Silver nanowire films are promising alternatives to tin-doped indium oxide(ITO)films as transparent conductive electrodes.In this paper,we report the use of vacuum filtration and a polydimethylsiloxane(PDMS)-assisted ...Silver nanowire films are promising alternatives to tin-doped indium oxide(ITO)films as transparent conductive electrodes.In this paper,we report the use of vacuum filtration and a polydimethylsiloxane(PDMS)-assisted transfer printing technique to fabricate silver nanowire films on both rigid and flexible substrates,bringing advantages such as the capability of patterned transfer,the best performance among various ITO alternatives(10Ω/sq at 85%transparency),and good adhesion to the underlying substrate,thus eliminating the previously reported adhesion problem.In addition,our method also allows the preparation of high quality patterned films of silver nanowires with different line widths and shapes in a matter of few minutes,making it a scalable process.Furthermore,use of an anodized aluminum oxide(AAO)membrane in the transfer process allows annealing of nanowire films at moderately high temperature to obtain films with extremely high conductivity and good transparency.Using this transfer technique,we obtained silver nanowire films on a flexible polyethylene terephthalate(PET)substrate with a transparency of 85%,a sheet resistance of 10Ω/sq,with good mechanical flexibility.Detailed analysis revealed that the Ag nanowire network exhibits two-dimensional percolation behavior with good agreement between experimentally observed and theoretically predicted values of critical volume。展开更多
The development of pressure sensors with highly sensitivity, fast response and facile fabrication technique is desirable for wearable electronics. Here, we successfully fabricated a flexible transparent capacitive pre...The development of pressure sensors with highly sensitivity, fast response and facile fabrication technique is desirable for wearable electronics. Here, we successfully fabricated a flexible transparent capacitive pressure sensor based on patterned microstructured silver nanowires(AgNWs)/polydimethylsiloxane(PDMS) composite dielectrics. Compared with the pure PDMS dielectric layer with planar structures, the patterned microstructured sensor exhibits a higher sensitivity(0.831 kPa^-1, <0.5 kPa), a lower detection limit,good stability and durability. The enhanced sensing mechanism about the conductive filler content and the patterned microstructures has also been discussed. A 5×5 sensor array was then fabricated to be used as flexible and transparent wearable touch keyboards systems. The fabricated pressure sensor has great potential in the future electronic skin area.展开更多
Transparent electrodes are essential components for optoelectronic devices such as displays and thin-film solar cells. Traditionally, the deposition of transparent conducting layers and the sealing of the device are s...Transparent electrodes are essential components for optoelectronic devices such as displays and thin-film solar cells. Traditionally, the deposition of transparent conducting layers and the sealing of the device are separate steps. Here we report on a highly transparent, conductive, and flexible ＂tape＂, which can be obtained by transferring silver nanowire networks to conventional transparent tape. We utilized the viscidity of the tape to reduce the junction resistance between silver nanowires and further protect the nanowires from corrosion, oxidation and mechanical damage. By this simple method, we obtained a flexible tape with high transparency （-90% at 550 nm wavelength） and low sheet resistance （approaching 22 Ω.sq^-1）. The transparent tape can be attached and stuck firmly on complex surfaces, making the surface highly conductive. We demonstrated the use of the tape as both a conducting layer and a sealing layer for flexible electronics applications including in-situ temperature monitoring and electrochromic devices.展开更多
Graphene oxide and silver nanowires were bar coated onto polyethylene terephthalate （PET） substrates and then welded using an ultraviolet （UV）-assisted flash light irradiation process to achieve both high electric...Graphene oxide and silver nanowires were bar coated onto polyethylene terephthalate （PET） substrates and then welded using an ultraviolet （UV）-assisted flash light irradiation process to achieve both high electrical conductivity and low haze. The irradiation process connected adjacent silver nanowires by welding, while simultaneously reducing the graphene oxide to graphene. This process was performed using a custom W-assisted flash light welding system at room temperature under ambient conditions and was extremely rapid, with processing time of several milliseconds. The effects of varying the weight fractions of the silver nanowires and graphene oxide and of varying the W-assisted flash light welding conditions （light energy and pulse duration） were investigated. The surface morphologies of the welded silver nanowire/graphene films were analyzed using scanning electron microscopy. Optical characterizations, including transmittance and haze measurements, were also conducted using a spectrophotometer. To test their resistance to oxidation, the welded silver nanowire/graphene films were subjected to high temperature in a furnace （100 ℃）, and their sheet resistances were measured every hour. The flash light welding process was found to yield silver nanowire/graphene films with high oxidation resistance, high conductivity （14.35 Ω·sq-1）, high transmittance （93.46%）, and low haze （0.9%）. This material showed uniform temperature distribution when applied as a resistive heating film.展开更多
