Optoelectronic memristor is generating growing research interest for high efficient computing and sensing-memory applications.In this work,an optoelectronic memristor with Au/a-C:Te/Pt structure is developed.Synaptic ...Optoelectronic memristor is generating growing research interest for high efficient computing and sensing-memory applications.In this work,an optoelectronic memristor with Au/a-C:Te/Pt structure is developed.Synaptic functions,i.e.,excita-tory post-synaptic current and pair-pulse facilitation are successfully mimicked with the memristor under electrical and optical stimulations.More importantly,the device exhibited distinguishable response currents by adjusting 4-bit input electrical/opti-cal signals.A multi-mode reservoir computing(RC)system is constructed with the optoelectronic memristors to emulate human tactile-visual fusion recognition and an accuracy of 98.7%is achieved.The optoelectronic memristor provides potential for developing multi-mode RC system.展开更多
Compound eyes(CEs)that feature ultra-compact structures and extraordinary versatility have revealed great potential for cutting-edge applications.However,the optoelectronic integration of CEs with available photodetec...Compound eyes(CEs)that feature ultra-compact structures and extraordinary versatility have revealed great potential for cutting-edge applications.However,the optoelectronic integration of CEs with available photodetectors is still challenging because the planar charge-coupled device(CCD)/complementary metal oxide semiconductor(CMOS)detector cannot match the spatially distributed images formed by CE ommatidia.To reach this end,we report here the optoelectronic integration of CEs by manufacturing 3D nonuniform ommatidia for developing an ultra-compact on-chip camera.As a proof-of-concept,we fabricated microscale CEs with uniform and nonuniform ommatidia through femtosecond laser two-photon photopolymerization,and compared their focusing/imaging performance both theoretically and experimentally.By engineering the surface profiles of the ommatidia at different positions of the CE,the images formed by all the ommatidia can be tuned on a plane.In this way,the nonuniform CE can be directly integrated with a commercial CMOS photodetector,forming an ultra-compact CE camera.Additionally,we further combine the CE camera with a microfluidic chip,which can further serve as an on-chip microscopic monitoring system.We anticipate that such an ultra-compact CE camera may find broad applications in microfluidics,robotics,and micro-optics.展开更多
Kesterite Cu2ZnSn(S,Se)4(CZTSSe)solar cells have drawn worldwide attention for their promising photovoltaics performance and earth-abundant element composition,yet the record efficiency of this type of device is still...Kesterite Cu2ZnSn(S,Se)4(CZTSSe)solar cells have drawn worldwide attention for their promising photovoltaics performance and earth-abundant element composition,yet the record efficiency of this type of device is still far lower than its theoretical conversion efficiency.Undesirable band alignment and severe non-radiative recombination at CZTSSe/CdS heterojunction interfaces are the major causes limiting the current/voltage output and overall device performance.Herein,we propose a novel two-step CdS deposition strategy to improve the quality of CZTSSe/CdS heterojunction interface and thereby improve the performance of CZTSSe solar cell.The two-step strategy includes firstly pre-deposits CdS thin layer on CZTSSe absorber layer by chemical bath deposition(CBD),followed with a mild heat treatment to facilitate element inter-diffusion,and secondly deposits an appropriate thickness of CdS layer by CBD to cover the whole surface of pre-deposited CdS and CZTSSe layers.The solar energy conversion efficiency of CZTSSe solar cells with two-step deposited CdS layer approaches to 8.76%(with an active area of about 0.19 cm2),which shows an encouraging improvement of over 87.98%or 30.16%compared to the devices with traditional CBD-deposited CdS layer without and with the mild annealing process,respectively.The performance enhancement by the two-step CdS deposition is attributed to the formation of more favorable band alignment at CZTSSe/CdS interface as well as the effective decrease in interfacial recombination paths on the basis of material and device characterizations.The two-step CdS deposition strategy is simple but effective,and should have large room to improve the quality of CZTSSe/CdS heterojunction interface and further lift up the conversion efficiency of CZTSSe solar cells.展开更多
Recently,electronic skins and fl exible wearable devices have been developed for widespread applications in medical monitoring,artifi cial intelligence,human–machine interaction,and artifi cial prosthetics.Flexible p...Recently,electronic skins and fl exible wearable devices have been developed for widespread applications in medical monitoring,artifi cial intelligence,human–machine interaction,and artifi cial prosthetics.Flexible proximity sensors can accurately perceive external objects without contact,introducing a new way to achieve an ultrasensitive perception of objects.This article reviews the progress of fl exible capacitive proximity sensors,fl exible triboelectric proximity sensors,and fl exible gate-enhanced proximity sensors,focusing on their applications in the electronic skin fi eld.Herein,their working mechanism,materials,preparation methods,and research progress are discussed in detail.Finally,we summarize the future challenges in developing fl exible proximity sensors.展开更多
Bandgap engineering by doping and co‐catalyst loading are two primary approaches to designing efficient photocatalysts by promoting visible‐light absorption and charge separation,respectively.Shifting of the TiO2con...Bandgap engineering by doping and co‐catalyst loading are two primary approaches to designing efficient photocatalysts by promoting visible‐light absorption and charge separation,respectively.Shifting of the TiO2conduction band edge is frequently applied to increase visible‐light absorption but also lowers the reductive properties of photo‐excited electrons.Herein,we report a visible‐light‐driven photocatalyst based on valance band edge control induced by oxygen excess defects and modification with a CuxO electron transfer co‐catalyst.The CuxO grafted oxygen‐rich TiO2microspheres were prepared by ultrasonic spray pyrolysis of the peroxotitanate precursor followed by a wet chemical impregnated treatment.We found that oxygen excess defects in TiO2shifted the valence band maximum upward and improved the visible‐light absorption.The CuxO grafted onto the surface acted as a co‐catalyst that efficiently reduced oxygen molecules to active intermediates(i.e.,O2??radial and H2O2),thus consuming the photo‐generated electrons.Consequently,the CuxO grafted oxygen‐rich TiO2microspheres achieved a photocatalytic activity respectively8.6,13.0and11.0as times high as those of oxygen‐rich TiO2,normal TiO2and CuxO grafted TiO2,for degradation of gaseous acetaldehyde under visible‐light irradiation.Our results suggest that high visible‐light photocatalytic efficiency can be achieved by combining oxygen excess defects to improve visible‐light absorption together with a CuxO electron transfer co‐catalyst.These findings provide a new approach to developing efficient heterojunction photocatalysts.展开更多
