| Transparent conductive film(TCF)is an important part of organic light-emitting diodes,touch screens,organic solar cells and other optoelectronic devices,and has received widespread attention.Although indium tin oxide(ITO)is the most common commercially available material,it has lots of problems such as high brittleness,high temperature required for the manufacturing process and indium scarcity.The silver nanowires(Ag NWs)have optical transmittance> 90% when sheet resistance <50 ?/sq.It has the advantage of being flexible and without high temperature in the preparation process and is expected to become an alternative material for ITO.The silver nanowire transparent conductive films(Ag NWs-TCFs)can be prepared by dissolving the Ag NWs in an organic solvent,However,how to solve the key problems such as improving the light transmittance of the TCFs,reducing the contact resistance between the Ag NWs and enhancing the patterning performance of the TCFs is still a hot issue in the current research.In order to solve these problems,this work designed to build a nano-silica layer on the TCFs,and a detailed study of its impact on transmittance,sheet resistance and laser etching.Considered of the problem that it is difficult to simultaneously improve the transmittance and the conductivity,it was proposed that a silica layer be formed on the surface of the Ag NWs-TCFs by using nano-silica can improve the light transmittance of the TCFs and reduce the sheet resistance.Nano-silica colloid was prepared by St?ber method,and the influence of the amount of tetraethyl orthosilicate(TEOS),ammonia,water and ethanol on the size and particle size distribution of the product was discussed in detail.Then we analyzed the process of agglomeration of silica with increasing particle size.It is found that with the increase of ammonia dosage,the particle size of the product first decreases and then increases.And as the particle size increases,spherical protrusions form on the surface of the nanoparticles to cause agglomeration.The silica with a size range of 20-200 nm is achieved.The prepared nano-silica colloid was used to build a silica layer on the Ag NWs-TCFs by the dip-coating method,and we analyzed the effects of size and concentration of silica on the morphology of conductive films in detail.Nano-silica can form a dense silica layer which has a significant increase in the transmittance when its thickness is 112 nm,like an anti-reflective film.At the same time,the interaction of the surface groups of Ag NWs and Si O2 can reduce the contact resistance between Ag NWs,to achieve the effect of increasing the transmittance and reducing the sheet resistance.When the particle size is 20 nm and the concentration is 20%,the silica layer has the best performance.The transmittance is as high as 91.2%(including 90.2% of the substrate),when sheet resistance is 25 ?/sq.The transmittance increased 4.1% in comparison to Ag NW-coated PET.To solve the problem that the PET substrate easily ablates at high temperature during the patterning process of the Ag NWs-TCFs,this work studied the response of the Si O2 layer to laser and the protective effect of Si O2 layer on the substrate.The difference of laser etching distance will affect the transmittance of Ag NWs-TCFs after patterning,and the transmittance decreased 7.4% when the etching distance is 0.05 mm.But the transmittance decreased only 1.4% after coating with nano-silica,due to the silica layer can effectively protect the integrity of the substrate during etching.The effects of nano-silica on the TCFs at different laser engraving parameters were analyzed in detail.The best laser etching parameters is the speed in 100 mm/s,frequency in 30 k Hz,power in 12 W for the PET substrate conductive film.After etching a diamond line,a touch device was successfully fabricated with the transmittance is 90.5%(including the substrate)at 550 nm.Finally we demonstrated the touch function of the device through the touch coordinate demo test software. |
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