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
The traditional CdS buffer layers in flexible CZTSSe solar cells lead to light absorption losses and environmental pollution problems. Therefore, the study of Cd-free buffer layer is very important for the realization...The traditional CdS buffer layers in flexible CZTSSe solar cells lead to light absorption losses and environmental pollution problems. Therefore, the study of Cd-free buffer layer is very important for the realization of environmentally friendly and efficient CZTSSe solar cells. The Zn1-xMgxO(ZnMgO) and Zn1-xSnxO(ZnSnO) alternate buffer layers are studied in this study using the simulation package solar cell capacitance simulator(SCAPS-1D) numerical simulation model, and the theoretical analysis is further verified by the results of the experiments. We simulate the performance of CZTSSe/ZnXO(X = Mg/Sn) heterojunction devices with different Mg/(Zn+Mg) and Sn/(Zn+Sn) ratios and analyze the intrinsic mechanism of the effect of conduction band offsets(CBO) on the device performance. The simulation results show that the CZTSSe/ZnXO(X = Mg/Sn) devices achieve optimal performance with a small “spike” band or “flat” band at Mg and Sn doping concentrations of 0.1 and 0.2, respectively. To investigate the potential of Zn_(0.9)Mg_(0.1O) and Zn_(0.8)Sn_(0.2)O as alternative buffer layers, carrier concentrations and thicknesses are analyzed. The simulation demonstrates that the Zn0.9Mg0.1O device with low carrier concentration has a high resistivity, serious carrier recombination, and a greater impact on performance from thickness variation. Numerical simulations and experimental results show the potential of the ZnSnO buffer layer as an alternative to toxic CdS, and the ZnMgO layer has the limitation as a substitute buffer layer. This paper provides the theoretical basis and experimental proof for further searching for a suitable flexible CZTSSe Cd-free buffer layer.展开更多
An integrated membrane system, membrane bioreactor-reverse osmosis (MBR-RO), has become highly efficient in producing high-quality water for municipal wastewater reclamation. However, disposal of a highly concentrated...An integrated membrane system, membrane bioreactor-reverse osmosis (MBR-RO), has become highly efficient in producing high-quality water for municipal wastewater reclamation. However, disposal of a highly concentrated waste stream (RO concentrate or RO retentate) generated in this combination is an important issue. This work investigated RO behaviour in an integrated pilot scale MBR-RO system for municipal wastewater reuse with the continuous recycling of RO retentate to the MBR influent. RO membrane retention and the fouling propensity were studied. RO concentrate, produced by the RO process at a fixed concentration factor (CF) of 3, was recycled continuously to the MBR, leading to water recovery of the entire process around 92%. Osmotic pressure model, saturation index method, high performance liquid chromatography equipped with size exclusion column (HPLC-SEC) and specific filtration test were used to analyse the fouling potential of the RO membrane. The results obtained showed that even though RO concentrate recycling changed remarkably, the compositions of both MBR permeate and RO concentrate, the quality of RO permeate remained almost constant in terms of organic matters, conductivity, and ionic salts. However, these high concentrations of organic or inorganic substances in RO concentrate were major factors leading to the RO membrane fouling. Before RO concentrate recycling, a decline of approximately 30% of the initial RO permeate flux was observed in the period when the CF was increasing to 3, mainly due to the osmotic pressure effect of retained ions and the deposits of organic matters at the RO membrane surface. After RO concentrate addition to the MBR, due to the continuous accumulation of ionic salts on the RO membrane surface, a gradual reduction in RO permeate flux (additional 19%) was also mainly attributed to the osmotic pressure effect of the retained ions. These observations showed that the continuous addition of RO concentrate to the MBR was successful in a combined MBR and RO process in terms of the excellent quality of RO permeate.展开更多
In this paper, a distributed algorithm is proposed to solve a kind of multi-objective optimization problem based on the alternating direction method of multipliers. Compared with the centralized algorithms, this algor...In this paper, a distributed algorithm is proposed to solve a kind of multi-objective optimization problem based on the alternating direction method of multipliers. Compared with the centralized algorithms, this algorithm does not need a central node. Therefore, it has the characteristics of low communication burden and high privacy. In addition, numerical experiments are provided to validate the effectiveness of the proposed algorithm.展开更多
Metal halide perovskites are crystalline materials originally developed out of scientific curiosity. They have shown great potential as active materials in optoelectronic applications. In the last 6 years, their certi...Metal halide perovskites are crystalline materials originally developed out of scientific curiosity. They have shown great potential as active materials in optoelectronic applications. In the last 6 years, their certified photovoltaic efficiencies have reached 22.1%. Compared to bulk halide perovskites, low-dimensional ones exhibited novel physical properties. The photoluminescence quantum yields of perovskite quantum dots are close to 100%. The external quantum efficiencies and current efficiencies of perovskite quantum dot light-emitting diodes have reached 8% and 43 cd A^(-1),respectively, and their nanowire lasers show ultralow-threshold room-temperature lasing with emission tunability and ease of synthesis. Perovskite nanowire photodetectors reached a responsivity of 10 A W^(-1)and a specific normalized detectivity of the order of 10^(12 )Jones. Different from most reported reviews focusing on photovoltaic applications, we summarize the rapid progress in the study of low-dimensional perovskite materials, as well as their promising applications in optoelectronic devices. In particular, we review the wide tunability of fabrication methods and the state-of-the-art research outputs of low-dimensional perovskite optoelectronic devices. Finally, the anticipated challenges and potential for this exciting research are proposed.展开更多