Copper nanowires(Cu NWs)are considered an excellent alternative to indium tin oxide(ITO)in flexible transparency electrodes(FTEs).However,the mixed particles and surface oxidation of Cu NWs degrade the transmittance a...Copper nanowires(Cu NWs)are considered an excellent alternative to indium tin oxide(ITO)in flexible transparency electrodes(FTEs).However,the mixed particles and surface oxidation of Cu NWs degrade the transmittance and conductivity of the electrodes.Therefore,highly purified Cu NWs without oxidation are vital for high-performance FTEs.Herein,a facile and effective purification process is introduced to purify Cu NWs in a water and n-hexane system,which takes advantage of the differences in hydrophilicity between Cu NWs and Cu NPs caused by their different adsorption affinities to octadecylamine(ODA).At the same sheet resistance,the transmittance of the purified Cu NW-based FTEs improved approximately 2%compared to that of non-purified Cu NW-based FTEs.Immersion of the electrode in glacial acetic acid removed the surface organics and oxides.After only 40 s of treatment,the sheet resistance dramatically decreased from 10^5 Ohm/sq to 31 Ohm/sq with a transmittance of 85%.In addition,the Cu NW-based FTE conductors showed excellent flexibility(remaining stable after 1000 bending cycles).The Cu NW-based FTEs were further applied to fabricate a flexible transparent heater.At a voltage of 10 V,the temperature of the heater reached 73℃,demonstrating the potential applications of this material in various fields.展开更多
Aluminium doped tin oxide films have been deposited onto glass substrates by using a simplified and low cost spray pyrolysis technique. The AI doping level varies between 0 and 30 at.% in the step of 5 at.%. The resis...Aluminium doped tin oxide films have been deposited onto glass substrates by using a simplified and low cost spray pyrolysis technique. The AI doping level varies between 0 and 30 at.% in the step of 5 at.%. The resistivity （p） is the minimum （0.38 Ω cm） for 20 at.% of AI doping. The possible mechanism behind the phenomenal zig-zag variation in resistivity with respect to AI doping is discussed in detail. The nature of conductivity changes from n-type to p-type when the AI doping level is 10 at.%. The results show that 20 at.% is the optimum doping level for good quality p-type SnO2：AI films suitable for transparent electronic devices.展开更多
Light-mediated therapeutics have attracted considerable attention as a method for the treatment of ophthalmologic diseases,such as age-related macular degeneration,because of their non-invasiveness and the effectivene...Light-mediated therapeutics have attracted considerable attention as a method for the treatment of ophthalmologic diseases,such as age-related macular degeneration,because of their non-invasiveness and the effectiveness to ameliorate the oxidative stress of retinal cells.However,the current phototherapeutic devices are opaque,bulky,and tethered forms,so they are not feasible for use in continuous treatment during the patient’s daily life.Herein,we report wireless,wearable phototherapeutic devices with red light-emitting diodes for continuous treatments.Red light-emitting diodes were formed to be conformal to three-dimensional surfaces of glasses and contact lenses.Furthermore,fabricated light-emitting diodes had either transparency or a miniaturized size so that the user’s view is not obstructed.Also,these devices were operated wirelessly with control of the light intensity.In addition,in-vitro and in-vivo tests using human retinal epithelial cells and a live rabbit demonstrated the effectiveness and reliable operation as phototherapeutic devices.展开更多
Silver nanowires (AgNWs) hold great promise for applications in wearable electronics, flexible solar cells, chemical and biological sensors, photonic/plasmonic circuits, and scanning probe microscopy (SPM) due to thei...Silver nanowires (AgNWs) hold great promise for applications in wearable electronics, flexible solar cells, chemical and biological sensors, photonic/plasmonic circuits, and scanning probe microscopy (SPM) due to their unique plasmonic, mechanical, and electronic properties. However, the lifetime, reliability, and operating conditions of AgNW-based devices are significantly restricted by their poor chemical stability, limiting their commercial potentials. Therefore, it is crucial to create a reliable oxidation barrier on AgNWs that provides long-term chemical stability to various optical, electrical, and mechanical devices while maintaining their high performance. Here we report a room-temperature solution-phase approach to grow an ultra-thin, epitaxial gold coating on AgNWs to effectively shield the Ag surface from environmental oxidation. The Ag@Au core-shell nanowires (Ag@Au NWs) remain stable in air for over six months, under elevated temperature and humidity (80 °C and 100% humidity) for twelve weeks, in physiological buffer solutions for three weeks, and can survive overnight treatment of an oxidative solution (2% H2O2). The Ag@Au core-shell NWs demonstrated comparable performance as pristine AgNWs in various electronic, optical, and mechanical devices, such as transparent mesh electrodes, surface-enhanced Raman spectroscopy (SERS) substrates, plasmonic waveguides, plasmonic nanofocusing probes, and high-aspect-ratio, high-resolution atomic force microscopy (AFM) probes. These Au@Ag core-shell NWs offer a universal solution towards chemically-stable AgNW-based devices without compromising material property or device performance.展开更多