Noble-metal/metal-oxide-semiconductor nanostructures as an important material platform have been applied in massive data storage.ZnO exhibits excellent optical modulation ability.However,plasmon induced charge separat...Noble-metal/metal-oxide-semiconductor nanostructures as an important material platform have been applied in massive data storage.ZnO exhibits excellent optical modulation ability.However,plasmon induced charge separation effect in Ag/ZnO systems is very weak due to the low chemical activity on surface of the oxide.Herein,we prepare ZnO nanowire arrays via the hydrothermal method,and measure their absorption spectra,photoluminescence spectra and electron paramagnetic resonance,proving the existence of oxygen defects in ZnO.Accordingly,an idea of“electron reverse transfer”is proposed such that blue-ray(403.4 nm)induces reduction of Ag^(+)ions through the excitation of ZnO.Rod-like and spherical silver nanoparticles emerge on the surface and in the gap of ZnO nanowire arrays,respectively,after the visible light stimulus.It is found that nanowire density,oxygen defects and surface roughness are dependent on hydrothermal time.The optimized diffraction efficiency of 0.08%is obtained for reconstructing hologram in the nanocomposite film.This work provides a bright way for construction of ZnO-based optoelectronic integrated devices.展开更多
Self-standing carbon-based substrates with satisfied structural stability and property adjustability have promising applications in flexible lithium(Li)metal batteries(FLMBs).Current strategies for modifying carbon ma...Self-standing carbon-based substrates with satisfied structural stability and property adjustability have promising applications in flexible lithium(Li)metal batteries(FLMBs).Current strategies for modifying carbon materials are normally carried out on powder carbon,and very few of them are suitable for self-standing carbon substrates.Herein,a pore-forming strategy based on the redox chemistry of metallic oxide nanodots is developed to prepare two porous carbon substrates for anode and cathode.Starting with cotton cloth,the resulting hollow carbon fibers substrate with nanopores effectively prevents from Li dendrites formation and large volume change in lithium metal anode(LMA).Simulations indicate that the porous structure leads to homogeneous ion flux,Li-ion concentration,and electric field during Li deposition.Li symmetrical cell based on this substrate remains stable for 8300 h with an ultralow voltage hysteresis of 9 mV.Via a similar route,porous carbon cloth substrate is obtained for subsequently seeding V_(2)O_(5)nanowires to prepare the cathode.The assembled FLMBs pouch cell delivers a capacity of 8.2 mAh with a high capacity retention of~100%even under dramatic deformation.The demonstrated strategy has far-reaching potential in preparing free-standing porous carbon-based materials for flexible energy storage devices.展开更多
Photoreforming hydrogen evolution(Pr-HE)of a water-pollutant system could simultaneously achieve efficient hydrogen production and pollutant degradation.It provides a new way to solve energy and environmental issues,b...Photoreforming hydrogen evolution(Pr-HE)of a water-pollutant system could simultaneously achieve efficient hydrogen production and pollutant degradation.It provides a new way to solve energy and environmental issues,but the poor internal charge separation still limits its performance.This work designed hetero-Janus nanofibers(HJNFs)with ordered electric field distribution and separated redox surfaces to promote Pr-HE of the water-pollutant system.Taking ZnO/NiO heterojunction as an example,the hetero-Janus structures were prepared via"Dual-channel"electrospinning and further confirmed by the element morphology analysis and asymmetric distribution of the XPS spectra.The theoretical simulation showed that Janus structures could effectively inhibit the electron trap and hole trap generation,then accelerate the directional carrier migration to the surface.Experimental investigations also confirmed that Janus structures could effectively suppress internal exciton luminescence and accelerate surface charge transfer.The Pr-HE amount and the corresponding propranolol(PRO)degradation rate of HJNFs were 7.9 and 1.5 times higher than hetero-mixed nanofibers(HMNFs).The enhancement factor of Pr-HE in water-PRO to pure water was about 3.1,but nearly zero for HMNFs.This prominent synergistic effect was due to the enhancement of charge separation and the inhibition of cascade side reaction from hetero-Janus structures.Furthermore,the synchronous Pr-HE and degradation reactions were significantly promoted by selective introducing Ag nanoparticles in one side of the HJNFs for enlarging the interfacial Fermi energy level difference.The hetero-Janus strategy offers a new perspective on designing efficient photoreforming photocatalysts for energy and environment applications.展开更多
The electron transport layer （ETL） plays an important role in planar heterojunction perovskite solar cell （PSCs）, by affecting the light-harvesting, electron injection and transportation processes, and especially ...The electron transport layer （ETL） plays an important role in planar heterojunction perovskite solar cell （PSCs）, by affecting the light-harvesting, electron injection and transportation processes, and especially the crystal- lization of perovskite absorber. In this work, we utilized a commercial TKD-TiO2 nanoparticle with a small diameter of 6 nm for the first time to prepare a compact ETL by spin coating. The packing of small-size particles endowed TKD-TiO2 ETL an appropriate surface-wettability, which is beneficial to the crystallization of perovskite deposited via solution-processed method. The uniform and high-transmittance TKD-TiO2 films were successfully incorporated into PSCs as ETLs. Further careful optimization of ETL thickness gave birth to a highest power conversion efficiency of 11.0%, which was much higher than that of PSC using an ETL with the same thickness made by spray pyrolysis. This TKD-TiO2 provided a universal solar material suitable for the further large-scale production of PSCs. The excellent morphology and the convenient preparation method of TKD-TiO2 film gave it an extensive application in photovoltaic devices.展开更多
