Preparation And Properties Of W₁₈O₄₉/PET-ITO Flexible Electrochromic Films

Electrochromic（EC）material refers to the reversible color change caused by the insertion and extraction of ions and under an applied electric field.Due to the special optoelectronic properties and energy-saving properties of materials,electrochromic materials have broad application prospects in energy-saving fields such as flexible display screens,smart windows,electronic paper,and energy-saving bracelets.The electrochromic material can actively adjust the lighting and shading performance of the glass,and the display point density of the display is intelligent,which is the direction of the development of building energy-saving materials and energy-saving displays.Compared with other electrochromic materials,tungsten oxide has attracted extensive attention due to its large electrochromic range and good cycle stability.High optical modulation range,low drive voltage,excellent cycle stability and environmental durability are key technologies for electrochromic materials for large-area electrochromic smart windows.In this paper,tungsten oxide（WOx）inorganic electrochromic materials were used as research objects.Flexible electrochromic thin films were prepared by spray coating,spin coating,inkjet printing combined with atomization deposition.The electrochromic performance was improved through adjustment of different experimental parameters.At the same time,the exploration of the semi-solid electrochromic devices and the preparation of the all-solid electrochromic electrolyte film were carried out.The electrochromic film prepared by spray coating showed that the optical modulation range of W₁₈O₄₉/PET-ITO flexible electrochromic film was the largest atλ=633 nm,ΔT=23%.When the film transmittance was changed by 90%,the coloring and fading times were 12.8 s and 10.6 s.Respectively,the W₁₈O₄₉/PET-ITO prepared by this method has good cycle stability,and the continuous coloring and fading cycle 3000 s the film still has high light transmittance（80.9%）.The results of inkjet printing combined with atomization deposition method showed that the PEDOT/PSS/W₁₈O₄₉/PET-ITO flexible electrochromic film has the largest optical modulation range atλ=733 nm,ΔT=45.33%.When the transmittance of the film was changed by 90%,the coloring time and the fading time were 23.2 s and 18.7 s.Respectively,the PEDOT/PSS/W₁₈O₄₉/PET-ITO flexible electrochromic film prepared by this method has excellent cycle stability,and the performance of the continuous coloring fading cycle 3000 s film was not attenuated,and the photoelectric performance can still be maintained above 80%after continuous reaction for 6500 s.Electrochromic device（EC device）refers to a device assembled by using an electrochromic material as a substrate.Generally,electrochromic devices have higher requirements on electrolytes,and electrolytes have the following characteristics:the electrolyte has high ion conduction characteristics;the electrolyte solution or film has high light transmittance;the chemical property can be kept stable during the electrochemical reaction cycle reaction;the small driving voltage can complete the process of coloring and fading cycle reaction;during the process,the electrolyte should be completely sealed in the device and should not leak.