The midcourse ballistic closely spaced objects（CSO） create blur pixel-cluster on the space-based infrared focal plane,making the super-resolution of CSO quite necessary.A novel algorithm of CSO joint super-resolutio...The midcourse ballistic closely spaced objects（CSO） create blur pixel-cluster on the space-based infrared focal plane,making the super-resolution of CSO quite necessary.A novel algorithm of CSO joint super-resolution and trajectory estimation is presented.The algorithm combines the focal plane CSO dynamics and radiation models,proposes a novel least square objective function from the space and time information,where CSO radiant intensity is excluded and initial dynamics（position and velocity） are chosen as the model parameters.Subsequently,the quantum-behaved particle swarm optimization（QPSO） is adopted to optimize the objective function to estimate model parameters,and then CSO focal plane trajectories and radiant intensities are computed.Meanwhile,the estimated CSO focal plane trajectories from multiple space-based infrared focal planes are associated and filtered to estimate the CSO stereo ballistic trajectories.Finally,the performance（CSO estimation precision of the focal plane coordinates,radiant intensities,and stereo ballistic trajectories,together with the computation load） of the algorithm is tested,and the results show that the algorithm is effective and feasible.展开更多
An infrared detector with high responsivity based on graphene-PbSe thin film heterojunction was reported.High-quality PbSe thin film and graphene were prepared by molecular beam epitaxy and chemical vapor deposition,r...An infrared detector with high responsivity based on graphene-PbSe thin film heterojunction was reported.High-quality PbSe thin film and graphene were prepared by molecular beam epitaxy and chemical vapor deposition,respectively.The physical characteristics of PbSe thin film and graphene were performed using X-ray diffraction(XRD),X-ray photoelectron spectroscopy(XPS)and Raman measurement.The photo transistor using PbSe thin film as a sensitizer and graphene as a channel to transport excitons exhibits peak responsivity and detectivity up to~420 A·W^(-1) and 5.9×10^(11) Jones(radiation intensity:0.75 mW·cm^(-2))at room temperature in the near-infrared(NIR)region,respectively.The high optical response is attributed to the photo-excited holes transferring from PbSe film to graphene under irradiation.Moreover,it is revealed that the responsivity of graphene-PbSe photo transistor is gate-tunable which is important in photodetectors.展开更多
The grain surfaces(film surface and grain boundary)of polycrystalline perovskite films are vulnerable sites in solar cells since they pose a high defect density and initiate the degradation of perovskite absorber.Achi...The grain surfaces(film surface and grain boundary)of polycrystalline perovskite films are vulnerable sites in solar cells since they pose a high defect density and initiate the degradation of perovskite absorber.Achieving simultaneously defect passivation and grain protection from moisture is crucial for the viability of perovskite solar cells.Here,an in situ cross-linked grain encapsulation(CLGE)strategy that improves both device stability and defect passivation is reported.Cross-linkable semiconducting small molecules are mixed into the antisolvent to uniformly form a compact and conducting cross-linked layer over the grain surfaces.This cross-linked coating layer not only passivates trap states and facilitates hole extraction,but also enhances the device stability by preventing moisture diffusion.Using the CLGE strategy,a high power conversion efficiency(PCE)of 22.7%is obtained in 1.55-eV bandgap planar perovskite solar cells.The unencapsulated devices with CLGE exhibit significantly enhanced device stability again moisture and maintain>90%of their initial PCE after shelf storage under ambient condition for over10,000 h.展开更多
The noise robustness and parameter estimation performance of the classical three-dimensional estimating signal parameter via rotational invariance techniques(3D-ESPRIT)algorithm are poor when the parameters of the geo...The noise robustness and parameter estimation performance of the classical three-dimensional estimating signal parameter via rotational invariance techniques(3D-ESPRIT)algorithm are poor when the parameters of the geometric theory of the diffraction(GTD)model are estimated at low signal-to-noise ratio(SNR).To solve this problem,a modified 3D-ESPRIT algorithm is proposed.The modified algorithm improves the parameter estimation accuracy by proposing a novel spatial smoothing technique.Firstly,we make cross-correlation of the auto-correlation matrices;then by averaging the cross-correlation matrices of the forward and backward spatial smoothing,we can obtain a novel equivalent spatial smoothing matrix.The formula of the modified algorithm is derived and the performance of this improved method is also analyzed.Then we compare root-meansquare-errors(RMSEs)of different parameters and the locating accuracy obtained by different algorithms.Furthermore,radar cross section(RCS)of radar targets is extrapolated.Simulation results verify the effectiveness and superiority of the modified 3DESPRIT algorithm.展开更多
In this paper,dual L defected hexagonal Photonic Crystal Ring Resonator(PCRR)using Channel Drop Filter(CDF)is designed for Coarse Wavelength Division Multiplexing(CWDM)systems.In this structure,the external rods of th...In this paper,dual L defected hexagonal Photonic Crystal Ring Resonator(PCRR)using Channel Drop Filter(CDF)is designed for Coarse Wavelength Division Multiplexing(CWDM)systems.In this structure,the external rods of the ring resonator are arranged in a hexagon and the internal rods are removed in L arrangement for introducing defects.Scatter rods are used to prevent leakage.By using the L defected hexagonal resonator,a multi-channel CDF is designed,which exhibits multiple wavelengths of CWDM(1500 nm–1600 nm)region.In addition,the selection of rod size and the position of rods in the proposed multi-channel CDF are validated by varying the radius of coupling and scattering rods,as well as the position of resonators,respectively.By using plane wave expansion and opti Finite Difference Time Domain(FDTD)method,the electromagnetic wave propagation and the photonic band gap are obtained.展开更多
