Defects at the grain boundaries(GBs)of perovskite film highly restrict both the efficiency and stability of perovskite solar cells(PSCs).Herein,organic small molecules of butanedioic acid(BA)and acetylenedicarboxylic ...Defects at the grain boundaries(GBs)of perovskite film highly restrict both the efficiency and stability of perovskite solar cells(PSCs).Herein,organic small molecules of butanedioic acid(BA)and acetylenedicarboxylic acid(AA),containing two carbonyl(C=O)groups and different core-units,were incorporated into perovskite as additives for PSCs application.Thanks to the strong coordination interaction between C=O group and under-coordinated Pb^(2+),the additives can effectively passivate film defects and regulate the perovskite crystallization,yielding high-quality perovskite films with lower defect densities.More importantly,the additives can efficiently regulate the charge transport behaviors in PSCs.Benefiting from the defects passivation and the regulation of charge carrier dynamics,the BA and AA-treaded PSCs show the power conversion efficiencies of 21.52%and 20.50%,which are higher than that of the control device(19.41%).Besides,the optimal devices exhibit a remarkable enhanced long-term stability and moisture tolerance compared to the pristine devices.Furthermore,the transient absorption spectrum reveals the mechanism of enhanced photovoltaic performances,attributing to the improvement of charge transport capability at the perovskite/Spiro-OMeTAD interfaces.This work affords a promising strategy to improve the efficiency and stability of PSCs through regulating the charge-carrier dynamic process in perovskite film.展开更多
A silicon-based photonic switch is proposed and simulated based on the multimode interference （MMI） principle and the free-carrier plasma dispersion effect in silicon-germanium. The proposed switch, designed for 1.5...A silicon-based photonic switch is proposed and simulated based on the multimode interference （MMI） principle and the free-carrier plasma dispersion effect in silicon-germanium. The proposed switch, designed for 1.55μm window operation,is useful for DWDM optical networks. The switch consists of two input single-mode ridge waveguide ports,a MMI section, and three output single-mode ridge waveguide ports. In the MMI section, two index-modulation regions are placed to divert input optical signals from the two input ports to each of the three output ports. Switching characteristics are demonstrated theoretically by a beam propagation method for 1.55μm operation. The simulated results show that the insertion loss of the switch is less than 1.43dB, and the crosstalk is between - 18 and - 32.8dB.展开更多
Flexible electronic devices have attracted much attention due to their practical and commercial value. Integration of thin films with soft substrate is an effective way to fabricate flexible electronic devices. Ga_2O_...Flexible electronic devices have attracted much attention due to their practical and commercial value. Integration of thin films with soft substrate is an effective way to fabricate flexible electronic devices. Ga_2O_3 thin films deposited directly on soft substrates would be amorphous mostly. However, the thickness of the thin film obtained by mechanical exfoliation method is difficult to control and the edge of the film is fragile and easy to be damaged. In this work, we fabricated free-standing Ga_2O_3 thin films using the water-soluble perovskite Sr_3Al_2O_6 as a sacrificial buffer layer. The obtained Ga_2O_3 thin films were polycrystalline. The thickness and dimension of the films were controllable. A flexible Ga_2O_3solar-blind UV photodetector was fabricated by transferring the free-standing Ga_2O_3 film on a flexible polyethylene terephthalate substrate. The results displayed that the photoelectric performances of the flexible Ga_2O_3 photodetector were not sensitive to bending of the device. The free-standing Ga_2O_3 thin films synthesized through the method described here can be transferred to any substrates or integrated with other thin films to fabricate electronic devices.展开更多
The use of α-power chirped fiber Bragg gratings for dispersion Cancellation in an optical fiber link is discussed.Numerical and theoretical investigation of recompressing the dispersion-broadened pulse by usingα-pow...The use of α-power chirped fiber Bragg gratings for dispersion Cancellation in an optical fiber link is discussed.Numerical and theoretical investigation of recompressing the dispersion-broadened pulse by usingα-power chirped gratings is made,which shows that,the dispersion-broadened Gaussian pulse after l00km standard fiber(with zero dispersion atλ=1.3μm)trnasmission atλ=1.55μm with initial width of T_(FWHM)=33ps(full width at half maximum)can be perfectly recompressed with the peak reflectivity of 82%by using a 30mm longα-power chirped fiber grating with properαvalue and optimal grating parameters.展开更多
Thin-film flexible solar cells are lightweight and mechanically robust.Along with rapidly advancing battery technology,flexible solar panels are expected to create niche products that require lightweight,mechanical fl...Thin-film flexible solar cells are lightweight and mechanically robust.Along with rapidly advancing battery technology,flexible solar panels are expected to create niche products that require lightweight,mechanical flexibility,and moldability into complex shapes,such as roof-panel for electric automobiles,foldable umbrellas,camping tents,etc.In this paper,we provide a comprehensive assessment of relevant materials suitable for making flexible solar cells.Substrate materials reviewed include metals,ceramics,glasses,and plastics.For active materials,we focus primarily on emerging new semiconductors including small organic donor/acceptor molecules,conjugated donor/acceptor polymers,and organometal halide perovskites.For electrode materials,transparent conducting oxides,thin metal films/nanowires,nanocarbons,and conducting polymers are reviewed.We also discuss the merits,weaknesses,and future perspectives of these materials for developing next-generation flexible photovoltaics.展开更多
