[Objective] The aim of this study was to extract RNA,DNA and protein from plants by using modified one step method.[Method]CTAB was used for the modifying of Biozol-based one step extraction method,which was then used...[Objective] The aim of this study was to extract RNA,DNA and protein from plants by using modified one step method.[Method]CTAB was used for the modifying of Biozol-based one step extraction method,which was then used for the isolation of RNA,DNA and protein from the roots of maize（Zea mays L.）,soybean（Glycine max L.）,alfalfa（Medicago sativa L.）and cucumber（Cucumis sativus L.）.And the heme oxygenase-1 gene（HO-1）and calcium-dependent protein kinase-1 gene（CDPK1）,as well as HO-1 protein were identified.[Result]The result of UV spectrophotometer determination and agarose gel electrophoresis analysis showed that the purity of obtained RNA and DNA sample was relatively high;HO-1 and CDPK1 gene exhibited the positive signals checked by RT-PCR;the extracted protein could be used for western blotting analysis;the whole isolation procedure cost 3 h.[Conclusion]This method can be used as a good reference for researcher and will offer a better value with a wide range of applications.展开更多
Vanadium nitrides were prepared via one step method of carbothermal reduction and nitridation of vanadium trioxide. Thermalgravimetric analysis （TGA） and X-ray diffraction were used to determine the reaction paths o...Vanadium nitrides were prepared via one step method of carbothermal reduction and nitridation of vanadium trioxide. Thermalgravimetric analysis （TGA） and X-ray diffraction were used to determine the reaction paths of vanadium carbide, namely the following sequential reaction： V2O3→V8C7 in higher temperature stage, the rule of vanadium nitride synthesized was established, and defined conditions of temperature for the production of the carbides and nitrides were determined. Vanadium oxycarbide may consist in the front process of carbothermal reduction of vanadium trioxide. In one step method for vanadium nitride by carbothermal reduction and nitridation of vanadium trioxide, the nitridation process is simultaneous with the carbothermal reduction. A one-step mechanism of the carbothermal reduction with simultaneous nitridation leaded to a lower terminal temperature in nitridation process for vanadium nitride produced, compared with that of carbothermal reduction process without nitridation. The grain size and shape of vanadium nitride were uniform, and had the shape of a cube. The one step method combined vacuum carborization and nitridation （namely two step method） into one process. It simplified the technological process and decreased the costs.展开更多
Graphitic carbon nitride(g-C_(3)N_(4))-based materials are regarded as one of the most potential photocatalysts for utilizing solar energy.In this work,we reported a facile one step in-situ hydrothermal-roasting metho...Graphitic carbon nitride(g-C_(3)N_(4))-based materials are regarded as one of the most potential photocatalysts for utilizing solar energy.In this work,we reported a facile one step in-situ hydrothermal-roasting method for preparing honeycomb-like g-C_(3)N_(4)/CeO_(2) nanosheets with abundant oxygen vacancies(g-C_(3)N_(4)/CeO_(2)-x).The hydrothermal-roasting and incomplete-sealed state can(i)generate an in-situ reducing atmosphere(CO,N2,NH3) to tune the concentration of oxygen vacancies in CeO_(2);(ii) beneficial to prevent continuous growth of g-C_(3)N_(4) and results in honeycomb-like g-C_(3)N_(4)/CeO_(2)-x hybrid nanosheets.What is more,the g-C_(3)N_(4)/CeO_(2)-x photocatalyst exhibited extended photoresponse range,increased specific surface area and obviously enhanced separation efficiency of photogenerated electron-hole pairs.As a proof-of-concept application,the optimized g-C_(3)N_(4)/CeO_(2)-xnanosheets could achieve 98% removal efficiency for Cr(Ⅵ) under visible light irradiation(λ≥420 nm)within 2.5 h,which is significantly better than those of pure g-C_(3)N_(4) and CeO_(2).This work provides a new idea for more rationally designing and constructing g-C_(3)N_(4)-based catalysts for efficient extended photochemical application.展开更多
In the present work, a simple scheme for the direct measurement of the concurrence of two-qubit pure states is proposed. The scheme is based on trapped ions and only needs one step when the two identical pure states a...In the present work, a simple scheme for the direct measurement of the concurrence of two-qubit pure states is proposed. The scheme is based on trapped ions and only needs one step when the two identical pure states are given. The vibrational mode in our proposal is only virtually excited, which is important in view of decoherence.Furthermore, the scheme is feasible based on current technologies.展开更多
