An in-depth understanding of the photoconductivity and photocarrier density at the interface is of great significance for improving the performance of optoelectronic devices. However, extraction of the photoconductivi...An in-depth understanding of the photoconductivity and photocarrier density at the interface is of great significance for improving the performance of optoelectronic devices. However, extraction of the photoconductivity and photocarrier density at the heterojunction interface remains elusive. Herein, we have obtained the photoconductivity and photocarrier density of 173 nm Sb2Se3/Si(type-Ⅰ heterojunction) and 90 nm Sb2Se3/Si(type-Ⅱ heterojunction) utilizing terahertz(THz) time-domain spectroscopy(THz-TDS) and a theoretical Drude model. Since type-Ⅰ heterojunctions accelerate carrier recombination and type-Ⅱ heterojunctions accelerate carrier separation, the photoconductivity and photocarrier density of the type-Ⅱ heterojunction(21.8×10^(4)S·m^(-1),1.5 × 10^(15)cm^(-3)) are higher than those of the type-Ⅰ heterojunction(11.8×10^(4)S·m^(-1),0.8×10^(15)cm^(-3)). These results demonstrate that a type-Ⅱ heterojunction is superior to a type-Ⅰ heterojunction for THz wave modulation. This work highlights THz-TDS as an effective tool for studying photoconductivity and photocarrier density at the heterojunction interface. In turn, the intriguing interfacial photoconductivity effect provides a way to improve the THz wave modulation performance.展开更多
Antimony-based materials have become promising anodes within lithium-ion batteries(LIBs)due to their low cost and the high theoretical capacity.However,there is a potential to further enhance the electrochemical perfo...Antimony-based materials have become promising anodes within lithium-ion batteries(LIBs)due to their low cost and the high theoretical capacity.However,there is a potential to further enhance the electrochemical performance of such antimony-based materials.Herein,Sb2Se3@C nanofibers(Sb2Se3@CNFs)are designed and obtained via a novel electrospinning method.Upon electrochemically testing as an anode within LIBs,the Sb2Se3@CNFs(annealed at 600℃)delivers a remarkably good cycling performance of 625 mAh/g at 100 mA/g after 100 cycles.Moreover,it still remains at 490 mAh/g after 500 cycles with an applied current density of 1.0 A/g.The excellent performance of the Sb2 Se3@CNFs can be attributed to the fact that the N-doped C matrices not only remit the volume expansion of materials,but also enhance the electrical and ionic conductivity thusly increasing the lithium-ion diffusion.The obtained Sb2Se3@CNFs are promising anode for LIBs in the future.展开更多
The mixed-dimensional integration of two-dimensional (2D) materials with non-2D materials can give rise to prominent advances in performance or function.To date,the mixed-dimensional one-dimensional (1D)/2D heterostru...The mixed-dimensional integration of two-dimensional (2D) materials with non-2D materials can give rise to prominent advances in performance or function.To date,the mixed-dimensional one-dimensional (1D)/2D heterostructures have been fabricated using various physical assembly approaches.However,direct epitaxial growth method which has notable advantages in preparing large-scale products and obtaining perfect interfaces is rarely investigated.Herein,we demonstrate for the first time the direct synthesis of the 1D/2D mixed-dimensional heterostructures by sequential vapor-phase growth of Sb2Se3 nanowires on WS2 monolayers.X-ray diffraction (XRD) pattern and Raman spectrum confirm the composition of the Sb2Se3/NS2 heterostructures.Transmission electron microscope (TEM) measurement demonstrates high quality of the heterostructures.Electrical transport characterization reveals that Sb2Se3 nanowire exhibits p-type characteristic and that WS2 monolayer exhibits n-type behavior,and that the p-n diode from 1D/2D mixed-dimensional Sb2Se3/WS2 heterostructure possesses obvious current rectification behavior.Optoelectronic measurements of the heterostructures show apparent photovoltaic response with an open-circuit voltage of 0.19 V,photoresponsivity of 1.51 A/W (Vds =5 V) and fast response time of less than 8 ms.The van der Waals epitaxial growth mode of Sb2Se3 nanowires on WS2 monolayers is verified by stripping the Sb2Se3 nanowire from the heterostructures using tape.Together,the direct van der Waals epitaxy opens a facile pathway to 1D/2D mixed-dimensional heterostructures for functional electronic and optoelectronic devices.展开更多