The passivation of non-radiative states and inhibition of band tailings are desirable for improving the open-circuit voltage(V_(oc))of CZTSSe thin-film solar cells.Recently,alkali metal doping has been investigated to...The passivation of non-radiative states and inhibition of band tailings are desirable for improving the open-circuit voltage(V_(oc))of CZTSSe thin-film solar cells.Recently,alkali metal doping has been investigated to passivate defects in CZTSSe films.Herein,we investigate Li doping effects by applying Li OH into CZTSSe precursor solutions,and verify that carrier transport is enhanced in the CZTSSe solar cells.Systematic characterizations demonstrate that Li doping can effectively passivate non-radiative recombination centers and reduce band tailings of the CZTSSe films,leading to the decrease in total defect density and the increase in separation distance between donor and acceptor.Fewer free carriers are trapped in the band tail states,which speeds up carrier transport and reduces the probability of deep-level defects capturing carriers.The charge recombination lifetime is about twice as long as that of the undoped CZTSSe device,implying the heterojunction interface recombination is also inhibited.Besides,Li doping can increase carrier concentration and enhance build-in voltage,leading to a better carrier collection.By adjusting the Li/(Li+Cu)ratio to 18%,the solar cell efficiency is increased significantly to 9.68%with the fill factor(FF)of 65.94%,which is the highest FF reported so far for the flexible CZTSSe solar cells.The increased efficiency is mainly attributed to the reduction of V_(oc)deficit and the improved CZTSSe/Cd S junction quality.These results open up a simple route to passivate non-radiative states and reduce the band tailings of the CZTSSe films and improve the efficiency of the flexible CZTSSe solar cells.展开更多
Flexible Cu2ZnSn(S,Se)4(CZTSSe)solar cells show great potential applications due to low-cost,nontoxicity,and stability.The device performances under an especial open circuit voltage(VOC)are limited by the defect recom...Flexible Cu2ZnSn(S,Se)4(CZTSSe)solar cells show great potential applications due to low-cost,nontoxicity,and stability.The device performances under an especial open circuit voltage(VOC)are limited by the defect recombination of CZTSSe/CdS heterojunction interface.We improve the deposition technique to obtain compact CdS layers without any pinholes for flexible CZTSSe solar cells on Mo foils.The efficiency of the device is improved from 5.7%to 6.86%by highquality junction interface.Furthermore,aiming at the S loss of CdS film,the S source concentration in deposition process is investigated to passivate the defects and improve the CdS film quality.The flexible Mo-foil-based CZTSSe solar cells are obtained to possess a 9.05%efficiency with a VOC of 0.44 V at an optimized S source concentration of 0.68 mol/L.Systematic physical measurements indicate that the S source control can effectively suppress the interface recombination and reduce the VOCdeficit.For the CZTSSe device bending characteristics,the device efficiency is almost constant after1000 bends,manifesting that the CZTSSe device has an excellent mechanical flexibility.The effective improvement strategy of CdS deposition is expected to provide a new perspective for promoting the conversion efficiency of CZTSSe solar cells.展开更多
The recent emerging progress of quantum dot ink(QD-ink)has overcome the complexity of multiple-step colloidal QD(CQD)film preparation and pronouncedly promoted the device performance.However,the detrimental hydroxyl(O...The recent emerging progress of quantum dot ink(QD-ink)has overcome the complexity of multiple-step colloidal QD(CQD)film preparation and pronouncedly promoted the device performance.However,the detrimental hydroxyl(OH)ligands induced from synthesis procedure have not been completely removed.Here,a halide ligand additive strategy was devised to optimize QD-ink process.It simultaneously reduced sub-bandgap states and converted them into iodide-passivated surface,which increase carrier mobility of the QDs films and achieve thicker absorber with improved performances.The corresponding power conversion efficiency of this optimized device reached 10.78%.(The control device was 9.56%.)Therefore,this stratege can support as a candidate strategy to solve the QD original limitation caused by hydroxyl ligands,which is also compatible with other CQD-based optoelectronic devices.展开更多
This paper proposes a method for the rapid detection of subsurface damage(SSD)of Si C using atmospheric inductivity coupled plasma.As a plasma etching method operated at ambient pressure with no bias voltage,this meth...This paper proposes a method for the rapid detection of subsurface damage(SSD)of Si C using atmospheric inductivity coupled plasma.As a plasma etching method operated at ambient pressure with no bias voltage,this method does not introduce any new SSD to the substrate.Plasma diagnosis and simulation are used to optimize the detection operation.Assisted by an Si C cover,a taper can be etched on the substrate with a high material removal rate.Confocal laser scanning microscopy and scanning electron microscope are used to analyze the etching results,and scanning transmission electron microscope(STEM)is adopted to confirm the accuracy of this method.The STEM result also indicates that etching does not introduce any SSD,and the thoroughly etched surface is a perfectly single crystal.A rapid SSD screening ability is also demonstrated,showing that this method is a promising approach for the rapid detection of SSD.展开更多
