Design And Investigation Of Electrochromic Devices Based On Catalytic And Complementary Dual Function Composite Counter Electrode

Under the action of applied electric field,electrochromic materials can change their optical properties reversibly and stably,which makes them stand out in many fields such as building energy conservation,electronic display,and scientific and technological products.With the increase of potential application scenarios,the focus is on the development of commercialized devices and the establishment of higher targets for their performance and durability.The most classic combination of WO3 and NiO in traditional thin-film devices,the complementary color properties of the two types of materials in the colored state make the WO3//NiO device appear ideal blueblack.However,due to the charge mismatch between the working and counter electrodes and the occurrence of ion trapping side reactions,the devices undergo significant performance degradation after only a few thousand electrochemical cycles,which hinders their industrialization.In this paper,a class of bifunctional composite counter electrodes with both catalytic and complementary properties was designed and prepared with the aim of improving the cycling stability of the complementary devices,inspired by the innovative work on the introduction of redox pair equilibrium charges in electrolytes,and the main research contents and results are as follows:In Chapter Three,we designed a composite counter electrode partially covered with NiO and Pt.The NiO electrochromic film is distributed in the middle part of the counter electrode to maintain the advantages of high optical contrast and deep coloration state of the device.The tetramethylthiourea/tetramethyldithiamine(TMTU/TMFDS2+)redox couple is introduced into the electrolyte to act as a charge balancing material,and the catalytic effect of Pt distributed at the periphery of NiO can significantly enhance the electrochemical activity of TMTU/TMFDS2+redox couple.Compared with the single-electrode devices,the WO3-based electrochromic devices(ECDs)prepared by matching the NiO/Pt bifunctional counter electrodes show a significant increase in transmittance modulation(over 65%)and high coloration efficiency(89.6 cm2 C-1),and can achieve up to 10,000 stable cycles,demonstrating that the new structure of the counter electrode makes the devices have the potential for long-term applications.In Chapter Four,in order to verify that the above-mentioned design of electrode structure is an effective way to improve performance of ECDs,we adopted the control variable method to replace the electrochromic component and catalytic material respectively.Experimental investigations based on PB,MoS2,TiO2 and other advanced materials have been conducted to improve the relevant performance of ECDs through structural design and material optimization.This also proves that the electrode structure innovation strategy has important research significance.