The past decade has witnessed the rapid increasement in power conversion efficiency of perovskite solar cells(PSCs).However,serious ion migration hampers their operational stability.Although dopants composed of varied...The past decade has witnessed the rapid increasement in power conversion efficiency of perovskite solar cells(PSCs).However,serious ion migration hampers their operational stability.Although dopants composed of varied cations and anions are introduced into perovskite to suppress ion migration,the impact of cations or anions is not individually explored,which hinders the evaluation of different cations and further application of doping strategy.Here we report that a special group of sulfonic anions(like CF_(3)SO_(3)^(-))successfully introduce alkaline earth ions(like Ca^(2+))into perovskite lattice compared to its halide counterparts.Furthermore,with effective crystallization regulation and defect passivation of sulfonic anions,perovskite with Ca(CF_(3)SO_(3))_(2)shows reduced PbI2 residue and metallic Pb0 defects;thereby,corresponding PSCs show an enhanced PCE of 24.95%.Finally by comparing the properties of perovskite with Ca(CF_(3)SO_(3))_(2)and FACF_(3)SO_(3),we found that doped Ca^(2+)significantly suppressed halide migration with an activation energy of 1.246 eV which accounts for the improved operational stability of Ca(CF_(3)SO_(3))_(2-)doped PSCs,while no obvious impact of Ca^(2+)on trap density is observed.Combining the benefits of cations and anions,this study presents an effective method to decouple the effects of cations and anions and fabricate efficient and stable PSCs.展开更多
The polymerase chain reaction is one of the most useful technical ad- vance and inventions in modern molecular biology. Developed in 1983 by Kary Mullis, PCR is now a common and indispensable technique used in medical...The polymerase chain reaction is one of the most useful technical ad- vance and inventions in modern molecular biology. Developed in 1983 by Kary Mullis, PCR is now a common and indispensable technique used in medical and bi- ology research labs for a variety of applications. A large number of articles relat- ed to PCR are available on the internet and other places. People know well about the basic principle and are very familiar with the procedures of the PCR. But, some details were neglected on the numbers of the target sequence and other DNA strands number after 30 to 35 cycles of the PCR. In most papers, the number of newly synthesized DNA strands including target DNA and non target DNA is am- biguous and even wrong. In this paper, highlights were given to the theoretical number of target DNA number in details and the exact number of the target DNA number can be concluded by analysis.展开更多
Photoresponsive memristors(i.e.,photomemristors)have been recently highly regarded to tackle data latency and energy consumption challenges in conventional Von Neumann architecture-based image recognition systems.Howe...Photoresponsive memristors(i.e.,photomemristors)have been recently highly regarded to tackle data latency and energy consumption challenges in conventional Von Neumann architecture-based image recognition systems.However,their efficacy in recognizing low-contrast images is quite limited,and while preprocessing algorithms are usually employed to enhance these images,which naturally introduce delays that hinder real-time recognition in complex conditions.To address this challenge,here we present a selfdriven polarization-sensitive ferroelectric photomemristor inspired by advanced biological systems.The proposed prototype device is engineered to extract image polarization information,enabling real-time and in-situ enhanced image recognition and classification capabilities.By combining the anisotropic optical feature of the two-dimensional material(ReSe_(2))and ferroelectric polarization of singlecrystalline diisopropylammonium bromide(DIPAB)thin film,tunable and self-driven polarized responsiveness with intelligence was achieved.With remarkable optoelectronic synaptic characteristics of the fabricated device,a significant enhancement was demonstrated in recognition probability—averaging an impressive 85.9% for low-contrast scenarios,in contrast to the mere 47.5% exhibited by traditional photomemristors.This holds substantial implications for the detection and recognition of subtle information in diverse scenes such as autonomous driving,medical imaging,and astronomical observation.展开更多