Extreme ultraviolet(EUV)source produced by laser-induced discharge plasma(LDP)is a potential technical means in inspection and metrology.A pulsed Nd:YAG laser is focused on a tin plate to produce an initial plasma the...Extreme ultraviolet(EUV)source produced by laser-induced discharge plasma(LDP)is a potential technical means in inspection and metrology.A pulsed Nd:YAG laser is focused on a tin plate to produce an initial plasma thereby triggering a discharge between high-voltage electrodes in a vacuum system.The process of micro-pinch formation during the current rising is recorded by a time-resolved intensified charge couple device camera.The evolution of electron temperature and density of LDP are obtained by optical emission spectrometry.An extreme ultraviolet spectrometer is built up to investigate the EUV spectrum of Sn LDP at 13.5 nm.The laser and discharge parameters such as laser energy,voltage,gap distance,and anode shape can influence the EUV emission.展开更多
Klyachko-Can-Binicioglu-Shumovsky （KCBS） inequality is a Bell-like inequality, the violation of which can be used to confirm the existence of quantum contextuality. However, the imperfection of detection efficiency ...Klyachko-Can-Binicioglu-Shumovsky （KCBS） inequality is a Bell-like inequality, the violation of which can be used to confirm the existence of quantum contextuality. However, the imperfection of detection efficiency may cause the so-called loophole in actual KCBS＇s experiments. We derive an alternative KCBS inequality to deal with the loophole in actual KCBS＇s experiments. We prove that if the experimental data violate this KCBS inequality, the loophole-free violation of the original KCBS inequality will occur. We show that the minimum detection efficiency needed for a loophole-free violation of the KCBS inequality is about 0.9738.展开更多
In this work, MoOx promoted Ir/SiO2 catalysts were prepared and used for the selective hydrogenolysis of tetrahydrofurfuryl alcohol （THFA） to 1,5-pentanediol in a continuous flow reactor. The effects of different no...In this work, MoOx promoted Ir/SiO2 catalysts were prepared and used for the selective hydrogenolysis of tetrahydrofurfuryl alcohol （THFA） to 1,5-pentanediol in a continuous flow reactor. The effects of different noble metals （Ir, Pt, Pd, Ru, Rh）, supports and Ir contents were screened. Among the investigated catalysts, 4 wt%Ir-MoOx/SiO2 with a Mo/Ir atomic ratio of 0.13 exhibited the best catalytic performance. The synergy between Ix particles and the partially reduced isolated MoOx species attached on them is essential for the excellent catalytic performance of Ix-MoOx/SiO2. The catalyst exhibited a better hydrogenolysis efficiency of THFA with the selectivity of 1,5-pentanediol of 65%-74% at a conversion of THFA of 70%-75% when the initial THFA concentration is ranging from 20 wt% and 40 wt%. And higher system pressure was also in favor of the conversion of THFA. During a stability test, the conversion of THFA and 1,5-pentanediol yield over Ix-MoOz/SiO2 decreased with reaction time, which can be explained by the leaching of Mo species during the reaction.展开更多
SiC nanowires and SiC/SiO2 core-shell structural nanowires were synthesized via a simple thermal evaporation of CoxSiy melts at the temperature of 1500?C. The morphologies and yields of those SiC nanowires can be tune...SiC nanowires and SiC/SiO2 core-shell structural nanowires were synthesized via a simple thermal evaporation of CoxSiy melts at the temperature of 1500?C. The morphologies and yields of those SiC nanowires can be tuned by altering the composition of CoxSiy. Nanowires obtained by thermal evaporation of Co Si are composed of SiC/SiO2 core-shell nanostructures with lengths up to several hundreds of micrometers, diameters of 4050 nm, and the thickness of amorphous SiO2 wrapping shell about 20 nm. SiC nanowires prepared by thermal evaporation of Co Si2 and Co2 Si melt are found to be hexagonal-prism-shaped nanorods, and the diameter of those nanorods is about 150 nm and the length is about 10 microns. All the SiC nanowires obtained possess [111] preferred growth direction with a high density stacking faults and twin defects. Taking into consideration the binary alloy diagram of Co Si and the participation of oxygen, we propose the vapor-solid growth mechanism of SiC nanowires and discuss the effect of the supersaturation of Si O on the morphology and yields of SiC nanowires.展开更多
This paper studies the structure and electronic properties of Li4Ti5O12, as anode material for lithium ion batteries, from first principles calculations. The results suggest that there are two kinds of unit cell of Li...This paper studies the structure and electronic properties of Li4Ti5O12, as anode material for lithium ion batteries, from first principles calculations. The results suggest that there are two kinds of unit cell of Li4Ti5O12： n-type and p-type. The two unit cells have different structures and electronic properties： the n-type with two 16d site Li ions is metallic by electron, while the p-type with three 16d Li ions is metallic by hole. However, the Li4Ti5O12 is an insulator. It is very interesting that one n-type cell and two p-type cells constitute one Li4Ti5O12 supercell which is insulating. The results show that the intercalation potential obtained with a p-type unit cell with one additional electron is quite close to the experimental value of 1.5 V.展开更多
A 4×4 beta-phase gallium oxide(β-Ga_(2)O_(3))deep-ultraviolet(DUV)rectangular 10-fingers interdigital metalsemiconductor-metal(MSM)photodetector array of high photo responsivity is introduced.The Ga2O_(3)thin fi...A 4×4 beta-phase gallium oxide(β-Ga_(2)O_(3))deep-ultraviolet(DUV)rectangular 10-fingers interdigital metalsemiconductor-metal(MSM)photodetector array of high photo responsivity is introduced.The Ga2O_(3)thin film is prepared through the metalorganic chemical vapor deposition technique,then used to construct the photodetector array via photolithography,lift-off,and ion beam sputtering methods.The one photodetector cell shows dark current of 1.94 p A,phototo-dark current ratio of 6×10_(7),photo responsivity of 634.15 A·W^(-1),specific detectivity of 5.93×1011cm·Hz1/2·W^(-1)(Jones),external quantum efficiency of 310000%,and linear dynamic region of 108.94 d B,indicating high performances for DUV photo detection.Furthermore,the 16-cell photodetector array displays uniform performances with decent deviation of 19.6%for photo responsivity.展开更多