We present a very simple scheme for generating four-qubit cluster states with one step using paritymeasurement based on dipole-induced transparency in a cavity-waveguide system.The scheme only uses the photondetectors...We present a very simple scheme for generating four-qubit cluster states with one step using paritymeasurement based on dipole-induced transparency in a cavity-waveguide system.The scheme only uses the photondetectors to check the parity of the spatially separated dipole,which are the same (even parity) or different (odd parity)through measuring the light fields in the waveguide.The initial entangled states remain after nondetective identificationand they can be used for successive tasks.展开更多
A membrane element model with bending modification based on element moment equilibrium is proposed for the first time by the authors, who apply the element model in one step inverse method and simulate the forming pro...A membrane element model with bending modification based on element moment equilibrium is proposed for the first time by the authors, who apply the element model in one step inverse method and simulate the forming process of a flower-shaped box using the membrane element model with and without this modification. The numerical results are compared with those of the incremental method to verify the validity of the element model developed in this paper.展开更多
This paper presents a very simple scheme for generating quantum controlled phase-shift gate with only one step by using the two vibrational modes of a trapped ion as the two qubits. The scheme couples two vibration de...This paper presents a very simple scheme for generating quantum controlled phase-shift gate with only one step by using the two vibrational modes of a trapped ion as the two qubits. The scheme couples two vibration degrees of freedom coupled with a suitable chosen laser excitation via the ionic states.展开更多
Editor’s Note:In the recent two yearssince ZTE’s NGN prod-uct series were put intomarket,ZTE has maderemarkable achieve-ments in the industry. Al-though a leading vendorin China, ZTE has beencontinuously doing busi-...Editor’s Note:In the recent two yearssince ZTE’s NGN prod-uct series were put intomarket,ZTE has maderemarkable achieve-ments in the industry. Al-though a leading vendorin China, ZTE has beencontinuously doing busi- ness in a prudent and practical way,which has been recognized by govern-ment authorities, carriers and customers.In order to learn more about ZTE’s NGNdevelopment strategy,we interviewedChen Jie, ZTE’s vice president and gen-eral manager of Network Division, aboutZTE’s NGN development strategy, R&Dadvantages and progress.展开更多
18 years ago, when exhibition industry was merely a concept in China, Liu Jianping, President of LINGTONG started to work on exhibition equipment and set up Lingtong Exhibition Products Co., Ltd in Changzhou. The comp...18 years ago, when exhibition industry was merely a concept in China, Liu Jianping, President of LINGTONG started to work on exhibition equipment and set up Lingtong Exhibition Products Co., Ltd in Changzhou. The company has become the earliest specialized company involved in development, research and production of exhibition equipment in China.展开更多
Selectivity-control has long been a central pursuit in organic chemistry.Most recent advances have focused on achieving individual forms of selectivity,such as chemo-,regio-,E/Z-,diastereo-,or enantioselectivity.Tradi...Selectivity-control has long been a central pursuit in organic chemistry.Most recent advances have focused on achieving individual forms of selectivity,such as chemo-,regio-,E/Z-,diastereo-,or enantioselectivity.Traditionally,multi-selectivities have been realized through one-dimensional linear synthetic routes,in which distinct sites are modified sequentially across multiple reaction steps.展开更多
To the Editor:Living donor liver transplantation continues to be a widely ac-cepted treatment for end-stage liver diseases[1].However,biliary complications remain a significant challenge,attributable to both surgical ...To the Editor:Living donor liver transplantation continues to be a widely ac-cepted treatment for end-stage liver diseases[1].However,biliary complications remain a significant challenge,attributable to both surgical and nonsurgical factors.These complications include bile leakage,biliary stricture,and choledocholithiasis,with a reported incidence of biliary stricture in pediatric living donor liver recip-ients ranging from 10%to 35%[2].Commonly employed thera-peutic approaches for biliary complications are endoscopic retro-grade cholangiopancreatography(ERCP),percutaneous transhepatic cholangioscopic lithotomy(PTCSL),and surgery,with ERCP often being the preferred initial treatment.展开更多
