Nanostructural Modulation Of Inorganic Electrochromic Materials And Functional Integrated Devices

Electrochromic?EC?materials are able to reversibly change colors by the intercalation and de-intercalation of ions and electrons under external electric filed.The electrochromic materials can be widely used for displays,smart windows,goggles,anti-dazzling mirrors and so on.Some electrochromic materials can be also utilized as pseudocapacitive materials,which concurrently possess energy-storage functions during color changes.Therefore,we can prepare materials and devices that integrate both electrochromic and energy-storage functions.The research object carried out in this dissertation is about inorganic electrochromic materials including tungsten trioxide?WO₃?and Prussian blue?PB?.The main research target is to improve the electrochromic optical modulation,response speed and coloration efficiency of WO₃ and PB by preparing nanostructured and composite materials to modulate the microstructures.Furthermore,functional integrated electrochromic and energy-storage device based on tungsten trioxide and PB is developed.This dissertation mainly consists of the following three parts:1.The preparation,electrochromic and energy storing properties of WO₃/ZnO nanocomposites.The ZnO:Al nanowire arrays were grown on transparent fluorine doped tin oxide?SnO₂:F,FTO?conductive glass via hydrothermal method.WO₃ was then deposited on the surface of the nanowires by pulsed laser deposition?PLD?,forming WO₃/ZnO:Al nanocomposites.The nanocomposites possess large surface area,facilitating ions diffusion,and effectively improving the optical modulation?46.5%?and response speed?t_c=4.5 s,t_b=1.3 s?.Moreover,WO₃/ZnO nanocomposites were also prepared on the flexible transparent PET/ZnO:Al substrates.The nanocomposites can integrate electrochromic and energy-storage functions,exhibiting large optical modulation?68.2%?,great coloration efficiency(80.6 cm² C^-1)and high areal capacitance(15.24 mF cm^-2).Besides,the color change during the charge/discharge process can indicate the energy-storage level,realizing the visualization of energy-storage level.2.The preparation,electrochromic and energy storing properties of WO₃?H₂O nanosheets.The WO₃?H₂O nanosheets were successfully formed on FTO glass without seed layer at low temperature by leveraging the chelating ability of citric acid.The ammonium chloride was used as capping agent to further control the thickness and density of WO₃?H₂O nanosheets.The WO₃?H₂O nanosheets can integrate electrochromic and energy-storage functions,exhibiting large optical modulation?79.0%?,high areal capacitance(43.3 mF cm^-2)and remarkable cyclic stability.Besides,the WO₃?H₂O nanosheets could also realize the visualization of energy-storage level.3.Multifunctional integrated electrochromic-energy storage device based on tungstentrioxideandPrussianblue.Themultifunctionalintegrated electrochromic-energy storage device was fabricated by using PB as positive electrode,WO₃?H₂O as negative electrode and Li ClO₄+PC solution as electrolyte.The device exhibits large optical modulation?61.7%?,fast response speed?t_c=1.84 s,t_b=1.95 s?,high coloration efficiency(139.4 cm² C^-1)and remarkable cyclic stability.The device shows broad optical modulation between fully charged and discharged states.Besides,color change during the charge/discharge process can indicate the energy-storage level of the device.Moreover,the device can be combined with Si-based solar cells to constitute a smart regulating system,which can effectively convert,store and use solar energy.The WO₃/ZnO nanocomposites,WO₃?H₂O nanosheets and multifunctional integrated device based on WO₃?H₂O and PB were successfully fabricated,realizing the functional combination of electrochromism and energy storage.Furthermore,the color change during the charge/discharge process can indicate the energy-storage level.