High-resolution organic arrays with diverse pixel types hold significant promise for various applications,such as full-color displays and photonic crystals.The direct growth of such arrays(e.g.,high-resolution multi-c...High-resolution organic arrays with diverse pixel types hold significant promise for various applications,such as full-color displays and photonic crystals.The direct growth of such arrays(e.g.,high-resolution multi-color patterns)cannot be achieved in a single step with conventional strategies.Here,we present a viable approach integrating a bottom-up solution strategy with phase-change materials(PCMs),specifically aggregation-induced emission(AIE)materials.Through intentional self-assembly,color-programmable organic micro-patterns featuring distinct phases or colors were created.Notably,manipulating the amount of involved substance for nucleation/crystallization was achieved by adjusting the sizes of pre-defined nucleation sites.This precise control resulted in varied phases and colors for each pixel.Thus,high-resolution organic micro-arrays with transfer-free multi-color pixels were directly achieved.These may open avenues for seamless,transfer-free growth of multifunctional micro-patterns using PCMs,holding immense potential for applications in high-resolution full-color imaging/displays,photonic crystals,information storage,and encryption,etc.展开更多
Anti-Stokes photoluminescence(ASPL)in low-dimensional van der Waals(vdW)layered materials is becoming increasingly attractive for its potential in advanced applications such as optical cooling,sub-energy band detectio...Anti-Stokes photoluminescence(ASPL)in low-dimensional van der Waals(vdW)layered materials is becoming increasingly attractive for its potential in advanced applications such as optical cooling,sub-energy band detection and optoelectronic devices.While transition metal dichalcogenides(TMDCs),among the most studied vdW semiconductors for ASPL,exhibit a direct bandgap exclusively in their monolayer form.This characteristic results in a short light-matter interaction distance and thus low ASPL emission efficiency,which seriously impedes the advancement of ASPL in vdW layered materials.In contrast,transition metal halide lead iodide(PbI_(2)),a vdW semiconductor with a direct bandgap in a wide range of thicknesses(⩾3 layers)superior to TMDCs,has shown promise for ASPL.However,the reported ASPL emission efficiency of PbI_(2) is notably low.Moreover,scant research has focused on the rich ASPL emission states in PbI_(2),particularly concerning the assignment of these emission states.Here,through a designed thickness selection,we observed more detailed ASPL emissions in submicrometer-thick PbI_(2) at room temperature,in addition to a series of previously unreported ASPL emission peaks that emerge at low temperatures.Importantly,the low-temperature ASPL of PbI_(2) exhibits an approximate 1000-fold enhancement compared to that observed at room temperature.This significant enhancement is attributed to the transition from phonon-assisted one-photon absorption to two-step photon absorption induced by resonance absorption effect,as well as substantially reduced nonradiative decays at low temperatures.Our findings enhance the comprehensive understanding of ASPL in PbI_(2),holding great significance for the development of ASPL applications.展开更多
Substrates provide the necessary support for scientific explorations of numerous promising features and exciting potential applications in two-dimensional (2D) transition metal dichalcogenides (TMDs). To utilize subst...Substrates provide the necessary support for scientific explorations of numerous promising features and exciting potential applications in two-dimensional (2D) transition metal dichalcogenides (TMDs). To utilize substrate engineering to alter the properties of 2D TMDs and avoid introducing unwanted adverse effects, various experimental techniques, such as high-frequency Raman spectroscopy, have been used to understand the interactions between 2D TMDs and substrates. However, sample-substrate interaction in 2D TMDs is not yet fully understood due to the lack of systematic studies by techniques that are sensitive to 2D TMD-substrate interaction. This work systematically investigates the interaction between tungsten disulfide (WS_(2)) monolayers and substrates by low-frequency Raman spectroscopy, which is very sensitive to WS_(2)-substrate interaction. Strong coupling with substrates is clearly revealed in chemical vapor deposition (CVD)-grown monolayer WS_(2) by its low-wavenumber interface mode. It is demonstrated that the enhanced sample-substrate interaction leads to tensile strain on monolayer WS_(2), which is induced during the cooling process of CVD growth and could be released for monolayer WS_(2) sample after transfer or fabricated by an annealing-free method such as mechanical exfoliation. These results not only suggest the effectiveness of low-frequency Raman spectroscopy for probing sample-substrate interactions in 2D TMDs, but also provide guidance for the design of high-performance devices with the desired sample-substrate coupling strength based on 2D TMDs.展开更多
