热电器件的界面稳定性是决定其服役可靠性和寿命的关键因素。对于方钴矿热电器件,为了抑制高温电极与方钴矿材料之间的相互扩散,需要在两者之间加入阻挡层。本工作选用Ti_(88)Al_(12)作为阻挡层,利用一步法热压烧结制备n型Yb_(0.3)Co_4S...热电器件的界面稳定性是决定其服役可靠性和寿命的关键因素。对于方钴矿热电器件,为了抑制高温电极与方钴矿材料之间的相互扩散,需要在两者之间加入阻挡层。本工作选用Ti_(88)Al_(12)作为阻挡层,利用一步法热压烧结制备n型Yb_(0.3)Co_4Sb_(12)/Ti_(88)Al_(12)/Yb_(0.3)Co_4Sb_(12)和p型CeFe3.85Mn0.15Sb12/Ti_(88)Al_(12)/CeFe3.85Mn0.15Sb12样品,研究Ti_(88)Al_(12)阻挡层与热电材料间的界面接触电阻率及微结构在加速老化实验中的演化规律。结果表明:在相同的老化条件下,n型样品的界面接触电阻率增加速度比p型样品慢,其激活能分别为84.1 k J/mol和68.8 k J/mol。对于n型样品,由元素扩散反应生成的金属间化合物中间层的增长及最终AlCo/TiCoSb层的开裂是导致界面接触电阻率增加的主要原因;而p型热电材料与Ti_(88)Al_(12)的热膨胀系数的差异加速了p型样品中界面裂纹的产生。展开更多
Focusing on the low open circuit voltage(V_(OC))and fill factor(FF)in flexible Cu_(2)ZnSn(S,Se)_(4)(CZTSSe)solar cells,indium(In)ions are introduced into the CZTSSe absorbers near Mo foils to modify the back interface...Focusing on the low open circuit voltage(V_(OC))and fill factor(FF)in flexible Cu_(2)ZnSn(S,Se)_(4)(CZTSSe)solar cells,indium(In)ions are introduced into the CZTSSe absorbers near Mo foils to modify the back interface and passivate deep level defects in CZTSSe bulk concurrently for improving the performance of flexible device.The results show that In doping effectively inhibits the formation of secondary phase(Cu(S,Se)_(2))and VSndefects.Further studies demonstrate that the barrier height at the back interface is decreased and the deep level defects(Cu_(Sn)defects)in CZTSSe bulk are passivated.Moreover,the carrier concentration is increased and the V_(OC) deficit(V_(OC,def))is decreased significantly due to In doping.Finally,the flexible CZTSSe solar cell with 10.01%power conversion efficiency(PCE)has been obtained.The synergistic strategy of interface modification and bulk defects passivation through In incorporation provides a new thought for the fabrication of efficient flexible kesterite-based solar cells.展开更多
Achieving high loading of active sulfur yet rational regulating the shuttle effect of lithium polysulfide(LiPS)is of great significance in pursuit of high-performance lithium-sulfur(Li-S)battery.Herein,we develop a fr...Achieving high loading of active sulfur yet rational regulating the shuttle effect of lithium polysulfide(LiPS)is of great significance in pursuit of high-performance lithium-sulfur(Li-S)battery.Herein,we develop a free-standing graphene nitrogen(N),phosphorus(P)and fluorine(F)co-doped mesoporous carbon-sulfur(G-NPFMC-S)film,which was used as a binder-free cathode in Li-S battery.The developed mesoporous carbon(MC)achieved a high specific surface area of 921 m^(2)·g^(-1)with a uniform pore size distribution of 15 nm.The inserted graphene network inside G-NPFMC-S cathode can effectively improve its electrical conductivity and simultaneously restrict the shuttle of LiPS.A high sulfur loading of 86%was achieved due to the excellent porous structures of graphene-NPFMC(G-NPFMC)composite.When implemented as a freestanding cathode in Li-S battery,this G-NPFMC-S achieved a high specific capacity(1,356 mAh·g^(-1)),favorable rate capability,and long-term cycling stability up to 500 cycles with a minimum capacity fading rate of 0.025%per cycle,outperforming the corresponding performances of NPFMC-sulfur(NPFMC-S)and MC-sulfur(MC-S).These promising results can be ascribed to the featured structures that formed inside G-NPFMC-S film,as that highly porous NPFMC can provide sufficient storage space for the loading of sulfur,while,the N,P,F-doped carbonic interface and the inserted graphene network help hinder the shuttle of LiPS via chemical adsorption and physical barrier effect.This proposed unique structure can provide a bright prospect in that high mass loading of active sulfur and restriction the shuttle of LiPS can be simultaneously achieved for Li-S battery.展开更多