We couple a ladder-type three-level superconducting artificial atom to a cavity. Adjusting the artificial atom to make the cavity be resonant with the two upper levels, we then probe the lower two levels of the artifi...We couple a ladder-type three-level superconducting artificial atom to a cavity. Adjusting the artificial atom to make the cavity be resonant with the two upper levels, we then probe the lower two levels of the artificial atom. When driving the cavity to a coherent state, the probe spectrum shows energy level splitting induced by the quantized electromagnetic field in the cavity. This splitting size is related to the coupling strength between the cavity and the artificial atom and, thus, is fixed after the sample is fabricated. This is in contrast to the classical Autler-Townes splitting of a three-level system in which the splitting is proportional to the driving amplitude, which can be continuously changed. Our experiment results show the difference between the classical microwave driving field and the quantum field of the cavity.展开更多
High-fidelity two-qubit gates are essential for the realization of large-scale quantum computation and simulation.Tunable coupler design is used to reduce the problem of parasitic coupling and frequency crowding in ma...High-fidelity two-qubit gates are essential for the realization of large-scale quantum computation and simulation.Tunable coupler design is used to reduce the problem of parasitic coupling and frequency crowding in manyqubit systems and thus thought to be advantageous. Here we design an extensible 5-qubit system in which center transmon qubit can couple to every four near-neighboring qubits via a capacitive tunable coupler and experimentally demonstrate high-fidelity controlled-phase(CZ) gate by manipulating central qubit and one nearneighboring qubit. Speckle purity benchmarking and cross entropy benchmarking are used to assess the purity fidelity and the fidelity of the CZ gate. The average purity fidelity of the CZ gate is 99.69±0.04% and the average fidelity of the CZ gate is 99.65±0.04%, which means that the control error is about 0.04%. Our work is helpful for resolving many challenges in implementation of large-scale quantum systems.展开更多
We study the motion of G-band bright points (GBPs) in the quiet Sun to obtain the characteristics of different motion types. A high resolution image sequence taken with the Hinode/Solar Optical Telescope (SOT) is ...We study the motion of G-band bright points (GBPs) in the quiet Sun to obtain the characteristics of different motion types. A high resolution image sequence taken with the Hinode/Solar Optical Telescope (SOT) is used, and GBPs are automat- ically tracked by segmenting 3D evolutional structures in a space-time cube. After putting the GBPs that do not move during their lifetimes aside, the non-stationary GBPs are categorized into three types based on an index of their motion type. Most GBPs that move in straight or nearly straight lines are categorized as a straight mo- tion type, a few moving in rotary paths into rotary motion, and the others fall into a motion type we called erratic. The mean horizontal velocities are 2.18±0.08 km s-1, 1.63±0.09km s^-1 and 1.33±0.07 km s^-1 for straight, erratic and rotary motion types, respectively. We find that a GBP drifts at a higher and constant velocity during its whole life if it moves in a straight line. However, it has a lower and variational velocity if it moves on a rotary path. The diffusive process is ballistic-, super- and sub-diffusion for straight, erratic and rotary motion types, respectively. The corresponding diffusion index (γ) and coefficients (K) are 2.13±0.09 and 850±37km^2 s^-1, 1.82±0.07 and 331 ±24 km^2 s^-1, and 0.73±0.19 and 13±9 km^2 s^-1. In terms of direction of motion, it is homogeneous and isotropic, and usually persists between neighboring frames, no matter what motion type a GBP is classified as.展开更多
Diamond is a promising material for the modern industry. It is widely used in different applications, such as cutting tools, optical windows, heat dissipation, and semiconductors.However, these application areas requi...Diamond is a promising material for the modern industry. It is widely used in different applications, such as cutting tools, optical windows, heat dissipation, and semiconductors.However, these application areas require exceptionally flattened and polished diamond surfaces.Unfortunately, due to the extreme hardness and chemical inertness of diamond, the polishing of diamond is challenging. Since the 1920s, various conventional and modern mechanical,chemical, and thermal polishing techniques have been proposed and developed for finishing diamond surfaces. Therefore, to impart proper guidance on selecting a good polishing technique for production practice, this paper presents an in-depth and informative literature survey of the current research and engineering developments regarding diamond polishing. At first, a brief review of the general developments and basic material removal principles is discussed. This review concludes with a detailed analysis of each techniques' polishing performance and critical challenges, and a discussion of the new insights and future applications of diamond polishing.展开更多
