Effect of mechanical stress on magnetic properties of an exchange-biased ferromagnetic/antiferromagnetic bilayer deposited on a flexible substrate is investigated. The hysteresis loops with different magnitudes and or...Effect of mechanical stress on magnetic properties of an exchange-biased ferromagnetic/antiferromagnetic bilayer deposited on a flexible substrate is investigated. The hysteresis loops with different magnitudes and orientations of the stress can be classified into three types. The corresponding physical conditions for each type of the loop are deduced based on the principle of minimal energy. The equation of the critical stress is derived, which can judge whether the loops show hysteresis or not. Numerical calculations suggest that except for the magnitude of the mechanical stress, the relative orientation of the stress is also an important factor to tune the exchange bias effect.展开更多
Recently, great efforts have been made in the fabrication of arbitrary warped devices to satisfy the requirement of wearable and lightweight electronic products. Direct growth of high crystalline quality films on flex...Recently, great efforts have been made in the fabrication of arbitrary warped devices to satisfy the requirement of wearable and lightweight electronic products. Direct growth of high crystalline quality films on flexible substrates is the most desirable method to fabricate flexible devices owing to the advantage of simple and compatible preparation technology with current semiconductor devices, while it is a very challenging work, and usually amorphous, polycrystalline or discontinuous single crystalline films are achieved. Here we demonstrate the direct growth of high-quality Bi2 Te3 single crystalline films on flexible polyimide substrates by the modified hot wall epitaxy technique. Experimental results reveal that adjacent crystallites are coherently coalesced to form a continuous film, although amounts of disoriented crystallites are generated due to fast growth rate. By inserting a quartz filter into the growth tube, the number density of disoriented crystallites is effectively reduced owing to the improved spiral interaction. Furthermore, flexible Bi2 Te3 photoconductors are fabricated and exhibit strong near-infrared photoconductive response under different degrees of bending, which also confirms the obtained fexible films suitable for electronic applications.展开更多
Failure strain determination of polymer-supported thin films is a key for the design of the flexible devices.A theoretical model R/R0=(L/L0)2(R,L are the electrical resistance and the length of the stretched film,resp...Failure strain determination of polymer-supported thin films is a key for the design of the flexible devices.A theoretical model R/R0=(L/L0)2(R,L are the electrical resistance and the length of the stretched film,respectively.R0,L0 are the corresponding initial values.)has been widely used to determine the fracture strain of thin films on flexible substrates.However,this equation loses its function in some special cases.Here,a simple and universal theoretical model was proposed to determine the fracture strain of metal thin films on flexible substrates in more generally situations.With this model,we investigated the thicknessdependent failure strains of Cu-5 at.%Al films with thickness of 10 nm,200 nm,1000 nm,and Ti films with thickness of 50 nm,100 nm,300 nm.This model was also employed to study the published data available.The results showed that the new model provided a fairly good prediction of the failure strains of different films.展开更多
Melamine is one of the most frequently detected adulterants in dairy products.The current study proposes a surface-enhanced Raman spectroscopy(SERS)-based analytical tool for fast and reliable screening of melamine in...Melamine is one of the most frequently detected adulterants in dairy products.The current study proposes a surface-enhanced Raman spectroscopy(SERS)-based analytical tool for fast and reliable screening of melamine in bovine milk.A hand-held Raman spectrometer was used in conjunction with a substrate composed of silver nanoparticles(AgNPs)that was 2D printed onto glass fiber(GF)filter paper.Under optimized conditions,a sensitive and fingerprint-like signal at 674 cm^(-1) was obtained.The AgNPs/GF substrate exhibited high sensitivity to melamine in milk down to 1.9498×10^(-5)mg/mL,which is well below the USA and EU safety limits(2.5×10^(-3)mg/mL).Remarkably,the proposed technology was also highly reproducible,showing spot-to-spot and block-to-block variations below 3.3%and 4.9%at 674 cm^(-1) in Raman intensity,respectively.The characteristic peak intensity and concentration of melamine showed an acceptable linear relationship(R^(2)=0.9909)within the range of 0.0001-1 mg/mL.Overall,the method established in this study can provide an efficient and effective method for the quantitative target screening and detection of melamine in dairy products.展开更多
The magneto-mechanical coupling effect and magnetic anisotropy of Fe10Co90(FeCo)films deposited on silicon wafer(Si),flexible polyethylene terephthalate(PET),freestanding polydimethylsiloxane(PDMS),and pre-stretched 2...The magneto-mechanical coupling effect and magnetic anisotropy of Fe10Co90(FeCo)films deposited on silicon wafer(Si),flexible polyethylene terephthalate(PET),freestanding polydimethylsiloxane(PDMS),and pre-stretched 20%PDMS substrates were studied in detail.The loop squareness ratio Mr/Ms and the coercive Hc of the FeCo film grown on a PET substrate can be obviously tuned by applying a small tensile-bending strain,and those of the FeCo film grown on a freestanding PDMS substrate can only be slightly changed when applying a relatively large tensile bending strain.For the FeCo film prepared on a 20%pre-stretched PDMS,a wrinkled morphology is obtained after removing the pre-strain.The wrinkled FeCo film can keep the magnetic properties unchanged when applying a relatively large tensile bending strain perpendicular to the wrinkles.This reveals that PDMS is an ideal substrate for magnetic films to realize flexible immutability.Our results may help for developing flexible magnetic devices.展开更多
Ultrasound(US)imaging is a fundamental tool in healthcare for the diagnosis of diverse conditions.Wearable,flexible ultrasound patches could expand the scope of US imaging to continuous,at-home monitoring without prof...Ultrasound(US)imaging is a fundamental tool in healthcare for the diagnosis of diverse conditions.Wearable,flexible ultrasound patches could expand the scope of US imaging to continuous,at-home monitoring without professional intervention,but require scaling to large numbers of transducer elements.This poses challenges in interconnect density,power consumption,and data bandwidth.To improve interconnect density,we present the first integration of flexible ultrasound transducers with flexible a-IGZO thin-film transistor(TFT)multiplexing electronics.In the Si CMOS readout chip,a new circuit technique cuts front-end power,while a log-delta ADC compresses data efficiently.Our system achieves an 8×reduction in required front-end circuitry and a 42%decrease in front-end power.The data needed to describe the ultrasound image are reduced five-fold,decreasing data transmission power by the same factor.These advances bring the vision of wearable high-density,large-area ultrasound imaging patches for monitoring one step closer.展开更多
