| With the rise of nanotechnology and printing electronics technology,electronic devices continue to develop in the direction of flexibility and wearable.Flexible electronics have become one of the forefront of research in academia and industry,they have set off a new electronic technology revolution around the world.As the core component of flexible devices,the performance and reliability of flexible transparent conductive films(TCFs)will determine the application range and service life of flexible devices,so the preparation of high performance and high reliability flexible conductive films is of great significance to promote the development of flexible electrons.Because silver nanowire(Ag NW)conductive film has excellent photoelectric properties,it is considered to be an ideal material for flexible devices.However,the performance of Ag NW conductive films will gradually deteriorate during working period,and its poor long-term work stability can easily lead to failure of device.In order to promote the large-scale application of Ag NWs conductive films,it is urgent to develop a simple,convenient and effective reliability enhancement technology.In this paper,the Ag NW TCFs prepared by electroplating method were put forward,and the effective connection between silver nanowires was realized by electroplating the protective layer on the surface of silver nanowires.The contact resistance between nanowires was reduced,and the thermal stability,chemical stability and mechanical stability of conductive films are greatly enhanced,and the high performance and reliable flexible conductive film was fabricated.Finally,the electroplated TCFs were successfully applied to wearable heating devices and flexible trackpad.The application range of Ag NW TCFs in flexible and wearable electrons was broadened.The growth mechanism of Ag NWs was analyzed,the ion regulation mechanism of anisotropic nucleation and directional growth for Ags is expounded.The main factors affecting the growth process of silver nanowires are systematically studied,and the role of different parameters in different growth stages of silver nanowires was clarified.It was found that the reaction temperature affected the reduction speed of silver and the growth rate of nanowires,the ion concentration affected the nucleation velocity of silver and the length of nanowires,and the interaction between oxygen and solution ions promoted silver nuclei in the nucleation stage and hindered the growth of nanowires in the growth stage,while the concentration of PVP concentration affected the final diameter of nanowires.The synthetic Ag NWs were characterized by transmission electron microscope(TEM),and it was made clear that the Ag NWs were a prism-prism five-rotational symmetric structure.The outer surfaces were {100} and {111},and the twin surface was {111},while the gap between the twin surfaces was composed of the twin band and the layer fault.According to the growth characteristics of Ag NWs,the reagent parameters and reaction conditions were tuned,and the Ag NWs with maximum average length up to 100 ?m were successfully manufactured.The eectroplating method was applied to the nano-scale connection,and the electroplating method was proposed for preparing Ag NWs based TCFs,which realizes the fast connection of the Ag NW mesh on the PET substrate at atmospheric environment.The effect of enhanced coating on the transmittance of transparent conductive film was avoided as the selective deposition of the coating layer.The transmittance of transparent conductive film with electroplated Ag NW TCFs was greater than 85% with the sheet resistance lower than 10 ?/sq.Based on NernstEinstein equation and Tohru's theory,the relationship between electroplating current and coating morphology was expounded from crystal growth and electroplating electrode electric field conditions: The larger the electroplating current,the lower the surface roughness of the coated grain,but the limit current was controlled by the concentration of the plating solution.Exceeding the limit current would cause the coating morphology out of control.Considering the lattice matching problem between the coating and the substrate,the lattice coordination relationship between different materials was understand: the lattice of the nickel layer and the silver body was matched with the(111)surface,the mismatch degree was 15.98%,but there was no lattice mismatch problem between the silver layer and the silver body.Therefore,the growth mechanism of silver plating layer and nickel plating layer on the surface of Ag NWs was different: the growth mode of nickel layer is based on S-K mode(mixed growth),while the growth of silver layer is based on F-M mode(layered growth),which leads to difference microscopic morphology of different coating materials.The nickel plating layer effectively improved the long-term working stability of the nanowire conductive film.The thermal stability,anti-electrochemical migration performance,antioxidant properties,mechanical stability and long-term storage stability of the TCFs were greatly improved comparing with the pure Ag NWs based TCFs and the plated-Ag nanowire based TCFs.The Rayleigh instability of Ag NWs made them unstable under high temperatures.But the thermal stability of Ag NWs was significantly improved after nickel plating,and there was no significant change in the morphology of the nanowires after heating under 200 ?.Nickel plating can form a dense oxide layer in the air,that prevent the internal Ag NWs from erosion of the external environment,nickel plated(plated-Ni)TCFs in NaCl solution survived after 1000 s without significant change of resistance.In the anti-electrochemical migration test,TCFs based on pure Ag NWs with a diameter of 125 nm was faliure only after 1.64 s,but the working time of plated-Ni TCFs was increased to 453.70 s.After electroplating,tight connections between Ag NWs were formed,then the mechanical stability of TCFs was been improved,the resistance of the TCFs was still stable after 4000 times cyclic bending.After three months storage,the transmittance of plated-Ni TCFs was not changed significantly,and the content of sulfur elements in the TCFs still remained low.The plated nickel layer had effectively avoided the oxidation and vulcanization problems of Ag NWs occurring during the long-term storage process.Wearable heating devices and flexible trackpad were prepared by using electoplated TCFs.The maximum working temperature of plated-Ni flexible heater can reach to 170 ?.After long time power test and 145 cycles on-off test,the heater can still work steady showing thier high stability.The flexible transparent trackpad prepared by plated-Ag TCFs has good flexibility and can realize the input of text and graphics in the bending state.It can be predicted that the electroplated TCFs have a broad application prospect in the field of flexible electronics. |
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