Single crystals of cobalt coordination compounds were obtained by one-pot hydrothermal reaction.Nickel ion exchange was used to produce the Ni–Co hetero-metal compound with tunable chemical composition.Using a nickel...Single crystals of cobalt coordination compounds were obtained by one-pot hydrothermal reaction.Nickel ion exchange was used to produce the Ni–Co hetero-metal compound with tunable chemical composition.Using a nickel-exchanged compound as the precursor,we developed a simple chemical reaction to synthesize large-scale 3D hierarchical Ni_(x)Co_(3−x)S_(4)(x=0.15–0.42)microflowers under ambient conditions.展开更多
Nanofibers of poly（vinyl pyrrolidone） （PVP）/Eu^3＋ with diameters of 300-900 nm were prepared by using sol-gel processing and electrospinning technique. The products were characterized by scanning electron microsc...Nanofibers of poly（vinyl pyrrolidone） （PVP）/Eu^3＋ with diameters of 300-900 nm were prepared by using sol-gel processing and electrospinning technique. The products were characterized by scanning electron microscope （SEM）, Fourier transform infrared spectroscopy （FT-IR）, and photoluminescence （PL）. The results indicated that, Eu^3＋ was successfully embedded in the onedimensional hybrid nanofibers, and the PVP/Eu^3＋ hybrid nanofibers had favorable photoluminescence properties.展开更多
A green route using a very simple and straightforward ultrasonic process under alkaline conditions, rather than a general chemical reduction process using hydrazine, was utilized to obtain the hydrophilic reduced grap...A green route using a very simple and straightforward ultrasonic process under alkaline conditions, rather than a general chemical reduction process using hydrazine, was utilized to obtain the hydrophilic reduced graphene oxide（RGO） sheets, via removing oxygen functional groups from graphene oxide（GO） and repairing the aromatic structure. It is found that the conductivity of the obtained RGO could be tuned by changing pH value in alkaline solution, and the current-voltage（I-V） curves of both GO and RGO are nonlinear and slightly asymmetric. Under the same applied voltage, the current of RGO is much larger than that of GO, indicating a pronounced increase in the electrical conductivity of RGO, compared to that of GO.展开更多
High-quality Zn-doped CdSe core-shell nanocrystals were successfully prepared by incorporating a stoichiometric amount of Zn precursor into the CdSe reaction system, in which the Se precursor was excess and an Se-rich...High-quality Zn-doped CdSe core-shell nanocrystals were successfully prepared by incorporating a stoichiometric amount of Zn precursor into the CdSe reaction system, in which the Se precursor was excess and an Se-rich surface was formed. By injecting different amounts of Zn precursor, the core-shell nanocrystals demonstrated by the emission spectra were formed. The obtained Zn-doped CdSe nanocrystals exhibit a photoluminescence efficiency from 30% to 85%, which is comparable to those for the reported CdSe/ZnS, CdSe/CdS in the literature. In particular, a shell ZnSe layer with different thicknesses of ZnSe can be formed in this experiment by only changing the amount of Zn precursor added, which is simple and effective.展开更多
In this study, the unipolar resistive switching （URS） and bipolar resistive switching （BRS） are demonstrated to be coexistent in the Ag/ZnO/Pt memory device, and both modes are observed to strongly depend on the p...In this study, the unipolar resistive switching （URS） and bipolar resistive switching （BRS） are demonstrated to be coexistent in the Ag/ZnO/Pt memory device, and both modes are observed to strongly depend on the polarity of forming voltage. The mechanisms of the URS and BRS behaviors could be attributed to the electric-field-induced migration of oxygen vacancies （Vo） and metal-Ag conducting filaments （CFs） respectively, which are confirmed by investigating the temperature dependences of low resistance states in both modes. Furthermore, we compare the resistive switching （RS） characteristics （e.g., forming and switching voltages, reset current and resistance states） between these two modes based on Vo- and Ag-CFs. The BRS mode shows better switching uniformity and lower power than the URS mode. Both of these modes exhibit good RS performances, including good retention, reliable cycling and high-speed switching. The result indicates that the coexistence of URS and BRS behaviors in a single device has great potential applications in future nonvolatile multi-level memory.展开更多
Mesoporous TiO2 nanofibers have been synthesized by a new method that combines sol-gel chemistry and electrospinning technique.The obtained mesoporous TiO2 nanofibers were characterized with scanning electron microsc...Mesoporous TiO2 nanofibers have been synthesized by a new method that combines sol-gel chemistry and electrospinning technique.The obtained mesoporous TiO2 nanofibers were characterized with scanning electron microscopy（SEM）,X-ray diffraction（XRD）,transmission electron microscopy（TEM） and nitrogen adsorptiondesorption isotherms.The photocatalytic performance was evaluated by the photocatalytic degradation of Rhodamine B under UV light irradiation.The results show that mesoporous TiO2 nanofibers exhibit higher photocatalytic activity compared with nonporous TiO2 nanofibers.展开更多
The development of electronic devices that possess the functionality of biological synapses is a crucial step towards neuromorphic computing.In this work,we present a WOx-based memristive device that can emulate volta...The development of electronic devices that possess the functionality of biological synapses is a crucial step towards neuromorphic computing.In this work,we present a WOx-based memristive device that can emulate voltage-dependent synaptic plasticity.By adjusting the amplitude of the applied voltage,we were able to reproduce short-term plasticity(STP)and the transition from STP to long-term potentiation.The stimulation with high intensity induced long-term enhancement of conductance without any decay process,thus representing a permanent memory behavior.Moreover,the image Boolean operations(including intersection,subtraction,and union)were also demonstrated in the memristive synapse array based on the above voltage-dependent plasticity.The experimental achievements of this study provide a new insight into the successful mimicry of essential characteristics of synaptic behaviors.展开更多
