Preparation And Performance Study Of SiO_x/AgNWs Nanocomposite Electrodes Based On Perhydropolysilazane

With the development of technology,flexible foldable and wearable devices are gradually coming into people’s life,of which flexible transparent electrodes are an indispensable key component of flexible electronic devices.Indium Tin Oxide(ITO)is the most commonly used transparent electrode nowadays,but ITO itself is brittle and not suitable for application in flexible devices.Among many new transparent electrode materials,silver nanowires(AgNWs)are the most competitive alternative to ITO transparent electrodes because of their superior optoelectronic properties,high flexibility and easy preparation process.However,AgNWs transparent electrodes also have the problems of poor stability and weak adhesion to substrates.In this thesis,we propose a method to prepare SiO_x/AgNWs composite electrode by using transparent and dense SiO_x prepared by conversion of perhydropolysilazane(PHPS)as a protective layer and compounding it with AgNWs network to achieve a significant improvement in electrode stability and interfacial adhesion without affecting transparency and conductivity.stability and interfacial adhesion without affecting the transparency and conductivity.In this paper,we firstly investigated the relationship between the composite electrode preparation process and its basic structure and properties,and then studied the stability and mechanical properties of the composite electrode as follows.(1)Preparation of SiO_x/AgNWs nanocomposite electrodes based on PHPS precursors.The AgNWs network with a permeability of 84%,a square resistance of10.99Ω/sq,and a surface roughness Ra of 36 nm was prepared by screening the size of AgNWs and its dispersion concentration;subsequently,the PHPS coating was prepared by spin-coating or scraping process on the AgNWs network,and the SiO_x/AgNWs coating transformed by PHPS under low-temperature UV irradiation,hygrothermal treatment and high-temperature annealing conditions was investigated.The effect of the coating on the basic properties of SiO_x/AgNWs composite electrode was investigated,where the best transformation process was low-temperature 254 nm UV irradiation,and the resulting composite electrode had a transmittance of 85%,a square resistance of 10.93Ω/sq,and a surface roughness Ra of 2.67 nm.(2)Stability study of SiO_x/AgNWs composite electrode.The high-temperature thermal stability,UV irradiation resistance,chemical resistance,humidity stability and mechanical stability of the SiO_x/AgNWs composite electrode were systematically investigated.The results showed that the SiO_x prepared by PHPS conversion effectively inhibited the diffusion of silver atoms on the surface of AgNWs,which enabled the composite electrode to work stably at 600℃.Meanwhile,the dense structure of SiO_x can effectively block the contact between AgNWs and water vapor,oxygen and other chemicals,which ensures that the SiO_x/AgNWs composite electrode can work stably under 254 nm UV irradiation for 360 min,302 nm mercury lamp irradiation for 360 h,high temperature and high humidity conditions(80℃/90%RH)for 15 days,1 M hydrochloric acid and 5 wt%sodium sulfide solution immersion for360 min,and ethanol,acetone and sodium sulfide solution immersion for 360 min.The properties remained stable after 360 min,and 72 h of immersion in ethanol,acetone,and isopropanol reagents.In addition,the results of mechanical property tests show that the composite electrode has excellent flexibility,interfacial adhesion and scratch resistance,and its relative resistance is basically unchanged after bending inward for3000 times at a bending radius of 2.5 mm,10 times peeling test with 3M tape and 9H pencil test.