Structural and magnetic properties of LiNi0.5Mn1.5O4 and LiNi0.5Mn1.5O4-δ are investigated using density- functional theory calculations. Results indicate that nonstoichiometric LiNi0.5Mn1.5O4-δ and stoichiometric L...Structural and magnetic properties of LiNi0.5Mn1.5O4 and LiNi0.5Mn1.5O4-δ are investigated using density- functional theory calculations. Results indicate that nonstoichiometric LiNi0.5Mn1.5O4-δ and stoichiometric LiNi0.5Mn1.5O4 exhibit two different structures, i.e., the face-centred cubic （Fd-3m） and primitive, or simple, cubic （P4332） space groups, respectively. It is found that the magnetic ground state of LiNi0.5Mn1.5O4（P4332 and Fd-3m） is a ferrimagnetic state in which the Ni and Mn sublattices are ferromagnetically ordered along the [110] direction whereas they are antiferromagnetic with respect to each other. We demonstrate that it is the presence of an O-vacancy in LiNi0.5Mn1.5O4-δ with the Fd-3m space group that results in its superior electronic conductivity compared with LiNi0.5Mn1.5O4 with the P4332 space group.展开更多
The(001)oriented BiFeO_(3)thin film was deposited on the Nb:SrTiO_(3)substrate by radio frequency magnetron sputtering technology,and the bipolar resistive switching effect was observed in the BiFeO_(3)/Nb:SrTiO_(3)he...The(001)oriented BiFeO_(3)thin film was deposited on the Nb:SrTiO_(3)substrate by radio frequency magnetron sputtering technology,and the bipolar resistive switching effect was observed in the BiFeO_(3)/Nb:SrTiO_(3)heterostructure.The results showed that the ratio between the high resistance and low resistance was more than two orders at a reading pulse of-0.5 V and it exhibited excellent retention over 3600 s.The current density-voltage characteristic was dominated by the space-charge-limited conduction.The resistive switching effect of the structure was attributed to the trapping/detrapping of the charge carriers.展开更多
Low visibility in foggy days results in less contrasted and blurred images with color distortion which adversely affects and leads to the sub-optimal performances in image and video monitoring systems. The causes of f...Low visibility in foggy days results in less contrasted and blurred images with color distortion which adversely affects and leads to the sub-optimal performances in image and video monitoring systems. The causes of foggy image degradation were explained in detail and the approaches of image enhancement and image restoration for defogging were introduced. The study proposed an enhanced and advanced form of the improved Retinex theory-based dehazing algorithm. The proposed algorithm achieved novel in the manner in which the dark channel prior was efficiently combined with the dark-channel prior into a single dehazing framework. The proposed approach performed the first stage in dehazing within the dark channel domain through implementation with an adaptive filter. This novel approach allowed for the dark channel features to be efficiently refined and boosted, a scheme, which according to the obtained results, significantly improved dehazing results in later stages. Experimental results showed that this approach did little to trade-off dehazing speed for efficiency. This makes the proposed algorithm a strong candidate for real-time systems due to its capability to realize efficient dehazing at considerably rapid speeds. Finally, experimental results were provided to validate the superior performance and efficiency of the proposed dehazing algorithm.展开更多
Cr-doped CdS nanowires were synthesized in large scale through thermal co-evaporation of CdS and metal Cr powders. General morphology, detailed microstructure and optical properties were characterized using various te...Cr-doped CdS nanowires were synthesized in large scale through thermal co-evaporation of CdS and metal Cr powders. General morphology, detailed microstructure and optical properties were characterized using various techniques. Devices consisting of individual Cr-doped CdS nanowire were fabricated and they exhibited remarkable rectifying characteristics. Ⅰ-Ⅴ curves of individual Cr-doped CdS nanowire devices demonstrate that the present nanowires are n-type doped and have high conductivity （10.96 Ω^-1cm^-1）, indicating great potential applications in nanoscale electronic and optoelectronic devices.展开更多
In the field of computer and machine vision, haze and fog lead to image degradation through various degradation mechanisms including but not limited to contrast attenuation, blurring and pixel distortions. This limits...In the field of computer and machine vision, haze and fog lead to image degradation through various degradation mechanisms including but not limited to contrast attenuation, blurring and pixel distortions. This limits the efficiency of machine vision systems such as video surveillance, target tracking and recognition. Various single image dark channel dehazing algorithms have aimed to tackle the problem of image hazing in a fast and efficient manner. Such algorithms rely upon the dark channel prior theory towards the estimation of the atmospheric light which offers itself as a crucial parameter towards dehazing. This paper studies the state-of-the-art in this area and puts forwards their strengths and weaknesses. Through experiments the efficiencies and shortcomings of these algorithms are shared. This information is essential for researchers and developers in providing a reference for the development of applications and future of the research field.展开更多