We present a practical method to avoid the mis-locking phenomenon in the saturated-absorption-spectrum laser- frequency-locking system and set up a simple theoretical model to explain the abnormal saturated absorption...We present a practical method to avoid the mis-locking phenomenon in the saturated-absorption-spectrum laser- frequency-locking system and set up a simple theoretical model to explain the abnormal saturated absorption spectrum. The method uses the normal and abnormal saturated absorption spectra of the same transition 52S1/2, F = 2-52P3/2, F1 = 3 saturated absorption of the 87Rb D2 resonance line. After subtracting these two signals with the help of electronics, we can obtain a spectrum with a single peak to lock the laser. In our experiment, we use the normal and inverse signals of the transitions 52S1/2, F = 2-52P3/2, F1 = 3 saturated absorption of the 87Rb D2 resonance line to lock a 780-nm distributed feedback （DFB） diode laser. This method improves the long-term locking performance and is suitable for other kinds of diode lasers.展开更多
The charge-storage characteristics of charge trapping memory devices containing different sizes of Au nanocrystals(NCs)sandwiched by Al2O3 tunneling and blocking layers are studied.A strong impact of both Au NC size a...The charge-storage characteristics of charge trapping memory devices containing different sizes of Au nanocrystals(NCs)sandwiched by Al2O3 tunneling and blocking layers are studied.A strong impact of both Au NC size and inter-NC distance on the charge trapping capability of the devices is observed.The total surface area of Au NCs associated with Au NC size is supposed to be a key factor in the charge-storage capability,and the device with larger size of Au NCs and a suitable inter-NC distance will possess better charge trapping capability.Variable range hopping as the lateral charge loss mechanism is considered as the main reason for the decrease of the charge trapping capability when Au NCs grow and overlap neighbors.展开更多
We investigate properties of perpendicular anisotropy magnetic tunnel junctions(pMTJs) with a stack structure MgO/CoFeB/Ta/CoFeB/MgO as the free layer(or recording layer),and obtain the necessary device parameters fro...We investigate properties of perpendicular anisotropy magnetic tunnel junctions(pMTJs) with a stack structure MgO/CoFeB/Ta/CoFeB/MgO as the free layer(or recording layer),and obtain the necessary device parameters from the tunneling magnetoresistance(TMR) vs.field loops and current-driven magnetization switching experiments.Based on the experimental results and device parameters,we further estimate current-driven switching performance of pMTJ including switching time and power,and their dependence on perpendicular magnetic anisotropy and damping constant of the free layer by SPICE-based circuit simulations.Our results show that the pMTJ cells exhibit a less than 1 ns switching time and write energies <1.4 pJ;meanwhile the lower perpendicular magnetic anisotropy(PMA) and damping constant can further reduce the switching time at the studied range of damping constant α <0.1.Additionally,our results demonstrate that the pMTJs with the thermal stability factor■73 can be easily transformed into spin-torque nano-oscillators from magnetic memory as microwave sources or detectors for telecommunication devices.展开更多
Wide spectral white light emitting diodes have been designed and grown on a sapphire substrate by using a metal-organic chemical vapor deposition system. Three quantum wells with blue-light-emitting, green-light-emitt...Wide spectral white light emitting diodes have been designed and grown on a sapphire substrate by using a metal-organic chemical vapor deposition system. Three quantum wells with blue-light-emitting, green-light-emitting and red-light-emitting structures were grown according to the design. The surface morphology of the film was observed by using atomic force microscopy. The films were characterized by their photoluminescence measurements. X-ray diffraction t9/2/9 scan spectroscopy was carried out on the multi-quantum wells. The secondary fringes of the symmetric ω/2θ X-ray diffraction scan peaks indicate that the thicknesses and the alloy compositions of the individual quantum wells are repeatable throughout the active region. The room temperature photoluminescence spectra of the structures indicate that the white light emission of the multi-quantum wells is obtained. The light spectrum covers 400 700 nm, which is almost the whole visible light spectrum.展开更多
The systematic trends and effect introduced by Zr and C co-doping to TiO2 of electronic structure and optical properties of anatase TiO2 have been calculated by the plane-wave ultra-soft pseudopotential density functi...The systematic trends and effect introduced by Zr and C co-doping to TiO2 of electronic structure and optical properties of anatase TiO2 have been calculated by the plane-wave ultra-soft pseudopotential density functional theory （DFT） method within the generalized gradient approximation （GGA） for the exchange-correlation potential. Through the current calculations, the density of states （DOS）, energy band structure and optical absorption coefficients have been obtained for TiO2 and compared with the doped TiO2, and the influence of electronic structure and optical properties caused by Zr and C co-doping has been presented qualitatively together. The results revealed that the energy band gap has been decreased owing to the doped Zr and C, whereas the optical absorption coefficients have been increased in the region of 400～800 nm and a red shift of absorption band can be found. Accordingly, photo catalytic activity of TiO2 has been enhanced. The current calculations are in good agreement with the experimental data.展开更多
Combining a progressive tandem junction design with a unique Si nanowire(SiNW)framework paves the way for the development of high‐onset‐potential photocathodes and enhancement of solar hydrogen production.Herein,a r...Combining a progressive tandem junction design with a unique Si nanowire(SiNW)framework paves the way for the development of high‐onset‐potential photocathodes and enhancement of solar hydrogen production.Herein,a radial tandem junction(RTJ)thin film water‐splitting photo‐cathode has been demonstrated experimentally for the first time.The photocathode is directly fab‐ricated on vapor‐liquid‐solid‐grown SiNWs and consists of two radially stacked p‐i‐n junctions,featuring hydrogenated amorphous silicon(a‐Si:H)as the outer absorber layer,which absorbs short wavelengths,and hydrogenated amorphous silicon germanium(a‐SiGe:H)as the inner layer,which absorbs long wavelengths.The randomly distributed SiNW framework enables highly efficient light‐trapping,which facilitates the use of very thin absorber layers of a‐Si:H(~50 nm)and a‐SiGe:H(~40 nm).In a neutral electrolyte(pH=7),the three‐dimensional(3D)RTJ photocathode delivers a high photocurrent onset of 1.15 V vs.the reversible hydrogen electrode(RHE),accompanied by a photocurrent of 2.98 mA/cm^(2) at 0 V vs.RHE,and an overall applied‐bias photon‐to‐current effi‐ciency of 1.72%.These results emphasize the promising role of 3D radial tandem technology in developing a new generation of durable,low‐cost,high‐onset‐potential photocathodes capable of large‐scale implementation。展开更多