In this work, a fast(0.5 h), green microwave-assisted synthesis of single crystalline Sb_2Se_3 nanowires was developed. For the first time we demonstrated a facile solvent-mediated process, whereby intriguing nanostru...In this work, a fast(0.5 h), green microwave-assisted synthesis of single crystalline Sb_2Se_3 nanowires was developed. For the first time we demonstrated a facile solvent-mediated process, whereby intriguing nanostructures including antimony selenide(Sb_2Se_3) nanowires and selenium(Se) microrods can be achieved by merely varying the volume ratio of ethylene glycol(EG) and H_2O free from expensive chemical and additional surfactant. The achieved uniform Sb_2Se_3 nanowire is single crystalline along [001]growth direction with a diameter of 100 nm and a length up to tens of micrometers. When evaluated as an anode of lithium-ion battery, Sb_2Se_3 nanowire can deliver a high reversible capacity of 650.2 m Ah g^(-1) at 100 mA g^(-1) and a capacity retention of 63.8% after long-term 1000 cycles at 1000 mA g^(-1), as well as superior rate capability(389.5 m Ah g^(-1) at 2000 mA g^(-1)). This easy solvent-mediated microwave synthesis approach exhibits its great universe and importance towards the fabrication of high-performance metal chalcogenide electrode materials for future low-cost, large-scale energy storage systems.展开更多
Antimony sulfide–selenide Sb2（S,Se）3,including Sb2S3and Sb2Se3,can be regarded as binary metal chalcogenides semiconductors since Sb2S3and Sb2Se3are isomorphous.They possess abundant elemental storage,nontoxicity,g...Antimony sulfide–selenide Sb2（S,Se）3,including Sb2S3and Sb2Se3,can be regarded as binary metal chalcogenides semiconductors since Sb2S3and Sb2Se3are isomorphous.They possess abundant elemental storage,nontoxicity,good stability with regard to moisture at elevated temperatures and suitable physical parameters for light absorption materials in solar cells.To date,quite a few attempts have been conducted in the materials synthesis,photovoltaic property investigation and device fabrication.Benefiting from previous investigation in thin film solar cells and new generation nanostructured solar cells,this class of materials has been applied in either sensitized-architecture or planar heterojunction solar cells.Decent power conversion efficiencies from 5%to 7.5%have been achieved.Apparently,further improvement on the efficiency is required for future practical applications.To give an overview of this research field,this paper displays some typical researches regarding the methodologies toward the antimony sulfide–selenide synthesis,development of interfacial materials and device fabrications,during which we highlight some critical findings that promote the efficiency enhancement.Finally,this paper proposes some outstanding issue regarding fundamental understanding of the materials,some viewpoints for the efficiency improvement and their future challenges in solar cell applications.展开更多
基金Project supported by the National Natural Science Foundation of China (Grant Nos. 12261141662, 12074311, and 12004310)。
文摘An in-depth understanding of the photoconductivity and photocarrier density at the interface is of great significance for improving the performance of optoelectronic devices. However, extraction of the photoconductivity and photocarrier density at the heterojunction interface remains elusive. Herein, we have obtained the photoconductivity and photocarrier density of 173 nm Sb2Se3/Si(type-Ⅰ heterojunction) and 90 nm Sb2Se3/Si(type-Ⅱ heterojunction) utilizing terahertz(THz) time-domain spectroscopy(THz-TDS) and a theoretical Drude model. Since type-Ⅰ heterojunctions accelerate carrier recombination and type-Ⅱ heterojunctions accelerate carrier separation, the photoconductivity and photocarrier density of the type-Ⅱ heterojunction(21.8×10^(4)S·m^(-1),1.5 × 10^(15)cm^(-3)) are higher than those of the type-Ⅰ heterojunction(11.8×10^(4)S·m^(-1),0.8×10^(15)cm^(-3)). These results demonstrate that a type-Ⅱ heterojunction is superior to a type-Ⅰ heterojunction for THz wave modulation. This work highlights THz-TDS as an effective tool for studying photoconductivity and photocarrier density at the heterojunction interface. In turn, the intriguing interfacial photoconductivity effect provides a way to improve the THz wave modulation performance.
基金supported by the National Natural Science Foundation of China(No.51302079)the Natural Science Foundation of Hunan Province(No.2017JJ1008)。
文摘Antimony-based materials have become promising anodes within lithium-ion batteries(LIBs)due to their low cost and the high theoretical capacity.However,there is a potential to further enhance the electrochemical performance of such antimony-based materials.Herein,Sb2Se3@C nanofibers(Sb2Se3@CNFs)are designed and obtained via a novel electrospinning method.Upon electrochemically testing as an anode within LIBs,the Sb2Se3@CNFs(annealed at 600℃)delivers a remarkably good cycling performance of 625 mAh/g at 100 mA/g after 100 cycles.Moreover,it still remains at 490 mAh/g after 500 cycles with an applied current density of 1.0 A/g.The excellent performance of the Sb2 Se3@CNFs can be attributed to the fact that the N-doped C matrices not only remit the volume expansion of materials,but also enhance the electrical and ionic conductivity thusly increasing the lithium-ion diffusion.The obtained Sb2Se3@CNFs are promising anode for LIBs in the future.
基金the Fundamental Research Funds of the Central Universities (No.531107051078)the Double First-Class University Initiative of Hunan University (No.531109100004). We also acknowledge the support from the National Natural Science Foundation of China (No.751214296)+1 种基金Hunan Key Laboratory of Two-Dimensional Materials (No.801200005)Strategic Priority Research Program of Chinese Academy of Science (No.XDB30000000).