Electronics over flexible substrates offer advantages of flexibility, portability and low cost, and promising applications in the areas of energy, information, defense science and medical service. In recent years, tre...Electronics over flexible substrates offer advantages of flexibility, portability and low cost, and promising applications in the areas of energy, information, defense science and medical service. In recent years, tremendous progress has been witnessed in the development of flexible wearable devices that can be potentially massively deployed. Of particular interest are intelligent wearable devices, such as sensors and storage cells, which can be integrated by flexible magnetoelectronic devices based on magnetic thin films. To examine this further, the magnetic properties of FeNi thin films with different thicknesses grown on flexible graphene substrate are investigated at room temperature. The coercivity increases with increasing thicknesses of FeNi thin film, which can be attributed to the increase of grain size and decrease of surface roughness. Moreover, the thickness modulated magnetic property shows a magnetic anisotropy shift increase with varying thicknesses of FeNi thin film by using measurements based on ferromagnetic resonance, which further enhances the resonance frequency. In addition, the resonance peak is quite stable after bending it for ten cycles. The result is promising for the future design of flexible magnetoelectronic devices.展开更多
Transparent conducting zirconium-doped zinc oxide （ZnO：Zr） thin films with high transparency, low resistivity and good adhesion were successfully prepared on water-cooled flexible substrates （polyethylene glycol t...Transparent conducting zirconium-doped zinc oxide （ZnO：Zr） thin films with high transparency, low resistivity and good adhesion were successfully prepared on water-cooled flexible substrates （polyethylene glycol terephthalate, PET） by RF magnetron sputtering. The structural, electrical and optical properties of the films were studied for different thicknesses in detail. X-ray diffraction （XRD） and scanning electron microscopy （SEM） revealed that all the deposited films are polycrystalline with a hexagonal structure and a preferred orientation perpendicular to the substrate. The lowest resistivity achieved is 1.55 × 10-3 Ω·cm for a thickness of 189 nm with a Hall mobility of 17.6 cm2/（V·s） and a carrier concentration of 2.15×1020 cm-3. All the films present a high transmittance of above 90% in the wavelength range of the visible spectrum.展开更多
Aluminium doped ZnO thin films（ZnO︰Al） were deposited on transparent polymer substrates at room temperature by rf magnetron sputtering method from a ZnO target with Al2O3 of 2.0 wt%. Argon gas pressure varied from ...Aluminium doped ZnO thin films（ZnO︰Al） were deposited on transparent polymer substrates at room temperature by rf magnetron sputtering method from a ZnO target with Al2O3 of 2.0 wt%. Argon gas pressure varied from 0.5 Pa to 2.5 Pa with radio frequency power of 120 W. XRD results showed that all the ZnO︰Al films had a polycrystalline hexagonal structure and a （002） preferred orientation with the c-axis perpendicular to the substrate. The grain sizes of the films were 6.3-14.8 nm.SEM images indicated the ZnO︰Al film with low Argon gas pressure was denser and the deposition rate of the films depended strongly on the Argon gas pressure, increasing firstly and then decreasing with increasing the pressure. The highest deposition rate was 5.2 nm/min at 1 Pa. The optical transmittance of the ZnO︰Al films increased and the blue shift of the absorption edge appeared when the Argon gas pressure increased. The highest transmittance of obtained ZnO︰Al films at 2.5 Pa was about 85% in the visible region. The electrical properties of the films were worsened with the increase of the Argon gas power from 1 Pa to 2.5 Pa. The resistivity of obtained film at 1.0 Pa was 2.79×10-2 Ω·cm.展开更多
In this study,the authors have shown the power conversion efficiency of flexible organic solar cells.The structure of the device is PET/ITO/PEDOT:PSS/P3HT:PCBM/AI.P3HT(poly-3-hexylthiophene).It was used as an electron...In this study,the authors have shown the power conversion efficiency of flexible organic solar cells.The structure of the device is PET/ITO/PEDOT:PSS/P3HT:PCBM/AI.P3HT(poly-3-hexylthiophene).It was used as an electron donor,PCBM([6,6]-phenyl C6 l-butyric acid methyl ester)as an electron acceptor and PEDOT:PSS used as a HIL(hole injection layer).These materials were deposited by spin coating method on the flexible substrates.Photolithography method is used to etch ITO.The electrical parameters of the fabricated cells were investigated by means of J(V),FF(fill factor),the efficiency(r/),photocurrent and IPCE measurement.It was observed that 45%of the absorbed photons are converted into current.The results obtained using etching technology by photolithography is better than that obtained in the clean room.展开更多
The flexible materials exhibit more favorable properties than most rigid substrates in flexibility,weight saving,mechanical reliability,and excellent environmental toughness.Particularly,flexible graphene film with un...The flexible materials exhibit more favorable properties than most rigid substrates in flexibility,weight saving,mechanical reliability,and excellent environmental toughness.Particularly,flexible graphene film with unique mechanical properties was extensively explored in high frequency devices.Herein,we report the characteristics of structure and magnetic properties at high frequency of Co2FeAl thin film with different thicknesses grown on flexible graphene substrate at room temperature.The exciting finding for the columnar structure of Co2FeAl thin film lays the foundation for excellent high frequency property of Co2FeAl/flexible graphene structure.In-plane magnetic anisotropy field varying with increasing thickness of Co2FeAl thin film can be obtained by measurement of ferromagnetic resonance,which can be ascribed to the enhancement of crystallinity and the increase of grain size.Meanwhile,the resonance frequency which can be achieved by the measurement of vector network analyzer with the microstrip method increases with increasing thickness of Co2FeAl thin film.Moreover,in our case with graphene film,the resonance magnetic field is quite stable though folded for twenty cycles,which demonstrates that good flexibility of graphene film and the stability of high frequency magnetic property of Co2FeAl thin film grown on flexible graphene substrate.These results are promising for the design of microwave devices and wireless communication equipment.展开更多