Ti_(3)C_(2) MXe ne servi ng as superior electrical con ductors prese nts more specific performa nee such as tran spar ency,con ductivity tha n gold(Au),and even could form a heterostructure with active materials of th...Ti_(3)C_(2) MXe ne servi ng as superior electrical con ductors prese nts more specific performa nee such as tran spar ency,con ductivity tha n gold(Au),and even could form a heterostructure with active materials of the functional devices.Here,a Ti_(3)C_(2) MXene-Te microplate van der Waals heterostructure based tran spare nt near-i nfrared photodetector(PD)is exploited.展开更多
Single-walled carbon nanotubes （SWNTs） possess high conductivity, mechanical strength, transparency, and flexibility, and are thus suitable for use in flexible electronics, transparent electrodes, and energy-storage...Single-walled carbon nanotubes （SWNTs） possess high conductivity, mechanical strength, transparency, and flexibility, and are thus suitable for use in flexible electronics, transparent electrodes, and energy-storage and energy-harvesting applications. However, to exploit these properties, SWNTs must be de-bundled in a surfactant solution to permit processing and use. We report a new method to prepare a SWNT-based transparent conducting film （TCF） using the diazo dye 3,3＇-（[1,1＇-biphenyl]-4,4＇-diyl）bis（4-amino naphthalene-1-sulfonic acid）, commonly known as Congo red （CR）, as a dispersant. Uniform 20-nm-thick TCFs were prepared on rigid glass and flexible polyethylene terephthalate （PET） substrates. The CR-SWNT dispersion and the CR-SWNT TCFs were characterized via UV-Vis-NIR, Raman spectroscopy, FT-IR spectroscopy, transmission electron microscopy （TEM）, field-emission scanning electron microscopy （FE-SEM） and dynamic light scattering （DLS） measurements. The sheet resistivity of the CRSWNT TCF was -34 ±6.6 Ω/□ with a transmittance of 81% at 550 nm, comparable to that of indium tin oxide-based films. Unlike SWNT dispersions prepared in common surfactants, such as sodium dodecyl sulfate （SDS）, sodium cholate （SC）, and Triton X-100, the CR-SWNT dispersion was amenable to forming TCF by drop coating. The CR-SWNT TCF was also very stable, maintaining a very low sheet resistivity even after 1,000 consecutive bending cycles of 8 mm bending radius. Further, manganese dioxide （MnO2） was electrochemically deposited on the CR-SWNT-PET film （MnO2-CR-SWNT-PET）. The as-prepared MnO2- CR-SWNT-PET electrode exhibited high specific capacitance and bendability, demonstrating promise as a candidate electrode material for flexible supercapacitors.展开更多
Oxide semiconductor alloys of x(LiGaO<SUB>2</SUB>)<SUB>1/2</SUB>-(1−x)ZnO were fabricated by the solid state reaction between β-LiGaO<SUB>2</SUB> and ZnO and rf-m...Oxide semiconductor alloys of x(LiGaO<SUB>2</SUB>)<SUB>1/2</SUB>-(1−x)ZnO were fabricated by the solid state reaction between β-LiGaO<SUB>2</SUB> and ZnO and rf-magnetron sputtering. For the solid state reaction, the wurtzite-type single phases were obtained in the composition range of x⩽0.38. The formation range of the alloys was wider than that of the (Mg<SUB>1−x </SUB>Zn<SUB> x </SUB>)O system, because the β-LiGaO<SUB>2</SUB> possesses a wurtzite-derived structure and approximately the same lattice constants with ZnO. The electrical resistivity and energy band gap of the 0.38(LiGaO<SUB>2</SUB>)<SUB>1/2</SUB>-0.62ZnO alloyed ceramic were 0.45 Ωcm and 3.7 eV, respectively, at room temperature. For the alloying by sputtering, the films consisting of the wurtzite-type single phase were obtained over the entire composition range of x(LiGaO<SUB>2</SUB>)<SUB>1/2</SUB>-(1−x)ZnO. The energy band gap was controllable in the range from 3.3 to 5.6 eV. For the as-deposited film fabricated using the 0.4(LiGaO<SUB>2</SUB>)<SUB>1/2</SUB>-0.6ZnO alloyed ceramic target, the energy band gap was 3.74 eV, and the electrical resistivity, carrier density and the Hall mobility at room temperature were 3.6 Ωcm, 3.4×10<SUP>17</SUP> cm<SUP>−3</SUP> and 5.6 cm<SUP>2</SUP> V<SUP>−1</SUP> s<SUP>−1</SUP>, respectively.展开更多
Flexible devices produced using organic materials have attracted the attention of many researchers. Important components of these flexible devices include transparent electrodes, which transmit visible light and posse...Flexible devices produced using organic materials have attracted the attention of many researchers. Important components of these flexible devices include transparent electrodes, which transmit visible light and possess conductivity. The present study improved the characteristics of a transparent conductive film that was made of poly(3, 4 ethylenedioxythiophene):poly(styrenesul-fonate) (PEDOT:PSS), an organic conductive material, and that had been prepared using ink-jet printing. To improve the resistance value and visible light transmittance of the film, the film substrate was first cleaned with ultraviolet/ozone treatment, and then the film was annealed after it was deposited on the substrate and dipped into a polar solvent. Consequently, the resistance value of the thin film decreased. However, the surface state of the film changed according to the treatment method and affected its visible light transmittance. Thus, the surface state of the film substrate, the annealing temperature after film deposition, and the dipping treatment with a polar solvent influenced the characteristics of a thin film.展开更多