As our modern society continuously embraces the captivating concepts of automation,artificial intelligence,virtual/augmented reality,and machine learning,information technology has extensively influenced all aspects o...As our modern society continuously embraces the captivating concepts of automation,artificial intelligence,virtual/augmented reality,and machine learning,information technology has extensively influenced all aspects of our personal,professional,and social lives.Information technology will continue to transform the world for decades to come.However,the innovation of information technology not only relies on the development of sophisticated algorithms and programming but also requires novel materials and high-performance devices to achieve interactions between humans and machines.With microprocessors and other key components shrinking down to nanoscale,electronic devices have fundamentally altered our communication and working patterns,ushering in a new era of the“Internet of Things.”However,current microelectronic technologies still need to overcome the physical limitations of traditional semiconductor materials to keep“Moore's law”alive.Researchers from different fields have realized that developing novel and reliable materials is essential to improving computing capability and device portability and functionality while reducing energy consumption.The unremitting efforts of cross-field research works have broadened the academic horizon and brought together materials scientists,chemists,applied and theoretical physicists,and electrical engineers,designing new material paradigms and state-of-the-art manufacturing methods or reviving present materials for brand-new applications for next-generation information technology.展开更多
TiO2-xNx thin films are deposited onto Si（100） and quartz substrates by arf magnetron sputtering method using a titanium metal disc as a target in Ar, N2, and 02 atmospheres. The substrate temperature is kept at 300...TiO2-xNx thin films are deposited onto Si（100） and quartz substrates by arf magnetron sputtering method using a titanium metal disc as a target in Ar, N2, and 02 atmospheres. The substrate temperature is kept at 300℃. The O2 and Ar gas flow rates are kept to be constants and the N gas flow rate is varied. TiO2-xNx films with different N contents are characterized by x-ray diffraction and x-ray photoelectron spectroscopy. The results indicate that the TiO2-xNx thin films can be obtained at 13% N and 15% N contents in the film, and the films with mixed TiO2 and TiN crystal can be obtained at 13% N and 15% N contents in the film. In terms of the results of x-ray photoelectron spectroscopy, N ls of β-N （396 eV） is the main component in the TiO2-xNx thin films. Because the energy level of β-N is positioned above the valence-band maximum of TiO2, an effective optical-energy gap decreases from 2.8 eV （for pure TiO2 film deposited by the same rf sputtering system） to 2.3 eV, which is verified by the optical-absorption spectra.展开更多
Er-doped 12Ca0.7Al2O3 （C12A7：Er） powders were prepared using the sol-gel method followed by annealing inorganic precursors. X-ray diffraction （XRD）, Raman and absorption spectra revealed that Er ions existed and ...Er-doped 12Ca0.7Al2O3 （C12A7：Er） powders were prepared using the sol-gel method followed by annealing inorganic precursors. X-ray diffraction （XRD）, Raman and absorption spectra revealed that Er ions existed and substituted Ca^2＋ lattice site in C12A7. The photoluminescence of C12A7：Er at room temperature was observed in the visible and infrared region using 488 nm （2.54 eV） Ar^＋ line as excitation source, respectively. The sharp and intense green emission bands with multi-peaks around 520 nm and 550 nm correspond to the transitions from the excited states ^2H11/2 and ^4S3/2 tO the ground state ^4I15/2, respectively. Furthermore, red emission band around 650 nm was also observed. It was attributed to the electronic transition from excited states ^4F9/2 to the ground state ^4I15/2 inside 4f-shell of Er^3＋ ions. The intensive infrared emission at 1.54 μm was attributed to the transition from the fast excited states of ^4I13/2 to the ground state （^4I15/2）. The temperature dependent photoluminescence of infrared emission showed that the integrated intensity reached a maximum value at near room temperature. The forbidden transitions of intra-4f shell electrons in free Er^3＋ ions were allowed in C12A7 owing to lack of the inversion symmetry in the Er^3＋ position in C12A7 crystal field. Our results suggested that C12A7：Er was a candidate for applications in Er-doped laser materials, and full color display.展开更多
We fabricated an inorganic-polymeric photoluminescent thin film based on ZnO nanoparticles, which were grown directly in the poly（vinylpyrrolidone） （PVP） matrix. The microstructure, composition, thermal stability,...We fabricated an inorganic-polymeric photoluminescent thin film based on ZnO nanoparticles, which were grown directly in the poly（vinylpyrrolidone） （PVP） matrix. The microstructure, composition, thermal stability, and the temperature-dependent photoluminescence of the thin film were investigated. X-ray diffraction （XRD） and transmission electron microscopy （TEM） results indicated that all the ZnO nanoparticles with a polycrys talline hexagonal wurzite structure were well separated from each other and were dispersed in the polymeric matrix homogeneously and randomly. Raman spectrum （Raman） showed a typical resonant multi-phonon process within the hybrid thin film. The shifts of infrared bands for PVP in the hybrid film should be attributed to strong coulombic interaction between ZnO and polymeric matrix. The stability of the hybrid film and the effect of the perturbation of ZnO on the stability were determined by means of the thermogravimetric analysis （TG） and differential thermal analysis （DTA）. The ultraviolet-visible adsorption （UV-vis） showed distinct excitonic features. The photoluminescent spectrum （PL） of the ZnO nanoparticles modified by PVP molecules showed markedly enhanced ultraviolet emission and significantly reduced green emission, which was due to the Perfect surface passivation of ZnO nanoparticles. Temperature dependent photoluminescent spectrum studies suggested that the ultraviolet emission was associated with bound exciton recombination.展开更多
基金supported by the"Science and Technology Development Plan Project of Jilin Province,China"(Grant No.20240101018JJ)the Fundamental Research Funds for the Central Universities(Grant No.2412023YQ004)the National Natural Science Foundation of China(Grant Nos.52072065,52272140,52372137,and U23A20568).