By designing and fabricating thin film electronic devices on a flexible substrate instead of more commonly used rigid substrate, flexible electronics produced has opened a field of special applications. In this articl...By designing and fabricating thin film electronic devices on a flexible substrate instead of more commonly used rigid substrate, flexible electronics produced has opened a field of special applications. In this article, we first reviewed available products that may be used as flexible substrates, their characteristics and unique advantages as supporting material for flexible electronic devices. Secondly, flexible perovskite solar cell is examined in detail, with special focus on its potential large-scale fabrication processes. In particular, a comprehensive review is provided on low cost solution printing techniques that is viewed highly as a viable tool for potential commercialization of the perovskite solar cells. Furthermore, a summary is given on green processing for the solution printing production of flexible perovskite devices.展开更多
Indium tin oxide(ITO)is widely used in transparent conductive films(TCFs);however,several disadvan-tages,such as high cost and toxicity of indium,limit its applications.Therefore,it is necessary to develop other mater...Indium tin oxide(ITO)is widely used in transparent conductive films(TCFs);however,several disadvan-tages,such as high cost and toxicity of indium,limit its applications.Therefore,it is necessary to develop other materials that can replace ITO.Silver nanowires or single walled carbon nanotubes(SWCNTs)have attracted considerable interest owing to their unique electrical,optical,and thermal stabilities,and thus,they are ideal for transparent electrodes for flexible or stretchable devices.In this study,we develop a novel architecture of composite TCFs on a polyethylene naphthalate(PEN)flexible substrate.Herein,the silver nanowires-SWCNTs films with nested density structure were fabricated through ultrasonic spraying technology by varying the spraying width.For achieving enhanced transmittance,we combined the larger irregular grids and holes with fewer nanowires stacked in the longitudinal direction,more optical chan-nels,and good carrier transport.Thereafter,aluminum-doped zinc oxide(AZO)was used as capping to the structure for enhancing the optical properties of the TCFs.The silver nanowires-SWCNTs/AZO(ASA)bilayer was obtained in the optimized architecture,which showed superior optoelectronic performance to that shown by commercial ITO with a high optical transmittance of 92%at the wavelength of 550 nm and low sheet resistance of 17/sq.In the specially structured conductive film,the significant improvement in the transmittance and uniformity of the sheet resistance was attributed to the effective nanowire junc-tion contact compared to that in ordinary structure of silver nanowires,which reduced the mean density of small clusters of nanowires.Compared with the silver nanowires-SWCNTs films,the ASA bilayer film exhibited excellent resistance to boiling,mechanical bending(10,000 cycles),and CO_(2)plasma.Moreover,the sheet resistance of ASA changed slightly after the tape tests,thereby illustrating a strong adhesion to the PEN substrate after the enclosure of AZO.Meanwhile,the AZO capping layer can enhance the op-tical transmittance between 600 and 1500 nm.In addition,the amorphous silicon photovoltaic devices with flexible ASA TCFs exhibited a power conversion efficiency(PCE)of 8.67%.After bending for 3000 times,the PCE was decreased to 8.20%,thereby demonstrating the potential of developed films to replace traditional ITO.展开更多
An approach based on film buckling under simple uniaxial tensile testing was utilized in this paper to quan- titatively estimate the interfacial energy of the nanostructured multilayer films （NMFs） adherent to flexi...An approach based on film buckling under simple uniaxial tensile testing was utilized in this paper to quan- titatively estimate the interfacial energy of the nanostructured multilayer films （NMFs） adherent to flexible substrates. The interfacial energies of polyimide-supported NMFs are determined to be ~ 5.0 J/m2 for Cu/Cr, ~4.1 J/m2 for Cu/Ta, ~ 2.8 J/m2 for Cu/Mo, ~ 1.1 J/m2 for Cu/Nb, and ~ 1.2 J/m2 for Cu/Zr NMFs. Furthermore, a linear relationship between the adhesion energy and the interfacial shear strength is clearly demonstrated for the Cu-based NMFs, which is highly indicative of the applicability and reliability of the modified models.展开更多
Conventional organic solar cell＇s （OSC） architectures, including rigid transparent substrate （Glass）, conductive electrode （Indium tin oxide, ITO） and small working areas, are widely utilized in organic photovo...Conventional organic solar cell＇s （OSC） architectures, including rigid transparent substrate （Glass）, conductive electrode （Indium tin oxide, ITO） and small working areas, are widely utilized in organic photovoltaic fields. However, such a structure as well as conventional spin-coating method obviously restrict their industrial application. In this article, we report the deposition of silver nanowires （AgNWs） on the flexible substrate by slot-die printing. The obtained AgNWs films exhibited a high transmittance and a low resistance, and were further used as the transparent conductive electrode ofOSCs. A typical conjugated polymer, poly[（2-5-bis（2-hexyldecyloxy）phenylene）-alt-（5,6-difluoro-4,7-di（thiophen-2-yl）benzo[c] [1,2,5]thiadiazole）] （PPDT2FBT）, was used as the active material to fabricate large-area （7 cm2） solar cells by a slot-die coating process. The power conversion efficiency （PCE） could reach 1.87% initially and further increased to 3.04% by thermal annealing. Compared to the performance of reference cell on ITO substrate, the result indicated that the AgNWs could be developed as an alternative substitute of conductive electrode to fabricate the large-area flexible OSCs by roll-to-roll printing.展开更多
The polyaniline （PANI） films doped with complex acid （sulfuric acid and sulfosalicylic acid） were prepared using the potentiostatic method on bare nickel flake （NF） and flexible polyethylene terephthalate （PET...The polyaniline （PANI） films doped with complex acid （sulfuric acid and sulfosalicylic acid） were prepared using the potentiostatic method on bare nickel flake （NF） and flexible polyethylene terephthalate （PET）/indium tin oxide （ITO） substrates. The contents of the PANI films,surface elements, electrochromic property and electrical conductivity were characterized by energy dispersive X-ray spectrometer （EDS）, cyclic voltammetry （CV） and electrochemical impedance spectroscopy （EIS）. The experimental results show that differences exist among cycle stability, redox reversibility and response time of polyaniline films on these two kinds of substrates, but the electrochromic phenomenon of the PANI films is in substantial agreement. The equilibrium transmittance spectra in the visible region （400-800 nm） for the PANI film on flexible PET/ITO substrate was obtained at different applied potential from -0.4 to 1.5 V. The results show that the transmittance of the PANI film by applying voltage is adjustable in a row and has excellent electrochromic performance.展开更多