We study the evolution pattern of isolated G-band bright points (GBPs) in terms of their size, intensity and velocity. Using a high resolution image sequence taken with the Hinode/Solar Optical Telescope (SOT), we...We study the evolution pattern of isolated G-band bright points (GBPs) in terms of their size, intensity and velocity. Using a high resolution image sequence taken with the Hinode/Solar Optical Telescope (SOT), we detect GBPs in each image by the Laplacian and Morphological Dilation algorithm, and track their evolutions by a 26-adjacent method in a three-dimensional space-time cube. For quantifying the evolution, we propose a quantification method based on lifetime normalization which aligns the different lifetimes to common stages. The quantification results show that, on average, the diameter of isolated GBPs changes from 166 to 173 km, then down to 165 km; the maximum intensity contrast changes from 1.012 to 1.027, then down to 1.011; however, the velocity changes from 1.709 to 1.593 km s-1, then up to 1.703 km s-i. The results indicate that the evolution follows a pattern such that the GBP is small, faint and fast-moving at the birth stage, becomes big, bright and slow-moving at the middle stage, then gets small, faint and fast-moving at the decay stage until disappearance. Although the differences are very small, a two-sample t-test is used to demonstrate there are significant differences in means between the distri- butions of the different stages. Furthermore, we quantify the relationship between the lifetimes of GBPs and their properties. It is found that there are positive correlations between the lifetimes and their sizes and intensities with correlation coefficients of 0.83 and 0.65, respectively; however, there is a negative correlation between the life- times and velocities with a correlation coefficient of-0.49. In summary, the longer the GBP persists, the bigger, brighter and slower it will be.展开更多
Six high-resolution TiO-band image sequences from the New Vacuum Solar Telescope (NVST) are used to investigate the properties of intergranular bright points (igBPs). We detect the igBPs using a Laplacian and morp...Six high-resolution TiO-band image sequences from the New Vacuum Solar Telescope (NVST) are used to investigate the properties of intergranular bright points (igBPs). We detect the igBPs using a Laplacian and morphological dilation algorithm (LMD) and automatically track them using a three- dimensional segmentation algorithm, and then investigate the morphologic, photometric and dynamic prop- erties of igBPs in terms of equivalent diameter, intensity contrast, lifetime, horizontal velocity, diffusion index, motion range and motion type. The statistical results confirm previous studies based on G-band or TiO-band igBPs from other telescopes. These results illustrate that TiO data from the NVST are stable and reliable, and are suitable for studying igBPs. In addition, our method is feasible for detecting and track- ing igBPs with TiO data from the NVST. With the aid of vector magnetograms obtained from the Solar Dynamics Observatory/Helioseismic and Magnetic Imager, the properties of igBPs are found to be strongly influenced by their embedded magnetic environments. The areal coverage, size and intensity contrast values of igBPs are generally larger in regions with higher magnetic flux. However, the dynamics of igBPs, includ- ing the horizontal velocity, diffusion index, ratio of motion range and index of motion type are generally larger in the regions with lower magnetic flux. This suggests that the absence of strong magnetic fields in the medium makes it possible for the igBPs to look smaller and weaker, diffuse faster, and move faster and further along a straighter path.展开更多
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supported by the National Natural Science Foundation of China (Grant Nos. 62074037 and 52002073)the Fund from the Fujian Science & Technology Innovation Laboratory for Optoelectronic Information of China (Grant No. 2021ZZ124)。
文摘The traditional CdS buffer layers in flexible CZTSSe solar cells lead to light absorption losses and environmental pollution problems. Therefore, the study of Cd-free buffer layer is very important for the realization of environmentally friendly and efficient CZTSSe solar cells. The Zn1-xMgxO(ZnMgO) and Zn1-xSnxO(ZnSnO) alternate buffer layers are studied in this study using the simulation package solar cell capacitance simulator(SCAPS-1D) numerical simulation model, and the theoretical analysis is further verified by the results of the experiments. We simulate the performance of CZTSSe/ZnXO(X = Mg/Sn) heterojunction devices with different Mg/(Zn+Mg) and Sn/(Zn+Sn) ratios and analyze the intrinsic mechanism of the effect of conduction band offsets(CBO) on the device performance. The simulation results show that the CZTSSe/ZnXO(X = Mg/Sn) devices achieve optimal performance with a small “spike” band or “flat” band at Mg and Sn doping concentrations of 0.1 and 0.2, respectively. To investigate the potential of Zn_(0.9)Mg_(0.1O) and Zn_(0.8)Sn_(0.2)O as alternative buffer layers, carrier concentrations and thicknesses are analyzed. The simulation demonstrates that the Zn0.9Mg0.1O device with low carrier concentration has a high resistivity, serious carrier recombination, and a greater impact on performance from thickness variation. Numerical simulations and experimental results show the potential of the ZnSnO buffer layer as an alternative to toxic CdS, and the ZnMgO layer has the limitation as a substitute buffer layer. This paper provides the theoretical basis and experimental proof for further searching for a suitable flexible CZTSSe Cd-free buffer layer.
