The amalgamation of multi-subjects often elicits novel materials,new concepts and unexpected applications.Recently,Ge2 Sb2 Te5,as the most established phasechange material,has been found to exhibit decent thermoelectr...The amalgamation of multi-subjects often elicits novel materials,new concepts and unexpected applications.Recently,Ge2 Sb2 Te5,as the most established phasechange material,has been found to exhibit decent thermoelectric performance in its stable,hexagonal phase.The challenge for higher figure of merit(zT) values lies in reducing the hole carrier concentration and enhancing the Seebeck coefficient,which,however,can be hardly realized by conventional doping.Here in this work,we report that the electrical properties of Ge2 Sb2 Te5 can be readily optimized by anion-site modulation.Specifically,Se/S substitution for Te induces stronger and more ionic bonding,lowering the hole density.Furthermore,an increase in electronic density of state is introduced by Se substitution,contributing to a large increase in Seebeck coefficient.Combined with the reduced thermal conductivity,maximum zT values above 0.7 at 800 K have been achieved in Se/S-alloyed materials,which is ~30% higher than that in the pristine Ge2Sb2 Te5.展开更多
High mechanical robustness is essential to the material’s processibility for the applications in flexible and miniaturized electronics.As state-of-the-art room-temperature thermoelectric materials,Ag_(2)Se_(1–x)Te_(...High mechanical robustness is essential to the material’s processibility for the applications in flexible and miniaturized electronics.As state-of-the-art room-temperature thermoelectric materials,Ag_(2)Se_(1–x)Te_(x)alloys exhibit superior thermoelectric transport properties but their mechanical properties remain largely unexplored.Herein,we systematically investigate the mechanical and thermoelectric properties of a series of Ag_(2)Se_(1–x)Te_(x)materials.Among them,Ag_(2)Se_(0.9)Te_(0.1)shows robust mechanical properties including a large compression strain of(26.7±4.5)%,a high compression strength of(279.2±49)MPa,and an excellent fracture toughness of(4.5±0.6)MPa m^(1/2).These robust mechanical properties are ascribed to the dense dislocations as well as possible sub-grain rotations.Combined with the excellent thermoelectric figure of merit,z T of 0.78 at 300 K and 1.1 at 380 K,the Ag_(2)Se_(1–x)Te_(x)alloys are promising candidates for robust and efficient thermoelectric applications near room temperature.展开更多
As a new type of inorganic ductile semiconductor,silver sulfide(α-Ag_(2)S)has garnered a plethora of interests in recent years due to its promising applications in flexible electronics.However,the lack of detailed de...As a new type of inorganic ductile semiconductor,silver sulfide(α-Ag_(2)S)has garnered a plethora of interests in recent years due to its promising applications in flexible electronics.However,the lack of detailed defect calculations and chemical intuition has largely hindered the optimization of material's performance.In this study,we systematically investigate the defect chemistry of extrinsic doping inα-Ag_(2)S using first-principles calculations.We computationally examine a broad suite of 17 dopants and find that all aliovalent elements have extremely low doping limits(<0.002%)in α-Ag_(2)S,rendering them ineffective in tuning the electron concentrations.In contrast,the isovalent elements Se and Te have relatively high doping limits,being consistent with the experimental observations.While the dopant Se or Te itself does not provide additional electrons,its introduction has a significant impact on the band gap,the band-edge position,and especially the formation energy of Ag interstitials,which effectively improve the electron concentrations by 2–3 orders of magnitudes.The size effects of Se and Te doping are responsible for the more favorable Ag interstitials in Ag_(2)S_(0.875)Se_(0.125) and Ag_(2)S_(0.875)Te_(0.125) with respect to pristine Ag2S.This work serves as a theoretical foundation for the rational design of Ag_(2)S-based functional materials.展开更多
Exploring new prototypes for a given chemical composition is of great importance and interest to several disciplines.As a famous semiconducting binary compound,InSe usually exhibits a two-dimensional layered structure...Exploring new prototypes for a given chemical composition is of great importance and interest to several disciplines.As a famous semiconducting binary compound,InSe usually exhibits a two-dimensional layered structure with decent physical and mechanical properties.However,it is less noticed that InSe can also adopt a monoclinic structure,denoted as mcl-InSe.The synthesis of such a phase usually re-quires high-pressure conditions,and the knowledge is quite scarce on its chemical bonding,lattice dynamics,and thermal transport.Here in this work,by developing a facile method combining me-chanical alloying and spark plasma sintering,we successfully synthesize mcl-InSe bulks with well-crystallized nanograins.The chemical bonding of mcl-InSe is understood as compared with layered InSe via charge analysis.Low cut-off frequencies of acoustic phonons and several low-lying optical modes are demonstrated.Noticeably,mcl-InSe exhibits a low room-temperature thermal conductivity of 0.6 W·m^(-1)·K^(-1),which is smaller than that of other materials in the IneSe system and many other selenides.Low-temperature thermal analyses corroborate the role of nanograin boundaries and low-frequency optical phonons in scattering acoustic phonons.This work provides new insights into the non-common prototype of the InSe binary compound with potential applications in thermoelectrics or thermal insulation.展开更多