文摘Optoelectronic memristor is generating growing research interest for high efficient computing and sensing-memory applications.In this work,an optoelectronic memristor with Au/a-C:Te/Pt structure is developed.Synaptic functions,i.e.,excita-tory post-synaptic current and pair-pulse facilitation are successfully mimicked with the memristor under electrical and optical stimulations.More importantly,the device exhibited distinguishable response currents by adjusting 4-bit input electrical/opti-cal signals.A multi-mode reservoir computing(RC)system is constructed with the optoelectronic memristors to emulate human tactile-visual fusion recognition and an accuracy of 98.7%is achieved.The optoelectronic memristor provides potential for developing multi-mode RC system.
基金financial supports from Natural Science Foundation of China(Grant No.61935008,T2325014,62205174 and 62275100)。
文摘Compound eyes(CEs)that feature ultra-compact structures and extraordinary versatility have revealed great potential for cutting-edge applications.However,the optoelectronic integration of CEs with available photodetectors is still challenging because the planar charge-coupled device(CCD)/complementary metal oxide semiconductor(CMOS)detector cannot match the spatially distributed images formed by CE ommatidia.To reach this end,we report here the optoelectronic integration of CEs by manufacturing 3D nonuniform ommatidia for developing an ultra-compact on-chip camera.As a proof-of-concept,we fabricated microscale CEs with uniform and nonuniform ommatidia through femtosecond laser two-photon photopolymerization,and compared their focusing/imaging performance both theoretically and experimentally.By engineering the surface profiles of the ommatidia at different positions of the CE,the images formed by all the ommatidia can be tuned on a plane.In this way,the nonuniform CE can be directly integrated with a commercial CMOS photodetector,forming an ultra-compact CE camera.Additionally,we further combine the CE camera with a microfluidic chip,which can further serve as an on-chip microscopic monitoring system.We anticipate that such an ultra-compact CE camera may find broad applications in microfluidics,robotics,and micro-optics.
基金supported by the National Natural Science Foundation of China(91833303,51872044,51372036,51202025 and 51602047)the Key Project of Chinese Ministry of Education(113020A)+3 种基金the 111 project(B13013)the Jilin Province Science and Technology Development Project(20180101175JC and 20140520096JH)the Fundamental Research Funds for the Central Universities(2412019FZ043)the Open Project of Key Laboratory for UV Emitting Materials and Technology of Ministry of Education(130028857).
文摘Kesterite Cu2ZnSn(S,Se)4(CZTSSe)solar cells have drawn worldwide attention for their promising photovoltaics performance and earth-abundant element composition,yet the record efficiency of this type of device is still far lower than its theoretical conversion efficiency.Undesirable band alignment and severe non-radiative recombination at CZTSSe/CdS heterojunction interfaces are the major causes limiting the current/voltage output and overall device performance.Herein,we propose a novel two-step CdS deposition strategy to improve the quality of CZTSSe/CdS heterojunction interface and thereby improve the performance of CZTSSe solar cell.The two-step strategy includes firstly pre-deposits CdS thin layer on CZTSSe absorber layer by chemical bath deposition(CBD),followed with a mild heat treatment to facilitate element inter-diffusion,and secondly deposits an appropriate thickness of CdS layer by CBD to cover the whole surface of pre-deposited CdS and CZTSSe layers.The solar energy conversion efficiency of CZTSSe solar cells with two-step deposited CdS layer approaches to 8.76%(with an active area of about 0.19 cm2),which shows an encouraging improvement of over 87.98%or 30.16%compared to the devices with traditional CBD-deposited CdS layer without and with the mild annealing process,respectively.The performance enhancement by the two-step CdS deposition is attributed to the formation of more favorable band alignment at CZTSSe/CdS interface as well as the effective decrease in interfacial recombination paths on the basis of material and device characterizations.The two-step CdS deposition strategy is simple but effective,and should have large room to improve the quality of CZTSSe/CdS heterojunction interface and further lift up the conversion efficiency of CZTSSe solar cells.
基金supported by the National Key R&D Program of China(Nos.2022 YFF 1202700 and 2022YFB3203500)National Natural Science Foundation of China(Nos.62225403,62375046,51973024,an d U19A2091)+2 种基金“111”Project(No.B13013)Natur al Sci ence Foundation of Jilin Pro vin ce(No.20230101113JC)the Funding from Jilin Pr ovince(No.20220502002GH).
文摘Recently,electronic skins and fl exible wearable devices have been developed for widespread applications in medical monitoring,artifi cial intelligence,human–machine interaction,and artifi cial prosthetics.Flexible proximity sensors can accurately perceive external objects without contact,introducing a new way to achieve an ultrasensitive perception of objects.This article reviews the progress of fl exible capacitive proximity sensors,fl exible triboelectric proximity sensors,and fl exible gate-enhanced proximity sensors,focusing on their applications in the electronic skin fi eld.Herein,their working mechanism,materials,preparation methods,and research progress are discussed in detail.Finally,we summarize the future challenges in developing fl exible proximity sensors.
基金supported by the National Natural Science Foundation of China(51072032,51372036,51702235)~~
文摘Bandgap engineering by doping and co‐catalyst loading are two primary approaches to designing efficient photocatalysts by promoting visible‐light absorption and charge separation,respectively.Shifting of the TiO2conduction band edge is frequently applied to increase visible‐light absorption but also lowers the reductive properties of photo‐excited electrons.Herein,we report a visible‐light‐driven photocatalyst based on valance band edge control induced by oxygen excess defects and modification with a CuxO electron transfer co‐catalyst.The CuxO grafted oxygen‐rich TiO2microspheres were prepared by ultrasonic spray pyrolysis of the peroxotitanate precursor followed by a wet chemical impregnated treatment.We found that oxygen excess defects in TiO2shifted the valence band maximum upward and improved the visible‐light absorption.The CuxO grafted onto the surface acted as a co‐catalyst that efficiently reduced oxygen molecules to active intermediates(i.e.,O2??radial and H2O2),thus consuming the photo‐generated electrons.Consequently,the CuxO grafted oxygen‐rich TiO2microspheres achieved a photocatalytic activity respectively8.6,13.0and11.0as times high as those of oxygen‐rich TiO2,normal TiO2and CuxO grafted TiO2,for degradation of gaseous acetaldehyde under visible‐light irradiation.Our results suggest that high visible‐light photocatalytic efficiency can be achieved by combining oxygen excess defects to improve visible‐light absorption together with a CuxO electron transfer co‐catalyst.These findings provide a new approach to developing efficient heterojunction photocatalysts.