The interface properties in two-dimensional(2D)layered materials and their van der Waals(vdW)homo-/heterostructures are of importance in both uncovering novel physical phenomena and optimizing device performance.Despi...The interface properties in two-dimensional(2D)layered materials and their van der Waals(vdW)homo-/heterostructures are of importance in both uncovering novel physical phenomena and optimizing device performance.Despite considerable research interest and enthusiasm direct toward the interlayer coupling in 2D homo-and heterostructures,there is limited research on the coupling at the 2D layered material-substrate interface.This limitation is due to the challenges in achieving direct detection.Currently,the coupling mechanisms at the 2D layered material-substrate interface is ambiguous,which needs greater attention.In this study,we have systematically investigated the interface coupling between monolayer WS_(2)and its supported substrates using high-temperature and high-vacuum in-situ Raman spectroscopy through monitoring the low-frequency Raman mode of monolayer WS_(2).Our findings reveal that both interfacial spacing and strain can significantly affect the coupling strength between the monolayer WS_(2)and the supported substrate.More notably,we found that the strategic introduction of appropriate interfacial strain can effectively enhance the interface coupling.Consequently,we have succeeded in achieving effective regulation of the sample-substrate coupling via a convenient way of controlling the cooling process during annealing.Our findings contribute to a deeper understanding of the coupling correlation between 2D layered materials and substrates,which is of great significance for the design and optimization of high-performance devices based on 2D layered semiconductors.展开更多
基金support from the National Key Research and Development Program of China(No.2022YFE0137400)the National Natural Science Foundation of China(Grant No.62274040).
文摘The past decade has witnessed the rapid increasement in power conversion efficiency of perovskite solar cells(PSCs).However,serious ion migration hampers their operational stability.Although dopants composed of varied cations and anions are introduced into perovskite to suppress ion migration,the impact of cations or anions is not individually explored,which hinders the evaluation of different cations and further application of doping strategy.Here we report that a special group of sulfonic anions(like CF_(3)SO_(3)^(-))successfully introduce alkaline earth ions(like Ca^(2+))into perovskite lattice compared to its halide counterparts.Furthermore,with effective crystallization regulation and defect passivation of sulfonic anions,perovskite with Ca(CF_(3)SO_(3))_(2)shows reduced PbI2 residue and metallic Pb0 defects;thereby,corresponding PSCs show an enhanced PCE of 24.95%.Finally by comparing the properties of perovskite with Ca(CF_(3)SO_(3))_(2)and FACF_(3)SO_(3),we found that doped Ca^(2+)significantly suppressed halide migration with an activation energy of 1.246 eV which accounts for the improved operational stability of Ca(CF_(3)SO_(3))_(2-)doped PSCs,while no obvious impact of Ca^(2+)on trap density is observed.Combining the benefits of cations and anions,this study presents an effective method to decouple the effects of cations and anions and fabricate efficient and stable PSCs.
文摘The polymerase chain reaction is one of the most useful technical ad- vance and inventions in modern molecular biology. Developed in 1983 by Kary Mullis, PCR is now a common and indispensable technique used in medical and bi- ology research labs for a variety of applications. A large number of articles relat- ed to PCR are available on the internet and other places. People know well about the basic principle and are very familiar with the procedures of the PCR. But, some details were neglected on the numbers of the target sequence and other DNA strands number after 30 to 35 cycles of the PCR. In most papers, the number of newly synthesized DNA strands including target DNA and non target DNA is am- biguous and even wrong. In this paper, highlights were given to the theoretical number of target DNA number in details and the exact number of the target DNA number can be concluded by analysis.
