Research On Preparation And Electrochromic Properties Of Thin Films And Devices Based On Molybdenum Oxide Nanostructures

With the development of society,the consumption of energy and resources has become more and more serious.People need to find different materials and technologies for energy saving.Electrochromic materials have attracted everyone’s attention,and their special properties have made them widely used in smart windows,displays,and anti-glare rearview mirrors.Molybdenum oxide is a transition metal oxide with high electrochemical activity and has important applications in electrochromic and other fields.In this thesis,a molybdenum oxide film was prepared on fluorine-doped tin oxide（FTO）conductive glass by electrochemical deposition method and hydrothermal method combined with heat treatment,and assembled into electrochromic devices,and the electrochromic properties of the film and the device were studied.The molybdenum oxide film and the polypyrrole film were assembled into a complementary electrochromic device and the electrochromic properties of the device were studied.The main research results of this paper are as follows:（1）The molybdenum oxide electrolyte was prepared by using molybdenum powder and hydrogen peroxide,and the molybdenum oxide electrochromic film was successfully prepared after heat treatment by the electrodeposition method.The effects of different voltages,different deposition times and different calcination temperatures on the electrochromic properties of molybdenum oxide were studied.The experimental results show that the electrochromic properties of the molybdenum oxide film obtained by depositing at a constant voltage of-1 V for 120 s and calcining at 450℃for 1 h are the best.The light modulation amplitude of the molybdenum oxide electrochromic film at 800 nm is 34.2%,the coloring time is 13.0 s,the fading time is 11.0 s,and the coloring efficiency is 75.3 cm²·C^-1.They were assembled into a molybdenum oxide electrochromic device.The light modulation amplitude of the device was 24.5%,the coloring efficiency was 54.4 cm²·C^-1,and the coloring time and fading time were 14.5 s and 35.5 s,respectively.（2）Using molybdenum powder,hydrogen peroxide,sodium nitrate,polyethylene glycol and other reagents to prepare the precursor solution,the molybdenum oxide film was prepared after heat treatment by the hydrothermal method,and the molybdenum oxide film obtained from different precursor concentrations and hydrothermal time was studied.Electrochromic performance of electrochromic devices based on molybdenum oxide thin films.Through the molybdenum oxide precursor concentration experiment and the hydrothermal time experiment,the experimental results show that the molybdenum oxide film prepared with a concentration of 0.05 mol·L^-1precursor solution and hydrothermally heated for 13 h has better electrochromic properties after heat treatment.The light modulation amplitude of the molybdenum oxide electrochromic film at 769 nm is 44.7%,the film coloring efficiency is88.9 cm²·C^-1,the coloring time is 15.5 s,and the fading time is 16.0 s.The electrochromic performance of the electrochromic device based on the molybdenum oxide film has decreased.The light modulation amplitude of the device at 795 nm is 28.8%,the coloring efficiency is79.5 cm²·C^-1,and the coloring time and fading time are 16.5 s and 15.0 s.（3）The polypyrrole film was prepared by electrodeposition method,and the molybdenum oxide film prepared by the combined heat treatment of the electrodeposition method and hydrothermal method was assembled into a complementary electrochromic device.The molybdenum oxide/polypyrrole complementary electrochromic device was studied Electrochromic properties.The light modulation amplitude of the molybdenum oxide/polypyrrole device assembled by the polypyrrole film and the molybdenum oxide film prepared by the electrodeposition method is 19.1%,the coloring time and the fading time are5.5 s and 23.5 s,and the coloring efficiency is 93.2 cm²·C^-1.The light modulation amplitude of the molybdenum oxide/polypyrrole complementary device assembled by the polypyrrole film and the molybdenum oxide film prepared by the hydrothermal method is 20.5%,the coloring time and fading time are 3.0 s and 18.0 s,respectively,and the coloring efficiency is160.3 cm²·C^-1.The coloring efficiency of the molybdenum oxide/polypyrrole complementary electrochromic device is higher than that of a single molybdenum oxide electrochromic device,indicating that the molybdenum oxide film and the polypyrrole film constitute a complementary electrochromic device that improves the electrochromic performance of the device.