We report the edge-defined-film-fed(EFG)-grown β-Ga_(2)O_(3)-based Schottky photodiodes.The device has a reverse leakage current of ~nA and a rectified ratio of ~10^(4) at ±5 V.In addition,the photodiode detecto...We report the edge-defined-film-fed(EFG)-grown β-Ga_(2)O_(3)-based Schottky photodiodes.The device has a reverse leakage current of ~nA and a rectified ratio of ~10^(4) at ±5 V.In addition,the photodiode detector shows a dark current of 0.3 pA,a photo-responsivity(R) of 2.875 mA/W,a special detectivity(D*) of 10^(10) Jones,and an external quantum efficiency(EQE) of 1.4% at zero bias,illustrating a self-powered operation.This work may advance the development of the Ga_(2)O_(3)-based Schottky diode solar-blind photodetectors.展开更多
Understanding the role of perovskite surface passivators in hot carriers transfer dynamics is important to develop highly efficient perovskite solar cells(PSCs).In this work,we have designed and synthesized a naphthal...Understanding the role of perovskite surface passivators in hot carriers transfer dynamics is important to develop highly efficient perovskite solar cells(PSCs).In this work,we have designed and synthesized a naphthalimide-based organic small molecule(NCN)for perovskite surface defect passivator.We reveal that the introduction of NCN not only reduces the density of perovskite defect-state,but also promotes hot carriers(HCs)cooling in perovskite through the transient absorption spectroscopy measurements.Fast HCs cooling permits HCs transfer from perovskite layer into NCN layer,thus resulting in the decreased charge-carrier recombination in NCN-treated device.As expected,the power conversion efficiency(PCE)of PSCs with NCN is enhanced to 22.02%from 19.95%for the control device.The findings are relevant for developing highly efficient PSCs.展开更多
A fascinating colloid phenomenon was observed in a specially designed template-assisted cell under an alternating electrical field. Most colloidal particles experienced the processes of aggregation, dispersion and cli...A fascinating colloid phenomenon was observed in a specially designed template-assisted cell under an alternating electrical field. Most colloidal particles experienced the processes of aggregation, dispersion and climbing up to the plateaus of the patterns pre-lithographed on the indium tin oxide glass as the frequency of the alternating electrical field increased. Two critical frequencies fcritl ≈ 15 kHz and fcrit2 ≈ 40 kHz, corresponding to the transitions of the colloid behaviour were observed. When f 〈 15 kHz, the particles were forced to aggregate along the grooves of the negative photoresist patterned template. When 15 kHz 〈 f 〈 40 kHz, the particle clusters became unstable and most particles started to disperse and were blocked by the fringes of the negative photoresist patterns. As the frequency increased to above 40 kHz, the majority of particles started to climb up to the plateaus of the patterns. Furthermore, the dynamics analysis for the behaviour of the colloids was given and we found out that positive or negative dielectrophoresis force, electrohydrodynamic force, particle-particle interactions and Brownian motion change with the frequency of the alternating electric field. Thus, changes of the related forces affect or control the behaviour of the colloids.展开更多
In the famous quantum communication scheme developed by Duan et al.[L.M.Duan,M.D.Lukin,J.I.Cirac,and P.Zoller,Nature(London) 414(2001) 413],the probability of successful generating a symmetric collective atomic state ...In the famous quantum communication scheme developed by Duan et al.[L.M.Duan,M.D.Lukin,J.I.Cirac,and P.Zoller,Nature(London) 414(2001) 413],the probability of successful generating a symmetric collective atomic state with a single-photon emitted have to be far smaller than 1 to obtain an acceptable entangled state.Based on strong dipole-dipole interaction between two Rydberg atoms,two simultaneous excitations in an atomic ensemble are greatly suppressed,which makes it possible to excite a mesoscopic cold atomic ensemble into a near-ideal singly-excited symmetric collective state accompanied by a signal-photon with near unity success probability.展开更多
基金National Natural Science Foundation of China(No.22065038)High-Level Talents Introduction in Yunnan Province(No.C619300A010)+3 种基金the Fund for Excellent Young Scholars of Yunnan(No.202001AW070008)Spring City Plan:the Highlevel Talent Promotion and Training Project of Kunming(No.2022SCP005)for financial supportthe support from the Postdoctoral Research Foundation of Yunnan University(No.W8223004)the Postdoctoral Foundation of Department of Human Resources and Social Security of Yunnan Province(No.C615300504046)。
文摘Defects at the grain boundaries(GBs)of perovskite film highly restrict both the efficiency and stability of perovskite solar cells(PSCs).Herein,organic small molecules of butanedioic acid(BA)and acetylenedicarboxylic acid(AA),containing two carbonyl(C=O)groups and different core-units,were incorporated into perovskite as additives for PSCs application.Thanks to the strong coordination interaction between C=O group and under-coordinated Pb^(2+),the additives can effectively passivate film defects and regulate the perovskite crystallization,yielding high-quality perovskite films with lower defect densities.More importantly,the additives can efficiently regulate the charge transport behaviors in PSCs.Benefiting from the defects passivation and the regulation of charge carrier dynamics,the BA and AA-treaded PSCs show the power conversion efficiencies of 21.52%and 20.50%,which are higher than that of the control device(19.41%).Besides,the optimal devices exhibit a remarkable enhanced long-term stability and moisture tolerance compared to the pristine devices.Furthermore,the transient absorption spectrum reveals the mechanism of enhanced photovoltaic performances,attributing to the improvement of charge transport capability at the perovskite/Spiro-OMeTAD interfaces.This work affords a promising strategy to improve the efficiency and stability of PSCs through regulating the charge-carrier dynamic process in perovskite film.