The nonuniform sampling method in hologram plane is proposed to reconstruct objects on multi-plane simultaneously. The hologram is nonuniformly sampled by decomposing it into several parts with various sampling rates....The nonuniform sampling method in hologram plane is proposed to reconstruct objects on multi-plane simultaneously. The hologram is nonuniformly sampled by decomposing it into several parts with various sampling rates. The hologram is calculated based on the nonuniform fast Fourier transform （NUFFT） algorithm. In the experiment, we load this nonuniformly sampled hologram on phases-only spatial light modulator （SLM）, and by illumination with collimated light objects with different sampling rates are reconstructed at different distant planes simultaneously. Both of the numerically simulation and optical experiments are performed to demonstrate the feasibility of our method. The experiment also shows that our proposed nonuniform sampled hologram for multi-plane objects is calculated by only one step, better than conventional method that needs several steps of calculation proportional to the numbers of object planes.展开更多
East Asia economic integration should start with free trade among ASEAN, China, Japan and South Korea Should East Asia pursue economic integration through the East Asia Free Trade Area (EAFTA) or the Comprehensive Eco...East Asia economic integration should start with free trade among ASEAN, China, Japan and South Korea Should East Asia pursue economic integration through the East Asia Free Trade Area (EAFTA) or the Comprehensive Economic展开更多
Pension program for unemployed urban residents becomes an indispensable part of the country’s pension system Every citizen is entitled to enjoy equal access to pension programs.It is a basic right endowed by the Cons...Pension program for unemployed urban residents becomes an indispensable part of the country’s pension system Every citizen is entitled to enjoy equal access to pension programs.It is a basic right endowed by the Constitution.For the Chinese Government,covering every citizen with the pension scheme is a solemn promiset o everyone.On July 1,2011,the pension programf or unemployed urban residents was implemented,which would provide much needed support for urban residents without jobs展开更多
Although the Pythagorean theorem has been around for thousands of years, the varied proofs and ideas that spin-off from it continue to fascinate. There are various ways in which the theorem can be stated. For example-...Although the Pythagorean theorem has been around for thousands of years, the varied proofs and ideas that spin-off from it continue to fascinate. There are various ways in which the theorem can be stated. For example-Given a right triangle , the sum of the areas of the legs will equal the square of the hypotenuse.展开更多
The technique of phase measuring profilometry using a single phase step method is proposed.This method can automatically obtain phase value at each pixel by using a discret cosine transform algorithm.The method is abl...The technique of phase measuring profilometry using a single phase step method is proposed.This method can automatically obtain phase value at each pixel by using a discret cosine transform algorithm.The method is able to automatically recognize any position between depression and elevation on an object surface.Theoretical analysis and experimental verification are presented.展开更多
Heterostructures constructed by two-dimensional(2D)material layers,which are usually prepared via a transfer/stacking method or van der Waals epitaxy,have achieved significant success in various optoelectronic devices...Heterostructures constructed by two-dimensional(2D)material layers,which are usually prepared via a transfer/stacking method or van der Waals epitaxy,have achieved significant success in various optoelectronic devices including solar cells,light-emitting diodes and photodetectors.However,to date,most of these heterostructures comprise 2D materials with a similar crystal structure.Thus,preparation of heterostructures with different crystal structures is desirable but still a great challenge.Herein,we report a one-step CVD strategy to successfully grow SnS_(2)/SnS vertical heterostructures on a mica substrate.Raman spectroscopy,atomic force microscopy(AFM)and transmission electron microscopy(TEM)characterizations