Filter Cloth Brushing Method To Prepare Large-size Silver Nanowire Transparent Conductive Film

Transparent conductive films have always attracted the interest of researchers because of their wide application in touch screens,light-emitting diodes,sensors,solar cells and transparent heaters.Today,the main transparent conductive film on the market is indium-doped tin oxide(ITO)coated on flexible substrates.However,the brittle nature of ITO transparent conductive film,the shortage of indium resources,high cost,yellowing and other shortcomings limit its application in the future fields of electronic devices in the future,especially in the field of flexible electronic devices.Silver nanowires have high thermal conductivity and electrical conductivity,and transparent conductive films prepared from them exhibit high optical transmittance,electrical conductivity,thermal conductivity and mechanical flexibility,which is a very promising ITO alternative material.Although many articles have reported on the preparation methods of transparent silver nanowire electrodes with superior performance,the uniformity of silver nanowire conductive films is relatively low.The standard deviation of the thin layer resistance value and average value is up to 30% or even higher,so improving the uniformity of silver nanowires has become a very urgent issue.At the same time,whether the distribution of silver nanowires is uniform is also a main factor that affects the photoelectric performance of transparent conductive films.The poor uniformity of the block resistance of the thin film will limit the application of silver nanowire transparent conductive thin film as a transparent electrode device.The traditional brushing method to prepare Ag NWs conductive film has the advantages of simple and easy and low cost,however,due to the limit of the amount of brush dipped in conductive ink,it is difficult to achieve continuous replenishment of solution and prepare a film with large area and high uniformity.Therefore,this paper proposes a method for preparing a film by brushing a filter cloth in order to coat a transparent conductive film with uniform resistance of silver nanowires.The specific works are as follows:(1)The filter cloth brushing method uses nylon filter cloth folded in half as brushing medium,mixes silver nanowires and hydroxypropyl methylcellulose(HPMC)solution as conductive ink.Then uses 3D printer to control the mobile brushing of the filter cloth to prepare silver nanowires conductive film realizing the continuous supply of conductive ink through automatic liquid supply by syringe pump to improve the uniformity of the film.The influence of different silver nanowire concentrations,different HPMC dispersion concentrations,brushing speed,different filter cloth pore sizes,syringe pump supply speed and other process parameters on the photoelectric properties of conductive films was explored,and Ag NWs transparent conductive films with good photoelectric properties were prepared.(2)High-uniformity silver nanowire conductive films were prepared on large-area PDMS flexible substrates and paper substrates.Different flexible substrates have different surface structures and need to be matched with different supply speeds.The influence of liquid supply speed on PDMS,printing paper and white cardboard substrate on the conductivity and uniformity of silver nanowire films was explored,the optimal liquid supply rate was determined,and a uniform large-area silver nanowire film was prepared.(3)Preparation and performance analysis of silver nanowire conductive thin film heater.Silver nanowire conductive thin film heaters were prepared on glass,PDMS and printer paper substrates to analyze the heating performance,switching repeatability,environmental stability and mechanical stability of the heaters.