Developing high-efficiency materials with earth-abundant and low-toxicity elements has become a popular trend in the field of thermoelectrics.Among these compounds,oxides and sulfides,the lighter,cheaper and green ana...Developing high-efficiency materials with earth-abundant and low-toxicity elements has become a popular trend in the field of thermoelectrics.Among these compounds,oxides and sulfides,the lighter,cheaper and green analogies of tellurides,have been extensively investigated and summarized as well defined classes.Nonetheless,the vast family of selenides with better electrical performance,lower thermal conductivity and higher thermoelectric efficiency have not been specially discussed.Here in this review,we present recent advances in binary and multinary selenide thermoelectric materials,covering traditional PbSe,liquid-like Cu_(2)Se,layered SnSe,diamond-like and disordered multinary compounds.The features of selenides are discussed based on both environmental concerns and from the perspective of chemical bonding,transport properties and performance.Emphasis is put on the“compositionstructure-processing-performance”relationship,and some interesting issues are addressed.Finally,challenges for thermoelectric selenides are discussed,and possible optimization strategies are also suggested.展开更多
By virtue of the excellent plasticity and tunable transport properties,Ag_(2)S-based materials demonstrate an intriguing prospect for flexible or hetero-shaped thermoelectric applications.Among them,Ag_(2)S_(1-x)Te_(x...By virtue of the excellent plasticity and tunable transport properties,Ag_(2)S-based materials demonstrate an intriguing prospect for flexible or hetero-shaped thermoelectric applications.Among them,Ag_(2)S_(1-x)Te_(x)exhibits rich and interesting variations in crystal structure,mechanical and thermoelectric transport properties.However,Te alloying obviously introduces extremely large order-disorder distributions of cations and anions,leading to quite complicated crystal structures and thermoelectric properties.Detailed composition-structure-performance correlation of Ag_(2)S_(1-x)Te_(x)still remains to be established.In this work,we designed and prepared a series of Ag_(2)S_(1-x)Te_(x)(x=0-0.3)materials with low Te content.We discovered that the monoclinic-to-cubic phase transition occurs around x=0.16 at room temperature.Te alloying plays a similar role as heating in facilitating this monoclinic-to-cubic phase transition,which is analyzed based on the thermodynamic principles.Compared with the monoclinic counterparts,the cubic-structured phases are more ductile and softer in mechanical properties.In addition,the cubic phases show a degenerately semiconducting behavior with higher thermoelectric performance.A maximum zT=0.8 at 600 K and bending strain larger than 20% at room temperature were obtained in Ag_(2)S_(0.7)Te_(0.3).This work provides a useful guidance for designing Ag_(2)S-based alloys with enhanced plasticity and high thermoelectric performance.展开更多
Cu-based chalcogenides have received increasing attention as promising thermoelectric materials due to their high efficiency,tunable transport properties,high elemental abundance and low toxicity.In this review,we sum...Cu-based chalcogenides have received increasing attention as promising thermoelectric materials due to their high efficiency,tunable transport properties,high elemental abundance and low toxicity.In this review,we summarize the recent research progress on this large family compounds covering diamond-like chalcogenides and liquid-like Cu2X (X=S,Se,Te)binary compounds as well as their multinary derivatives.These materials have the general features of two sublattices to decouple electron and phonon transport properties.On the one hand,the complex crystal structure and the disordered or even liquid-like sublattice bring about an intrinsically low lattice thermal conductivity.On the other hand, the rigid sublattice constitutes the charge-transport network, maintaining a decent electrical performance.For specific material systems,we demonstrate their unique structural features and outline the structure-performance correlation. Various design strategies including doping,alloying,band engineering and nanostructure architecture,covering nearly all the material scale,are also presented.Finally,the potential of the application of Cu-based chalcogenides as high-performance thermoelectric materials is briefly discussed from material design to device development.展开更多