reveal that the heterostructure is formed by stacking of pyramid-shaped SnS_(2)of the hexagonal structure onto the rhombus SnS flake of the orthorhombic structure.The photodetector based on the SnS_(2)/SnS heterostructure demonstrates high optoelectronic performance:a 27.7 A W^(-1)photoresponsivity,2.2×10^(3)on/off ratio,less than 10 ms response time and 2.1×10^(10)jones specific detectivity.The superior performance originates from the high crystal quality of the as-grown heterostructure and its vertical device architecture.This study can expand our capability to fabricate a variety of two-dimensional heterostructures and make these heterostructures highly desirable as novel building blocks for potential applications in electronic and optoelectronic devices.展开更多
Organic-inorganic lead halide perovskites represent a group of materials with diverse structures and promising optical/optoelectronic properties.The performance of perovskite based solar cells relies tremendously on t...Organic-inorganic lead halide perovskites represent a group of materials with diverse structures and promising optical/optoelectronic properties.The performance of perovskite based solar cells relies tremendously on the structure/properties of the absorber.The physicochemical properties of the perovskite active layer depend on the substrate,preparation methods,environments and the starting materials.In this study,we investigated the effects of starting materials in the precursor solution on the physicochemical properties of the resulting one-step spin coated MA_(0.8)FA_(0.2)PbI_(3-y)Br_(y) film and the photovoltaic performance of the corresponding inverted(p-i-n)perovskite solar cells.Two precursor solutions containing exactly the same atom stoichiometry were prepared from two different groups of starting materials(Group A:CH_(3)NH_(3)I,CH(NH_(2))_(2)I,CH_(3)NH_(3)Br,and PbI_(2);Group B:CH_(3)NH_(3)I,CH(NH_(2))_(2)I,PbI_(2) and PbBr_(2)).The MA_(0.8)FA_(0.2)PbI_(3-y)Br_(y) films(A1 and A2)prepared from the A precursor solution had better photovoltaic performances compared to those(B1 and B2)obtained from the B precursor solution for the same y values.The stoichiometry of the film to achieve the best photovoltaic performance(the corresponding cell has the highest efficiency)is not the same for the A-group(prepared from the A precursor solution)and B-group films(prepared from the B precursor solution).The photovoltaic performance of the perovskite film is directly correlated to the crystallinity,morphology and defect sites of the film as evidenced by GIXRD,scanning electron microscopy(SEM)and transient photoluminescence(TRPL)data.The morphology of the mixed-halide perovskite films depends on the homogeneity of the halide stoichiometries.The A-group films with more possible halide stoichiometries have better crystallinity and continuity compared to those of the B-group films,probably due to the difference in the crystallization rates for the two group perovskite films.Therefore,for preparing mixed-halide perovskites with the same average halide stoichiometry,starting materials that can produce perovskite films with more halide stoichiometries are a better choice.展开更多
基金Supported by Opening Program of Physiologial Key Laboratory for Cultivation of Tropical Crops in Hainan Province(Key Opening Bio-logial Laboratory of Rubber of Ministry of Agriculture/Breeding Basein State and Provincial Key Laboratory)(KLOF0907)Major and Special Program for Cultivation of Genetically Modified New Varieties(No.2009ZX08012-014B)+1 种基金National Natural Science Foundation of China(No.30971711)Natural Science Foundation in Jiangsu Province(No.BK2009309)~~
文摘[Objective] The aim of this study was to extract RNA,DNA and protein from plants by using modified one step method.[Method]CTAB was used for the modifying of Biozol-based one step extraction method,which was then used for the isolation of RNA,DNA and protein from the roots of maize（Zea mays L.）,soybean（Glycine max L.）,alfalfa（Medicago sativa L.）and cucumber（Cucumis sativus L.）.And the heme oxygenase-1 gene（HO-1）and calcium-dependent protein kinase-1 gene（CDPK1）,as well as HO-1 protein were identified.[Result]The result of UV spectrophotometer determination and agarose gel electrophoresis analysis showed that the purity of obtained RNA and DNA sample was relatively high;HO-1 and CDPK1 gene exhibited the positive signals checked by RT-PCR;the extracted protein could be used for western blotting analysis;the whole isolation procedure cost 3 h.[Conclusion]This method can be used as a good reference for researcher and will offer a better value with a wide range of applications.