Effective manipulations of thermal expansion and conductivity are significant for improving operational performances of protective coatings,thermoelectric,and radiators.This work uncovers determinant mechanisms of the...Effective manipulations of thermal expansion and conductivity are significant for improving operational performances of protective coatings,thermoelectric,and radiators.This work uncovers determinant mechanisms of the thermal expansion and conductivity of symbiotic ScTaO_(4)/SmTaO_(4) composites as thermal/environmental barrier coatings(T/EBCs),and we consider the effects of interface stress and thermal resistance.The weak bonding and interface stress among composite grains manipulate coefficient of thermal expansion(CTE)stretching from 6.4×10^(−6) to 10.7×10^(−6) K^(−1) at 1300℃,which gets close to that of substrates in T/EBC systems.The multiscale effects,including phonon scattering at the interface,mitigation of the phonon speed(vp),and lattice point defects,synergistically depress phonon thermal transports,and we estimate the proportions of different parts.The interface thermal resistance(R)reduces the thermal conductivity(k)by depressing phonon speed and scattering phonons because of different acoustic properties and weak bonding between symbiotic ScTaO_(4) and SmTaO_(4) ceramics in the composites.This study proves that CTE of tantalates can be artificially regulated to match those of different substrates to expand their applications,and the uncovered multiscale effects can be used to manipulate thermal transports of various materials.展开更多
Semiconducting monolayer （ML） blue phosphorene （BlueP） shares similar stability with ML black phosphorene （BP）, and it has recently been grown on an Au surface. Potential ML BlueP devices often require direct co...Semiconducting monolayer （ML） blue phosphorene （BlueP） shares similar stability with ML black phosphorene （BP）, and it has recently been grown on an Au surface. Potential ML BlueP devices often require direct contact with metal to enable the injection of carriers. Using ab initio electronic structure calculations and quantum transport simulations, for the first time, we perform a systematic study of the interfacial properties of ML BlueP in contact with metals spanning a wide work function range in a field effect transistor （FET） configuration. ML BlueP has undergone metallization owing to strong interaction with five metals. There is a strong Fermi level pinning （FLP） in the ML BlueP FETs due to the metal-induced gap states （MIGS） with a pinning factor of 0.42. ML BlueP forms n-type Schottky contact with Sc, Ag, and Pt electrodes with electron Schottky barrier heights （SBHs） of 0.22, 0.22, and 0.80 eV, respectively, and p-type Schottky contact with Au and Pd electrodes with hole SBHs of 0.61 and 0.79 eV, respectively. The MIGS are eliminated by inserting graphene between ML BlueP and the metal electrode, accompanied by a transition from a strong FLP to a weak FLP. Our study not only provides insight into the ML BlueP-metal interfaces, but also helps in the design of ML BlueP devices.展开更多
Highly c-axis oriented ZnO thin films were deposited on Si substrates by the pulsed laser deposition (PLD) method. At different growth temperatures, 200 nm silver films as the contact metal were deposited on the ZnO t...Highly c-axis oriented ZnO thin films were deposited on Si substrates by the pulsed laser deposition (PLD) method. At different growth temperatures, 200 nm silver films as the contact metal were deposited on the ZnO thin films. The growth temperatures have great influence on the crystal quality of Ag films. Current-voltage characteristics were measured at room temperature. The Schottky contacts between Ag and ZnO thin films were successfully obtained when silver electrodes were deposited at 150°C and 200°C. Ohmic contacts were formed while the growth temperatures were lower than 150°C or higher than 200°C. After analysis, the forming of Ag/ZnO Schottky contacts was shown to be dependent on the appearance of the p-type inversion layer at the interface between Ag and ZnO layers.展开更多