Flexible electronics ushers in a revolution to the electronics industry in the 21st century.Ideally,all components of a flexible electronic device including the functional component shall comply with the deformation t...Flexible electronics ushers in a revolution to the electronics industry in the 21st century.Ideally,all components of a flexible electronic device including the functional component shall comply with the deformation to ensure the structural and functional integrity,imposing a pressing need for developing roomtemperature strain-tolerant semiconductors.To this end,there is a long-standing material dilemma:inorganic semiconductors are typically brittle at room temperature except for size-induced flexibility;by contrast,organic semiconductors are intrinsically soft and flexible but the electrical performance is poor.This is why the discovery of bulk plasticity in Ag2S at room temperature and ZnS in darkness is groundbreaking in solving this long-standing material dilemma between the mechanical deformability and the electrical performance.The present review summarizes the background knowledge and latest advances in the emerging field of plastic inorganic semiconductors.At the outset,we argue that the plasticity of inorganic semiconductors is vital to strain tolerance of electronic devices,which has not been adequately emphasized.The mechanisms of plasticity are illustrated from the perspective of chemical bonding and dislocations.Plastic inorganic materials,for example,ionic crystals(insulators),ZnS in darkness,and Ag2S,are discussed in detail in terms of their prominent mechanical properties and potential applications.We conclude the article with several key scientific and technological questions to address in the future study.展开更多
Thermal conductivity is one of the most fundamental properties of materials with the value being determined by nearly all-scale structural features and multiple physical processes.Rapidly judging material’s thermal c...Thermal conductivity is one of the most fundamental properties of materials with the value being determined by nearly all-scale structural features and multiple physical processes.Rapidly judging material’s thermal conductivity is extremely important but challenging for the applications.The material genome paradigm offers a revolutionary way to efficiently screen and discover materials with designed properties by using accessible indicators.But such a performance indicator for thermal conductivity is quite difficult to propose due to the existence of multiple mechanisms and processes,especially for the materials with complex structures such as chalcogenides.In this study,the number mismatch between cations and anions is proposed as a practical performance indicator for lattice thermal conductivity in complex copper and silver chalcogenides,which can be used to explain the observed experimental data and find new low thermal conductivity materials.Such a number mismatch brings about rich phenomena to affect thermal conductivity including the complication of the unit cell and the creation of chemical hierarchy,point defects,rattling modes and lone-pair electrons.It is expected that this rich-connotation performance indicator can be also extended to other complex materials to discover designed thermal conductivities.展开更多
Indium selenide(InSe)crystals are reported to show exceptional plasticity,a new property to twodimensional van der Waals(2D vdW)semiconductors.However,the correlation between plasticity and specific prototypes is uncl...Indium selenide(InSe)crystals are reported to show exceptional plasticity,a new property to twodimensional van der Waals(2D vdW)semiconductors.However,the correlation between plasticity and specific prototypes is unclear,and the understanding of detailed plastic deformation mechanisms is inadequate.Here three prototypes of InSe are predicted to be plastically deformable by calculation,and the plasticity of polymorphic crystals is verified by experiment.Moreover,distinct nanoindentation behaviors are seen on the cleavage and cross-section surfaces.The modulus and hardness of InSe are the lowest ones among a large variety of materials.The plastic deformation is further perceived from chemical interactions during the slip process.Particularly for the cross-layer slip,the initial In-Se bonds break while new In-In and Se-Se bonds are newly formed,maintaining a decent interaction strength.The remarkable plasticity and softness alongside the novel physical properties,endow InSe great promise for application in deformable and flexible electronics.展开更多
基金financially supported by the National Key Research and Development Program of China(Nos.2017YFA0700705 and 2018YFB0703600)the National Natural Science Foundation of China(Nos.51625205,91963208 and 51802333)Shanghai Sailing Program(No.18YF1426700)。
文摘The amalgamation of multi-subjects often elicits novel materials,new concepts and unexpected applications.Recently,Ge2 Sb2 Te5,as the most established phasechange material,has been found to exhibit decent thermoelectric performance in its stable,hexagonal phase.The challenge for higher figure of merit(zT) values lies in reducing the hole carrier concentration and enhancing the Seebeck coefficient,which,however,can be hardly realized by conventional doping.Here in this work,we report that the electrical properties of Ge2 Sb2 Te5 can be readily optimized by anion-site modulation.Specifically,Se/S substitution for Te induces stronger and more ionic bonding,lowering the hole density.Furthermore,an increase in electronic density of state is introduced by Se substitution,contributing to a large increase in Seebeck coefficient.Combined with the reduced thermal conductivity,maximum zT values above 0.7 at 800 K have been achieved in Se/S-alloyed materials,which is ~30% higher than that in the pristine Ge2Sb2 Te5.