文摘A silicon-based photonic switch is proposed and simulated based on the multimode interference （MMI） principle and the free-carrier plasma dispersion effect in silicon-germanium. The proposed switch, designed for 1.55μm window operation,is useful for DWDM optical networks. The switch consists of two input single-mode ridge waveguide ports,a MMI section, and three output single-mode ridge waveguide ports. In the MMI section, two index-modulation regions are placed to divert input optical signals from the two input ports to each of the three output ports. Switching characteristics are demonstrated theoretically by a beam propagation method for 1.55μm operation. The simulated results show that the insertion loss of the switch is less than 1.43dB, and the crosstalk is between - 18 and - 32.8dB.
基金Project supported by the National Natural Science Foundation of China(Grant Nos.51572033,51572241,61774019,61704153,and 11404029)the Fund of State Key Laboratory of IPOC(BUPT)+1 种基金the Open Fund of IPOC(BUPT)Beijing Municipal Commission of Science and Technology,China(Grant No.SX2018-04)
文摘Flexible electronic devices have attracted much attention due to their practical and commercial value. Integration of thin films with soft substrate is an effective way to fabricate flexible electronic devices. Ga_2O_3 thin films deposited directly on soft substrates would be amorphous mostly. However, the thickness of the thin film obtained by mechanical exfoliation method is difficult to control and the edge of the film is fragile and easy to be damaged. In this work, we fabricated free-standing Ga_2O_3 thin films using the water-soluble perovskite Sr_3Al_2O_6 as a sacrificial buffer layer. The obtained Ga_2O_3 thin films were polycrystalline. The thickness and dimension of the films were controllable. A flexible Ga_2O_3solar-blind UV photodetector was fabricated by transferring the free-standing Ga_2O_3 film on a flexible polyethylene terephthalate substrate. The results displayed that the photoelectric performances of the flexible Ga_2O_3 photodetector were not sensitive to bending of the device. The free-standing Ga_2O_3 thin films synthesized through the method described here can be transferred to any substrates or integrated with other thin films to fabricate electronic devices.
基金Supported by the National Natural Science Foundation of China.
文摘The use of α-power chirped fiber Bragg gratings for dispersion Cancellation in an optical fiber link is discussed.Numerical and theoretical investigation of recompressing the dispersion-broadened pulse by usingα-power chirped gratings is made,which shows that,the dispersion-broadened Gaussian pulse after l00km standard fiber(with zero dispersion atλ=1.3μm)trnasmission atλ=1.55μm with initial width of T_(FWHM)=33ps(full width at half maximum)can be perfectly recompressed with the peak reflectivity of 82%by using a 30mm longα-power chirped fiber grating with properαvalue and optimal grating parameters.
基金Z.H.Lu would like to acknowledge the Natural Science and Engineering Research Council of Canada,and the National Natural Science Foundation of China(Grant No.11774304)for providing research fund.H.Y.Yu would like to acknowledge the financial support by Research and Application of Key Technologies of GaN-based Power Devices on Si Substrate(Grant No:2019B010128001)Research on key technologies for optimization of IoT chips and product development(Grant No.2019B010142001)+1 种基金and Study and optimization of electrostatic discharge mechanism for GaN HEMT devices(Grant No:JCYJ20180305180619573)Research of AlGaN HEMT MEMS sensor for work in extreme environment(Grant No:JCYJ20170412153356899).
文摘Thin-film flexible solar cells are lightweight and mechanically robust.Along with rapidly advancing battery technology,flexible solar panels are expected to create niche products that require lightweight,mechanical flexibility,and moldability into complex shapes,such as roof-panel for electric automobiles,foldable umbrellas,camping tents,etc.In this paper,we provide a comprehensive assessment of relevant materials suitable for making flexible solar cells.Substrate materials reviewed include metals,ceramics,glasses,and plastics.For active materials,we focus primarily on emerging new semiconductors including small organic donor/acceptor molecules,conjugated donor/acceptor polymers,and organometal halide perovskites.For electrode materials,transparent conducting oxides,thin metal films/nanowires,nanocarbons,and conducting polymers are reviewed.We also discuss the merits,weaknesses,and future perspectives of these materials for developing next-generation flexible photovoltaics.