文摘热电器件的界面稳定性是决定其服役可靠性和寿命的关键因素。对于方钴矿热电器件,为了抑制高温电极与方钴矿材料之间的相互扩散,需要在两者之间加入阻挡层。本工作选用Ti_(88)Al_(12)作为阻挡层,利用一步法热压烧结制备n型Yb_(0.3)Co_4Sb_(12)/Ti_(88)Al_(12)/Yb_(0.3)Co_4Sb_(12)和p型CeFe3.85Mn0.15Sb12/Ti_(88)Al_(12)/CeFe3.85Mn0.15Sb12样品,研究Ti_(88)Al_(12)阻挡层与热电材料间的界面接触电阻率及微结构在加速老化实验中的演化规律。结果表明:在相同的老化条件下,n型样品的界面接触电阻率增加速度比p型样品慢,其激活能分别为84.1 k J/mol和68.8 k J/mol。对于n型样品,由元素扩散反应生成的金属间化合物中间层的增长及最终AlCo/TiCoSb层的开裂是导致界面接触电阻率增加的主要原因;而p型热电材料与Ti_(88)Al_(12)的热膨胀系数的差异加速了p型样品中界面裂纹的产生。
基金supported by the National Natural Science Foundation of China(62074037)the Science and Technology Department of Fujian Province(2020I0006)the Fujian Science&Technology Innovation Laboratory for Optoelectronic Information of China(2021ZZ124)。
文摘Focusing on the low open circuit voltage(V_(OC))and fill factor(FF)in flexible Cu_(2)ZnSn(S,Se)_(4)(CZTSSe)solar cells,indium(In)ions are introduced into the CZTSSe absorbers near Mo foils to modify the back interface and passivate deep level defects in CZTSSe bulk concurrently for improving the performance of flexible device.The results show that In doping effectively inhibits the formation of secondary phase(Cu(S,Se)_(2))and VSndefects.Further studies demonstrate that the barrier height at the back interface is decreased and the deep level defects(Cu_(Sn)defects)in CZTSSe bulk are passivated.Moreover,the carrier concentration is increased and the V_(OC) deficit(V_(OC,def))is decreased significantly due to In doping.Finally,the flexible CZTSSe solar cell with 10.01%power conversion efficiency(PCE)has been obtained.The synergistic strategy of interface modification and bulk defects passivation through In incorporation provides a new thought for the fabrication of efficient flexible kesterite-based solar cells.
基金This work was financially supported by the National Natural Science Foundation of China(Nos.52270006 and 22209063)the Natural Science Foundation of the Jiangsu Higher Education Institutions of China(19KJA460004)the Priority Academic Program Development of Jiangsu Higher Education Institutions,and the Natural Science Foundation of Xuzhou City(KC21283).
文摘Achieving high loading of active sulfur yet rational regulating the shuttle effect of lithium polysulfide(LiPS)is of great significance in pursuit of high-performance lithium-sulfur(Li-S)battery.Herein,we develop a free-standing graphene nitrogen(N),phosphorus(P)and fluorine(F)co-doped mesoporous carbon-sulfur(G-NPFMC-S)film,which was used as a binder-free cathode in Li-S battery.The developed mesoporous carbon(MC)achieved a high specific surface area of 921 m^(2)·g^(-1)with a uniform pore size distribution of 15 nm.The inserted graphene network inside G-NPFMC-S cathode can effectively improve its electrical conductivity and simultaneously restrict the shuttle of LiPS.A high sulfur loading of 86%was achieved due to the excellent porous structures of graphene-NPFMC(G-NPFMC)composite.When implemented as a freestanding cathode in Li-S battery,this G-NPFMC-S achieved a high specific capacity(1,356 mAh·g^(-1)),favorable rate capability,and long-term cycling stability up to 500 cycles with a minimum capacity fading rate of 0.025%per cycle,outperforming the corresponding performances of NPFMC-sulfur(NPFMC-S)and MC-sulfur(MC-S).These promising results can be ascribed to the featured structures that formed inside G-NPFMC-S film,as that highly porous NPFMC can provide sufficient storage space for the loading of sulfur,while,the N,P,F-doped carbonic interface and the inserted graphene network help hinder the shuttle of LiPS via chemical adsorption and physical barrier effect.This proposed unique structure can provide a bright prospect in that high mass loading of active sulfur and restriction the shuttle of LiPS can be simultaneously achieved for Li-S battery.