基金supported by the National Natural Science Foundation of China(Grant Nos.11974073,U19A2091,and 51732003)the Overseas Expertise Introduction Project for Discipline Innovation(Grant No.B13013)+1 种基金the Natural Science Foundation of Jilin Province of China(Grant No.20180101218JC)The 13th Five-Year Scientific Research Planning Project of the Education Department of Jilin Province,China(Grant No.JJKH20201161KJ)。
文摘Noble-metal/metal-oxide-semiconductor nanostructures as an important material platform have been applied in massive data storage.ZnO exhibits excellent optical modulation ability.However,plasmon induced charge separation effect in Ag/ZnO systems is very weak due to the low chemical activity on surface of the oxide.Herein,we prepare ZnO nanowire arrays via the hydrothermal method,and measure their absorption spectra,photoluminescence spectra and electron paramagnetic resonance,proving the existence of oxygen defects in ZnO.Accordingly,an idea of“electron reverse transfer”is proposed such that blue-ray(403.4 nm)induces reduction of Ag^(+)ions through the excitation of ZnO.Rod-like and spherical silver nanoparticles emerge on the surface and in the gap of ZnO nanowire arrays,respectively,after the visible light stimulus.It is found that nanowire density,oxygen defects and surface roughness are dependent on hydrothermal time.The optimized diffraction efficiency of 0.08%is obtained for reconstructing hologram in the nanocomposite film.This work provides a bright way for construction of ZnO-based optoelectronic integrated devices.
基金supported by NSFC(22035001,21574018,51433003)the National Science and Engineering Council of Canada,and the Fundamental Research Funds for the Central Universities(2412019ZD002)。
文摘Self-standing carbon-based substrates with satisfied structural stability and property adjustability have promising applications in flexible lithium(Li)metal batteries(FLMBs).Current strategies for modifying carbon materials are normally carried out on powder carbon,and very few of them are suitable for self-standing carbon substrates.Herein,a pore-forming strategy based on the redox chemistry of metallic oxide nanodots is developed to prepare two porous carbon substrates for anode and cathode.Starting with cotton cloth,the resulting hollow carbon fibers substrate with nanopores effectively prevents from Li dendrites formation and large volume change in lithium metal anode(LMA).Simulations indicate that the porous structure leads to homogeneous ion flux,Li-ion concentration,and electric field during Li deposition.Li symmetrical cell based on this substrate remains stable for 8300 h with an ultralow voltage hysteresis of 9 mV.Via a similar route,porous carbon cloth substrate is obtained for subsequently seeding V_(2)O_(5)nanowires to prepare the cathode.The assembled FLMBs pouch cell delivers a capacity of 8.2 mAh with a high capacity retention of~100%even under dramatic deformation.The demonstrated strategy has far-reaching potential in preparing free-standing porous carbon-based materials for flexible energy storage devices.
基金supported by the National Natural Science Foundation of China(Nos.52072064,51972051,62171115,and 51732003)the 111 Project(No.B13013).
文摘Photoreforming hydrogen evolution(Pr-HE)of a water-pollutant system could simultaneously achieve efficient hydrogen production and pollutant degradation.It provides a new way to solve energy and environmental issues,but the poor internal charge separation still limits its performance.This work designed hetero-Janus nanofibers(HJNFs)with ordered electric field distribution and separated redox surfaces to promote Pr-HE of the water-pollutant system.Taking ZnO/NiO heterojunction as an example,the hetero-Janus structures were prepared via"Dual-channel"electrospinning and further confirmed by the element morphology analysis and asymmetric distribution of the XPS spectra.The theoretical simulation showed that Janus structures could effectively inhibit the electron trap and hole trap generation,then accelerate the directional carrier migration to the surface.Experimental investigations also confirmed that Janus structures could effectively suppress internal exciton luminescence and accelerate surface charge transfer.The Pr-HE amount and the corresponding propranolol(PRO)degradation rate of HJNFs were 7.9 and 1.5 times higher than hetero-mixed nanofibers(HMNFs).The enhancement factor of Pr-HE in water-PRO to pure water was about 3.1,but nearly zero for HMNFs.This prominent synergistic effect was due to the enhancement of charge separation and the inhibition of cascade side reaction from hetero-Janus structures.Furthermore,the synchronous Pr-HE and degradation reactions were significantly promoted by selective introducing Ag nanoparticles in one side of the HJNFs for enlarging the interfacial Fermi energy level difference.The hetero-Janus strategy offers a new perspective on designing efficient photoreforming photocatalysts for energy and environment applications.
基金supported by the Natural Science Foundation of China(grant no.91233204,51372036 and 51102001)the Key Project of Chinese Ministry of Education(no.113020A)+4 种基金the Specialized Research Fund for the Doctoral Program of Higher Education(20120043110002)the National Basic Research Program(2012CB933703)the 111 project(no.B13013)the International Science & Technology Cooperation Program of China(2013DFG50150)the Fundamental Research Funds for the Central Universities(2412015KJ010 and 14ZZ1510)
文摘The electron transport layer （ETL） plays an important role in planar heterojunction perovskite solar cell （PSCs）, by affecting the light-harvesting, electron injection and transportation processes, and especially the crystal- lization of perovskite absorber. In this work, we utilized a commercial TKD-TiO2 nanoparticle with a small diameter of 6 nm for the first time to prepare a compact ETL by spin coating. The packing of small-size particles endowed TKD-TiO2 ETL an appropriate surface-wettability, which is beneficial to the crystallization of perovskite deposited via solution-processed method. The uniform and high-transmittance TKD-TiO2 films were successfully incorporated into PSCs as ETLs. Further careful optimization of ETL thickness gave birth to a highest power conversion efficiency of 11.0%, which was much higher than that of PSC using an ETL with the same thickness made by spray pyrolysis. This TKD-TiO2 provided a universal solar material suitable for the further large-scale production of PSCs. The excellent morphology and the convenient preparation method of TKD-TiO2 film gave it an extensive application in photovoltaic devices.