基金Project supported by the Basic and Applied Basic Research Major Program of Guangdong Province,China(Grant No.2019B030302003).
文摘Extreme ultraviolet(EUV)source produced by laser-induced discharge plasma(LDP)is a potential technical means in inspection and metrology.A pulsed Nd:YAG laser is focused on a tin plate to produce an initial plasma thereby triggering a discharge between high-voltage electrodes in a vacuum system.The process of micro-pinch formation during the current rising is recorded by a time-resolved intensified charge couple device camera.The evolution of electron temperature and density of LDP are obtained by optical emission spectrometry.An extreme ultraviolet spectrometer is built up to investigate the EUV spectrum of Sn LDP at 13.5 nm.The laser and discharge parameters such as laser energy,voltage,gap distance,and anode shape can influence the EUV emission.
基金Project supported by the National Natural Science Foundation of China(Grant No.11005031)the Natural Science Foundation of Zhejiang Province,China(Grant No.Y6110314)
文摘Klyachko-Can-Binicioglu-Shumovsky （KCBS） inequality is a Bell-like inequality, the violation of which can be used to confirm the existence of quantum contextuality. However, the imperfection of detection efficiency may cause the so-called loophole in actual KCBS＇s experiments. We derive an alternative KCBS inequality to deal with the loophole in actual KCBS＇s experiments. We prove that if the experimental data violate this KCBS inequality, the loophole-free violation of the original KCBS inequality will occur. We show that the minimum detection efficiency needed for a loophole-free violation of the KCBS inequality is about 0.9738.
基金supported by the National Natural Science Foundation of China(No.21106143,No.21277140)100-Talent Project of Dalian Institute of Chemical Physics(DICP)+1 种基金the Independent Innovation Foundation of State Key Laboratory of Catalysis(No.R201113)the Zhejiang Provincial Natural Science Foundation of China(LR12E02001)
文摘In this work, MoOx promoted Ir/SiO2 catalysts were prepared and used for the selective hydrogenolysis of tetrahydrofurfuryl alcohol （THFA） to 1,5-pentanediol in a continuous flow reactor. The effects of different noble metals （Ir, Pt, Pd, Ru, Rh）, supports and Ir contents were screened. Among the investigated catalysts, 4 wt%Ir-MoOx/SiO2 with a Mo/Ir atomic ratio of 0.13 exhibited the best catalytic performance. The synergy between Ix particles and the partially reduced isolated MoOx species attached on them is essential for the excellent catalytic performance of Ix-MoOx/SiO2. The catalyst exhibited a better hydrogenolysis efficiency of THFA with the selectivity of 1,5-pentanediol of 65%-74% at a conversion of THFA of 70%-75% when the initial THFA concentration is ranging from 20 wt% and 40 wt%. And higher system pressure was also in favor of the conversion of THFA. During a stability test, the conversion of THFA and 1,5-pentanediol yield over Ix-MoOz/SiO2 decreased with reaction time, which can be explained by the leaching of Mo species during the reaction.
基金supported by the National Nature Science Foundation of the People’s Republic of China(Grant no.50902124)the National Basic Research Program of China(973 Program)(Grant no.2010CB933501)+1 种基金financial support from the Zhejiang Provincial Natural Science Foundation(Grant no.Y4090468)Science and Technology Department of Zhejiang Province(Grant no.2009F70046)
文摘SiC nanowires and SiC/SiO2 core-shell structural nanowires were synthesized via a simple thermal evaporation of CoxSiy melts at the temperature of 1500?C. The morphologies and yields of those SiC nanowires can be tuned by altering the composition of CoxSiy. Nanowires obtained by thermal evaporation of Co Si are composed of SiC/SiO2 core-shell nanostructures with lengths up to several hundreds of micrometers, diameters of 4050 nm, and the thickness of amorphous SiO2 wrapping shell about 20 nm. SiC nanowires prepared by thermal evaporation of Co Si2 and Co2 Si melt are found to be hexagonal-prism-shaped nanorods, and the diameter of those nanorods is about 150 nm and the length is about 10 microns. All the SiC nanowires obtained possess [111] preferred growth direction with a high density stacking faults and twin defects. Taking into consideration the binary alloy diagram of Co Si and the participation of oxygen, we propose the vapor-solid growth mechanism of SiC nanowires and discuss the effect of the supersaturation of Si O on the morphology and yields of SiC nanowires.
基金Project supported by the National Natural Science Foundation of China (Grant Nos 10604023 and 50802089)Science Foundation of Department of Education of Jiangxi Province (Grant No 2007-121)+1 种基金supported by Qianjiang Talent Project(Grant No 2007R10028)Natural Science Foundation of Zhejiang Province (Grant No Y407188)
文摘This paper studies the structure and electronic properties of Li4Ti5O12, as anode material for lithium ion batteries, from first principles calculations. The results suggest that there are two kinds of unit cell of Li4Ti5O12： n-type and p-type. The two unit cells have different structures and electronic properties： the n-type with two 16d site Li ions is metallic by electron, while the p-type with three 16d Li ions is metallic by hole. However, the Li4Ti5O12 is an insulator. It is very interesting that one n-type cell and two p-type cells constitute one Li4Ti5O12 supercell which is insulating. The results show that the intercalation potential obtained with a p-type unit cell with one additional electron is quite close to the experimental value of 1.5 V.