Stretchable and transparent electrodes(STEs)based on silver nanowires(AgNWs)have garnered considerable attention due to their unique optoelectronic features.However,the low oxidation resistance of AgNWs severely limit...Stretchable and transparent electrodes(STEs)based on silver nanowires(AgNWs)have garnered considerable attention due to their unique optoelectronic features.However,the low oxidation resistance of AgNWs severely limits the reliability and durability of devices based on such STEs.The present work reports a type of core-sheath silver@gold nanowires(Ag@Au NWs)with a morphology resembling dual-headed matchsticks and an average Au sheath thickness of 2.5 nm.By starting with such Ag@Au NWs,STEs with an optical transmittance of 78.7%,a haze of 13.0%,a sheet resistance of 13.5Ω·sq.−1,and a maximum tensile strain of 240%can be formed with the aid of capillary-force-induced welding.The resultant STEs exhibit exceptional oxidation resistance,high-temperature resistance,and chemical/electrochemical stability owing to the conformal and dense Au sheath.Furthermore,non-enzymatic glucose biosensors are fabricated employing the Ag@Au NW STEs.The electrocatalytic oxidation currents are proportional to glucose concentrations with a high sensitivity of 967μA·mM−1·cm−2 and a detection limit of 125μM over a detection range of 0.6 to 16 mM.Additionally,the biosensors demonstrate an appealing robustness and antiinterference characteristics,high repeatability,and great stability that make them adequate for practical use.展开更多
A rapid,simple and cost-effective polyol method has been developed for the synthesis of silver nanowires with high aspect ratio and high purity.The aspect ratios of the silver nanowires as high as ca.1000(average leng...A rapid,simple and cost-effective polyol method has been developed for the synthesis of silver nanowires with high aspect ratio and high purity.The aspect ratios of the silver nanowires as high as ca.1000(average length 40μm and some even as long as 80μm,diameter 50-100 nm)were obtained via optimizing the reaction conditions.Transparent electrodes with excellent optoelectronic performances(optical transmittance of 90%,sheet resistance of 23.2Ω/□and optical transmittance of 87%,sheet resistance of 19.7Ω/□)comparable to commercial ITO were fab-ricated via simple spin coating the resulting silver nanowires onto the glass substrates.The high optoelectronic per-formances and the facile all-solution process of the as-prepared transparent electrodes render them rather promising candidates for use in cost-effective large-area optoelectronic devices.展开更多
Stretchable and conformal humidity sensors that can be attached to the human body for continuously monitoring the humidity of the environment around the human body or the moisture level of the human skin can play an i...Stretchable and conformal humidity sensors that can be attached to the human body for continuously monitoring the humidity of the environment around the human body or the moisture level of the human skin can play an important role in electronic skin and personal healthcare applications. However, most stretchable humidity sensors are based on the geometric engineering of non-stretchable components and only a few detailed studies are available on stretchable humidity sensors under applied mechanical deformations. In this paper, we propose a transparent, stretchable humidity sensor with a simple fabrication process, having intrinsically stretchable components that provide high stretchability, sensitivity, and stability along with fast response and relaxation time. Composed of reduced graphene oxide-polyurethane composites and an elastomeric conductive electrode, this device exhibits impressive response and relaxation time as fast as 3.5 and 7 s, respectively. The responsivity and the response and relaxation time of the device in the presence of humidity remain almost unchanged under stretching up to a strain of 60% and after 10,000 stretching cycles at a 40% strain. Further, these stretchable humidity sensors can be easily and conformally attached to a finger for monitoring the humidity levels of the environment around the human body, wet objects, or human skin.展开更多
Graphene with an exceptional combination of electronic, optical and outstanding mechanical features has been proved to lead a completely different kind of 2-D electronics. The most exciting feature of graphene is its ...Graphene with an exceptional combination of electronic, optical and outstanding mechanical features has been proved to lead a completely different kind of 2-D electronics. The most exciting feature of graphene is its ultra-thin thickness, that can be conformally contacted to any kind of rough surface without losing much of its transparency and conductivity. Graphene has been explored demonstrating various prototype flexible electronic applications, however, its potentiality has been proven wherever transparent conductive electrodes（TCEs） are needed in a flexible, stretchable format. Graphene-based TCEs in flexible electronic applications showed greatly superior performance over their conventionally available competitor indium tin oxide（ITO）. Moreover, enormous applications have been emerging, especially in wearable devices that can be potentially used in our daily life as well as in biomedical areas. However, the production of high-quality, defect-free large area graphene is still a challenge and the main hurdle in the commercialization of flexible and wearable products. The objective of the present review paper is to summarize the progress made so far in graphene-based flexible and wearable applications. The current developments including challenges and future perspectives arc also highlighted.展开更多
基金funded by the U.S.Department of Energy,Office of Science and Office of Basic Energy Sciences under Award No.DE-SC0001013.