Polyimide (Kapton, Dupont Corp.) based magnetostrictive thin film structures were designed and fabricated for micro device applications. In particular the growth of films on flexible substrates was studied to allow a ...Polyimide (Kapton, Dupont Corp.) based magnetostrictive thin film structures were designed and fabricated for micro device applications. In particular the growth of films on flexible substrates was studied to allow a simple integration of the system in miniaturized magnetostrictive devices. The films were fabricated on different substrates to compare their different magnetic and structural properties. It showed much more magnetostriction and higher impact resistance results compared with traditional Si based film type actuators. In the fabrication process, amorphous TbDyFe films with thicknesses of 500 nm, 1 μm, 1.5 μm respectively, were deposited on the designed substrate by DC magnetron sputtering. During sputtering process the substrate holder was maintained at room temperature. After the sputter process, X-ray diffraction studies were also carried out to determine the film structure and thickness of the sputtered film. At last, magnetization from VSM (Vibrating Sample Magnetometer) and magnetostriction from optical cantilever method of each structure were measured to estimate the magneto-mechanical characteristics under the external magnetic field lower than 0.7 T for micro-system applications.展开更多
We present a simple and efficient process for fabricating Ⅲ-Nitride(Ⅲ-N)mechanical resonators on flexible metal substrates.This method combines Van der Waals epitaxy of Ⅲ-N epilayers with the deposition of a thick ...We present a simple and efficient process for fabricating Ⅲ-Nitride(Ⅲ-N)mechanical resonators on flexible metal substrates.This method combines Van der Waals epitaxy of Ⅲ-N epilayers with the deposition of a thick metal stressor atop the Ⅲ-N layers.During thermal treatment,the 30μm thick metal stressor deposited on a 300 nm AlGaN/500 nm GaN layer grown on a 3 nm two-dimensional hexagonal-Boron Nitride(2D h-BN)release layer,initiates a one-step Self-Lift-Off and Transfer(SLOT)process.This process effectively transfers the Ⅲ-N heterostructure from the h-BN/Sapphire growth wafer to the flexible metal stressor substrate.Additional local etching of the metal stressor and deposition of front electrodes allow for releasing self-standing Ⅲ-N layers with integrated actuation.Fabricated Ⅲ-N MEMS drum resonators were analyzed using optical profilometry and laser Doppler vibrometer,enabling the observation of static deflections and distinct vibration modes.Finite element method(FEM)simulations were also performed to further understand experimental observations and assess the mechanical properties of the released Ⅲ-N layers,particularly enabling the estimation of stress in the GaN and AlGaN released layers.This straightforward approach not only provides a practical solution for cost-effective Ⅲ-N MEMS resonators but also ensures flexibility,and crack-free structures.展开更多
In this work,emerging perovskite-inspired Cu_(2)AgBiI_(6)(CABI)solar cells were successfully fabricated on flexible substrates,demonstrating that the transition from rigid to flexible materials does not compromise dev...In this work,emerging perovskite-inspired Cu_(2)AgBiI_(6)(CABI)solar cells were successfully fabricated on flexible substrates,demonstrating that the transition from rigid to flexible materials does not compromise device performance.This underscores the versatility of CABI on two different kinds of sub strates.Additionally,t o optimize charge extraction,we selected a polymeric hole-transport material(HTM),PPDT2FBT,whose energy levels align with CABI.The PPDT2FBT-based devices outperformed those using the well-known poly(3-hexylthiophene)(P3HT),le ading to power conversion efficiencies as high as approximately 0.8%.These results suggest that PPDT2FBT may hold promise as a HTM for use in low-toxicity,perovskite-inspired photovoltaic systems,such as those based on CABI.Furthermore,roll-to-roll p rocessing techniques,crucial for scalable production,were tested.However,controlling the morphology of the active layer remains a significant challenge.These findings represent critical steps toward the large-scale manufacturing and commercialization of flexible,PIM-based solar cells.展开更多
The flexibility of nanoparticle films is a topic of rapidly growing interest in both scientific and engineering researches due to their numerous potential applications in a broad range of wearable electronics and biom...The flexibility of nanoparticle films is a topic of rapidly growing interest in both scientific and engineering researches due to their numerous potential applications in a broad range of wearable electronics and biomedical devices.This article presents the elucidation of the properties of nanoparticle films.Here,a flexible film is fabricated based on polyethylene terephthalate(PET)and magnetic iron oxide at the nanoscale using layer-by-layer technology.The 2D thin flexible film material can be bent at different angles from 0°to 360°.With an increase in elastic deformation angles,the magnetocaloric effect of the film gradually increases in the alternating magnetic field.The test results from a vibrating sample magnetometer and a low-frequency impedance analyzer demonstrate that the film has a good magnetic response and anisotropy.The magnetocaloric effect and magnetic induction effect are controlled by deformation,providing a new idea for the application of elastic films.It combines the flexibility of the nanoparticle PET substrate and,in the future,it may be used for skin adhesion for administration and magnetic stimulation control.展开更多
基金Supported by the Youth Science Foundation of Shanxi Province under Grant No 2013021010-3the National Natural Science Foundation of China under Grant Nos 61434002 and 11404202
文摘Effect of mechanical stress on magnetic properties of an exchange-biased ferromagnetic/antiferromagnetic bilayer deposited on a flexible substrate is investigated. The hysteresis loops with different magnitudes and orientations of the stress can be classified into three types. The corresponding physical conditions for each type of the loop are deduced based on the principle of minimal energy. The equation of the critical stress is derived, which can judge whether the loops show hysteresis or not. Numerical calculations suggest that except for the magnitude of the mechanical stress, the relative orientation of the stress is also an important factor to tune the exchange bias effect.