基金supported by the National Key Research and Development Program of China for International Cooperation under Grant 2023YFE0117100the National Natural Science Foundation of China(Nos.62074040 and 62074045).
文摘Photoresponsive memristors(i.e.,photomemristors)have been recently highly regarded to tackle data latency and energy consumption challenges in conventional Von Neumann architecture-based image recognition systems.However,their efficacy in recognizing low-contrast images is quite limited,and while preprocessing algorithms are usually employed to enhance these images,which naturally introduce delays that hinder real-time recognition in complex conditions.To address this challenge,here we present a selfdriven polarization-sensitive ferroelectric photomemristor inspired by advanced biological systems.The proposed prototype device is engineered to extract image polarization information,enabling real-time and in-situ enhanced image recognition and classification capabilities.By combining the anisotropic optical feature of the two-dimensional material(ReSe_(2))and ferroelectric polarization of singlecrystalline diisopropylammonium bromide(DIPAB)thin film,tunable and self-driven polarized responsiveness with intelligence was achieved.With remarkable optoelectronic synaptic characteristics of the fabricated device,a significant enhancement was demonstrated in recognition probability—averaging an impressive 85.9% for low-contrast scenarios,in contrast to the mere 47.5% exhibited by traditional photomemristors.This holds substantial implications for the detection and recognition of subtle information in diverse scenes such as autonomous driving,medical imaging,and astronomical observation.
基金supported by the National Natural Science Foundation of China (62074045, 62074040, 22309134)China Postdoctoral Science Foundation (2022M712402)Shanghai Rising-Star Program (23YF1449200)。
文摘High-resolution organic arrays with diverse pixel types hold significant promise for various applications,such as full-color displays and photonic crystals.The direct growth of such arrays(e.g.,high-resolution multi-color patterns)cannot be achieved in a single step with conventional strategies.Here,we present a viable approach integrating a bottom-up solution strategy with phase-change materials(PCMs),specifically aggregation-induced emission(AIE)materials.Through intentional self-assembly,color-programmable organic micro-patterns featuring distinct phases or colors were created.Notably,manipulating the amount of involved substance for nucleation/crystallization was achieved by adjusting the sizes of pre-defined nucleation sites.This precise control resulted in varied phases and colors for each pixel.Thus,high-resolution organic micro-arrays with transfer-free multi-color pixels were directly achieved.These may open avenues for seamless,transfer-free growth of multifunctional micro-patterns using PCMs,holding immense potential for applications in high-resolution full-color imaging/displays,photonic crystals,information storage,and encryption,etc.
基金supported by the National Natural Science Foundation of China(62374037)the Shanghai Municipal Natural Science Foundation(20ZR1403200)the National Young 1000 Talent Plan of China。
文摘Anti-Stokes photoluminescence(ASPL)in low-dimensional van der Waals(vdW)layered materials is becoming increasingly attractive for its potential in advanced applications such as optical cooling,sub-energy band detection and optoelectronic devices.While transition metal dichalcogenides(TMDCs),among the most studied vdW semiconductors for ASPL,exhibit a direct bandgap exclusively in their monolayer form.This characteristic results in a short light-matter interaction distance and thus low ASPL emission efficiency,which seriously impedes the advancement of ASPL in vdW layered materials.In contrast,transition metal halide lead iodide(PbI_(2)),a vdW semiconductor with a direct bandgap in a wide range of thicknesses(⩾3 layers)superior to TMDCs,has shown promise for ASPL.However,the reported ASPL emission efficiency of PbI_(2) is notably low.Moreover,scant research has focused on the rich ASPL emission states in PbI_(2),particularly concerning the assignment of these emission states.Here,through a designed thickness selection,we observed more detailed ASPL emissions in submicrometer-thick PbI_(2) at room temperature,in addition to a series of previously unreported ASPL emission peaks that emerge at low temperatures.Importantly,the low-temperature ASPL of PbI_(2) exhibits an approximate 1000-fold enhancement compared to that observed at room temperature.This significant enhancement is attributed to the transition from phonon-assisted one-photon absorption to two-step photon absorption induced by resonance absorption effect,as well as substantially reduced nonradiative decays at low temperatures.Our findings enhance the comprehensive understanding of ASPL in PbI_(2),holding great significance for the development of ASPL applications.
