Study On Electrochromic Properties Of Nanostructured TiO₂/WO₃ Composite Film Deposited By Magnetron Sputtering

Tungsten trioxide(WO₃)thin film is an important inorganic electrochromic material,but the electrochromic devices based on pure WO₃film can not meet the requirements of practical application in many aspects such as coloring efficiency and cycle stability.Titanium dioxide(TiO₂)has the advantages of non-toxicity,inexpensive,suitable enenrgy band potential and high photoelectric conversion efficiency.In this study,TiO₂was doped into WO₃film to ensure that the synergistic effect of the two can be used to improve the shortcomings of single material,and then improve the electrochromic performance.In this study,the nanostructured TiO₂/WO₃composite thin films were deposited by grazing angle magnetron sputtering.The thin films were characterized by SEM,EDS and XRD and other analytical methods.At the same time,the electrochromic properties of the thin films were tested by electrochemical workstation and UV-Vis spectrophotometer.The effects of sputtering power and substrate temperature on the microstructure,crystal structure,electrochromic properties and optical properties of TiO₂/WO₃composite thin films were investigated.The outcomes indicate that the optimum sputtering power is 200W and the optimum substrate temperature is 150?.The electrochromic properties of TiO₂/WO₃composite thin films are compared with those of WO₃films.The specific research results are as follows:Firstly,the electrochromic properties and optical performances of the composite thin films prepared at room temperatureat were deposited at different sputtering powers.When the sputtering power is 200W,the ion implantation and desorption rates of the composite films are 4.57×10^-11cm²/s and 3.17×10^-11cm²/s,respectively,and the coloring/fading response times are 7.1s and 10.6s,respectively.After 500 cycles,the charge capacity of the composite films decreased slightly,and the reduced charge capacity was 5.28m C/cm²,indicating that the cycling stability of the composite films was excellent at this sputtering power.In terms of optical properties,the optical density change and coloring efficiency reach the maximum values,which are 0.51 and12.82cm²/C,respectively.The optimal sputtering power is 200W.Secondly,the electrochromic properties and optical performances of the composite thin films prepared at sputtering power 200W were deposited at different substrate temperatures.When the substrate temperature is 150?,the composite film is in the polycrystalline structure with coexistence of crystalline and amorphous states,with the maximum ion implantation and desorption rates of 7.23×10^-11cm²/s and6.51×10^-11cm²/s,respectively.The response time of coloring/fading is 4.7s and 5.2s,respectively.After 500 cycles,the charge capacity decreases slightly,and the reduced charge capacity is 3.04m C/cm².In terms of optical properties,the optical density change and coloring efficiency reach the maximum values,which are 0.81 and16.75cm²/C respectively,so the optimal substrate temperature is 150?.Finally,the nanostructured TiO₂/WO₃composite films and WO₃films were prepared under optimized conditions(200W sputtering power and 150?substrate temperature),and their electrochromic properties were compared.The results show that the ion diffusion rate of TiO₂/WO₃composite film is higher than that of WO₃film,and the cycle stability and response speed of TiO₂/WO₃composite film are better than that of WO₃film.At the wavelength of 600 nm,TiO₂/WO₃composite film and WO₃film have similar optical density change and coloring efficiency,and the band gap of TiO₂/WO₃composite film is inferior to the energy gap of pure WO₃film,which indicates that TiO₂/WO₃composite film has red shift in visible light range,which improves the electron transmission efficiency and reduces the energy required for electron transport.The memory storage capacity of TiO₂/WO₃composite film is higher than that of WO₃film,and the color retention time is longer.