文摘Silver nanowire films are promising alternatives to tin-doped indium oxide(ITO)films as transparent conductive electrodes.In this paper,we report the use of vacuum filtration and a polydimethylsiloxane(PDMS)-assisted transfer printing technique to fabricate silver nanowire films on both rigid and flexible substrates,bringing advantages such as the capability of patterned transfer,the best performance among various ITO alternatives(10Ω/sq at 85%transparency),and good adhesion to the underlying substrate,thus eliminating the previously reported adhesion problem.In addition,our method also allows the preparation of high quality patterned films of silver nanowires with different line widths and shapes in a matter of few minutes,making it a scalable process.Furthermore,use of an anodized aluminum oxide(AAO)membrane in the transfer process allows annealing of nanowire films at moderately high temperature to obtain films with extremely high conductivity and good transparency.Using this transfer technique,we obtained silver nanowire films on a flexible polyethylene terephthalate(PET)substrate with a transparency of 85%,a sheet resistance of 10Ω/sq,with good mechanical flexibility.Detailed analysis revealed that the Ag nanowire network exhibits two-dimensional percolation behavior with good agreement between experimentally observed and theoretically predicted values of critical volume。
基金supported by the National Natural Science Foundation for Distinguished Young Scholars of China(NSFC,61625404)the Key Research Program of Frontier Sciences,CAS(QYZDY-SSW-JWC004)the NSFC(61504136)
文摘The development of pressure sensors with highly sensitivity, fast response and facile fabrication technique is desirable for wearable electronics. Here, we successfully fabricated a flexible transparent capacitive pressure sensor based on patterned microstructured silver nanowires(AgNWs)/polydimethylsiloxane(PDMS) composite dielectrics. Compared with the pure PDMS dielectric layer with planar structures, the patterned microstructured sensor exhibits a higher sensitivity(0.831 kPa^-1, <0.5 kPa), a lower detection limit,good stability and durability. The enhanced sensing mechanism about the conductive filler content and the patterned microstructures has also been discussed. A 5×5 sensor array was then fabricated to be used as flexible and transparent wearable touch keyboards systems. The fabricated pressure sensor has great potential in the future electronic skin area.
基金This work was supported by the National Basic Research Program of China （Nos. 2015CB932500 and 2013CB632702） and the National Natural Science Foundation of China （No. 51302141）. H. W. acknowledges the support from the 1000 Youth Talents Plan of China.
文摘Transparent electrodes are essential components for optoelectronic devices such as displays and thin-film solar cells. Traditionally, the deposition of transparent conducting layers and the sealing of the device are separate steps. Here we report on a highly transparent, conductive, and flexible ＂tape＂, which can be obtained by transferring silver nanowire networks to conventional transparent tape. We utilized the viscidity of the tape to reduce the junction resistance between silver nanowires and further protect the nanowires from corrosion, oxidation and mechanical damage. By this simple method, we obtained a flexible tape with high transparency （-90% at 550 nm wavelength） and low sheet resistance （approaching 22 Ω.sq^-1）. The transparent tape can be attached and stuck firmly on complex surfaces, making the surface highly conductive. We demonstrated the use of the tape as both a conducting layer and a sealing layer for flexible electronics applications including in-situ temperature monitoring and electrochromic devices.
文摘Graphene oxide and silver nanowires were bar coated onto polyethylene terephthalate （PET） substrates and then welded using an ultraviolet （UV）-assisted flash light irradiation process to achieve both high electrical conductivity and low haze. The irradiation process connected adjacent silver nanowires by welding, while simultaneously reducing the graphene oxide to graphene. This process was performed using a custom W-assisted flash light welding system at room temperature under ambient conditions and was extremely rapid, with processing time of several milliseconds. The effects of varying the weight fractions of the silver nanowires and graphene oxide and of varying the W-assisted flash light welding conditions （light energy and pulse duration） were investigated. The surface morphologies of the welded silver nanowire/graphene films were analyzed using scanning electron microscopy. Optical characterizations, including transmittance and haze measurements, were also conducted using a spectrophotometer. To test their resistance to oxidation, the welded silver nanowire/graphene films were subjected to high temperature in a furnace （100 ℃）, and their sheet resistances were measured every hour. The flash light welding process was found to yield silver nanowire/graphene films with high oxidation resistance, high conductivity （14.35 Ω·sq-1）, high transmittance （93.46%）, and low haze （0.9%）. This material showed uniform temperature distribution when applied as a resistive heating film.
基金the National Natural Science Foundation of China(Grant No.51522503)the Program for New Century Excellent Talents in University(NCET-13-0175).