基金Supported by the National Basic Research Program of China under Grant No 2012CB619200the National Natural Science Foundation of China under Grant Nos 61290304,11074265 and 11174307+1 种基金the Natural Science Foundation of Shanghai under Grant No 16ZR1441200the Frontier Science Research Project(Key Programs)of Chinese Academy of Sciences under Grant No QYZDJ-SSW-SLH018
文摘Recently, great efforts have been made in the fabrication of arbitrary warped devices to satisfy the requirement of wearable and lightweight electronic products. Direct growth of high crystalline quality films on flexible substrates is the most desirable method to fabricate flexible devices owing to the advantage of simple and compatible preparation technology with current semiconductor devices, while it is a very challenging work, and usually amorphous, polycrystalline or discontinuous single crystalline films are achieved. Here we demonstrate the direct growth of high-quality Bi2 Te3 single crystalline films on flexible polyimide substrates by the modified hot wall epitaxy technique. Experimental results reveal that adjacent crystallites are coherently coalesced to form a continuous film, although amounts of disoriented crystallites are generated due to fast growth rate. By inserting a quartz filter into the growth tube, the number density of disoriented crystallites is effectively reduced owing to the improved spiral interaction. Furthermore, flexible Bi2 Te3 photoconductors are fabricated and exhibit strong near-infrared photoconductive response under different degrees of bending, which also confirms the obtained fexible films suitable for electronic applications.
基金the National Natural Science Foundation of China(Nos.51601198 and 51571199)the Foundation for Outstanding Young Scholar,Institute of Metal Research(IMR),China+1 种基金the Natural Science Foundation of Liaoning Province of China(No.20180510025)the Foundation for Outstanding Young Scholar,the Shenyang National Laboratory for Materials Science,China(No.L2019F23)。
文摘Failure strain determination of polymer-supported thin films is a key for the design of the flexible devices.A theoretical model R/R0=(L/L0)2(R,L are the electrical resistance and the length of the stretched film,respectively.R0,L0 are the corresponding initial values.)has been widely used to determine the fracture strain of thin films on flexible substrates.However,this equation loses its function in some special cases.Here,a simple and universal theoretical model was proposed to determine the fracture strain of metal thin films on flexible substrates in more generally situations.With this model,we investigated the thicknessdependent failure strains of Cu-5 at.%Al films with thickness of 10 nm,200 nm,1000 nm,and Ti films with thickness of 50 nm,100 nm,300 nm.This model was also employed to study the published data available.The results showed that the new model provided a fairly good prediction of the failure strains of different films.
基金supported by National Natural Science Foundation of China(21804058)Shanxi Scholarship Council of China(2021-068)+1 种基金Shanxi Agricultural University High-Level Talent Project(2021XG013)Shanxi Postdoc Reward(SXBYKY2022001).
文摘Melamine is one of the most frequently detected adulterants in dairy products.The current study proposes a surface-enhanced Raman spectroscopy(SERS)-based analytical tool for fast and reliable screening of melamine in bovine milk.A hand-held Raman spectrometer was used in conjunction with a substrate composed of silver nanoparticles(AgNPs)that was 2D printed onto glass fiber(GF)filter paper.Under optimized conditions,a sensitive and fingerprint-like signal at 674 cm^(-1) was obtained.The AgNPs/GF substrate exhibited high sensitivity to melamine in milk down to 1.9498×10^(-5)mg/mL,which is well below the USA and EU safety limits(2.5×10^(-3)mg/mL).Remarkably,the proposed technology was also highly reproducible,showing spot-to-spot and block-to-block variations below 3.3%and 4.9%at 674 cm^(-1) in Raman intensity,respectively.The characteristic peak intensity and concentration of melamine showed an acceptable linear relationship(R^(2)=0.9909)within the range of 0.0001-1 mg/mL.Overall,the method established in this study can provide an efficient and effective method for the quantitative target screening and detection of melamine in dairy products.
基金Project supported by the National Natural Science Foundation of China(Grant Nos.11674336 and 11874150).
文摘The magneto-mechanical coupling effect and magnetic anisotropy of Fe10Co90(FeCo)films deposited on silicon wafer(Si),flexible polyethylene terephthalate(PET),freestanding polydimethylsiloxane(PDMS),and pre-stretched 20%PDMS substrates were studied in detail.The loop squareness ratio Mr/Ms and the coercive Hc of the FeCo film grown on a PET substrate can be obviously tuned by applying a small tensile-bending strain,and those of the FeCo film grown on a freestanding PDMS substrate can only be slightly changed when applying a relatively large tensile bending strain.For the FeCo film prepared on a 20%pre-stretched PDMS,a wrinkled morphology is obtained after removing the pre-strain.The wrinkled FeCo film can keep the magnetic properties unchanged when applying a relatively large tensile bending strain perpendicular to the wrinkles.This reveals that PDMS is an ideal substrate for magnetic films to realize flexible immutability.Our results may help for developing flexible magnetic devices.
基金supported by the Dutch Research Council(NWO)under Project 17608。
文摘Ultrasound(US)imaging is a fundamental tool in healthcare for the diagnosis of diverse conditions.Wearable,flexible ultrasound patches could expand the scope of US imaging to continuous,at-home monitoring without professional intervention,but require scaling to large numbers of transducer elements.This poses challenges in interconnect density,power consumption,and data bandwidth.To improve interconnect density,we present the first integration of flexible ultrasound transducers with flexible a-IGZO thin-film transistor(TFT)multiplexing electronics.In the Si CMOS readout chip,a new circuit technique cuts front-end power,while a log-delta ADC compresses data efficiently.Our system achieves an 8×reduction in required front-end circuitry and a 42%decrease in front-end power.The data needed to describe the ultrasound image are reduced five-fold,decreasing data transmission power by the same factor.These advances bring the vision of wearable high-density,large-area ultrasound imaging patches for monitoring one step closer.
