Optimization Of Electrochromic Properties And Large-area Preparation Based On Tungsten Oxide

In this paper,composite electrochromic materials such as WO₃@Ti O₂and Ag@WO₃ were prepared by using some methods like hydrothermal method,electrophoretic deposition and photodeposition.A series of electrochromic properties of composite electrochromic materials such as optical modulation,coloring efficiency,response time and cyclic stability were thoroughly explored.At the same time,in order to solve the problems of large-area electrochromic devices package difficulties and liquid leakage,this paper also explored and studied how to prepare large-area solid-state electrochromic devices.The concrete contents are as follows:（1）Study on the electrochromic properties of Ti O₂ modified WO₃We prepared the WO₃@Ti O₂ core-shell structure composite material by using two-step synthesis of hydrothermal method and electrophoretic deposition method.At the same time,we explored the effect of different film thickness on the optical modulation range and optimized the film thickness of the WO₃@Ti O₂ composite material.After a series of electrochemical and electrochromic performance tests,compared with pure WO₃ film,WO₃@Ti O₂ composite material has a larger specific surface area and more active sites.And it also provides more channels for lithium ion implantation and Extraction,which reduces the accumulation of lithium ions and accelerates the diffusion rate.Therefore,compared to WO₃ thin film working electrode,the WO₃@Ti O₂ electrochromic device has a larger optical modulation range（55%）,faster response time（coloring 8.9s,fading 4.0 s）and better cycle stability.（2）The effect of nano-Ag on the electrochromic properties of WO₃ filmWe use the hydrothermal method and electrophoretic deposition method described in the previous chapter to prepare WO₃ nanomaterials,and then deposit a layer of nano-Ag particles on the WO₃ film by using a simple and cost-effective photodeposition method.We use WO₃electrochromic device as a comparative experiment.The results show that Ag@WO₃ has a larger light modulation range（58%）,faster response time（coloring 12.0s,fading 4.0s）,and more excellent electrochemical Cyclic stability.It shows that the loading of nano-Ag particles can reduce the impedance,and then increase the transmission rate of ions,finally improve the electrochromic performance and electrochemical activity of the device.（3）Research on the preparation of large-area patterned WO₃ solid-state electrochromic devices by screen printingWe try to use screen printing method to print tungsten oxide paste on ITO/FTO substrate to achieve large area and pattern effect.The WO₃ color-changing layer and the solid electrolyte conductive layer are printed layer by layer on the ITO/FTO substrate to ensure that the color-changing layer and the conductive layer completely overlap.And the transparent area is scraped and coated with a transparent adhesive for encapsulation,which can effectively solve the traditional liquid electrolyte leakage liquid.The preparation method has the benefits of simple process and low cost.It also provides a possible preparation method for industrial production of large-area solid-state electrochromic devices.