文摘An integrated membrane system, membrane bioreactor-reverse osmosis (MBR-RO), has become highly efficient in producing high-quality water for municipal wastewater reclamation. However, disposal of a highly concentrated waste stream (RO concentrate or RO retentate) generated in this combination is an important issue. This work investigated RO behaviour in an integrated pilot scale MBR-RO system for municipal wastewater reuse with the continuous recycling of RO retentate to the MBR influent. RO membrane retention and the fouling propensity were studied. RO concentrate, produced by the RO process at a fixed concentration factor (CF) of 3, was recycled continuously to the MBR, leading to water recovery of the entire process around 92%. Osmotic pressure model, saturation index method, high performance liquid chromatography equipped with size exclusion column (HPLC-SEC) and specific filtration test were used to analyse the fouling potential of the RO membrane. The results obtained showed that even though RO concentrate recycling changed remarkably, the compositions of both MBR permeate and RO concentrate, the quality of RO permeate remained almost constant in terms of organic matters, conductivity, and ionic salts. However, these high concentrations of organic or inorganic substances in RO concentrate were major factors leading to the RO membrane fouling. Before RO concentrate recycling, a decline of approximately 30% of the initial RO permeate flux was observed in the period when the CF was increasing to 3, mainly due to the osmotic pressure effect of retained ions and the deposits of organic matters at the RO membrane surface. After RO concentrate addition to the MBR, due to the continuous accumulation of ionic salts on the RO membrane surface, a gradual reduction in RO permeate flux (additional 19%) was also mainly attributed to the osmotic pressure effect of the retained ions. These observations showed that the continuous addition of RO concentrate to the MBR was successful in a combined MBR and RO process in terms of the excellent quality of RO permeate.
文摘In this paper, a distributed algorithm is proposed to solve a kind of multi-objective optimization problem based on the alternating direction method of multipliers. Compared with the centralized algorithms, this algorithm does not need a central node. Therefore, it has the characteristics of low communication burden and high privacy. In addition, numerical experiments are provided to validate the effectiveness of the proposed algorithm.
基金supported by the Doctoral Program of Higher Education(20130142120075)the Fundamental Research Funds for the Central Universities(HUST:2016YXMS032)National Key Research and Development Program of China(Grant No.2016YFB0700702)
文摘Metal halide perovskites are crystalline materials originally developed out of scientific curiosity. They have shown great potential as active materials in optoelectronic applications. In the last 6 years, their certified photovoltaic efficiencies have reached 22.1%. Compared to bulk halide perovskites, low-dimensional ones exhibited novel physical properties. The photoluminescence quantum yields of perovskite quantum dots are close to 100%. The external quantum efficiencies and current efficiencies of perovskite quantum dot light-emitting diodes have reached 8% and 43 cd A^(-1),respectively, and their nanowire lasers show ultralow-threshold room-temperature lasing with emission tunability and ease of synthesis. Perovskite nanowire photodetectors reached a responsivity of 10 A W^(-1)and a specific normalized detectivity of the order of 10^(12 )Jones. Different from most reported reviews focusing on photovoltaic applications, we summarize the rapid progress in the study of low-dimensional perovskite materials, as well as their promising applications in optoelectronic devices. In particular, we review the wide tunability of fabrication methods and the state-of-the-art research outputs of low-dimensional perovskite optoelectronic devices. Finally, the anticipated challenges and potential for this exciting research are proposed.