基金Project supported by the National Natural Science Foundation of China(Grant No.61774019)Natural Science Research Start-up Foundation of Recruiting Talents of Nanjing University of Posts and Telecommunications(Grant Nos.XK1060921115 and XK1060921002)。
文摘A 4×4 beta-phase gallium oxide(β-Ga_(2)O_(3))deep-ultraviolet(DUV)rectangular 10-fingers interdigital metalsemiconductor-metal(MSM)photodetector array of high photo responsivity is introduced.The Ga2O_(3)thin film is prepared through the metalorganic chemical vapor deposition technique,then used to construct the photodetector array via photolithography,lift-off,and ion beam sputtering methods.The one photodetector cell shows dark current of 1.94 p A,phototo-dark current ratio of 6×10_(7),photo responsivity of 634.15 A·W^(-1),specific detectivity of 5.93×1011cm·Hz1/2·W^(-1)(Jones),external quantum efficiency of 310000%,and linear dynamic region of 108.94 d B,indicating high performances for DUV photo detection.Furthermore,the 16-cell photodetector array displays uniform performances with decent deviation of 19.6%for photo responsivity.
基金Project supported by the National Natural Science Foundation of China(Grant Nos.51072183 and 50802089)the Natural Science Foundation of Zhejiang Province,China(Grant No.Y4090280)
文摘Structural and magnetic properties of LiNi0.5Mn1.5O4 and LiNi0.5Mn1.5O4-δ are investigated using density- functional theory calculations. Results indicate that nonstoichiometric LiNi0.5Mn1.5O4-δ and stoichiometric LiNi0.5Mn1.5O4 exhibit two different structures, i.e., the face-centred cubic （Fd-3m） and primitive, or simple, cubic （P4332） space groups, respectively. It is found that the magnetic ground state of LiNi0.5Mn1.5O4（P4332 and Fd-3m） is a ferrimagnetic state in which the Ni and Mn sublattices are ferromagnetically ordered along the [110] direction whereas they are antiferromagnetic with respect to each other. We demonstrate that it is the presence of an O-vacancy in LiNi0.5Mn1.5O4-δ with the Fd-3m space group that results in its superior electronic conductivity compared with LiNi0.5Mn1.5O4 with the P4332 space group.
基金Funded by the National Natural Science Foundation of China(Nos.61201046 and 61306057)the Beijing Natural Science Foundation of China(Nos.4162013,2132023 and 4164082)+2 种基金the Beijing Postdoctoral Research Foundation(No.2015ZZ-33)the Scientific Research Project of Beijing Educational Committee(No.KM201610005005)the Scientific Research Foundation for Returned Overseas Chinese Scholars,State Education Ministry
文摘The(001)oriented BiFeO_(3)thin film was deposited on the Nb:SrTiO_(3)substrate by radio frequency magnetron sputtering technology,and the bipolar resistive switching effect was observed in the BiFeO_(3)/Nb:SrTiO_(3)heterostructure.The results showed that the ratio between the high resistance and low resistance was more than two orders at a reading pulse of-0.5 V and it exhibited excellent retention over 3600 s.The current density-voltage characteristic was dominated by the space-charge-limited conduction.The resistive switching effect of the structure was attributed to the trapping/detrapping of the charge carriers.
文摘Low visibility in foggy days results in less contrasted and blurred images with color distortion which adversely affects and leads to the sub-optimal performances in image and video monitoring systems. The causes of foggy image degradation were explained in detail and the approaches of image enhancement and image restoration for defogging were introduced. The study proposed an enhanced and advanced form of the improved Retinex theory-based dehazing algorithm. The proposed algorithm achieved novel in the manner in which the dark channel prior was efficiently combined with the dark-channel prior into a single dehazing framework. The proposed approach performed the first stage in dehazing within the dark channel domain through implementation with an adaptive filter. This novel approach allowed for the dark channel features to be efficiently refined and boosted, a scheme, which according to the obtained results, significantly improved dehazing results in later stages. Experimental results showed that this approach did little to trade-off dehazing speed for efficiency. This makes the proposed algorithm a strong candidate for real-time systems due to its capability to realize efficient dehazing at considerably rapid speeds. Finally, experimental results were provided to validate the superior performance and efficiency of the proposed dehazing algorithm.
基金Project supported by the key project of Zhejiang Provincial Natural Science Foundation （Grant No Z605131） and the National Natural Science Foundation of China （Grant No 60571029）. Tang Wei-Hua was supported by the 100-outstanding Talents Project of Chinese Academy of Sciences and the Creative Research Group of National Natural Science Foundation of China （Grant No 60321001）.
文摘Cr-doped CdS nanowires were synthesized in large scale through thermal co-evaporation of CdS and metal Cr powders. General morphology, detailed microstructure and optical properties were characterized using various techniques. Devices consisting of individual Cr-doped CdS nanowire were fabricated and they exhibited remarkable rectifying characteristics. Ⅰ-Ⅴ curves of individual Cr-doped CdS nanowire devices demonstrate that the present nanowires are n-type doped and have high conductivity （10.96 Ω^-1cm^-1）, indicating great potential applications in nanoscale electronic and optoelectronic devices.