文摘Copper nanowires(Cu NWs)are considered an excellent alternative to indium tin oxide(ITO)in flexible transparency electrodes(FTEs).However,the mixed particles and surface oxidation of Cu NWs degrade the transmittance and conductivity of the electrodes.Therefore,highly purified Cu NWs without oxidation are vital for high-performance FTEs.Herein,a facile and effective purification process is introduced to purify Cu NWs in a water and n-hexane system,which takes advantage of the differences in hydrophilicity between Cu NWs and Cu NPs caused by their different adsorption affinities to octadecylamine(ODA).At the same sheet resistance,the transmittance of the purified Cu NW-based FTEs improved approximately 2%compared to that of non-purified Cu NW-based FTEs.Immersion of the electrode in glacial acetic acid removed the surface organics and oxides.After only 40 s of treatment,the sheet resistance dramatically decreased from 10^5 Ohm/sq to 31 Ohm/sq with a transmittance of 85%.In addition,the Cu NW-based FTE conductors showed excellent flexibility(remaining stable after 1000 bending cycles).The Cu NW-based FTEs were further applied to fabricate a flexible transparent heater.At a voltage of 10 V,the temperature of the heater reached 73℃,demonstrating the potential applications of this material in various fields.
基金Financial support from the University Grants Commission ofIndia through the Major Research Project(F.No.40-28/2011(SR))the DST Grant(D.O.No.SR/S2/CMP-35/2004)
文摘Aluminium doped tin oxide films have been deposited onto glass substrates by using a simplified and low cost spray pyrolysis technique. The AI doping level varies between 0 and 30 at.% in the step of 5 at.%. The resistivity （p） is the minimum （0.38 Ω cm） for 20 at.% of AI doping. The possible mechanism behind the phenomenal zig-zag variation in resistivity with respect to AI doping is discussed in detail. The nature of conductivity changes from n-type to p-type when the AI doping level is 10 at.%. The results show that 20 at.% is the optimum doping level for good quality p-type SnO2：AI films suitable for transparent electronic devices.
基金This work was supported by the Ministry of Science&ICT(MSIT)and the Ministry of Trade,Industry and Energy(MOTIE)of Korea through the National Research Foundation(2019R1A2B5B03069358,2016R1A5A1009926)the Bio&Medical Technology Development Program(2018M3A9F1021649),the Nano Material Technology Development Program(2015M3A7B4050308 and 2016M3A7B4910635)the Industrial Technology Innovation Program(10080577).Also,the authors thank financial support by the Institute for Basic Science(IBS-R026-D1)and the Research Program(2018-22-0194)funded by Yonsei University.All in-vivo studies were conducted according to the guidelines of the National Institutes of Health for care and use of laboratory animals and with the approval of the Institute of Animal Care and Use Committee of UNIST(UNISTIACUC-16-19).
文摘Light-mediated therapeutics have attracted considerable attention as a method for the treatment of ophthalmologic diseases,such as age-related macular degeneration,because of their non-invasiveness and the effectiveness to ameliorate the oxidative stress of retinal cells.However,the current phototherapeutic devices are opaque,bulky,and tethered forms,so they are not feasible for use in continuous treatment during the patient’s daily life.Herein,we report wireless,wearable phototherapeutic devices with red light-emitting diodes for continuous treatments.Red light-emitting diodes were formed to be conformal to three-dimensional surfaces of glasses and contact lenses.Furthermore,fabricated light-emitting diodes had either transparency or a miniaturized size so that the user’s view is not obstructed.Also,these devices were operated wirelessly with control of the light intensity.In addition,in-vitro and in-vivo tests using human retinal epithelial cells and a live rabbit demonstrated the effectiveness and reliable operation as phototherapeutic devices.
基金This material is based upon work supported by the National Science Foundation under gant No.CHE-1654794.The authors acknowledge Prof.Yadong Yin from the Department of Chemistry,UC Riverside for helpful discussion.
文摘Silver nanowires (AgNWs) hold great promise for applications in wearable electronics, flexible solar cells, chemical and biological sensors, photonic/plasmonic circuits, and scanning probe microscopy (SPM) due to their unique plasmonic, mechanical, and electronic properties. However, the lifetime, reliability, and operating conditions of AgNW-based devices are significantly restricted by their poor chemical stability, limiting their commercial potentials. Therefore, it is crucial to create a reliable oxidation barrier on AgNWs that provides long-term chemical stability to various optical, electrical, and mechanical devices while maintaining their high performance. Here we report a room-temperature solution-phase approach to grow an ultra-thin, epitaxial gold coating on AgNWs to effectively shield the Ag surface from environmental oxidation. The Ag@Au core-shell nanowires (Ag@Au NWs) remain stable in air for over six months, under elevated temperature and humidity (80 °C and 100% humidity) for twelve weeks, in physiological buffer solutions for three weeks, and can survive overnight treatment of an oxidative solution (2% H2O2). The Ag@Au core-shell NWs demonstrated comparable performance as pristine AgNWs in various electronic, optical, and mechanical devices, such as transparent mesh electrodes, surface-enhanced Raman spectroscopy (SERS) substrates, plasmonic waveguides, plasmonic nanofocusing probes, and high-aspect-ratio, high-resolution atomic force microscopy (AFM) probes. These Au@Ag core-shell NWs offer a universal solution towards chemically-stable AgNW-based devices without compromising material property or device performance.