Blue-red complex light emitting InGaN/GaN multi-quantum well(MQW)structures are fabricated by metal organic chemical vapor deposition(MOCVD).The structures are grown on a 2-inch diameter(0001)oriented(c−face)sapphire ...Blue-red complex light emitting InGaN/GaN multi-quantum well(MQW)structures are fabricated by metal organic chemical vapor deposition(MOCVD).The structures are grown on a 2-inch diameter(0001)oriented(c−face)sapphire substrate,which consists of an approximately 2-µm−thick GaN template and a five-period layer consisting of a 4.9-nm-thick In0.18Ga0.82N well layer and a GaN barrier layer.The surface morphology of the MQW structures is observed by an atomic force microscope(AFM),which indicates the presence of islands of several tens of nanometers in height on the surface.The high resolution x−ray diffraction(XRD)θ/2θscan is carried out on the symmetric(0002)of the InGaN/GaN MQW structures.At least four order satellite peaks presented in the XRD spectrum indicate that the thickness and alloy compositions of the individual quantum wells are repeatable throughout the active region.Besides the 364 nm GaN band edge emission,two main emissions of blue and amber light from these MQWs are found,which possibly originate from the carrier recombinations in the InGaN/GaN QWs and InGaN quasi-quantum dots embedded in the QWs.展开更多
The forward current transport mechanism and Schottky barrier characteristics of a Ni/Au contact on n-GaN are studied by using temperature-dependent current-voltage(T–I–V)and capacitance-voltage(C–V)measurements.The...The forward current transport mechanism and Schottky barrier characteristics of a Ni/Au contact on n-GaN are studied by using temperature-dependent current-voltage(T–I–V)and capacitance-voltage(C–V)measurements.The low-forward-bias I–V curve of the Schottky junction is found to be dominated by trap-assisted tunneling below 400 K,and thus can not be used to deduce the Schottky barrier height(SBH)based on the thermionic emission(TE)model.On the other hand,TE transport mechanism dominates the high-forward-bias region and a modified I–V method is adopted to deduce the effective barrier height.It is found that the estimated SBH(~0.95 eV at 300 K)by the I–V method is~0.20 eV lower than that obtained by the C–V method,which is explained by a barrier inhomogeneity model over the Schottky contact area.展开更多
We report a perpendicular magnetic tunnel junction(p MTJ)cell with a tunnel magnetoresistance(TMR)ratio of nearly 200%at room temperature based on Co Fe B/Ta/Co Fe B as the free layer(FL)and a synthetic antiferromagne...We report a perpendicular magnetic tunnel junction(p MTJ)cell with a tunnel magnetoresistance(TMR)ratio of nearly 200%at room temperature based on Co Fe B/Ta/Co Fe B as the free layer(FL)and a synthetic antiferromagnetic(SAF)multilayer[Pt/Co]/Ru/[Pt/Co]/Ta/Co Fe B as the reference layer(RL).The field-driven magnetization switching measurements show that the p MTJs exhibit an anomalous TMR hysteresis loop.The spin-polarized layer Co Fe B of SAF-RL has a lower critical switching field than that of FL.The reason is related to the interlayer exchange coupling(IEC)through a moderately thick Ta spacer layer among SAF-RLs,which generates a moderate and negative bias magnetic field on Co Fe B of RL.However,the IEC among RLs has a negligible influence on the current-driven magnetization switching of FL and its magnetization dynamics.展开更多
Magnonic devices based on spin waves are considered as a new generation of energy-efficient and high-speed devices for storage and processing of information.Here we experimentally demonstrate that three distinct domin...Magnonic devices based on spin waves are considered as a new generation of energy-efficient and high-speed devices for storage and processing of information.Here we experimentally demonstrate that three distinct dominated magneto-dynamic modes are excited simultaneously and coexist in a transversely magnetized ferromagnetic wire by the ferromagnetic resonance(FMR)technique.Besides the uniform FMR mode,the spin-wave well mode,the backward volume magnetostatic spin-wave mode,and the perpendicular standing spin-wave mode are experimentally observed and further confirmed with more detailed spatial profiles by micromagnetic simulation.Furthermore,our experimental approach can also access and reveal damping coefficients of these spin-wave modes,which provides essential information for development of magnonic devices in the future.展开更多
Solid-state batteries are widely recognized as the next-generation energy storage devices with high specific energy,high safety,and high environmental adaptability.However,the research and development of solid-state b...Solid-state batteries are widely recognized as the next-generation energy storage devices with high specific energy,high safety,and high environmental adaptability.However,the research and development of solid-state batteries are resource-intensive and time-consuming due to their complex chemical environment,rendering performance prediction arduous and delaying large-scale industrialization.Artificial intelligence serves as an accelerator for solid-state battery development by enabling efficient material screening and performance prediction.This review will systematically examine how the latest progress in using machine learning(ML)algorithms can be used to mine extensive material databases and accelerate the discovery of high-performance cathode,anode,and electrolyte materials suitable for solid-state batteries.Furthermore,the use of ML technology to accurately estimate and predict key performance indicators in the solid-state battery management system will be discussed,among which are state of charge,state of health,remaining useful life,and battery capacity.Finally,we will summarize the main challenges encountered in the current research,such as data quality issues and poor code portability,and propose possible solutions and development paths.These will provide clear guidance for future research and technological reiteration.展开更多