文摘Vanadium nitrides were prepared via one step method of carbothermal reduction and nitridation of vanadium trioxide. Thermalgravimetric analysis （TGA） and X-ray diffraction were used to determine the reaction paths of vanadium carbide, namely the following sequential reaction： V2O3→V8C7 in higher temperature stage, the rule of vanadium nitride synthesized was established, and defined conditions of temperature for the production of the carbides and nitrides were determined. Vanadium oxycarbide may consist in the front process of carbothermal reduction of vanadium trioxide. In one step method for vanadium nitride by carbothermal reduction and nitridation of vanadium trioxide, the nitridation process is simultaneous with the carbothermal reduction. A one-step mechanism of the carbothermal reduction with simultaneous nitridation leaded to a lower terminal temperature in nitridation process for vanadium nitride produced, compared with that of carbothermal reduction process without nitridation. The grain size and shape of vanadium nitride were uniform, and had the shape of a cube. The one step method combined vacuum carborization and nitridation （namely two step method） into one process. It simplified the technological process and decreased the costs.
基金the National Natural Science Foundation of China(Nos.21103024,61171008)Natural Science Foundation of Zhejiang Province(No.LY19B060006)+1 种基金National Key Research and Development Program of China(No.2018YFB1502900)Technology Development Project of Jiaxing University(No.70518047)。
文摘Graphitic carbon nitride(g-C_(3)N_(4))-based materials are regarded as one of the most potential photocatalysts for utilizing solar energy.In this work,we reported a facile one step in-situ hydrothermal-roasting method for preparing honeycomb-like g-C_(3)N_(4)/CeO_(2) nanosheets with abundant oxygen vacancies(g-C_(3)N_(4)/CeO_(2)-x).The hydrothermal-roasting and incomplete-sealed state can(i)generate an in-situ reducing atmosphere(CO,N2,NH3) to tune the concentration of oxygen vacancies in CeO_(2);(ii) beneficial to prevent continuous growth of g-C_(3)N_(4) and results in honeycomb-like g-C_(3)N_(4)/CeO_(2)-x hybrid nanosheets.What is more,the g-C_(3)N_(4)/CeO_(2)-x photocatalyst exhibited extended photoresponse range,increased specific surface area and obviously enhanced separation efficiency of photogenerated electron-hole pairs.As a proof-of-concept application,the optimized g-C_(3)N_(4)/CeO_(2)-xnanosheets could achieve 98% removal efficiency for Cr(Ⅵ) under visible light irradiation(λ≥420 nm)within 2.5 h,which is significantly better than those of pure g-C_(3)N_(4) and CeO_(2).This work provides a new idea for more rationally designing and constructing g-C_(3)N_(4)-based catalysts for efficient extended photochemical application.
基金supported by the National Natural Science Foundation of China under Grant No.60878059the Funds of Educational Committee of Fujian Province under Grant Nos.JB07043 and JB08066the Fund from Fujian Normal University under Grant No.BKL2007092
文摘In the present work, a simple scheme for the direct measurement of the concurrence of two-qubit pure states is proposed. The scheme is based on trapped ions and only needs one step when the two identical pure states are given. The vibrational mode in our proposal is only virtually excited, which is important in view of decoherence.Furthermore, the scheme is feasible based on current technologies.
基金National Natural Science Foundation of China under Grant No.10574001the Program of the Education Department of Anhui Province under Grant No.2004kj029the Talent Foundation of Anhui University
文摘We present a very simple scheme for generating four-qubit cluster states with one step using paritymeasurement based on dipole-induced transparency in a cavity-waveguide system.The scheme only uses the photondetectors to check the parity of the spatially separated dipole,which are the same (even parity) or different (odd parity)through measuring the light fields in the waveguide.The initial entangled states remain after nondetective identificationand they can be used for successive tasks.
基金Project supported by the National Natural Science Foundation of China (No. 51075187)
文摘A membrane element model with bending modification based on element moment equilibrium is proposed for the first time by the authors, who apply the element model in one step inverse method and simulate the forming process of a flower-shaped box using the membrane element model with and without this modification. The numerical results are compared with those of the incremental method to verify the validity of the element model developed in this paper.