基金Project supported by the National Natural Science Foundation of China (Grant Nos. 51901163 and 12104171)the Fundamental Research Funds for the Central Universities (Grant No. 2021XXJS025)the Natural Science Foundation of Hubei Province (Grants No. 2024AFB888)。
文摘Electronics over flexible substrates offer advantages of flexibility, portability and low cost, and promising applications in the areas of energy, information, defense science and medical service. In recent years, tremendous progress has been witnessed in the development of flexible wearable devices that can be potentially massively deployed. Of particular interest are intelligent wearable devices, such as sensors and storage cells, which can be integrated by flexible magnetoelectronic devices based on magnetic thin films. To examine this further, the magnetic properties of FeNi thin films with different thicknesses grown on flexible graphene substrate are investigated at room temperature. The coercivity increases with increasing thicknesses of FeNi thin film, which can be attributed to the increase of grain size and decrease of surface roughness. Moreover, the thickness modulated magnetic property shows a magnetic anisotropy shift increase with varying thicknesses of FeNi thin film by using measurements based on ferromagnetic resonance, which further enhances the resonance frequency. In addition, the resonance peak is quite stable after bending it for ten cycles. The result is promising for the future design of flexible magnetoelectronic devices.
文摘Transparent conducting zirconium-doped zinc oxide （ZnO：Zr） thin films with high transparency, low resistivity and good adhesion were successfully prepared on water-cooled flexible substrates （polyethylene glycol terephthalate, PET） by RF magnetron sputtering. The structural, electrical and optical properties of the films were studied for different thicknesses in detail. X-ray diffraction （XRD） and scanning electron microscopy （SEM） revealed that all the deposited films are polycrystalline with a hexagonal structure and a preferred orientation perpendicular to the substrate. The lowest resistivity achieved is 1.55 × 10-3 Ω·cm for a thickness of 189 nm with a Hall mobility of 17.6 cm2/（V·s） and a carrier concentration of 2.15×1020 cm-3. All the films present a high transmittance of above 90% in the wavelength range of the visible spectrum.
基金Funded by Key Project of Natural Science Foundation of Hubei Province(No.2008CDA025)
文摘Aluminium doped ZnO thin films（ZnO︰Al） were deposited on transparent polymer substrates at room temperature by rf magnetron sputtering method from a ZnO target with Al2O3 of 2.0 wt%. Argon gas pressure varied from 0.5 Pa to 2.5 Pa with radio frequency power of 120 W. XRD results showed that all the ZnO︰Al films had a polycrystalline hexagonal structure and a （002） preferred orientation with the c-axis perpendicular to the substrate. The grain sizes of the films were 6.3-14.8 nm.SEM images indicated the ZnO︰Al film with low Argon gas pressure was denser and the deposition rate of the films depended strongly on the Argon gas pressure, increasing firstly and then decreasing with increasing the pressure. The highest deposition rate was 5.2 nm/min at 1 Pa. The optical transmittance of the ZnO︰Al films increased and the blue shift of the absorption edge appeared when the Argon gas pressure increased. The highest transmittance of obtained ZnO︰Al films at 2.5 Pa was about 85% in the visible region. The electrical properties of the films were worsened with the increase of the Argon gas power from 1 Pa to 2.5 Pa. The resistivity of obtained film at 1.0 Pa was 2.79×10-2 Ω·cm.
文摘In this study,the authors have shown the power conversion efficiency of flexible organic solar cells.The structure of the device is PET/ITO/PEDOT:PSS/P3HT:PCBM/AI.P3HT(poly-3-hexylthiophene).It was used as an electron donor,PCBM([6,6]-phenyl C6 l-butyric acid methyl ester)as an electron acceptor and PEDOT:PSS used as a HIL(hole injection layer).These materials were deposited by spin coating method on the flexible substrates.Photolithography method is used to etch ITO.The electrical parameters of the fabricated cells were investigated by means of J(V),FF(fill factor),the efficiency(r/),photocurrent and IPCE measurement.It was observed that 45%of the absorbed photons are converted into current.The results obtained using etching technology by photolithography is better than that obtained in the clean room.
基金Project supported by the National Natural Science Foundation of China(Grant Nos.51901163 and 12104171)the Fundamental Research Funds for the Central Universities(Grant No.2021XXJS025).
文摘The flexible materials exhibit more favorable properties than most rigid substrates in flexibility,weight saving,mechanical reliability,and excellent environmental toughness.Particularly,flexible graphene film with unique mechanical properties was extensively explored in high frequency devices.Herein,we report the characteristics of structure and magnetic properties at high frequency of Co2FeAl thin film with different thicknesses grown on flexible graphene substrate at room temperature.The exciting finding for the columnar structure of Co2FeAl thin film lays the foundation for excellent high frequency property of Co2FeAl/flexible graphene structure.In-plane magnetic anisotropy field varying with increasing thickness of Co2FeAl thin film can be obtained by measurement of ferromagnetic resonance,which can be ascribed to the enhancement of crystallinity and the increase of grain size.Meanwhile,the resonance frequency which can be achieved by the measurement of vector network analyzer with the microstrip method increases with increasing thickness of Co2FeAl thin film.Moreover,in our case with graphene film,the resonance magnetic field is quite stable though folded for twenty cycles,which demonstrates that good flexibility of graphene film and the stability of high frequency magnetic property of Co2FeAl thin film grown on flexible graphene substrate.These results are promising for the design of microwave devices and wireless communication equipment.