Hydrogen has emerged as a promising clean energy carrier,and the development of cost-effective electrocatalysts that retain high activity under acidic media is crucial for advancing proton exchange membrane water elec...Hydrogen has emerged as a promising clean energy carrier,and the development of cost-effective electrocatalysts that retain high activity under acidic media is crucial for advancing proton exchange membrane water electrolysis(PEMWE).Here,we propose the SiO_(x)/RuCoO_(x)nanoparticles(SiO_(x)/RuCoO_(x)NPs)as bifunctional electrocatalysts for efficient hydrogen evolution reaction(HER)and oxygen evolution reaction(OER)under acidic media.The Ru-O-Si interface,along with charge transfer between Ru and Co,modulates the d-band electronic structure of the Ru site,achieving superior performance with a low HER overpotential of 18 mV at 10 mA cm^(-2)and a turnover frequency of 8.86 H_(2)s^(-1)at 100 mV.For OER,the overpotential is 217 mV at 10 mA cm^(-2).SiO_(x)/RuCoO_(x)NPs exhibit a cell voltage of 1.482 V at 10 mA cm^(-2)with an energy conversion efficiency of 83.0%.This work takes a significant step toward achieving efficient and cost-effective bifunctional electrocatalysts for water splitting,playing a critical role in the transition to clean energy technologies.展开更多
Sequential processing(SqP)of the active layer offers independent optimization of the donor and acceptor with more targeted solvent design,which is considered the most promising strategy for achieving efficient organic...Sequential processing(SqP)of the active layer offers independent optimization of the donor and acceptor with more targeted solvent design,which is considered the most promising strategy for achieving efficient organic solar cells(OSCs).In the SqP method,the favorable interpenetrating network seriously depends on the fine control of the bottom layer swelling.However,the choice of solvent(s)for both the donor and acceptor have been mostly based on a trial-and-error manner.A single solvent often cannot achieve sufficient yet not excessive swelling,which has long been a difficulty in the high efficient SqP OSCs.Herein,two new isomeric molecules are introduced to fine-tune the nucleation and crystallization dynamics that allows judicious control over the swelling of the bottom layer.The strong non-covalent interaction between the isomeric molecule and active materials provides an excellent driving force for optimize the swelling-process.Among them,the molecule with high dipole moment promotes earlier nucleation of the PM6 and provides extended time for crystallization during SqP,improving bulk morphology and vertical phase segregation.As a result,champion efficiencies of 17.38%and 20.00%(certified 19.70%)are achieved based on PM6/PYF-T-o(all-polymer)and PM6/BTP-eC9 devices casted by toluene solvent.展开更多
The 8 μm thick single-crystalline α-Ga2O3 epilayers have been heteroepitaxially grown on sapphire(0001) substrates via mist chemical vapor deposition technique. High resolution X-ray diffraction measurements show th...The 8 μm thick single-crystalline α-Ga2O3 epilayers have been heteroepitaxially grown on sapphire(0001) substrates via mist chemical vapor deposition technique. High resolution X-ray diffraction measurements show that the full-widths-at-halfmaximum(FWHM) of rocking curves for the(0006) and(10-14) planes are 0.024° and 0.24°, and the corresponding densities of screw and edge dislocations are 2.24 × 106 and 1.63 × 109 cm-2, respectively, indicative of high single crystallinity. The out-ofplane and in-plane epitaxial relationships are [0001] α-Ga2O3//[0001] α-Al2O3 and [11-20] α-Ga2O3//[11-20] α-Al2O3, respectively.The lateral domain size is in micron scale and the indirect bandgap is determined as 5.03 eV by transmittance spectra. Raman measurement indicates that the lattice-mismatch induced compressive residual strain cannot be ruled out despite the large thickness of the α-Ga2O3 epilayer. The achieved high quality α-Ga2O3 may provide an alternative material platform for developing high performance power devices and solar-blind photodetectors.展开更多
Electromagnetic detection satellite（EDS） is a type of Earth observation satellite（EOS）. Satellites observation and data down-link scheduling plays a significant role in improving the efficiency of satellite observ...Electromagnetic detection satellite（EDS） is a type of Earth observation satellite（EOS）. Satellites observation and data down-link scheduling plays a significant role in improving the efficiency of satellite observation systems. However, the current works mainly focus on the scheduling of imaging satellites, little work focuses on the scheduling of EDSes for its specific requirements.And current works mainly schedule satellite resources and data down-link resources separately, not considering them in a globally optimal perspective. The EDSes and data down-link resources are scheduled in an integrated process and the scheduling result is searched globally. Considering the specific constraints of EDS, a coordinate scheduling model for EDS observation tasks and data transmission jobs is established and an algorithm based on the genetic algorithm is proposed. Furthermore, the convergence of our algorithm is proved. To deal with some specific constraints, a solution repairing algorithm of polynomial computing time is designed. Finally, some experiments are conducted to validate the correctness and practicability of our scheduling algorithms.展开更多
基金supported by China Postdoctoral Science Foundation(20080149320080430223)the Natural Science Foundation of An-hui Province (090412043)
文摘The midcourse ballistic closely spaced objects（CSO） create blur pixel-cluster on the space-based infrared focal plane,making the super-resolution of CSO quite necessary.A novel algorithm of CSO joint super-resolution and trajectory estimation is presented.The algorithm combines the focal plane CSO dynamics and radiation models,proposes a novel least square objective function from the space and time information,where CSO radiant intensity is excluded and initial dynamics（position and velocity） are chosen as the model parameters.Subsequently,the quantum-behaved particle swarm optimization（QPSO） is adopted to optimize the objective function to estimate model parameters,and then CSO focal plane trajectories and radiant intensities are computed.Meanwhile,the estimated CSO focal plane trajectories from multiple space-based infrared focal planes are associated and filtered to estimate the CSO stereo ballistic trajectories.Finally,the performance（CSO estimation precision of the focal plane coordinates,radiant intensities,and stereo ballistic trajectories,together with the computation load） of the algorithm is tested,and the results show that the algorithm is effective and feasible.
