling.Ever since Ioffe’s inference in 1950s that heavily doped semiconductors make the best thermoelectrics,inorganic semiconductors and semimetals have remained the cornerstone of high-performance thermoelectric materials.In this article,we review the recent advances in inorganic material thermoelectrics with special emphases on:(i)the complementary local-global view of material and the roles of configurational entropy and Fermi surface complexity in material screening;(ii)the emerging schemes of resonant bonding,dynamic disorder,“gap”engineering,pudding-mold-shaped bands in material performance enhancement;(iii)a list of promising bulk materials,such as host-vip structures,half-Heusler compounds,silicides,Zintl phases,and incommensurate structures;and(iv)state-of-the-art materials synthesis and fabrication techniques.These advances will facilitate the development of next-generation bulk thermoelectric materials.
基金supported by the National Key Research and Development Program of China(2022YFB3803900)and the Research Platform of Material Genome and the Synergic Extreme Condition User Facility in Huairou,Beijing,China.
文摘Mg_(3)(Sb,Bi)_(2)-based thermoelectrics(TEs)show promise for near-room-temperature energy conversion and TE-cooling applications.However,further improvements in electrical power factors and figure-of-merits(zTs)are constrained by precise Mg-vacancy regulation and elucidation of underlying mechanisms.Herein,we report a novel in-situ Mg-vacancy engineering strategy in Mg_(3)(Sb,Bi)_(2)where excess Mg is generated from local reactions between a selection of specific transition metals and the component anionic element(s)in Mg_(3)(Sb,Bi)_(2)during spark-plasma-sintering.This process effectively refills matrix Mg-vacancies through the subsequent global diffusion of Mg cations in Mg_(3)(Sb,Bi)_(2)lattices.This local-reaction-global-diffusion concept,contrasting with reported mechanisms associated with localized grain-boundary engineering,is elaborated through multiscale investigation.Vacancy-restrained Mg_(3)(Sb,Bi)_(2)demonstrates remarkably enhanced carrier mobility and zTs,achieving record-high power factors.Our fabricated Mg_(3)Sb_(0.5)Bi_(1.5)/MgAgSb and Mg_(3)SbBi/MgAgSb modules achieve record-high dual-output performance with power-density/efficiency values of 1.23 W cm^(−2)/11.7%and 1.05 W cm^(−2)/12.8%,respectively,under a temperature difference(ΔT)of 315 K.The constructed Mg_(3)Sb_(0.5)Bi_(1.5)/Bi_(0.5)Sb_(1.5)Te_(3)and Mg_(3)Sb_(0.75)Bi_(1.25)/Bi_(0.5)Sb_(1.5)Te_(3)Peltier modules deliver competitive coolingΔTmax exceeding 70 and 67 K,respectively,at 303 K.The concept is expected to extend to the defect engineering of other energy materials(e.g.,SnTe and PbSe TEs),TE-interface materials,and metal-semiconductor interfaces with optimized functionalities.
基金supported by the National Key R&D Program of China(Grant No.2022YFB4602401)the National Natural Science Foundation of China(Grant No.51706039)+2 种基金the Fundamental Research Funds for the Central Universities(Grant No.2572020BF01)the CAS-XDC Project(Grant No.XDC0150303)the Innovation Foundation for Doctoral Program of Forestry Engineering of Northeast Forestry University(Grant No.LYGC202216)。
文摘Thermoelectric materials convert heat directly into electricity and are therefore promising for energy harvesting and environmental applications.Ideal high-performance thermoelectrics combine ultralow lattice thermal conductivity,κL,with high carrier mobility,a paradigm commonly termed phonon-glass electron-crystal.However,strong coupling between electronic and phononic transport complicates simultaneous optimization of these properties.BecauseκL is largely independent of electronic transport,targeted suppression ofκL is an effective route to partially decouple heat and charge transport.This review summarizes recent advances in reducingκL via two complementary approaches:phonon engineering of bulk nanostructured systems and phonon engineering of low-dimensional materials.In bulk systems,κL may be minimized while retaining high electrical conductivity and maximizing the thermoelectric figure of merit ZT by controlling three fundamental phonon parameters:the volumetric specific heat cv,the phonon group velocity vg,and the phonon relaxation timeτ.Low-dimensional architectures,including superlattices,nanowires,and nanocomposites,supply additional levers to suppress lattice heat transport and to tailor the electronic structure.Integrating multiscale and multimodal phononcontrol strategies enables significant reductions inκL without sacrificing electronic performance,thereby advancing the phonon-glass electron-crystal paradigm.
