Pulsed Electrochemical Preparation And Electrochromic Application Of WO₃ Nanofilms

Electrochromism is the phenomenon that a material can change its optical properties continuously and reversibly within a certain voltage window.Electrochromism devices(ECDs)consume no energy other than the color/fade state switch.Therefore,electrochromic technology has attracted wide attention in many promising application fields such as energy-saving information display,smart window and rearview mirror.Although considerable progress has been made in both theoretical and practical applications of ECD in recent years,the rapid development of modern ECD not only more relies on advanced manufacturing techniques but also puts higher requirements on the quality and function of electrochromic films.Thus,ECD still presents significant performance challenges in terms of greater optical control,shorter switching times,long-term cyclic stability in different environments,and lighter,thinner,and better mechanical flexibility.Based on this,this paper introduced Ag nanofibers to replace the traditional rigid conductive substrate as the flexible electrode of ECD,and innovatively constructed a flexible and transparent conductive substrate of WO3/Ag nanofibers/WO3/PET(W/Ag NFs/W/PET).Then,the porous WO3 film was deposited on the surface of the flexible electrode by pulse electrodeposition method and applied to the all-solid flexible ECD for electrochromic lens,etc.The specific research results are as follows:(1)W/Ag NFs/W/PET transparent electrode with sandwich structure was prepared by electrostatic spinning and magnetron sputtering technology.It has high transmission rate(90.0%),high conductivity(6.3 ?/sq),high mechanical flexibility and anti-oxidation corrosion required by modern flexible electrochromic equipment,and can also be used in the electrochemical deposition field where there is a blank in the preparation of flexible devices(2)Based on the optimal conductive substrate,WO3 composite electrodes with uniform,lamellar porosity were prepared by pulse electrochemical deposition.Its lamellar porous structure expands the micro specific surface area of contact between the electrochromic layer and the electrolyte,and prevents the ions from causing expansion of the main material during the embedding of WO3 layer and affecting the cycling stability of the whole electrode.At the wavelength of 633.0 nm,the optical contrast of the color-changing film is 90%.More importantly,WO3 electrode with high mechanical flexibility can suffer± 1800° bending for 400 times under curvature radius of 2.0 mm,after that,maintaining stability of the optical contrast.(3)Based on the optimal W03 composite electrode,we applied it to all solid state electrochromic sunglasses and smart windows.Under different operating voltages,the ECDs carried out optical state switching uniformly.