基金supported by the National Science Foundation of China(grant no.21001090,21443003 and 21103153)Program for Innovative Research Team(in Science and Technology)in University of Henan Province(grant no.2012IRTSTHN021)Education Department of Henan Province(grant no.13A150648).
文摘Single crystals of cobalt coordination compounds were obtained by one-pot hydrothermal reaction.Nickel ion exchange was used to produce the Ni–Co hetero-metal compound with tunable chemical composition.Using a nickel-exchanged compound as the precursor,we developed a simple chemical reaction to synthesize large-scale 3D hierarchical Ni_(x)Co_(3−x)S_(4)(x=0.15–0.42)microflowers under ambient conditions.
基金the National Natural Science Foundation of China （No. 50572014） the Program for New Century Excellent Talents in University （NCET-05-0322）.
文摘Nanofibers of poly（vinyl pyrrolidone） （PVP）/Eu^3＋ with diameters of 300-900 nm were prepared by using sol-gel processing and electrospinning technique. The products were characterized by scanning electron microscope （SEM）, Fourier transform infrared spectroscopy （FT-IR）, and photoluminescence （PL）. The results indicated that, Eu^3＋ was successfully embedded in the onedimensional hybrid nanofibers, and the PVP/Eu^3＋ hybrid nanofibers had favorable photoluminescence properties.
基金Supported by the National Natural Science Foundation of China(Nos.50525204, 50832001)the Special PhD Program of Ministry of Education, China(No.200801830025)+1 种基金the Program for Changjiang Scholars and Innovative Research Team in University of Chinathe "211" and "985" Project of Jilin University, China
文摘A green route using a very simple and straightforward ultrasonic process under alkaline conditions, rather than a general chemical reduction process using hydrazine, was utilized to obtain the hydrophilic reduced graphene oxide（RGO） sheets, via removing oxygen functional groups from graphene oxide（GO） and repairing the aromatic structure. It is found that the conductivity of the obtained RGO could be tuned by changing pH value in alkaline solution, and the current-voltage（I-V） curves of both GO and RGO are nonlinear and slightly asymmetric. Under the same applied voltage, the current of RGO is much larger than that of GO, indicating a pronounced increase in the electrical conductivity of RGO, compared to that of GO.
文摘High-quality Zn-doped CdSe core-shell nanocrystals were successfully prepared by incorporating a stoichiometric amount of Zn precursor into the CdSe reaction system, in which the Se precursor was excess and an Se-rich surface was formed. By injecting different amounts of Zn precursor, the core-shell nanocrystals demonstrated by the emission spectra were formed. The obtained Zn-doped CdSe nanocrystals exhibit a photoluminescence efficiency from 30% to 85%, which is comparable to those for the reported CdSe/ZnS, CdSe/CdS in the literature. In particular, a shell ZnSe layer with different thicknesses of ZnSe can be formed in this experiment by only changing the amount of Zn precursor added, which is simple and effective.
基金Project supported by the National Natural Science Foundation of China for Excellent Young Scholars(Grant No.51422201)the National Natural Science Foundation of China(Grant Nos.51172041,51372035,11304035,61574031,and 61404026)+4 种基金the National Basic Research Program of China(Grant No.2012CB933703)the"111"Project,China(Grant No.B13013)the Fund from Jilin Province,China(Grant Nos.20140520106JH and 20140201008GX)the Research Fund for the Doctoral Program of Higher Education,China(Grant No.20130043110004)the Fundamental Research Funds for the Central Universities,China(Grant Nos.2412015KJ008 and 2412016KJ003)
文摘In this study, the unipolar resistive switching （URS） and bipolar resistive switching （BRS） are demonstrated to be coexistent in the Ag/ZnO/Pt memory device, and both modes are observed to strongly depend on the polarity of forming voltage. The mechanisms of the URS and BRS behaviors could be attributed to the electric-field-induced migration of oxygen vacancies （Vo） and metal-Ag conducting filaments （CFs） respectively, which are confirmed by investigating the temperature dependences of low resistance states in both modes. Furthermore, we compare the resistive switching （RS） characteristics （e.g., forming and switching voltages, reset current and resistance states） between these two modes based on Vo- and Ag-CFs. The BRS mode shows better switching uniformity and lower power than the URS mode. Both of these modes exhibit good RS performances, including good retention, reliable cycling and high-speed switching. The result indicates that the coexistence of URS and BRS behaviors in a single device has great potential applications in future nonvolatile multi-level memory.
基金Supported by the National Natural Science Foundation of China(Nos.21076094,20743005)
文摘Mesoporous TiO2 nanofibers have been synthesized by a new method that combines sol-gel chemistry and electrospinning technique.The obtained mesoporous TiO2 nanofibers were characterized with scanning electron microscopy（SEM）,X-ray diffraction（XRD）,transmission electron microscopy（TEM） and nitrogen adsorptiondesorption isotherms.The photocatalytic performance was evaluated by the photocatalytic degradation of Rhodamine B under UV light irradiation.The results show that mesoporous TiO2 nanofibers exhibit higher photocatalytic activity compared with nonporous TiO2 nanofibers.
基金the fund from Ministry of Science and Technology of China(Nos.2018YFE0118300 and 2019YFB2205100)the NSFC Program(Nos.11974072,51701037,51732003,51872043,51902048,61774031,61574031 and U19A2091)+4 种基金the“111”Project(No.B13013)the fund from Ministry of Education of China(No.6141A02033414)The fund from China Postdoctoral Science Foundation(No.2019M661185)The Fundamental Research Funds for the Central Universities(No.2412019QD015)the Fund from Jilin Province(JJKH20201163KJ).