基金the financial support of the National Key Research and Development Project funding from the Ministry of Science and Technology of China(Grants Nos.2016YFA0202400and 2016YFA0202404)the Peacock Team Project funding from Shenzhen Science and Technology Innovation Committee(Grant No.KQTD2015033110182370)
文摘By designing and fabricating thin film electronic devices on a flexible substrate instead of more commonly used rigid substrate, flexible electronics produced has opened a field of special applications. In this article, we first reviewed available products that may be used as flexible substrates, their characteristics and unique advantages as supporting material for flexible electronic devices. Secondly, flexible perovskite solar cell is examined in detail, with special focus on its potential large-scale fabrication processes. In particular, a comprehensive review is provided on low cost solution printing techniques that is viewed highly as a viable tool for potential commercialization of the perovskite solar cells. Furthermore, a summary is given on green processing for the solution printing production of flexible perovskite devices.
基金Foundation for Advanced Talents in 2017(No.21200-5175162)The National Natural Science Foun-dation of China(No.62164009).Inner Mongolia University Re-search Foundation for Advanced Talents in 2021(No.10000-21311201/005).Additionally,the authors acknowledge the finan-cial support of Taif University Researchers Supporting Project(No.TURSP-2020/05),Taif University,Taif,Saudi Arabia.
文摘Indium tin oxide(ITO)is widely used in transparent conductive films(TCFs);however,several disadvan-tages,such as high cost and toxicity of indium,limit its applications.Therefore,it is necessary to develop other materials that can replace ITO.Silver nanowires or single walled carbon nanotubes(SWCNTs)have attracted considerable interest owing to their unique electrical,optical,and thermal stabilities,and thus,they are ideal for transparent electrodes for flexible or stretchable devices.In this study,we develop a novel architecture of composite TCFs on a polyethylene naphthalate(PEN)flexible substrate.Herein,the silver nanowires-SWCNTs films with nested density structure were fabricated through ultrasonic spraying technology by varying the spraying width.For achieving enhanced transmittance,we combined the larger irregular grids and holes with fewer nanowires stacked in the longitudinal direction,more optical chan-nels,and good carrier transport.Thereafter,aluminum-doped zinc oxide(AZO)was used as capping to the structure for enhancing the optical properties of the TCFs.The silver nanowires-SWCNTs/AZO(ASA)bilayer was obtained in the optimized architecture,which showed superior optoelectronic performance to that shown by commercial ITO with a high optical transmittance of 92%at the wavelength of 550 nm and low sheet resistance of 17/sq.In the specially structured conductive film,the significant improvement in the transmittance and uniformity of the sheet resistance was attributed to the effective nanowire junc-tion contact compared to that in ordinary structure of silver nanowires,which reduced the mean density of small clusters of nanowires.Compared with the silver nanowires-SWCNTs films,the ASA bilayer film exhibited excellent resistance to boiling,mechanical bending(10,000 cycles),and CO_(2)plasma.Moreover,the sheet resistance of ASA changed slightly after the tape tests,thereby illustrating a strong adhesion to the PEN substrate after the enclosure of AZO.Meanwhile,the AZO capping layer can enhance the op-tical transmittance between 600 and 1500 nm.In addition,the amorphous silicon photovoltaic devices with flexible ASA TCFs exhibited a power conversion efficiency(PCE)of 8.67%.After bending for 3000 times,the PCE was decreased to 8.20%,thereby demonstrating the potential of developed films to replace traditional ITO.
基金financially supported by the National Natural Science Foundation of China(Nos.5132100351322104+6 种基金51201123 and 51571157)the National Basic Research Program of China(No.2010CB631003)the 111 Project of China(No.B06025)the support from Fundamental Research Funds for the Central UniversitiesTengfei Scholar projectChina Postdoctoral Science Foundation(No.2012M521765)Shaanxi Province Postdoctoral Scientific Research Projects for part of financial support
文摘An approach based on film buckling under simple uniaxial tensile testing was utilized in this paper to quan- titatively estimate the interfacial energy of the nanostructured multilayer films （NMFs） adherent to flexible substrates. The interfacial energies of polyimide-supported NMFs are determined to be ~ 5.0 J/m2 for Cu/Cr, ~4.1 J/m2 for Cu/Ta, ~ 2.8 J/m2 for Cu/Mo, ~ 1.1 J/m2 for Cu/Nb, and ~ 1.2 J/m2 for Cu/Zr NMFs. Furthermore, a linear relationship between the adhesion energy and the interfacial shear strength is clearly demonstrated for the Cu-based NMFs, which is highly indicative of the applicability and reliability of the modified models.
基金financially supported by the National Natural Science Foundation of China(Nos.21125420 and 21474022)the Chinese Academy of Sciences
文摘Conventional organic solar cell＇s （OSC） architectures, including rigid transparent substrate （Glass）, conductive electrode （Indium tin oxide, ITO） and small working areas, are widely utilized in organic photovoltaic fields. However, such a structure as well as conventional spin-coating method obviously restrict their industrial application. In this article, we report the deposition of silver nanowires （AgNWs） on the flexible substrate by slot-die printing. The obtained AgNWs films exhibited a high transmittance and a low resistance, and were further used as the transparent conductive electrode ofOSCs. A typical conjugated polymer, poly[（2-5-bis（2-hexyldecyloxy）phenylene）-alt-（5,6-difluoro-4,7-di（thiophen-2-yl）benzo[c] [1,2,5]thiadiazole）] （PPDT2FBT）, was used as the active material to fabricate large-area （7 cm2） solar cells by a slot-die coating process. The power conversion efficiency （PCE） could reach 1.87% initially and further increased to 3.04% by thermal annealing. Compared to the performance of reference cell on ITO substrate, the result indicated that the AgNWs could be developed as an alternative substitute of conductive electrode to fabricate the large-area flexible OSCs by roll-to-roll printing.