基金financially supported by the National Natural Science Foundation of China(No.51572043)。
文摘An infrared detector with high responsivity based on graphene-PbSe thin film heterojunction was reported.High-quality PbSe thin film and graphene were prepared by molecular beam epitaxy and chemical vapor deposition,respectively.The physical characteristics of PbSe thin film and graphene were performed using X-ray diffraction(XRD),X-ray photoelectron spectroscopy(XPS)and Raman measurement.The photo transistor using PbSe thin film as a sensitizer and graphene as a channel to transport excitons exhibits peak responsivity and detectivity up to~420 A·W^(-1) and 5.9×10^(11) Jones(radiation intensity:0.75 mW·cm^(-2))at room temperature in the near-infrared(NIR)region,respectively.The high optical response is attributed to the photo-excited holes transferring from PbSe film to graphene under irradiation.Moreover,it is revealed that the responsivity of graphene-PbSe photo transistor is gate-tunable which is important in photodetectors.
基金financially supported by the National Key R&D Program of China(2018YFB1500102,2018YFB2200101)the National Natural Science Foundation of China(61974063,61921005)+3 种基金Natural Science Foundation of Jiangsu Province(BK20190315)the Fundamental Research Funds for the Central Universities(14380168)the Thousand Talent Program for Young Outstanding Scientists in ChinaProgram for Innovative Talents and Entrepreneur in Jiangsu。
文摘The grain surfaces(film surface and grain boundary)of polycrystalline perovskite films are vulnerable sites in solar cells since they pose a high defect density and initiate the degradation of perovskite absorber.Achieving simultaneously defect passivation and grain protection from moisture is crucial for the viability of perovskite solar cells.Here,an in situ cross-linked grain encapsulation(CLGE)strategy that improves both device stability and defect passivation is reported.Cross-linkable semiconducting small molecules are mixed into the antisolvent to uniformly form a compact and conducting cross-linked layer over the grain surfaces.This cross-linked coating layer not only passivates trap states and facilitates hole extraction,but also enhances the device stability by preventing moisture diffusion.Using the CLGE strategy,a high power conversion efficiency(PCE)of 22.7%is obtained in 1.55-eV bandgap planar perovskite solar cells.The unencapsulated devices with CLGE exhibit significantly enhanced device stability again moisture and maintain>90%of their initial PCE after shelf storage under ambient condition for over10,000 h.
基金This work was supported by the National Natural Science Foundation of China(61372033).
文摘The noise robustness and parameter estimation performance of the classical three-dimensional estimating signal parameter via rotational invariance techniques(3D-ESPRIT)algorithm are poor when the parameters of the geometric theory of the diffraction(GTD)model are estimated at low signal-to-noise ratio(SNR).To solve this problem,a modified 3D-ESPRIT algorithm is proposed.The modified algorithm improves the parameter estimation accuracy by proposing a novel spatial smoothing technique.Firstly,we make cross-correlation of the auto-correlation matrices;then by averaging the cross-correlation matrices of the forward and backward spatial smoothing,we can obtain a novel equivalent spatial smoothing matrix.The formula of the modified algorithm is derived and the performance of this improved method is also analyzed.Then we compare root-meansquare-errors(RMSEs)of different parameters and the locating accuracy obtained by different algorithms.Furthermore,radar cross section(RCS)of radar targets is extrapolated.Simulation results verify the effectiveness and superiority of the modified 3DESPRIT algorithm.
文摘In this paper,dual L defected hexagonal Photonic Crystal Ring Resonator(PCRR)using Channel Drop Filter(CDF)is designed for Coarse Wavelength Division Multiplexing(CWDM)systems.In this structure,the external rods of the ring resonator are arranged in a hexagon and the internal rods are removed in L arrangement for introducing defects.Scatter rods are used to prevent leakage.By using the L defected hexagonal resonator,a multi-channel CDF is designed,which exhibits multiple wavelengths of CWDM(1500 nm–1600 nm)region.In addition,the selection of rod size and the position of rods in the proposed multi-channel CDF are validated by varying the radius of coupling and scattering rods,as well as the position of resonators,respectively.By using plane wave expansion and opti Finite Difference Time Domain(FDTD)method,the electromagnetic wave propagation and the photonic band gap are obtained.
基金supported by the National Natural Science Foundation of China(Grant No.11174015)
文摘We present a practical method to avoid the mis-locking phenomenon in the saturated-absorption-spectrum laser- frequency-locking system and set up a simple theoretical model to explain the abnormal saturated absorption spectrum. The method uses the normal and abnormal saturated absorption spectra of the same transition 52S1/2, F = 2-52P3/2, F1 = 3 saturated absorption of the 87Rb D2 resonance line. After subtracting these two signals with the help of electronics, we can obtain a spectrum with a single peak to lock the laser. In our experiment, we use the normal and inverse signals of the transitions 52S1/2, F = 2-52P3/2, F1 = 3 saturated absorption of the 87Rb D2 resonance line to lock a 780-nm distributed feedback （DFB） diode laser. This method improves the long-term locking performance and is suitable for other kinds of diode lasers.
