Preparation And Properties Of Transparent Electrode And Electrochromic Device Based On Silver Nanowire

Flexible devices have been widely studied for their low cost,low energy consumption,and environmental protection.Flexible electrodes are an integral part of flexible electronic devices.Research and development of high-performance flexible conductive materials play an important role in the development of flexible devices.Silver nanowires(AgNWs),as a new type of nanomaterials,have high electrical conductivity,excellent optical properties and good flexibility,and have become a research hotspot in the field of flexible conductive film materials at domestic and overseas.In this thesis,AgNWs were synthesized by using polyol method,silver nitrate and ethylene glycol as raw materials.AgNWs conductive films were prepared on glass and flexible substrate by drop-coating and filtration transfer method.The electrochromic devices(ECDs)were assembled from electrochromic gel.The influencing factors of the light transmittance and conductivity of the AgNWs electrode and performance of ECDs were investigated.The main research contents were as follows:(1)AgNWs were synthesized by polyol method using ethylene glycol and silver nitrate as raw materials.The effects of stirring mode,reaction time,concentration of control agent,type of control agent,molecular weight and addition amount of surfactant and on the morphology of AgNWs were studied.The structure and morphology of AgNWs were characterized by X-ray diffraction,Fourier transform infrared spectrometer and scanning electron microscopy.The results showed that after magnetic stirring,the diameter of the AgNWs few changed,but the length of the AgNWs became shorter and nanoparticles increased.With the increase of reaction time,the length and diameter of AgNWs increased gradually.With the increase of control agent concentration,the diameter of AgNWs increased,and a small number of particles and short nanorods are generated.With the increase of content of single polyvinylpyrrolid(PVP),the diameter of AgNWs decreased first and then increased.With mixed PVP with different molecular weight as surfactant,sodium bromide(NaBr)as the control agent,reaction temperature was 160?,reaction time was 20 min,concentration of NaBr was 0.02mol/L,the diameter of AgNWs was minimum(about 25nm).(2)The synthesized AgNWs were prepared into dispersion,and the transparent conductive film was prepared by a drop-coating and filtration transfer methods(FTM)on the glass substrate.The effects of concentration of AgNWs dispersion and the number of film layers on the transmittance and electrical resistance of conductive films were discussed.The changes of transmittance and resistance of conductive films under vacuum heating,drying heating,UV irradiation and natural placement were measured by Uv-vis spectrophotometer and digital multimeter.The results showed that the transparent electrode prepared by drop-coating,when the concentration of dispersion was 2.5mg/mL,layer number was 8,the transmittance of electrode through was 68%,and it's resistance was 78?;For transparent electrode prepared by FTM,when the synthesis reaction time of AgNWs was 3h,the concentration of dispersion was 0.002mol/L,the transmittance of electrode reached to 80%,and it's resistance was 47?;Under the conditions of vacuum heating,drying heating,ultraviolet irradiation and natural placement,the transmittance of electrode decreased slightly with time.Through the analysis of the resistance change of conductive electrode under different conditions,it was found that the stability of electrode was best in the environment of vacuum heating.(3)The electrochromic gel was prepared by adding ethyl viologen diperchlorate or ferrocene into polymer gel electrolyte,and was used as an electrochromic layer.The ECD was assembled with the gel and ITO electrode,and it properties was investigated.The results showed that the device prepared with the composite electrochromic gel of ethyl viologen diperchlorate and ferrocene had better performance.It changed from colorless to light blue when the voltage increased from 0V to +3V.The change of transmittance at 605 nm was 28%,and the coloration time and bleaching time were 0.1s and 0.3s,respectively.The AgNWs dispersion(1mg/mL,0.2mL)was transferred to a flexible polydimethylsiloxane(PDMS)substrate by FTM to prepare transparent electrode.Its transmittance was 83% and the resistance was 78?.The flexible electrode and composite gel were assembled into ECD,its performance was studied.It was found that the flexible device changed from light yellow to dark blue under when the voltage from 0V to +3V,and its optical contrast was 0.534.