基金This work is supported by the National Natural Science Foundation of China(Nos.62004197 and 61774040)the Ministry of Education of Singapore(No.MOE2019-T2-1-004)+5 种基金the Singapore National Research Foundation under the Competitive Research Programs(No.NRF-CRP-21-2018-0007)the National Key R&D Program of China(No.2018YFA0703700)the National Young 1000 Talent Plan of China,the Shanghai Municipal Natural Science Foundation(No.20ZR1403200)the Shanghai Municipal Science and Technology Commission(No.18JC1410300)the Fudan University-CIOMP Joint Fund(No.FC2018-002)the Natural Science Foundation of Liaoning Province,China(Nos.2019-BS-243 and 2019-MS-320).
文摘Substrates provide the necessary support for scientific explorations of numerous promising features and exciting potential applications in two-dimensional (2D) transition metal dichalcogenides (TMDs). To utilize substrate engineering to alter the properties of 2D TMDs and avoid introducing unwanted adverse effects, various experimental techniques, such as high-frequency Raman spectroscopy, have been used to understand the interactions between 2D TMDs and substrates. However, sample-substrate interaction in 2D TMDs is not yet fully understood due to the lack of systematic studies by techniques that are sensitive to 2D TMD-substrate interaction. This work systematically investigates the interaction between tungsten disulfide (WS_(2)) monolayers and substrates by low-frequency Raman spectroscopy, which is very sensitive to WS_(2)-substrate interaction. Strong coupling with substrates is clearly revealed in chemical vapor deposition (CVD)-grown monolayer WS_(2) by its low-wavenumber interface mode. It is demonstrated that the enhanced sample-substrate interaction leads to tensile strain on monolayer WS_(2), which is induced during the cooling process of CVD growth and could be released for monolayer WS_(2) sample after transfer or fabricated by an annealing-free method such as mechanical exfoliation. These results not only suggest the effectiveness of low-frequency Raman spectroscopy for probing sample-substrate interactions in 2D TMDs, but also provide guidance for the design of high-performance devices with the desired sample-substrate coupling strength based on 2D TMDs.
基金supported by the National Key R&D Program of China(2018YFA0703700)the National Natural Science Foundation of China(62374037)+1 种基金Shanghai Municipal Natural Science Foundation(20ZR1403200)the National Young 1000 Talent Plan of China。
文摘The interface properties in two-dimensional(2D)layered materials and their van der Waals(vdW)homo-/heterostructures are of importance in both uncovering novel physical phenomena and optimizing device performance.Despite considerable research interest and enthusiasm direct toward the interlayer coupling in 2D homo-and heterostructures,there is limited research on the coupling at the 2D layered material-substrate interface.This limitation is due to the challenges in achieving direct detection.Currently,the coupling mechanisms at the 2D layered material-substrate interface is ambiguous,which needs greater attention.In this study,we have systematically investigated the interface coupling between monolayer WS_(2)and its supported substrates using high-temperature and high-vacuum in-situ Raman spectroscopy through monitoring the low-frequency Raman mode of monolayer WS_(2).Our findings reveal that both interfacial spacing and strain can significantly affect the coupling strength between the monolayer WS_(2)and the supported substrate.More notably,we found that the strategic introduction of appropriate interfacial strain can effectively enhance the interface coupling.Consequently,we have succeeded in achieving effective regulation of the sample-substrate coupling via a convenient way of controlling the cooling process during annealing.Our findings contribute to a deeper understanding of the coupling correlation between 2D layered materials and substrates,which is of great significance for the design and optimization of high-performance devices based on 2D layered semiconductors.