基金This work was supported by the National Natural Science Foundation of China(No.61888102).
文摘Ti_(3)C_(2) MXe ne servi ng as superior electrical con ductors prese nts more specific performa nee such as tran spar ency,con ductivity tha n gold(Au),and even could form a heterostructure with active materials of the functional devices.Here,a Ti_(3)C_(2) MXene-Te microplate van der Waals heterostructure based tran spare nt near-i nfrared photodetector(PD)is exploited.
文摘Single-walled carbon nanotubes （SWNTs） possess high conductivity, mechanical strength, transparency, and flexibility, and are thus suitable for use in flexible electronics, transparent electrodes, and energy-storage and energy-harvesting applications. However, to exploit these properties, SWNTs must be de-bundled in a surfactant solution to permit processing and use. We report a new method to prepare a SWNT-based transparent conducting film （TCF） using the diazo dye 3,3＇-（[1,1＇-biphenyl]-4,4＇-diyl）bis（4-amino naphthalene-1-sulfonic acid）, commonly known as Congo red （CR）, as a dispersant. Uniform 20-nm-thick TCFs were prepared on rigid glass and flexible polyethylene terephthalate （PET） substrates. The CR-SWNT dispersion and the CR-SWNT TCFs were characterized via UV-Vis-NIR, Raman spectroscopy, FT-IR spectroscopy, transmission electron microscopy （TEM）, field-emission scanning electron microscopy （FE-SEM） and dynamic light scattering （DLS） measurements. The sheet resistivity of the CRSWNT TCF was -34 ±6.6 Ω/□ with a transmittance of 81% at 550 nm, comparable to that of indium tin oxide-based films. Unlike SWNT dispersions prepared in common surfactants, such as sodium dodecyl sulfate （SDS）, sodium cholate （SC）, and Triton X-100, the CR-SWNT dispersion was amenable to forming TCF by drop coating. The CR-SWNT TCF was also very stable, maintaining a very low sheet resistivity even after 1,000 consecutive bending cycles of 8 mm bending radius. Further, manganese dioxide （MnO2） was electrochemically deposited on the CR-SWNT-PET film （MnO2-CR-SWNT-PET）. The as-prepared MnO2- CR-SWNT-PET electrode exhibited high specific capacitance and bendability, demonstrating promise as a candidate electrode material for flexible supercapacitors.
文摘Oxide semiconductor alloys of x(LiGaO<SUB>2</SUB>)<SUB>1/2</SUB>-(1−x)ZnO were fabricated by the solid state reaction between β-LiGaO<SUB>2</SUB> and ZnO and rf-magnetron sputtering. For the solid state reaction, the wurtzite-type single phases were obtained in the composition range of x⩽0.38. The formation range of the alloys was wider than that of the (Mg<SUB>1−x </SUB>Zn<SUB> x </SUB>)O system, because the β-LiGaO<SUB>2</SUB> possesses a wurtzite-derived structure and approximately the same lattice constants with ZnO. The electrical resistivity and energy band gap of the 0.38(LiGaO<SUB>2</SUB>)<SUB>1/2</SUB>-0.62ZnO alloyed ceramic were 0.45 Ωcm and 3.7 eV, respectively, at room temperature. For the alloying by sputtering, the films consisting of the wurtzite-type single phase were obtained over the entire composition range of x(LiGaO<SUB>2</SUB>)<SUB>1/2</SUB>-(1−x)ZnO. The energy band gap was controllable in the range from 3.3 to 5.6 eV. For the as-deposited film fabricated using the 0.4(LiGaO<SUB>2</SUB>)<SUB>1/2</SUB>-0.6ZnO alloyed ceramic target, the energy band gap was 3.74 eV, and the electrical resistivity, carrier density and the Hall mobility at room temperature were 3.6 Ωcm, 3.4×10<SUP>17</SUP> cm<SUP>−3</SUP> and 5.6 cm<SUP>2</SUP> V<SUP>−1</SUP> s<SUP>−1</SUP>, respectively.
文摘Flexible devices produced using organic materials have attracted the attention of many researchers. Important components of these flexible devices include transparent electrodes, which transmit visible light and possess conductivity. The present study improved the characteristics of a transparent conductive film that was made of poly(3, 4 ethylenedioxythiophene):poly(styrenesul-fonate) (PEDOT:PSS), an organic conductive material, and that had been prepared using ink-jet printing. To improve the resistance value and visible light transmittance of the film, the film substrate was first cleaned with ultraviolet/ozone treatment, and then the film was annealed after it was deposited on the substrate and dipped into a polar solvent. Consequently, the resistance value of the thin film decreased. However, the surface state of the film changed according to the treatment method and affected its visible light transmittance. Thus, the surface state of the film substrate, the annealing temperature after film deposition, and the dipping treatment with a polar solvent influenced the characteristics of a thin film.