文摘The mixed-dimensional integration of two-dimensional (2D) materials with non-2D materials can give rise to prominent advances in performance or function.To date,the mixed-dimensional one-dimensional (1D)/2D heterostructures have been fabricated using various physical assembly approaches.However,direct epitaxial growth method which has notable advantages in preparing large-scale products and obtaining perfect interfaces is rarely investigated.Herein,we demonstrate for the first time the direct synthesis of the 1D/2D mixed-dimensional heterostructures by sequential vapor-phase growth of Sb2Se3 nanowires on WS2 monolayers.X-ray diffraction (XRD) pattern and Raman spectrum confirm the composition of the Sb2Se3/NS2 heterostructures.Transmission electron microscope (TEM) measurement demonstrates high quality of the heterostructures.Electrical transport characterization reveals that Sb2Se3 nanowire exhibits p-type characteristic and that WS2 monolayer exhibits n-type behavior,and that the p-n diode from 1D/2D mixed-dimensional Sb2Se3/WS2 heterostructure possesses obvious current rectification behavior.Optoelectronic measurements of the heterostructures show apparent photovoltaic response with an open-circuit voltage of 0.19 V,photoresponsivity of 1.51 A/W (Vds =5 V) and fast response time of less than 8 ms.The van der Waals epitaxial growth mode of Sb2Se3 nanowires on WS2 monolayers is verified by stripping the Sb2Se3 nanowire from the heterostructures using tape.Together,the direct van der Waals epitaxy opens a facile pathway to 1D/2D mixed-dimensional heterostructures for functional electronic and optoelectronic devices.
基金supported by the National Fund for Fostering Talents of Basic Science (J1103212)the Foundation for Outstanding Young Scientist in Shandong Province (BS2010CL036)~~
基金supported by the National Key Research and Development Program of China(2016YFA0202603)the National Basic Research Program of China(2013CB934103)+5 种基金the National Natural Science Foundation of China(51521001,51602239)the National Natural Science Fund for Distinguished Young Scholars(51425204)Yellow Crane Talent(Science&Technology)Program of Wuhan Citythe Fundamental Research Funds for the Central Universities(WUT:2016III001,2016III003,2016IVA090)the Programme of Introducing Talents of Discipline to Universities(B17034)support from the Lorraine Region(nowpart of Grand Est Region)Cooperation Research Lorraine/Hubei Program 2015/2017
文摘In this work, a fast(0.5 h), green microwave-assisted synthesis of single crystalline Sb_2Se_3 nanowires was developed. For the first time we demonstrated a facile solvent-mediated process, whereby intriguing nanostructures including antimony selenide(Sb_2Se_3) nanowires and selenium(Se) microrods can be achieved by merely varying the volume ratio of ethylene glycol(EG) and H_2O free from expensive chemical and additional surfactant. The achieved uniform Sb_2Se_3 nanowire is single crystalline along [001]growth direction with a diameter of 100 nm and a length up to tens of micrometers. When evaluated as an anode of lithium-ion battery, Sb_2Se_3 nanowire can deliver a high reversible capacity of 650.2 m Ah g^(-1) at 100 mA g^(-1) and a capacity retention of 63.8% after long-term 1000 cycles at 1000 mA g^(-1), as well as superior rate capability(389.5 m Ah g^(-1) at 2000 mA g^(-1)). This easy solvent-mediated microwave synthesis approach exhibits its great universe and importance towards the fabrication of high-performance metal chalcogenide electrode materials for future low-cost, large-scale energy storage systems.
基金supported by the Recruitment Program of Global Expertsthe Fundamental Research Funds for the Central Universities(Nos.WK2060140022,WK2060140023 and WK2060140024)
文摘Antimony sulfide–selenide Sb2（S,Se）3,including Sb2S3and Sb2Se3,can be regarded as binary metal chalcogenides semiconductors since Sb2S3and Sb2Se3are isomorphous.They possess abundant elemental storage,nontoxicity,good stability with regard to moisture at elevated temperatures and suitable physical parameters for light absorption materials in solar cells.To date,quite a few attempts have been conducted in the materials synthesis,photovoltaic property investigation and device fabrication.Benefiting from previous investigation in thin film solar cells and new generation nanostructured solar cells,this class of materials has been applied in either sensitized-architecture or planar heterojunction solar cells.Decent power conversion efficiencies from 5%to 7.5%have been achieved.Apparently,further improvement on the efficiency is required for future practical applications.To give an overview of this research field,this paper displays some typical researches regarding the methodologies toward the antimony sulfide–selenide synthesis,development of interfacial materials and device fabrications,during which we highlight some critical findings that promote the efficiency enhancement.Finally,this paper proposes some outstanding issue regarding fundamental understanding of the materials,some viewpoints for the efficiency improvement and their future challenges in solar cell applications.