基金supported by the National Natural Science Foundation of China (Grant No 10574001)the Program of the Education Department of Anhui Province (2004kj029) of China+1 种基金the Talent Foundation of Anhui University of Chinathe Youth Program of Fuyang Teachers College of China (Grant Nos 2005LQ03 and 2005LQ04)
文摘This paper presents a very simple scheme for generating quantum controlled phase-shift gate with only one step by using the two vibrational modes of a trapped ion as the two qubits. The scheme couples two vibration degrees of freedom coupled with a suitable chosen laser excitation via the ionic states.
文摘Editor’s Note:In the recent two yearssince ZTE’s NGN prod-uct series were put intomarket,ZTE has maderemarkable achieve-ments in the industry. Al-though a leading vendorin China, ZTE has beencontinuously doing busi- ness in a prudent and practical way,which has been recognized by govern-ment authorities, carriers and customers.In order to learn more about ZTE’s NGNdevelopment strategy,we interviewedChen Jie, ZTE’s vice president and gen-eral manager of Network Division, aboutZTE’s NGN development strategy, R&Dadvantages and progress.
文摘18 years ago, when exhibition industry was merely a concept in China, Liu Jianping, President of LINGTONG started to work on exhibition equipment and set up Lingtong Exhibition Products Co., Ltd in Changzhou. The company has become the earliest specialized company involved in development, research and production of exhibition equipment in China.
文摘Selectivity-control has long been a central pursuit in organic chemistry.Most recent advances have focused on achieving individual forms of selectivity,such as chemo-,regio-,E/Z-,diastereo-,or enantioselectivity.Traditionally,multi-selectivities have been realized through one-dimensional linear synthetic routes,in which distinct sites are modified sequentially across multiple reaction steps.
文摘To the Editor:Living donor liver transplantation continues to be a widely ac-cepted treatment for end-stage liver diseases[1].However,biliary complications remain a significant challenge,attributable to both surgical and nonsurgical factors.These complications include bile leakage,biliary stricture,and choledocholithiasis,with a reported incidence of biliary stricture in pediatric living donor liver recip-ients ranging from 10%to 35%[2].Commonly employed thera-peutic approaches for biliary complications are endoscopic retro-grade cholangiopancreatography(ERCP),percutaneous transhepatic cholangioscopic lithotomy(PTCSL),and surgery,with ERCP often being the preferred initial treatment.
基金supported by the National"973"Program of China(Nos.2013CB328803 and 2013CB328804)the National"863"Program of China (Nos.2012AA03A302 and 2013AA013904)the Aeronautical Science Foundation of China(No.20125169021)
文摘The nonuniform sampling method in hologram plane is proposed to reconstruct objects on multi-plane simultaneously. The hologram is nonuniformly sampled by decomposing it into several parts with various sampling rates. The hologram is calculated based on the nonuniform fast Fourier transform （NUFFT） algorithm. In the experiment, we load this nonuniformly sampled hologram on phases-only spatial light modulator （SLM）, and by illumination with collimated light objects with different sampling rates are reconstructed at different distant planes simultaneously. Both of the numerically simulation and optical experiments are performed to demonstrate the feasibility of our method. The experiment also shows that our proposed nonuniform sampled hologram for multi-plane objects is calculated by only one step, better than conventional method that needs several steps of calculation proportional to the numbers of object planes.
文摘East Asia economic integration should start with free trade among ASEAN, China, Japan and South Korea Should East Asia pursue economic integration through the East Asia Free Trade Area (EAFTA) or the Comprehensive Economic
文摘Pension program for unemployed urban residents becomes an indispensable part of the country’s pension system Every citizen is entitled to enjoy equal access to pension programs.It is a basic right endowed by the Constitution.For the Chinese Government,covering every citizen with the pension scheme is a solemn promiset o everyone.On July 1,2011,the pension programf or unemployed urban residents was implemented,which would provide much needed support for urban residents without jobs
文摘Although the Pythagorean theorem has been around for thousands of years, the varied proofs and ideas that spin-off from it continue to fascinate. There are various ways in which the theorem can be stated. For example-Given a right triangle , the sum of the areas of the legs will equal the square of the hypotenuse.