文摘In the field of computer and machine vision, haze and fog lead to image degradation through various degradation mechanisms including but not limited to contrast attenuation, blurring and pixel distortions. This limits the efficiency of machine vision systems such as video surveillance, target tracking and recognition. Various single image dark channel dehazing algorithms have aimed to tackle the problem of image hazing in a fast and efficient manner. Such algorithms rely upon the dark channel prior theory towards the estimation of the atmospheric light which offers itself as a crucial parameter towards dehazing. This paper studies the state-of-the-art in this area and puts forwards their strengths and weaknesses. Through experiments the efficiencies and shortcomings of these algorithms are shared. This information is essential for researchers and developers in providing a reference for the development of applications and future of the research field.
基金Project supported by BUPT Excellent Ph.D.Students Foundation(Grant No.CX2020314)the National Natural Science Foundation of China(Grant Nos.61774019,51572033,and 51572241)+1 种基金the Fund of State Key Laboratory of Information Photonics and Optical Communications(BUPT)the Fundamental Research Funds for the Central Universities,China。
文摘We report the edge-defined-film-fed(EFG)-grown β-Ga_(2)O_(3)-based Schottky photodiodes.The device has a reverse leakage current of ~nA and a rectified ratio of ~10^(4) at ±5 V.In addition,the photodiode detector shows a dark current of 0.3 pA,a photo-responsivity(R) of 2.875 mA/W,a special detectivity(D*) of 10^(10) Jones,and an external quantum efficiency(EQE) of 1.4% at zero bias,illustrating a self-powered operation.This work may advance the development of the Ga_(2)O_(3)-based Schottky diode solar-blind photodetectors.
基金High-Level Talents Introduction in Yunnan Province(No.C619300A010)the Fund for Excellent Young Scholars of Yunnan(No.202001AW070008)+5 种基金Spring City Plan:the High-level Talent Promotion and Training Project of Kunming(No.2022SCP005)for financial supportsupport from the Postdoctoral Foundation of Department of Human Resources and Social Security of Yunnan Province(No.C615300504046)Postdoctoral Research Foundation of Yunnan University(No.W8223004)the National Natural Science Foundation of China(No.22209144)the Project of Natural Science Foundation of Yunnan(Nos.202101AU070034 and 202101AT070337)the Innovation and Entrepreneurship Training Program for college students(No.202110673032)。
文摘Understanding the role of perovskite surface passivators in hot carriers transfer dynamics is important to develop highly efficient perovskite solar cells(PSCs).In this work,we have designed and synthesized a naphthalimide-based organic small molecule(NCN)for perovskite surface defect passivator.We reveal that the introduction of NCN not only reduces the density of perovskite defect-state,but also promotes hot carriers(HCs)cooling in perovskite through the transient absorption spectroscopy measurements.Fast HCs cooling permits HCs transfer from perovskite layer into NCN layer,thus resulting in the decreased charge-carrier recombination in NCN-treated device.As expected,the power conversion efficiency(PCE)of PSCs with NCN is enhanced to 22.02%from 19.95%for the control device.The findings are relevant for developing highly efficient PSCs.
基金Project supported by the National Natural Science Foundation of China (Grant Nos.10874153 and 50773003)the Science Foundation of Zhejiang Sci-Tech University of China,and the Innovation Research Project for Graduate Student of Zhejiang Province of China (Grant No.YK 2009051)
文摘A fascinating colloid phenomenon was observed in a specially designed template-assisted cell under an alternating electrical field. Most colloidal particles experienced the processes of aggregation, dispersion and climbing up to the plateaus of the patterns pre-lithographed on the indium tin oxide glass as the frequency of the alternating electrical field increased. Two critical frequencies fcritl ≈ 15 kHz and fcrit2 ≈ 40 kHz, corresponding to the transitions of the colloid behaviour were observed. When f 〈 15 kHz, the particles were forced to aggregate along the grooves of the negative photoresist patterned template. When 15 kHz 〈 f 〈 40 kHz, the particle clusters became unstable and most particles started to disperse and were blocked by the fringes of the negative photoresist patterns. As the frequency increased to above 40 kHz, the majority of particles started to climb up to the plateaus of the patterns. Furthermore, the dynamics analysis for the behaviour of the colloids was given and we found out that positive or negative dielectrophoresis force, electrohydrodynamic force, particle-particle interactions and Brownian motion change with the frequency of the alternating electric field. Thus, changes of the related forces affect or control the behaviour of the colloids.
基金Supported by the National Natural Science Foundation of China under Grant Nos. 61076094,11072218,and 11272287Zhejiang Provincial Natural Science Foundation of China under Grant No. Y6110314Scientific Research Fund of Zhejiang Provincial Education Department under Grant No. Y200909693
文摘In the famous quantum communication scheme developed by Duan et al.[L.M.Duan,M.D.Lukin,J.I.Cirac,and P.Zoller,Nature(London) 414(2001) 413],the probability of successful generating a symmetric collective atomic state with a single-photon emitted have to be far smaller than 1 to obtain an acceptable entangled state.Based on strong dipole-dipole interaction between two Rydberg atoms,two simultaneous excitations in an atomic ensemble are greatly suppressed,which makes it possible to excite a mesoscopic cold atomic ensemble into a near-ideal singly-excited symmetric collective state accompanied by a signal-photon with near unity success probability.