基金supported by the National Natural Science Foundation of China(62074037,52002073)the Science and Technology Department of Fujian Province(2020I0006)+3 种基金the Natural Science Foundation of Fujian Province(2019J01218)the Fujian Science&Technology Innovation Laboratory for Optoelectronic Information of China(2021ZZ124)the Education and Scientific Research Project of Fujian Province(JAT200372)the Scientific Research Project of Fujian Jiangxia University(JXZ2019006)。
文摘The passivation of non-radiative states and inhibition of band tailings are desirable for improving the open-circuit voltage(V_(oc))of CZTSSe thin-film solar cells.Recently,alkali metal doping has been investigated to passivate defects in CZTSSe films.Herein,we investigate Li doping effects by applying Li OH into CZTSSe precursor solutions,and verify that carrier transport is enhanced in the CZTSSe solar cells.Systematic characterizations demonstrate that Li doping can effectively passivate non-radiative recombination centers and reduce band tailings of the CZTSSe films,leading to the decrease in total defect density and the increase in separation distance between donor and acceptor.Fewer free carriers are trapped in the band tail states,which speeds up carrier transport and reduces the probability of deep-level defects capturing carriers.The charge recombination lifetime is about twice as long as that of the undoped CZTSSe device,implying the heterojunction interface recombination is also inhibited.Besides,Li doping can increase carrier concentration and enhance build-in voltage,leading to a better carrier collection.By adjusting the Li/(Li+Cu)ratio to 18%,the solar cell efficiency is increased significantly to 9.68%with the fill factor(FF)of 65.94%,which is the highest FF reported so far for the flexible CZTSSe solar cells.The increased efficiency is mainly attributed to the reduction of V_(oc)deficit and the improved CZTSSe/Cd S junction quality.These results open up a simple route to passivate non-radiative states and reduce the band tailings of the CZTSSe films and improve the efficiency of the flexible CZTSSe solar cells.
基金Project supported by the National Natural Science Foundation of China(Grant Nos.62074037,61574038,51961165108,and 51972332)the Natural Science Foundation of Fujian Province,China(Grant No.2017J01503)+2 种基金the Education and Scientific Research Project of Fujian Province,China(Grant No.JAT190010)the Open Project Program of the State Key Laboratory of Photocatalysis on Energy and Environment,China(Grant No.SKLPEE-202011)Fuzhou University,China。
文摘Flexible Cu2ZnSn(S,Se)4(CZTSSe)solar cells show great potential applications due to low-cost,nontoxicity,and stability.The device performances under an especial open circuit voltage(VOC)are limited by the defect recombination of CZTSSe/CdS heterojunction interface.We improve the deposition technique to obtain compact CdS layers without any pinholes for flexible CZTSSe solar cells on Mo foils.The efficiency of the device is improved from 5.7%to 6.86%by highquality junction interface.Furthermore,aiming at the S loss of CdS film,the S source concentration in deposition process is investigated to passivate the defects and improve the CdS film quality.The flexible Mo-foil-based CZTSSe solar cells are obtained to possess a 9.05%efficiency with a VOC of 0.44 V at an optimized S source concentration of 0.68 mol/L.Systematic physical measurements indicate that the S source control can effectively suppress the interface recombination and reduce the VOCdeficit.For the CZTSSe device bending characteristics,the device efficiency is almost constant after1000 bends,manifesting that the CZTSSe device has an excellent mechanical flexibility.The effective improvement strategy of CdS deposition is expected to provide a new perspective for promoting the conversion efficiency of CZTSSe solar cells.
基金This work was supported by the following funds: National Natural Science Foundation of China (No.30670951) Guangdong Provincial+5 种基金 Natural Science Foundation (No.06021322) Fund of Guangzhou Municipal Scientific Problem-Solving Program (No. 2003 Z 3-E0381) Fund of Guangdong Provincial Scientific Problem-Solving Program (No.2005 B31211002) Guangdong Provincial Government and Ministry of Education Project com- bining project initiation, study and research (No.2009B090300277).
基金financially supported by National Natural Science Foundation of China (61874165,51761145048,and 21833009)the Foundation of Shenzhen Science and Technology Innovation Committee (JCYJ20170413113645633)+2 种基金Major State Basic Research Development Program of China (2016YFB0700702)the Guangdong-Hong Kong joint innovation project (2016A050503012)Guangdong Natural Science Funds for Distinguished Young Scholars (2015A030306044)
文摘The recent emerging progress of quantum dot ink(QD-ink)has overcome the complexity of multiple-step colloidal QD(CQD)film preparation and pronouncedly promoted the device performance.However,the detrimental hydroxyl(OH)ligands induced from synthesis procedure have not been completely removed.Here,a halide ligand additive strategy was devised to optimize QD-ink process.It simultaneously reduced sub-bandgap states and converted them into iodide-passivated surface,which increase carrier mobility of the QDs films and achieve thicker absorber with improved performances.The corresponding power conversion efficiency of this optimized device reached 10.78%.(The control device was 9.56%.)Therefore,this stratege can support as a candidate strategy to solve the QD original limitation caused by hydroxyl ligands,which is also compatible with other CQD-based optoelectronic devices.