基金Supported by the National Natural Science Foundation of China under Grant No 61176124the National Basic Research Program of China under Grant No 2010CB934201the Priority Academic Program Development of Jiangsu Higher Education Institutions.
文摘The charge-storage characteristics of charge trapping memory devices containing different sizes of Au nanocrystals(NCs)sandwiched by Al2O3 tunneling and blocking layers are studied.A strong impact of both Au NC size and inter-NC distance on the charge trapping capability of the devices is observed.The total surface area of Au NCs associated with Au NC size is supposed to be a key factor in the charge-storage capability,and the device with larger size of Au NCs and a suitable inter-NC distance will possess better charge trapping capability.Variable range hopping as the lateral charge loss mechanism is considered as the main reason for the decrease of the charge trapping capability when Au NCs grow and overlap neighbors.
基金Project supported by State Grid Corporation of China under the 2018 Science and Technology Project of State Grid Corporation:Research on electromagnetic measurement technology based on EIT and TMR(Grant No.JL71-18-007)。
文摘We investigate properties of perpendicular anisotropy magnetic tunnel junctions(pMTJs) with a stack structure MgO/CoFeB/Ta/CoFeB/MgO as the free layer(or recording layer),and obtain the necessary device parameters from the tunneling magnetoresistance(TMR) vs.field loops and current-driven magnetization switching experiments.Based on the experimental results and device parameters,we further estimate current-driven switching performance of pMTJ including switching time and power,and their dependence on perpendicular magnetic anisotropy and damping constant of the free layer by SPICE-based circuit simulations.Our results show that the pMTJ cells exhibit a less than 1 ns switching time and write energies <1.4 pJ;meanwhile the lower perpendicular magnetic anisotropy(PMA) and damping constant can further reduce the switching time at the studied range of damping constant α <0.1.Additionally,our results demonstrate that the pMTJs with the thermal stability factor■73 can be easily transformed into spin-torque nano-oscillators from magnetic memory as microwave sources or detectors for telecommunication devices.
基金supported by the Special Funds for Major State Basic Research Project,China(Grant No.2011CB301900)the Hi-tech Research Project,China(Grant No.2009AA03A198)+2 种基金the National Natural Science Foundation of China(Grant Nos.60990311, 60721063,60906025,60936004,60731160628,and 60820106003)the Nature Science Foundation of Jiangsu Province,China (Grant Nos.BK2008019,BK2010385,BK2009255,and BK2010178)the Research Funds from NJU-Yangzhou Institute of Opto-electronics,China
文摘Wide spectral white light emitting diodes have been designed and grown on a sapphire substrate by using a metal-organic chemical vapor deposition system. Three quantum wells with blue-light-emitting, green-light-emitting and red-light-emitting structures were grown according to the design. The surface morphology of the film was observed by using atomic force microscopy. The films were characterized by their photoluminescence measurements. X-ray diffraction t9/2/9 scan spectroscopy was carried out on the multi-quantum wells. The secondary fringes of the symmetric ω/2θ X-ray diffraction scan peaks indicate that the thicknesses and the alloy compositions of the individual quantum wells are repeatable throughout the active region. The room temperature photoluminescence spectra of the structures indicate that the white light emission of the multi-quantum wells is obtained. The light spectrum covers 400 700 nm, which is almost the whole visible light spectrum.
基金supported by the National Natural Science Foundation of China (No. 60937003)
文摘The systematic trends and effect introduced by Zr and C co-doping to TiO2 of electronic structure and optical properties of anatase TiO2 have been calculated by the plane-wave ultra-soft pseudopotential density functional theory （DFT） method within the generalized gradient approximation （GGA） for the exchange-correlation potential. Through the current calculations, the density of states （DOS）, energy band structure and optical absorption coefficients have been obtained for TiO2 and compared with the doped TiO2, and the influence of electronic structure and optical properties caused by Zr and C co-doping has been presented qualitatively together. The results revealed that the energy band gap has been decreased owing to the doped Zr and C, whereas the optical absorption coefficients have been increased in the region of 400～800 nm and a red shift of absorption band can be found. Accordingly, photo catalytic activity of TiO2 has been enhanced. The current calculations are in good agreement with the experimental data.
文摘Combining a progressive tandem junction design with a unique Si nanowire(SiNW)framework paves the way for the development of high‐onset‐potential photocathodes and enhancement of solar hydrogen production.Herein,a radial tandem junction(RTJ)thin film water‐splitting photo‐cathode has been demonstrated experimentally for the first time.The photocathode is directly fab‐ricated on vapor‐liquid‐solid‐grown SiNWs and consists of two radially stacked p‐i‐n junctions,featuring hydrogenated amorphous silicon(a‐Si:H)as the outer absorber layer,which absorbs short wavelengths,and hydrogenated amorphous silicon germanium(a‐SiGe:H)as the inner layer,which absorbs long wavelengths.The randomly distributed SiNW framework enables highly efficient light‐trapping,which facilitates the use of very thin absorber layers of a‐Si:H(~50 nm)and a‐SiGe:H(~40 nm).In a neutral electrolyte(pH=7),the three‐dimensional(3D)RTJ photocathode delivers a high photocurrent onset of 1.15 V vs.the reversible hydrogen electrode(RHE),accompanied by a photocurrent of 2.98 mA/cm^(2) at 0 V vs.RHE,and an overall applied‐bias photon‐to‐current effi‐ciency of 1.72%.These results emphasize the promising role of 3D radial tandem technology in developing a new generation of durable,low‐cost,high‐onset‐potential photocathodes capable of large‐scale implementation。
基金by the National Basic Research Program of China under Grant No 2011CB301900the National High-Technology Research and Development Program of China under Grant No 2009AA03A198+2 种基金the National Natural Science Foundation of China under Grant Nos 60721063,60676057,60731160628,60820106003,60990311 and 60906025the Natural Science Foundation of Jiangsu Province(BK2008019,BK2009255)the Research Funds from NJU-Yangzhou Institute of Opto-electronics.
