Study On Inorganic Electrochromic Films And Multicolor Electrochromic Devices

As the core material of electrochromic devices in commercial applications,inorganic electrochromic materials have many advantages,such as strong controllability,low driving voltage,high contrast,low cost,wide operating temperature range and so on.However,there are still some problems,such as slow response speed,unclear color changing mechanism and single color,which affect their further development in the field of electrochromic display.In this paper,electrochromic thin films were prepared based on inorganic electrochromic materials,and their properties and color changing mechanism were studied.The optimized thin films were used in the research of multi-color inorganic electrochromic devices,mainly to solve the problem of single color of inorganic electrochromic devices.Firstly,the electrochromic film of nickel oxide was prepared by sol-gel method.The effect of annealing temperature on the nickel oxide thin film was studied.The results showed that:(1)the nickel oxide precursor was transformed into nickel oxide crystal at annealing temperature of 300 degrees.With the increase of annealing temperature,the crystallinity of the film increased,the crystallite size grew,and the lattice distortion decreased.(2)the electrochromic reaction of Ni O occurs at the interface of microcrystals,and the implantation of ions and electrons in this project will affect the carrier concentration of the film,thus affecting the optical transmittance of the film,so smaller grain size can bring better electrochromic performance;(3)the electrochromic film annealed at 300?has better electrochromic performance and coloring efficiency 7 cm²/C,and the optical modulation range between the colored and bleached States is 41%.Then,the effect of sputtering pressure on the tungsten oxide film was studied.The amorphous tungsten oxide film was sputtered at room temperature.Due to the higher density of the films deposited at low pressure,the quality of tungsten oxide is higher,so it has a larger coloring depth and a higher coloring depth,but there is a certain ion retention effect;at the same time,the tungsten oxide films sputtered at low pressure have more oxygen vacancies and higher coloring efficiency.Considering comprehensively,12.5 m Torr is selected as the working pressure for preparing tungsten oxide thin films.Under this condition,the prepared tungsten oxide thin films have relatively good comprehensive properties,with a coloring efficiency of15.82 cm2/C and an optical modulation range of 40%.Finally,the multi-color inorganic electrochromic device is studied,and the Bragg mirror model of W-WO₃ is successfully constructed.Under the guidance of the model,the reflective multi-color inorganic electrochromic devices were successfully fabricated.By adjusting the thickness of tungsten oxide film,the electrochromic devices with different colors were constructed.Under the voltage of±3V,four different types of color conversion(yellow-blue,orange-grass green,cyan green-sea blue and purple-indigo)are realized.The average coloring response is 1s and the average bleaching time is 2s.The problems of single color and slow response speed of inorganic electrochromic devices are solved.In addition,the simulation model of transmission multi-color inorganic electrochromic device is constructed.Through the simulation of different electrode materials,the possibility of constructing transmission multi-color inorganic electrochromic device is discussed.