基金The authors acknowledge financial support from National Natural Science Foundation of China(Nos.52073026 and U20A20264).
文摘Stretchable and transparent electrodes(STEs)based on silver nanowires(AgNWs)have garnered considerable attention due to their unique optoelectronic features.However,the low oxidation resistance of AgNWs severely limits the reliability and durability of devices based on such STEs.The present work reports a type of core-sheath silver@gold nanowires(Ag@Au NWs)with a morphology resembling dual-headed matchsticks and an average Au sheath thickness of 2.5 nm.By starting with such Ag@Au NWs,STEs with an optical transmittance of 78.7%,a haze of 13.0%,a sheet resistance of 13.5Ω·sq.−1,and a maximum tensile strain of 240%can be formed with the aid of capillary-force-induced welding.The resultant STEs exhibit exceptional oxidation resistance,high-temperature resistance,and chemical/electrochemical stability owing to the conformal and dense Au sheath.Furthermore,non-enzymatic glucose biosensors are fabricated employing the Ag@Au NW STEs.The electrocatalytic oxidation currents are proportional to glucose concentrations with a high sensitivity of 967μA·mM−1·cm−2 and a detection limit of 125μM over a detection range of 0.6 to 16 mM.Additionally,the biosensors demonstrate an appealing robustness and antiinterference characteristics,high repeatability,and great stability that make them adequate for practical use.
基金support from the National Key Basic Research Program of China (973 Program,2014CB648300)the National Natural Science Foundation of China (21422402,20904024,51173081,61136003,61106036)+7 种基金the Natural Science Foundation of Jiangsu Province (BK20140060,BK20130037,BK2011760)Program for New Century Excellent Talents in University (NCET-13-0872)Specialized Research Fund for the Doctoral Program of Higher Education (20133223110008)the Ministry of Education of China (IRT1148)the NUPT Scientific Foundation (NY213119)the Priority Academic Program Development of Jiangsu Higher Education Institutions (PAPD)the Six Talent Plan (2012XCL035)Qing Lan Project of Jiangsu Province.
文摘A rapid,simple and cost-effective polyol method has been developed for the synthesis of silver nanowires with high aspect ratio and high purity.The aspect ratios of the silver nanowires as high as ca.1000(average length 40μm and some even as long as 80μm,diameter 50-100 nm)were obtained via optimizing the reaction conditions.Transparent electrodes with excellent optoelectronic performances(optical transmittance of 90%,sheet resistance of 23.2Ω/□and optical transmittance of 87%,sheet resistance of 19.7Ω/□)comparable to commercial ITO were fab-ricated via simple spin coating the resulting silver nanowires onto the glass substrates.The high optoelectronic per-formances and the facile all-solution process of the as-prepared transparent electrodes render them rather promising candidates for use in cost-effective large-area optoelectronic devices.
文摘Stretchable and conformal humidity sensors that can be attached to the human body for continuously monitoring the humidity of the environment around the human body or the moisture level of the human skin can play an important role in electronic skin and personal healthcare applications. However, most stretchable humidity sensors are based on the geometric engineering of non-stretchable components and only a few detailed studies are available on stretchable humidity sensors under applied mechanical deformations. In this paper, we propose a transparent, stretchable humidity sensor with a simple fabrication process, having intrinsically stretchable components that provide high stretchability, sensitivity, and stability along with fast response and relaxation time. Composed of reduced graphene oxide-polyurethane composites and an elastomeric conductive electrode, this device exhibits impressive response and relaxation time as fast as 3.5 and 7 s, respectively. The responsivity and the response and relaxation time of the device in the presence of humidity remain almost unchanged under stretching up to a strain of 60% and after 10,000 stretching cycles at a 40% strain. Further, these stretchable humidity sensors can be easily and conformally attached to a finger for monitoring the humidity levels of the environment around the human body, wet objects, or human skin.
基金supported by the National Research Foundation of Korea(No.NRF-2015R1A3A2066337)
文摘Graphene with an exceptional combination of electronic, optical and outstanding mechanical features has been proved to lead a completely different kind of 2-D electronics. The most exciting feature of graphene is its ultra-thin thickness, that can be conformally contacted to any kind of rough surface without losing much of its transparency and conductivity. Graphene has been explored demonstrating various prototype flexible electronic applications, however, its potentiality has been proven wherever transparent conductive electrodes（TCEs） are needed in a flexible, stretchable format. Graphene-based TCEs in flexible electronic applications showed greatly superior performance over their conventionally available competitor indium tin oxide（ITO）. Moreover, enormous applications have been emerging, especially in wearable devices that can be potentially used in our daily life as well as in biomedical areas. However, the production of high-quality, defect-free large area graphene is still a challenge and the main hurdle in the commercialization of flexible and wearable products. The objective of the present review paper is to summarize the progress made so far in graphene-based flexible and wearable applications. The current developments including challenges and future perspectives arc also highlighted.