基金supported by the National Natural Science Foundation of China(92463310,52373292)supported by the National Natural Science Foundation of China(52232010)supported by the Zhejiang Provincial Natural Science Foundation of China(LD25E020001)。
文摘High mechanical robustness is essential to the material’s processibility for the applications in flexible and miniaturized electronics.As state-of-the-art room-temperature thermoelectric materials,Ag_(2)Se_(1–x)Te_(x)alloys exhibit superior thermoelectric transport properties but their mechanical properties remain largely unexplored.Herein,we systematically investigate the mechanical and thermoelectric properties of a series of Ag_(2)Se_(1–x)Te_(x)materials.Among them,Ag_(2)Se_(0.9)Te_(0.1)shows robust mechanical properties including a large compression strain of(26.7±4.5)%,a high compression strength of(279.2±49)MPa,and an excellent fracture toughness of(4.5±0.6)MPa m^(1/2).These robust mechanical properties are ascribed to the dense dislocations as well as possible sub-grain rotations.Combined with the excellent thermoelectric figure of merit,z T of 0.78 at 300 K and 1.1 at 380 K,the Ag_(2)Se_(1–x)Te_(x)alloys are promising candidates for robust and efficient thermoelectric applications near room temperature.
基金This work was supported by the National Natural Science Foundation of China(No.52372209 and 52232010)the Shanghai Pilot Program for Basic Research-Chinese Academy of Science,Shanghai Branch(JCYJ-SHFY-2022-002)。
文摘As a new type of inorganic ductile semiconductor,silver sulfide(α-Ag_(2)S)has garnered a plethora of interests in recent years due to its promising applications in flexible electronics.However,the lack of detailed defect calculations and chemical intuition has largely hindered the optimization of material's performance.In this study,we systematically investigate the defect chemistry of extrinsic doping inα-Ag_(2)S using first-principles calculations.We computationally examine a broad suite of 17 dopants and find that all aliovalent elements have extremely low doping limits(<0.002%)in α-Ag_(2)S,rendering them ineffective in tuning the electron concentrations.In contrast,the isovalent elements Se and Te have relatively high doping limits,being consistent with the experimental observations.While the dopant Se or Te itself does not provide additional electrons,its introduction has a significant impact on the band gap,the band-edge position,and especially the formation energy of Ag interstitials,which effectively improve the electron concentrations by 2–3 orders of magnitudes.The size effects of Se and Te doping are responsible for the more favorable Ag interstitials in Ag_(2)S_(0.875)Se_(0.125) and Ag_(2)S_(0.875)Te_(0.125) with respect to pristine Ag2S.This work serves as a theoretical foundation for the rational design of Ag_(2)S-based functional materials.
基金supported by the National Natural Science Foundation of China(T2122013,52232010)the Basic Research Project of the Shanghai Science and Technology Committee(20JC1415100).