基金supported by the National Natural Science Foundation of China(52035009,52005243)the Science and Technology Innovation Committee of Shenzhen Municipality(JCYJ20200109141003910,GJHZ20180928155412525)。
文摘This paper proposes a method for the rapid detection of subsurface damage(SSD)of Si C using atmospheric inductivity coupled plasma.As a plasma etching method operated at ambient pressure with no bias voltage,this method does not introduce any new SSD to the substrate.Plasma diagnosis and simulation are used to optimize the detection operation.Assisted by an Si C cover,a taper can be etched on the substrate with a high material removal rate.Confocal laser scanning microscopy and scanning electron microscope are used to analyze the etching results,and scanning transmission electron microscope(STEM)is adopted to confirm the accuracy of this method.The STEM result also indicates that etching does not introduce any SSD,and the thoroughly etched surface is a perfectly single crystal.A rapid SSD screening ability is also demonstrated,showing that this method is a promising approach for the rapid detection of SSD.
基金Project supported by the Science Funds from the Ministry of Science and Technology of China(Grant Nos.2014CB921401,2017YFA0304300,2014CB921202,and 2016YFA0300601)the National Natural Science Foundation of China(Grant No.11674376)the Strategic Priority Research Program of the Chinese Academy of Sciences(Grant No.XDB07010300)
文摘We couple a ladder-type three-level superconducting artificial atom to a cavity. Adjusting the artificial atom to make the cavity be resonant with the two upper levels, we then probe the lower two levels of the artificial atom. When driving the cavity to a coherent state, the probe spectrum shows energy level splitting induced by the quantized electromagnetic field in the cavity. This splitting size is related to the coupling strength between the cavity and the artificial atom and, thus, is fixed after the sample is fabricated. This is in contrast to the classical Autler-Townes splitting of a three-level system in which the splitting is proportional to the driving amplitude, which can be continuously changed. Our experiment results show the difference between the classical microwave driving field and the quantum field of the cavity.
基金the National Key R&D Program of China(Grant No.2017YFA0304300)the Chinese Academy of Sciences+6 种基金Anhui Initiative in Quantum Information TechnologiesTechnology Committee of Shanghai Municipalitythe National Natural Science Foundation of China(Grants Nos.11905217,11774326,and 11905294)the Shanghai Municipal Science and Technology Major Project(Grant No.2019SHZDZX01)the Natural Science Foundation of Shanghai(Grant No.19ZR1462700)the Key-Area Research and Development Program of Guangdong Provice(Grant No.2020B0303030001)the Youth Talent Lifting Project(Grant No.2020-JCJQ-QT-030)。
文摘High-fidelity two-qubit gates are essential for the realization of large-scale quantum computation and simulation.Tunable coupler design is used to reduce the problem of parasitic coupling and frequency crowding in manyqubit systems and thus thought to be advantageous. Here we design an extensible 5-qubit system in which center transmon qubit can couple to every four near-neighboring qubits via a capacitive tunable coupler and experimentally demonstrate high-fidelity controlled-phase(CZ) gate by manipulating central qubit and one nearneighboring qubit. Speckle purity benchmarking and cross entropy benchmarking are used to assess the purity fidelity and the fidelity of the CZ gate. The average purity fidelity of the CZ gate is 99.69±0.04% and the average fidelity of the CZ gate is 99.65±0.04%, which means that the control error is about 0.04%. Our work is helpful for resolving many challenges in implementation of large-scale quantum systems.
基金Supported by the National Natural Science Foundation of China
文摘We study the motion of G-band bright points (GBPs) in the quiet Sun to obtain the characteristics of different motion types. A high resolution image sequence taken with the Hinode/Solar Optical Telescope (SOT) is used, and GBPs are automat- ically tracked by segmenting 3D evolutional structures in a space-time cube. After putting the GBPs that do not move during their lifetimes aside, the non-stationary GBPs are categorized into three types based on an index of their motion type. Most GBPs that move in straight or nearly straight lines are categorized as a straight mo- tion type, a few moving in rotary paths into rotary motion, and the others fall into a motion type we called erratic. The mean horizontal velocities are 2.18±0.08 km s-1, 1.63±0.09km s^-1 and 1.33±0.07 km s^-1 for straight, erratic and rotary motion types, respectively. We find that a GBP drifts at a higher and constant velocity during its whole life if it moves in a straight line. However, it has a lower and variational velocity if it moves on a rotary path. The diffusive process is ballistic-, super- and sub-diffusion for straight, erratic and rotary motion types, respectively. The corresponding diffusion index (γ) and coefficients (K) are 2.13±0.09 and 850±37km^2 s^-1, 1.82±0.07 and 331 ±24 km^2 s^-1, and 0.73±0.19 and 13±9 km^2 s^-1. In terms of direction of motion, it is homogeneous and isotropic, and usually persists between neighboring frames, no matter what motion type a GBP is classified as.