文摘The development of electronic devices that possess the functionality of biological synapses is a crucial step towards neuromorphic computing.In this work,we present a WOx-based memristive device that can emulate voltage-dependent synaptic plasticity.By adjusting the amplitude of the applied voltage,we were able to reproduce short-term plasticity(STP)and the transition from STP to long-term potentiation.The stimulation with high intensity induced long-term enhancement of conductance without any decay process,thus representing a permanent memory behavior.Moreover,the image Boolean operations(including intersection,subtraction,and union)were also demonstrated in the memristive synapse array based on the above voltage-dependent plasticity.The experimental achievements of this study provide a new insight into the successful mimicry of essential characteristics of synaptic behaviors.
文摘As our modern society continuously embraces the captivating concepts of automation,artificial intelligence,virtual/augmented reality,and machine learning,information technology has extensively influenced all aspects of our personal,professional,and social lives.Information technology will continue to transform the world for decades to come.However,the innovation of information technology not only relies on the development of sophisticated algorithms and programming but also requires novel materials and high-performance devices to achieve interactions between humans and machines.With microprocessors and other key components shrinking down to nanoscale,electronic devices have fundamentally altered our communication and working patterns,ushering in a new era of the“Internet of Things.”However,current microelectronic technologies still need to overcome the physical limitations of traditional semiconductor materials to keep“Moore's law”alive.Researchers from different fields have realized that developing novel and reliable materials is essential to improving computing capability and device portability and functionality while reducing energy consumption.The unremitting efforts of cross-field research works have broadened the academic horizon and brought together materials scientists,chemists,applied and theoretical physicists,and electrical engineers,designing new material paradigms and state-of-the-art manufacturing methods or reviving present materials for brand-new applications for next-generation information technology.
基金Supported by the National Natural Science Foundation of China uuder Grant No 60176003.
文摘TiO2-xNx thin films are deposited onto Si（100） and quartz substrates by arf magnetron sputtering method using a titanium metal disc as a target in Ar, N2, and 02 atmospheres. The substrate temperature is kept at 300℃. The O2 and Ar gas flow rates are kept to be constants and the N gas flow rate is varied. TiO2-xNx films with different N contents are characterized by x-ray diffraction and x-ray photoelectron spectroscopy. The results indicate that the TiO2-xNx thin films can be obtained at 13% N and 15% N contents in the film, and the films with mixed TiO2 and TiN crystal can be obtained at 13% N and 15% N contents in the film. In terms of the results of x-ray photoelectron spectroscopy, N ls of β-N （396 eV） is the main component in the TiO2-xNx thin films. Because the energy level of β-N is positioned above the valence-band maximum of TiO2, an effective optical-energy gap decreases from 2.8 eV （for pure TiO2 film deposited by the same rf sputtering system） to 2.3 eV, which is verified by the optical-absorption spectra.
基金the Project of Chinese Ministry of Education (108045)Jilin Science and Technology Development Project (20060507)+1 种基金the National Natural Science Foundation of China (60576040)the Scientific Research Foundation for the Returned Over-seas Chinese Scholars, State Education Ministry and Science Foundation for Young Teachers of Northeast Normal University (2005025)
文摘Er-doped 12Ca0.7Al2O3 （C12A7：Er） powders were prepared using the sol-gel method followed by annealing inorganic precursors. X-ray diffraction （XRD）, Raman and absorption spectra revealed that Er ions existed and substituted Ca^2＋ lattice site in C12A7. The photoluminescence of C12A7：Er at room temperature was observed in the visible and infrared region using 488 nm （2.54 eV） Ar^＋ line as excitation source, respectively. The sharp and intense green emission bands with multi-peaks around 520 nm and 550 nm correspond to the transitions from the excited states ^2H11/2 and ^4S3/2 tO the ground state ^4I15/2, respectively. Furthermore, red emission band around 650 nm was also observed. It was attributed to the electronic transition from excited states ^4F9/2 to the ground state ^4I15/2 inside 4f-shell of Er^3＋ ions. The intensive infrared emission at 1.54 μm was attributed to the transition from the fast excited states of ^4I13/2 to the ground state （^4I15/2）. The temperature dependent photoluminescence of infrared emission showed that the integrated intensity reached a maximum value at near room temperature. The forbidden transitions of intra-4f shell electrons in free Er^3＋ ions were allowed in C12A7 owing to lack of the inversion symmetry in the Er^3＋ position in C12A7 crystal field. Our results suggested that C12A7：Er was a candidate for applications in Er-doped laser materials, and full color display.
基金This work was supported by the National Natural Science Foundation of China （No. 60376009） for the financial support.
文摘We fabricated an inorganic-polymeric photoluminescent thin film based on ZnO nanoparticles, which were grown directly in the poly（vinylpyrrolidone） （PVP） matrix. The microstructure, composition, thermal stability, and the temperature-dependent photoluminescence of the thin film were investigated. X-ray diffraction （XRD） and transmission electron microscopy （TEM） results indicated that all the ZnO nanoparticles with a polycrys talline hexagonal wurzite structure were well separated from each other and were dispersed in the polymeric matrix homogeneously and randomly. Raman spectrum （Raman） showed a typical resonant multi-phonon process within the hybrid thin film. The shifts of infrared bands for PVP in the hybrid film should be attributed to strong coulombic interaction between ZnO and polymeric matrix. The stability of the hybrid film and the effect of the perturbation of ZnO on the stability were determined by means of the thermogravimetric analysis （TG） and differential thermal analysis （DTA）. The ultraviolet-visible adsorption （UV-vis） showed distinct excitonic features. The photoluminescent spectrum （PL） of the ZnO nanoparticles modified by PVP molecules showed markedly enhanced ultraviolet emission and significantly reduced green emission, which was due to the Perfect surface passivation of ZnO nanoparticles. Temperature dependent photoluminescent spectrum studies suggested that the ultraviolet emission was associated with bound exciton recombination.