文摘Exploring new prototypes for a given chemical composition is of great importance and interest to several disciplines.As a famous semiconducting binary compound,InSe usually exhibits a two-dimensional layered structure with decent physical and mechanical properties.However,it is less noticed that InSe can also adopt a monoclinic structure,denoted as mcl-InSe.The synthesis of such a phase usually re-quires high-pressure conditions,and the knowledge is quite scarce on its chemical bonding,lattice dynamics,and thermal transport.Here in this work,by developing a facile method combining me-chanical alloying and spark plasma sintering,we successfully synthesize mcl-InSe bulks with well-crystallized nanograins.The chemical bonding of mcl-InSe is understood as compared with layered InSe via charge analysis.Low cut-off frequencies of acoustic phonons and several low-lying optical modes are demonstrated.Noticeably,mcl-InSe exhibits a low room-temperature thermal conductivity of 0.6 W·m^(-1)·K^(-1),which is smaller than that of other materials in the IneSe system and many other selenides.Low-temperature thermal analyses corroborate the role of nanograin boundaries and low-frequency optical phonons in scattering acoustic phonons.This work provides new insights into the non-common prototype of the InSe binary compound with potential applications in thermoelectrics or thermal insulation.
基金the Basic Science Center Project of NSFC(Grant No.51788104)the National Natural Science Foundation(No.11474176)as well as the Shenzhen Science and Technology Plan Project(No.JCYJ20150827165038323).
文摘Developing high-efficiency materials with earth-abundant and low-toxicity elements has become a popular trend in the field of thermoelectrics.Among these compounds,oxides and sulfides,the lighter,cheaper and green analogies of tellurides,have been extensively investigated and summarized as well defined classes.Nonetheless,the vast family of selenides with better electrical performance,lower thermal conductivity and higher thermoelectric efficiency have not been specially discussed.Here in this review,we present recent advances in binary and multinary selenide thermoelectric materials,covering traditional PbSe,liquid-like Cu_(2)Se,layered SnSe,diamond-like and disordered multinary compounds.The features of selenides are discussed based on both environmental concerns and from the perspective of chemical bonding,transport properties and performance.Emphasis is put on the“compositionstructure-processing-performance”relationship,and some interesting issues are addressed.Finally,challenges for thermoelectric selenides are discussed,and possible optimization strategies are also suggested.
基金This work is supported by the National Key Research and Development Program of China(2018YFB0703600)National Natural Science Foundation of China(91963208,51625205,51961135106,51802333)+2 种基金the CAS-DOE Program of Chinese Academy of Sciences(121631KYSB20180060)the Shanghai Government(20JC1415100)the Swedish Research Council(VR 2018e06030).
文摘By virtue of the excellent plasticity and tunable transport properties,Ag_(2)S-based materials demonstrate an intriguing prospect for flexible or hetero-shaped thermoelectric applications.Among them,Ag_(2)S_(1-x)Te_(x)exhibits rich and interesting variations in crystal structure,mechanical and thermoelectric transport properties.However,Te alloying obviously introduces extremely large order-disorder distributions of cations and anions,leading to quite complicated crystal structures and thermoelectric properties.Detailed composition-structure-performance correlation of Ag_(2)S_(1-x)Te_(x)still remains to be established.In this work,we designed and prepared a series of Ag_(2)S_(1-x)Te_(x)(x=0-0.3)materials with low Te content.We discovered that the monoclinic-to-cubic phase transition occurs around x=0.16 at room temperature.Te alloying plays a similar role as heating in facilitating this monoclinic-to-cubic phase transition,which is analyzed based on the thermodynamic principles.Compared with the monoclinic counterparts,the cubic-structured phases are more ductile and softer in mechanical properties.In addition,the cubic phases show a degenerately semiconducting behavior with higher thermoelectric performance.A maximum zT=0.8 at 600 K and bending strain larger than 20% at room temperature were obtained in Ag_(2)S_(0.7)Te_(0.3).This work provides a useful guidance for designing Ag_(2)S-based alloys with enhanced plasticity and high thermoelectric performance.
基金supported by the National Key Research and Development Program of China (2018YFB0703600)the National Natural Science Foundation of China (51625205)+3 种基金 the Key Research Program of Chinese Academy of Sciences (KFZD-SW-421)Program of Shanghai Subject Chief Scientist (16XD1403900)Youth Innovation Promotion Association, CAS (2016232)Shanghai Sailing Program (18YF1426700).