基金Funded by the National Natural Science Foundation of China (No.201760 66)
文摘The polyaniline （PANI） films doped with complex acid （sulfuric acid and sulfosalicylic acid） were prepared using the potentiostatic method on bare nickel flake （NF） and flexible polyethylene terephthalate （PET）/indium tin oxide （ITO） substrates. The contents of the PANI films,surface elements, electrochromic property and electrical conductivity were characterized by energy dispersive X-ray spectrometer （EDS）, cyclic voltammetry （CV） and electrochemical impedance spectroscopy （EIS）. The experimental results show that differences exist among cycle stability, redox reversibility and response time of polyaniline films on these two kinds of substrates, but the electrochromic phenomenon of the PANI films is in substantial agreement. The equilibrium transmittance spectra in the visible region （400-800 nm） for the PANI film on flexible PET/ITO substrate was obtained at different applied potential from -0.4 to 1.5 V. The results show that the transmittance of the PANI film by applying voltage is adjustable in a row and has excellent electrochromic performance.
文摘Polyimide (Kapton, Dupont Corp.) based magnetostrictive thin film structures were designed and fabricated for micro device applications. In particular the growth of films on flexible substrates was studied to allow a simple integration of the system in miniaturized magnetostrictive devices. The films were fabricated on different substrates to compare their different magnetic and structural properties. It showed much more magnetostriction and higher impact resistance results compared with traditional Si based film type actuators. In the fabrication process, amorphous TbDyFe films with thicknesses of 500 nm, 1 μm, 1.5 μm respectively, were deposited on the designed substrate by DC magnetron sputtering. During sputtering process the substrate holder was maintained at room temperature. After the sputter process, X-ray diffraction studies were also carried out to determine the film structure and thickness of the sputtered film. At last, magnetization from VSM (Vibrating Sample Magnetometer) and magnetostriction from optical cantilever method of each structure were measured to estimate the magneto-mechanical characteristics under the external magnetic field lower than 0.7 T for micro-system applications.
基金supported by the French National Research Agency(ANR)under the research projects FLEXIGAN(grant ANR-22-CE51-0009)FLEXMEMS(IC ARTS)+1 种基金partially INMOST(grant ANR-19-CE08-0025)supported by the Region Grand Est in France,the French national technological network RENATECH and the Institut Lafayette in Metz.
文摘We present a simple and efficient process for fabricating Ⅲ-Nitride(Ⅲ-N)mechanical resonators on flexible metal substrates.This method combines Van der Waals epitaxy of Ⅲ-N epilayers with the deposition of a thick metal stressor atop the Ⅲ-N layers.During thermal treatment,the 30μm thick metal stressor deposited on a 300 nm AlGaN/500 nm GaN layer grown on a 3 nm two-dimensional hexagonal-Boron Nitride(2D h-BN)release layer,initiates a one-step Self-Lift-Off and Transfer(SLOT)process.This process effectively transfers the Ⅲ-N heterostructure from the h-BN/Sapphire growth wafer to the flexible metal stressor substrate.Additional local etching of the metal stressor and deposition of front electrodes allow for releasing self-standing Ⅲ-N layers with integrated actuation.Fabricated Ⅲ-N MEMS drum resonators were analyzed using optical profilometry and laser Doppler vibrometer,enabling the observation of static deflections and distinct vibration modes.Finite element method(FEM)simulations were also performed to further understand experimental observations and assess the mechanical properties of the released Ⅲ-N layers,particularly enabling the estimation of stress in the GaN and AlGaN released layers.This straightforward approach not only provides a practical solution for cost-effective Ⅲ-N MEMS resonators but also ensures flexibility,and crack-free structures.
基金the Research Council of Finland Flagship Programme,Photonics Research and Innovation(PREIN),decision number 346545supported by the Research Council of Finland,Printed intelligence infrastructure funding,decision 358621+1 种基金support of Research Council of Finland,Decision No.347772.P.V.and G.K.G.acknowledge Jane and Aatos Erkko foundation(SOL-TECH project)for funding.P.V.and G.K.G.also thank the SPOT-IT project founded by the CETPartnership,the Clean and E nergy Transition Partnership under the 2022 CET Partnership joint call for research proposal,co-founded by the European Commission(GA 101069750)with the founding of the organizations detailed on https://cetpartnership.eu/funding-agencies-and-call-mo dules.
文摘In this work,emerging perovskite-inspired Cu_(2)AgBiI_(6)(CABI)solar cells were successfully fabricated on flexible substrates,demonstrating that the transition from rigid to flexible materials does not compromise device performance.This underscores the versatility of CABI on two different kinds of sub strates.Additionally,t o optimize charge extraction,we selected a polymeric hole-transport material(HTM),PPDT2FBT,whose energy levels align with CABI.The PPDT2FBT-based devices outperformed those using the well-known poly(3-hexylthiophene)(P3HT),le ading to power conversion efficiencies as high as approximately 0.8%.These results suggest that PPDT2FBT may hold promise as a HTM for use in low-toxicity,perovskite-inspired photovoltaic systems,such as those based on CABI.Furthermore,roll-to-roll p rocessing techniques,crucial for scalable production,were tested.However,controlling the morphology of the active layer remains a significant challenge.These findings represent critical steps toward the large-scale manufacturing and commercialization of flexible,PIM-based solar cells.
基金Project supported by Scientific Research Funds(Grant No.7001/700199)Henan Provincial Department Scientific Research Project(Grant No.22A430034).
文摘The flexibility of nanoparticle films is a topic of rapidly growing interest in both scientific and engineering researches due to their numerous potential applications in a broad range of wearable electronics and biomedical devices.This article presents the elucidation of the properties of nanoparticle films.Here,a flexible film is fabricated based on polyethylene terephthalate(PET)and magnetic iron oxide at the nanoscale using layer-by-layer technology.The 2D thin flexible film material can be bent at different angles from 0°to 360°.With an increase in elastic deformation angles,the magnetocaloric effect of the film gradually increases in the alternating magnetic field.The test results from a vibrating sample magnetometer and a low-frequency impedance analyzer demonstrate that the film has a good magnetic response and anisotropy.The magnetocaloric effect and magnetic induction effect are controlled by deformation,providing a new idea for the application of elastic films.It combines the flexibility of the nanoparticle PET substrate and,in the future,it may be used for skin adhesion for administration and magnetic stimulation control.