文摘Blue-red complex light emitting InGaN/GaN multi-quantum well(MQW)structures are fabricated by metal organic chemical vapor deposition(MOCVD).The structures are grown on a 2-inch diameter(0001)oriented(c−face)sapphire substrate,which consists of an approximately 2-µm−thick GaN template and a five-period layer consisting of a 4.9-nm-thick In0.18Ga0.82N well layer and a GaN barrier layer.The surface morphology of the MQW structures is observed by an atomic force microscope(AFM),which indicates the presence of islands of several tens of nanometers in height on the surface.The high resolution x−ray diffraction(XRD)θ/2θscan is carried out on the symmetric(0002)of the InGaN/GaN MQW structures.At least four order satellite peaks presented in the XRD spectrum indicate that the thickness and alloy compositions of the individual quantum wells are repeatable throughout the active region.Besides the 364 nm GaN band edge emission,two main emissions of blue and amber light from these MQWs are found,which possibly originate from the carrier recombinations in the InGaN/GaN QWs and InGaN quasi-quantum dots embedded in the QWs.
基金Supported by the National Basic Research Program of China under Grant No 2010CB327504the National Natural Science Foundation of China under Grant Nos 60936004 and 11074280+1 种基金the Fundamental Research Funds for the Central Universities of China under Grant Nos JUSRP111A42,JUSRP211A37 and JUSRP20914the State Key Laboratory of ASIC&System under Grant No 11KF003.
文摘The forward current transport mechanism and Schottky barrier characteristics of a Ni/Au contact on n-GaN are studied by using temperature-dependent current-voltage(T–I–V)and capacitance-voltage(C–V)measurements.The low-forward-bias I–V curve of the Schottky junction is found to be dominated by trap-assisted tunneling below 400 K,and thus can not be used to deduce the Schottky barrier height(SBH)based on the thermionic emission(TE)model.On the other hand,TE transport mechanism dominates the high-forward-bias region and a modified I–V method is adopted to deduce the effective barrier height.It is found that the estimated SBH(~0.95 eV at 300 K)by the I–V method is~0.20 eV lower than that obtained by the C–V method,which is explained by a barrier inhomogeneity model over the Schottky contact area.
基金Supported by the National Key Research and Development Program of China(Grant No.2016YFA0300803)the Open Research Fund of Jiangsu Provincial Key Laboratory for Nanotechnology+1 种基金the National Natural Science Foundation of China(Grant Nos.11774150 and 11874135)the Natural Science Foundation of Jiangsu Province of China(Grant No.BK20170627)。
文摘We report a perpendicular magnetic tunnel junction(p MTJ)cell with a tunnel magnetoresistance(TMR)ratio of nearly 200%at room temperature based on Co Fe B/Ta/Co Fe B as the free layer(FL)and a synthetic antiferromagnetic(SAF)multilayer[Pt/Co]/Ru/[Pt/Co]/Ta/Co Fe B as the reference layer(RL).The field-driven magnetization switching measurements show that the p MTJs exhibit an anomalous TMR hysteresis loop.The spin-polarized layer Co Fe B of SAF-RL has a lower critical switching field than that of FL.The reason is related to the interlayer exchange coupling(IEC)through a moderately thick Ta spacer layer among SAF-RLs,which generates a moderate and negative bias magnetic field on Co Fe B of RL.However,the IEC among RLs has a negligible influence on the current-driven magnetization switching of FL and its magnetization dynamics.
基金Supported by the National Key Research and Development Program of China(Grant No.2016YFA0300803)the Open Research Fund of Jiangsu Provincial Key Laboratory for Nanotechnology,the National Natural Science Foundation of China(Grant Nos.11774150 and 11704191)the Natural Science Foundation of Jiangsu Province(Grant Nos.BK20171026 and BK20170627).
文摘Magnonic devices based on spin waves are considered as a new generation of energy-efficient and high-speed devices for storage and processing of information.Here we experimentally demonstrate that three distinct dominated magneto-dynamic modes are excited simultaneously and coexist in a transversely magnetized ferromagnetic wire by the ferromagnetic resonance(FMR)technique.Besides the uniform FMR mode,the spin-wave well mode,the backward volume magnetostatic spin-wave mode,and the perpendicular standing spin-wave mode are experimentally observed and further confirmed with more detailed spatial profiles by micromagnetic simulation.Furthermore,our experimental approach can also access and reveal damping coefficients of these spin-wave modes,which provides essential information for development of magnonic devices in the future.
基金the National Key Research Program of China under granted No.92164201National Natural Science Foundation of China for Distinguished Young Scholars No.62325403+2 种基金Natural Science Foundation of Jiangsu Province(BK20230498)Jiangsu Funding Program for Excellent Postdoctoral Talent(2024ZB427)the National Natural Science Foundation of China(62304147).
文摘Solid-state batteries are widely recognized as the next-generation energy storage devices with high specific energy,high safety,and high environmental adaptability.However,the research and development of solid-state batteries are resource-intensive and time-consuming due to their complex chemical environment,rendering performance prediction arduous and delaying large-scale industrialization.Artificial intelligence serves as an accelerator for solid-state battery development by enabling efficient material screening and performance prediction.This review will systematically examine how the latest progress in using machine learning(ML)algorithms can be used to mine extensive material databases and accelerate the discovery of high-performance cathode,anode,and electrolyte materials suitable for solid-state batteries.Furthermore,the use of ML technology to accurately estimate and predict key performance indicators in the solid-state battery management system will be discussed,among which are state of charge,state of health,remaining useful life,and battery capacity.Finally,we will summarize the main challenges encountered in the current research,such as data quality issues and poor code portability,and propose possible solutions and development paths.These will provide clear guidance for future research and technological reiteration.