文摘Cu-based chalcogenides have received increasing attention as promising thermoelectric materials due to their high efficiency,tunable transport properties,high elemental abundance and low toxicity.In this review,we summarize the recent research progress on this large family compounds covering diamond-like chalcogenides and liquid-like Cu2X (X=S,Se,Te)binary compounds as well as their multinary derivatives.These materials have the general features of two sublattices to decouple electron and phonon transport properties.On the one hand,the complex crystal structure and the disordered or even liquid-like sublattice bring about an intrinsically low lattice thermal conductivity.On the other hand, the rigid sublattice constitutes the charge-transport network, maintaining a decent electrical performance.For specific material systems,we demonstrate their unique structural features and outline the structure-performance correlation. Various design strategies including doping,alloying,band engineering and nanostructure architecture,covering nearly all the material scale,are also presented.Finally,the potential of the application of Cu-based chalcogenides as high-performance thermoelectric materials is briefly discussed from material design to device development.
基金National Key Research and Development Program of China,Grant/Award Number:2018YFB0703600National Natural Science Foundation of China,Grant/Award Numbers:51625205,51961135106,91963208Shanghai Sailing Program,Grant/Award Number:18YF1426700。
文摘Flexible electronics ushers in a revolution to the electronics industry in the 21st century.Ideally,all components of a flexible electronic device including the functional component shall comply with the deformation to ensure the structural and functional integrity,imposing a pressing need for developing roomtemperature strain-tolerant semiconductors.To this end,there is a long-standing material dilemma:inorganic semiconductors are typically brittle at room temperature except for size-induced flexibility;by contrast,organic semiconductors are intrinsically soft and flexible but the electrical performance is poor.This is why the discovery of bulk plasticity in Ag2S at room temperature and ZnS in darkness is groundbreaking in solving this long-standing material dilemma between the mechanical deformability and the electrical performance.The present review summarizes the background knowledge and latest advances in the emerging field of plastic inorganic semiconductors.At the outset,we argue that the plasticity of inorganic semiconductors is vital to strain tolerance of electronic devices,which has not been adequately emphasized.The mechanisms of plasticity are illustrated from the perspective of chemical bonding and dislocations.Plastic inorganic materials,for example,ionic crystals(insulators),ZnS in darkness,and Ag2S,are discussed in detail in terms of their prominent mechanical properties and potential applications.We conclude the article with several key scientific and technological questions to address in the future study.
基金This work is supported by the National Key Research and Development Program of China(2018YFB0703600)the National Natural Science Foundation of China(51625205,91963208,and 51802333)+1 种基金the Key Research Program of Chinese Academy of Sciences(KFZD-SW-421)the Youth Innovation Promotion Association of CAS(2016232).
文摘Thermal conductivity is one of the most fundamental properties of materials with the value being determined by nearly all-scale structural features and multiple physical processes.Rapidly judging material’s thermal conductivity is extremely important but challenging for the applications.The material genome paradigm offers a revolutionary way to efficiently screen and discover materials with designed properties by using accessible indicators.But such a performance indicator for thermal conductivity is quite difficult to propose due to the existence of multiple mechanisms and processes,especially for the materials with complex structures such as chalcogenides.In this study,the number mismatch between cations and anions is proposed as a practical performance indicator for lattice thermal conductivity in complex copper and silver chalcogenides,which can be used to explain the observed experimental data and find new low thermal conductivity materials.Such a number mismatch brings about rich phenomena to affect thermal conductivity including the complication of the unit cell and the creation of chemical hierarchy,point defects,rattling modes and lone-pair electrons.It is expected that this rich-connotation performance indicator can be also extended to other complex materials to discover designed thermal conductivities.
基金the National Natural Science Foundation of China(T2122013,52232010)the Basic Research Project of the Shanghai Science and Technology Committee(20JC1415100)。
文摘Indium selenide(InSe)crystals are reported to show exceptional plasticity,a new property to twodimensional van der Waals(2D vdW)semiconductors.However,the correlation between plasticity and specific prototypes is unclear,and the understanding of detailed plastic deformation mechanisms is inadequate.Here three prototypes of InSe are predicted to be plastically deformable by calculation,and the plasticity of polymorphic crystals is verified by experiment.Moreover,distinct nanoindentation behaviors are seen on the cleavage and cross-section surfaces.The modulus and hardness of InSe are the lowest ones among a large variety of materials.The plastic deformation is further perceived from chemical interactions during the slip process.Particularly for the cross-layer slip,the initial In-Se bonds break while new In-In and Se-Se bonds are newly formed,maintaining a decent interaction strength.The remarkable plasticity and softness alongside the novel physical properties,endow InSe great promise for application in deformable and flexible electronics.
