Growth And Electrochromic Properties Of Transition Metal Oxide Nano "Core-shell" Structure Films Based On Ag Doped WO₃

As transition metal oxide(TMO)materials,WO₃?TiO₂?MoO₃?V₂O₅and Ta₂O₅have been widely studied for their electrochromic properties.However,each of these metal oxide materials has its own advantages and disadvantages in terms of electrochromic performance.Therefore,it is an effective way to improve the electrochromic performance to realize the complementary performance by means of structural composition.In addition,the compact physical structure and smooth surface morphology of pure TMO films reduce the ion diffusion efficiency as electrochromic films,and their special crystal structure will greatly limit the rate of ion implantation/extraction.Therefore,in this study,by magnetron sputtering method,Ag doping was used to induce the preparation of WO₃nanoparticles as a"core"layer,and on this basis,other TMO films were prepared to form a"core-shell"type nanocomposite structure.The advantages of this structure lie in that the oxygen vacancy defect is provided by the doping of Ag metal,and the near-infrared modulation is realized by the local surface plasmonic resonance effect.Nanoparticles can improve ion transport efficiency and increase reaction sites.The band gap of"core-shell"nanoparticle films was widened by composite TMO material,and the spectral absorption range of the films was enhanced.Ag doped WO₃nanoparticle films were successfully prepared by co-sputtering with Ag target and W target.The influence of sputtering process parameters on the morphology and properties of the films was investigated to obtain the optimal preparation conditions.The average particle diameter of the prepared nanoparticle films was about 180nm,and the particle coverage area accounted for about 85%.In this study,it was found that the continuous co-sputtering of Ag/W target would lead to the excessive doping content of Ag in the film,which would lead to the decrease of the film transmittance.Therefore,on the basis of ensuring the growth quality of nanoparticles,the nanoparticle films were prepared with a shorter co-sputtering duration.At the same time,in order not to affect the electrochromic performance of the film,we continue to grow WO₃films on Ag/WO₃nanoparticles to form a double-layer structure(WO₃-Ag/WO₃).The diameter of the film nanoparticles is about 200nm,the coverage area of the particles is about 90%,and the transmittance of the film at 550nm is 82%.Ti O₂?Mo O₃?V₂O₅and Ta₂O₅films were prepared by magnetron sputtering on the basis of Ag/WO₃/WO₃composite films respectively,forming a"core-shell"type three-layer composite structure,namely Ag/WO₃/WO₃/TMO(Ti O₂?Mo O₃?V₂O₅?Ta₂O₅),and the optimal power parameters for the preparation of TMO"shell"layer were investigated.The WO₃-Ag/WO₃/Ti O₂structure has the best performance by surface physical morphology and photoelectric properties characterization.The specific capacitance of WO₃-Ag/WO₃/Ti O₂structure is 6.76m F/cm²,the coloration response time is 6s and the fading response time is 9s,the ionic diffusion coefficient is 2.35×10^-10cm²/s,the optical modulation at near infrared band(2000nm)is?T=61.20%,the CV performance attenuation is 8.23%after 1000 cycles,and the visible light(600nm)is 83.3cm²/C.