基金supported by the National Natural Science Foundation of China(No.51972094)Hebei Provincial Department of Science and Technology(Grant No.236Z4403G,246Z4401G)+1 种基金Science Research Project of Hebei Education Department(No.279JZX2024008)Research Innovation Team Project of Hebei University(No.150000321008 and IT2023A04).
文摘Bi_(2)Se_(3) has emerged as a promising thermoelectric(TE)material due to its environmentally benign composition and earth-abundant constituents.However,the practical implementation of Bi_(2)Se_(3)-based systems remains challenging due to suboptimal TE performance.This study demonstrates the fabrication of c-axis oriented Bi_(2)Se_(3) thin films through pulsed laser deposition,with subsequent selenization treatment significantly enhancing TE performance through dual optimization of carrier concentration and crystallographic alignment.A strategic post-deposition selenization process effectively mitigates selenium vacancies and correspondingly reduces the carrier concentration to 2.0×10^(19) cm^(−3) while improving in-plane carrier mobility.A high power factor(PF)of about 9.5μW·cm^(−1)·K^(−2) is achieved at 475 K in the highly c-axis oriented Bi_(2)Se_(3) thin films selenized for about 60 min,outperforming the reported state-of-the-art Bi_(2)Se_(3) films.Demonstrating practical applicability,an 8-leg planar thin-film device generates an exceptional power density of 441.3μW/cm^(2) under a 25 K temperature gradient,establishing new performance benchmarks for chalcogenide-based microgenerators.These findings provide crucial insights into defect engineering and structural optimization strategies for developing high-performance TE devices compatible with self-powered microelectronic applications.
基金funded by the US Department of Energy through the Computational Science Graduate Fellowship(DOE CSGF)under grant number DE-SC0020347.M.Y.Tsupport from the Johannes and Julia Randall Weertman Graduate Fellowshipsupport of award 70NANB19H005 from the US Department of Commerce,National Institute of Standards and Technology,as part of the Center for Hierarchical Materials Design(CHiMaD).
文摘Thermoelectric properties of topological insulators have traditionally been examined in the context of their metallic surface states.However,recent studies have begun to unveil intriguing thermoelectric effects emerging from the bulk electronic states of topological insulators,which have largely been overlooked in the past.Charge transport phenomena through the bulk are especially important under typical operating conditions of thermoelectric devices,necessitating a comprehensive review of both surface and bulk transport in topological insulators.Here,we review thermoelectric properties that are uniquely observed in topological insulators,placing special emphasis on unconventional phenomena emerging from bulk states.We demonstrate that unusual thermoelectric effects arising from bulk states,such as band inversion-driven warping,can be discerned in experiments through a simple analysis of the weighted mobility.We believe that there is still plenty to uncover within the bulk of topological insulators,yet our current understanding can already inspire new strategies for designing and discovering new materials for next-generation thermoelectrics.
基金supported financially by the National Key R&D Program of China(grant no.2022YFE0130600)the National Natural Science Foundation of China(grant nos.22075001 and 92156019)+2 种基金the King Abdullah University of Science and Technology(KAUST)Competitive Research Grants under award no.ORA-CRG10-2021-4668support from the KAUST Office of Sponsored Research under award no.OSA-CRG2021-4668supported by the High-performance Computing Platform of Peking University.
文摘To date,extensive efforts have been devoted to designing new conjugated polymers with long alkyl or ethylene glycol sidechains.However,these sidechains are insulators,limiting further performance enhancement in doped conjugated polymers.Moreover,the most widely used chlorinated solvents are toxic,limiting the practical applications of many conjugated polymers.Here,we report a water/alcohol processable n-type conjugated polymer P(Py2FT),featuring side chain-free cationic backbones.P(Py2FT)exhibits a high n-type electrical conductivity of up to 28.1 S cm^(−1)and a high thermoelectric power factor of up to 28.7μWm^(−1)K^(−2),comparable to some conventional n-type conjugated polymers reported recently.More importantly,cationic polymers display tight molecular packings and interesting enhanced backbone planarity after n-doping,which,we envision,provides a new research direction to address the sidechain issue in conventional conjugated polymers.Our work demonstrates that sidechain-free cationic polymers have great potential for green-solvent-processed heavily doped organic electronics.