文摘The technique of phase measuring profilometry using a single phase step method is proposed.This method can automatically obtain phase value at each pixel by using a discret cosine transform algorithm.The method is able to automatically recognize any position between depression and elevation on an object surface.Theoretical analysis and experimental verification are presented.
基金financial supports received from MOST of China(2016YFA0200602)the National Natural Science Foundation of China(21421063,11474260,11374274,11504364)+1 种基金the Chinese Academy of Sciences(XDB01020200)the Anhui Natural Science Foundation(1608085QA17).
文摘Heterostructures constructed by two-dimensional(2D)material layers,which are usually prepared via a transfer/stacking method or van der Waals epitaxy,have achieved significant success in various optoelectronic devices including solar cells,light-emitting diodes and photodetectors.However,to date,most of these heterostructures comprise 2D materials with a similar crystal structure.Thus,preparation of heterostructures with different crystal structures is desirable but still a great challenge.Herein,we report a one-step CVD strategy to successfully grow SnS_(2)/SnS vertical heterostructures on a mica substrate.Raman spectroscopy,atomic force microscopy(AFM)and transmission electron microscopy(TEM)characterizations reveal that the heterostructure is formed by stacking of pyramid-shaped SnS_(2)of the hexagonal structure onto the rhombus SnS flake of the orthorhombic structure.The photodetector based on the SnS_(2)/SnS heterostructure demonstrates high optoelectronic performance:a 27.7 A W^(-1)photoresponsivity,2.2×10^(3)on/off ratio,less than 10 ms response time and 2.1×10^(10)jones specific detectivity.The superior performance originates from the high crystal quality of the as-grown heterostructure and its vertical device architecture.This study can expand our capability to fabricate a variety of two-dimensional heterostructures and make these heterostructures highly desirable as novel building blocks for potential applications in electronic and optoelectronic devices.
文摘Organic-inorganic lead halide perovskites represent a group of materials with diverse structures and promising optical/optoelectronic properties.The performance of perovskite based solar cells relies tremendously on the structure/properties of the absorber.The physicochemical properties of the perovskite active layer depend on the substrate,preparation methods,environments and the starting materials.In this study,we investigated the effects of starting materials in the precursor solution on the physicochemical properties of the resulting one-step spin coated MA_(0.8)FA_(0.2)PbI_(3-y)Br_(y) film and the photovoltaic performance of the corresponding inverted(p-i-n)perovskite solar cells.Two precursor solutions containing exactly the same atom stoichiometry were prepared from two different groups of starting materials(Group A:CH_(3)NH_(3)I,CH(NH_(2))_(2)I,CH_(3)NH_(3)Br,and PbI_(2);Group B:CH_(3)NH_(3)I,CH(NH_(2))_(2)I,PbI_(2) and PbBr_(2)).The MA_(0.8)FA_(0.2)PbI_(3-y)Br_(y) films(A1 and A2)prepared from the A precursor solution had better photovoltaic performances compared to those(B1 and B2)obtained from the B precursor solution for the same y values.The stoichiometry of the film to achieve the best photovoltaic performance(the corresponding cell has the highest efficiency)is not the same for the A-group(prepared from the A precursor solution)and B-group films(prepared from the B precursor solution).The photovoltaic performance of the perovskite film is directly correlated to the crystallinity,morphology and defect sites of the film as evidenced by GIXRD,scanning electron microscopy(SEM)and transient photoluminescence(TRPL)data.The morphology of the mixed-halide perovskite films depends on the homogeneity of the halide stoichiometries.The A-group films with more possible halide stoichiometries have better crystallinity and continuity compared to those of the B-group films,probably due to the difference in the crystallization rates for the two group perovskite films.Therefore,for preparing mixed-halide perovskites with the same average halide stoichiometry,starting materials that can produce perovskite films with more halide stoichiometries are a better choice.