基金Thanks for the supports from the National Natural Science Foundation of China(No.91960103)National Key Research and Development Program of China(No.2022YFB3708600)+1 种基金the Rare and Precious Metals Material Genetic Engineering Project of Yunnan Province(No.202102AB080019-1)the Top Innovative Talents of Graduate Students of Kunming University of Science and Technology。
文摘Effective manipulations of thermal expansion and conductivity are significant for improving operational performances of protective coatings,thermoelectric,and radiators.This work uncovers determinant mechanisms of the thermal expansion and conductivity of symbiotic ScTaO_(4)/SmTaO_(4) composites as thermal/environmental barrier coatings(T/EBCs),and we consider the effects of interface stress and thermal resistance.The weak bonding and interface stress among composite grains manipulate coefficient of thermal expansion(CTE)stretching from 6.4×10^(−6) to 10.7×10^(−6) K^(−1) at 1300℃,which gets close to that of substrates in T/EBC systems.The multiscale effects,including phonon scattering at the interface,mitigation of the phonon speed(vp),and lattice point defects,synergistically depress phonon thermal transports,and we estimate the proportions of different parts.The interface thermal resistance(R)reduces the thermal conductivity(k)by depressing phonon speed and scattering phonons because of different acoustic properties and weak bonding between symbiotic ScTaO_(4) and SmTaO_(4) ceramics in the composites.This study proves that CTE of tantalates can be artificially regulated to match those of different substrates to expand their applications,and the uncovered multiscale effects can be used to manipulate thermal transports of various materials.
基金This work was supported by the National Natural Science Foundation of China （Nos. 11274016, 11474012, 11674005, 11274233, and 11664026）, the National Basic Research Program of China （Nos. 2013CB932604 and 2012CB619304）, Ministry of Science and Technology （National Materials Genome Project） of China （Nos. 2016YFA0301300 and 2016YFB0700600）, and Foundation of Henan Educational Committee （No. 17A430026）.
文摘Semiconducting monolayer （ML） blue phosphorene （BlueP） shares similar stability with ML black phosphorene （BP）, and it has recently been grown on an Au surface. Potential ML BlueP devices often require direct contact with metal to enable the injection of carriers. Using ab initio electronic structure calculations and quantum transport simulations, for the first time, we perform a systematic study of the interfacial properties of ML BlueP in contact with metals spanning a wide work function range in a field effect transistor （FET） configuration. ML BlueP has undergone metallization owing to strong interaction with five metals. There is a strong Fermi level pinning （FLP） in the ML BlueP FETs due to the metal-induced gap states （MIGS） with a pinning factor of 0.42. ML BlueP forms n-type Schottky contact with Sc, Ag, and Pt electrodes with electron Schottky barrier heights （SBHs） of 0.22, 0.22, and 0.80 eV, respectively, and p-type Schottky contact with Au and Pd electrodes with hole SBHs of 0.61 and 0.79 eV, respectively. The MIGS are eliminated by inserting graphene between ML BlueP and the metal electrode, accompanied by a transition from a strong FLP to a weak FLP. Our study not only provides insight into the ML BlueP-metal interfaces, but also helps in the design of ML BlueP devices.
文摘Highly c-axis oriented ZnO thin films were deposited on Si substrates by the pulsed laser deposition (PLD) method. At different growth temperatures, 200 nm silver films as the contact metal were deposited on the ZnO thin films. The growth temperatures have great influence on the crystal quality of Ag films. Current-voltage characteristics were measured at room temperature. The Schottky contacts between Ag and ZnO thin films were successfully obtained when silver electrodes were deposited at 150°C and 200°C. Ohmic contacts were formed while the growth temperatures were lower than 150°C or higher than 200°C. After analysis, the forming of Ag/ZnO Schottky contacts was shown to be dependent on the appearance of the p-type inversion layer at the interface between Ag and ZnO layers.