基金financially supported by the National Natural Science Foundation of China(No.61921005)the Key R&D Project of Nantong(No.GZ2024004)
文摘Hydrogen has emerged as a promising clean energy carrier,and the development of cost-effective electrocatalysts that retain high activity under acidic media is crucial for advancing proton exchange membrane water electrolysis(PEMWE).Here,we propose the SiO_(x)/RuCoO_(x)nanoparticles(SiO_(x)/RuCoO_(x)NPs)as bifunctional electrocatalysts for efficient hydrogen evolution reaction(HER)and oxygen evolution reaction(OER)under acidic media.The Ru-O-Si interface,along with charge transfer between Ru and Co,modulates the d-band electronic structure of the Ru site,achieving superior performance with a low HER overpotential of 18 mV at 10 mA cm^(-2)and a turnover frequency of 8.86 H_(2)s^(-1)at 100 mV.For OER,the overpotential is 217 mV at 10 mA cm^(-2).SiO_(x)/RuCoO_(x)NPs exhibit a cell voltage of 1.482 V at 10 mA cm^(-2)with an energy conversion efficiency of 83.0%.This work takes a significant step toward achieving efficient and cost-effective bifunctional electrocatalysts for water splitting,playing a critical role in the transition to clean energy technologies.
基金supported by the Guangdong Basic and Applied Basic Research Foundation (2022A1515010875)National Natural Science Foundation of China (12404480)+4 种基金Shenzhen Science and Technology Program (JCYJ20240813113238050, JCYJ20240813113306008)Education Department of Guangdong Province (2021KCXTD045)National Natural Science Foundation of China (12274303)the Shenzhen Key Laboratory of Applied Technologies of Super-Diamond and Functional Crystals (ZDSYS20230626091303007)Characteristic Innovation Foundation of Higher Education Institutions of Guangdong Province (2022KTSCX116)
文摘Sequential processing(SqP)of the active layer offers independent optimization of the donor and acceptor with more targeted solvent design,which is considered the most promising strategy for achieving efficient organic solar cells(OSCs).In the SqP method,the favorable interpenetrating network seriously depends on the fine control of the bottom layer swelling.However,the choice of solvent(s)for both the donor and acceptor have been mostly based on a trial-and-error manner.A single solvent often cannot achieve sufficient yet not excessive swelling,which has long been a difficulty in the high efficient SqP OSCs.Herein,two new isomeric molecules are introduced to fine-tune the nucleation and crystallization dynamics that allows judicious control over the swelling of the bottom layer.The strong non-covalent interaction between the isomeric molecule and active materials provides an excellent driving force for optimize the swelling-process.Among them,the molecule with high dipole moment promotes earlier nucleation of the PM6 and provides extended time for crystallization during SqP,improving bulk morphology and vertical phase segregation.As a result,champion efficiencies of 17.38%and 20.00%(certified 19.70%)are achieved based on PM6/PYF-T-o(all-polymer)and PM6/BTP-eC9 devices casted by toluene solvent.
基金supported by the National Key Research and Development Project(No.2017YFB0403003)Shenzhen Fundamental Research Project(Nos.201773239,201888588)+4 种基金the National Natural Science Foundation of China(Nos.61774081,61322403)State Key Laboratory of Wide-Bandgap Semiconductor Power Electric Devices(No.2017KF001)the Natural Science Foundation of Jiangsu Province(No.BK20161401)the Six Talent Peaks Project in Jiangsu Province(Mo.2014XXRJ001)the Fundamental Research Funds for the C entral Universities(Nos.021014380093,021014380085)
文摘The 8 μm thick single-crystalline α-Ga2O3 epilayers have been heteroepitaxially grown on sapphire(0001) substrates via mist chemical vapor deposition technique. High resolution X-ray diffraction measurements show that the full-widths-at-halfmaximum(FWHM) of rocking curves for the(0006) and(10-14) planes are 0.024° and 0.24°, and the corresponding densities of screw and edge dislocations are 2.24 × 106 and 1.63 × 109 cm-2, respectively, indicative of high single crystallinity. The out-ofplane and in-plane epitaxial relationships are [0001] α-Ga2O3//[0001] α-Al2O3 and [11-20] α-Ga2O3//[11-20] α-Al2O3, respectively.The lateral domain size is in micron scale and the indirect bandgap is determined as 5.03 eV by transmittance spectra. Raman measurement indicates that the lattice-mismatch induced compressive residual strain cannot be ruled out despite the large thickness of the α-Ga2O3 epilayer. The achieved high quality α-Ga2O3 may provide an alternative material platform for developing high performance power devices and solar-blind photodetectors.
基金supported by the National Natural Science Foundation of China(6110118461174159)
文摘Electromagnetic detection satellite（EDS） is a type of Earth observation satellite（EOS）. Satellites observation and data down-link scheduling plays a significant role in improving the efficiency of satellite observation systems. However, the current works mainly focus on the scheduling of imaging satellites, little work focuses on the scheduling of EDSes for its specific requirements.And current works mainly schedule satellite resources and data down-link resources separately, not considering them in a globally optimal perspective. The EDSes and data down-link resources are scheduled in an integrated process and the scheduling result is searched globally. Considering the specific constraints of EDS, a coordinate scheduling model for EDS observation tasks and data transmission jobs is established and an algorithm based on the genetic algorithm is proposed. Furthermore, the convergence of our algorithm is proved. To deal with some specific constraints, a solution repairing algorithm of polynomial computing time is designed. Finally, some experiments are conducted to validate the correctness and practicability of our scheduling algorithms.