基金financial support for this work from the Guangdong Basic and Applied Basic Research Foundation (2019A1515111133)the National Natural Science Foundation of China (Grant Nos. 52035009, 52005243)the research fund for International Cooperation (GJHZ20180928155412525) from the Science and Technology Innovation Committee of Shenzhen Municipality, Shenzhen, China。
文摘Diamond is a promising material for the modern industry. It is widely used in different applications, such as cutting tools, optical windows, heat dissipation, and semiconductors.However, these application areas require exceptionally flattened and polished diamond surfaces.Unfortunately, due to the extreme hardness and chemical inertness of diamond, the polishing of diamond is challenging. Since the 1920s, various conventional and modern mechanical,chemical, and thermal polishing techniques have been proposed and developed for finishing diamond surfaces. Therefore, to impart proper guidance on selecting a good polishing technique for production practice, this paper presents an in-depth and informative literature survey of the current research and engineering developments regarding diamond polishing. At first, a brief review of the general developments and basic material removal principles is discussed. This review concludes with a detailed analysis of each techniques' polishing performance and critical challenges, and a discussion of the new insights and future applications of diamond polishing.
基金Supported by the National Natural Science Foundation of China
文摘We study the evolution pattern of isolated G-band bright points (GBPs) in terms of their size, intensity and velocity. Using a high resolution image sequence taken with the Hinode/Solar Optical Telescope (SOT), we detect GBPs in each image by the Laplacian and Morphological Dilation algorithm, and track their evolutions by a 26-adjacent method in a three-dimensional space-time cube. For quantifying the evolution, we propose a quantification method based on lifetime normalization which aligns the different lifetimes to common stages. The quantification results show that, on average, the diameter of isolated GBPs changes from 166 to 173 km, then down to 165 km; the maximum intensity contrast changes from 1.012 to 1.027, then down to 1.011; however, the velocity changes from 1.709 to 1.593 km s-1, then up to 1.703 km s-i. The results indicate that the evolution follows a pattern such that the GBP is small, faint and fast-moving at the birth stage, becomes big, bright and slow-moving at the middle stage, then gets small, faint and fast-moving at the decay stage until disappearance. Although the differences are very small, a two-sample t-test is used to demonstrate there are significant differences in means between the distri- butions of the different stages. Furthermore, we quantify the relationship between the lifetimes of GBPs and their properties. It is found that there are positive correlations between the lifetimes and their sizes and intensities with correlation coefficients of 0.83 and 0.65, respectively; however, there is a negative correlation between the life- times and velocities with a correlation coefficient of-0.49. In summary, the longer the GBP persists, the bigger, brighter and slower it will be.
基金the support received from the National Natural Science Foundation of China (Nos. 11573012, 11303011, 11263004, 11163004 and U1231205)the Open Research Program of the Key Laboratory of Solar Activity of the Chinese Academy of Sciences (Nos. KLSA201414 and KLSA201505)
文摘Six high-resolution TiO-band image sequences from the New Vacuum Solar Telescope (NVST) are used to investigate the properties of intergranular bright points (igBPs). We detect the igBPs using a Laplacian and morphological dilation algorithm (LMD) and automatically track them using a three- dimensional segmentation algorithm, and then investigate the morphologic, photometric and dynamic prop- erties of igBPs in terms of equivalent diameter, intensity contrast, lifetime, horizontal velocity, diffusion index, motion range and motion type. The statistical results confirm previous studies based on G-band or TiO-band igBPs from other telescopes. These results illustrate that TiO data from the NVST are stable and reliable, and are suitable for studying igBPs. In addition, our method is feasible for detecting and track- ing igBPs with TiO data from the NVST. With the aid of vector magnetograms obtained from the Solar Dynamics Observatory/Helioseismic and Magnetic Imager, the properties of igBPs are found to be strongly influenced by their embedded magnetic environments. The areal coverage, size and intensity contrast values of igBPs are generally larger in regions with higher magnetic flux. However, the dynamics of igBPs, includ- ing the horizontal velocity, diffusion index, ratio of motion range and index of motion type are generally larger in the regions with lower magnetic flux. This suggests that the absence of strong magnetic fields in the medium makes it possible for the igBPs to look smaller and weaker, diffuse faster, and move faster and further along a straighter path.