| Color is one of the intrinsic characteristics of materials,and the reversible swich of color is the basis of beautiful design,information display,dimming and temperature control technology.Electrochromic（EC）material can actively control its own color state under the action of electric field,to meet the needs of different scenes.Based on electrochromic technology,a new generation of electrochromic smart window,passive display devices and optical stealth materials can be developed for building/automotive energy saving,information display,anti-glare blinding and military camouflage.Prussian blue（PB）is a common EC material,which can realize the reversible transformation of transparent,blue,green,and yellow.It has many advantages such as stable color change,fast response,low cost,and high biosecurity.Prussian blue EC films are generally prepared by electrodeposition and hydrothermal methods.However,cracks in the electrodeposition process will cause the film to flake off.The hydrothermal method requires high-temperature and high-pressure environment,so it is difficult to achieve large area preparation.The technology of preparing high-performance PB films under atmospheric pressure environment needs to be developed urgently.In addition,the simplified structure,electrode matching,and stability design of Prussian blue EC devices hinder their further development.This paper mainly focuses on the controllable preparation of high-performance Prussian blue EC coating under atmospheric pressure,the simplified structure design and electrode matching of Prussian blue EC devices.Specific contents are as follows:（1）In-situ replacement reaction of high-performance Prussian blue EC coating under atmospheric pressure:The composite coating of Fe（OH）3 and ITO nanoparticles（Fe（OH）3/ITO-np）is coated on the transparent conductive glass as a sacrificial layer.Fe（OH）3 was etched with hydrochloric acid to release Fe3+,which was precipitated with[Fe（CN）6]4–in the electrolyte.PB/ITO-np electrochromic layers were prepared under atmospheric pressure.Since PB is formed by slowly replacing Fe（OH）3 in the sacrificial layer containing iron,the surface of the prepared PB/ITO-np composite coating is uniform and almost no cracks occur.Electrochromic performance tests show that the composite coating has excellent optical modulation capability（ΔT=59.9%@633 nm）,rapid color-changing response（coloring 8 s/fading 12 s）and excellent cycling stability（1200 cycles/fading cycles,transmittance remains 77%）.PB/ITO-np coating also has good charge storage ability,which can be used to construct color-changing storage dual-function devices.The process is simple and does not need to be carried out in a closed environment.It provides a new idea for the continuous preparation of high-performance PB coating in large area.（2）Simplified of PB EC device based on electrolyte/counter electrode integration:[Fe（CN）6]3–/[Fe（CN）6]4–redox pairs were introduced into KCl electrolyte,and the mixed electrolyte was used for charge transfer and energy storage.Prussian blue EC device with electrolyte/counter electrode integration was developed.The peak of[Fe（CN）6]3–/[Fe（CN）6]4–redox pairs（0.14～0.35 V）are close to PB（0.12～0.32 V）.Therefore,the driving voltage of device can be significantly reduced,and the side reactions of hydrogen evolution and oxygen absorption can be inhibited.However,the direct contact between[Fe（CN）6]3–/[Fe（CN）6]4–and PB film will result in charge transfer,which will make the device lose the ability of color memory.Therefore,Perfluorinated sulfonic acid（PFSA）resin with cation exchange properties was introduced to prevent charge transfer between PB and[Fe（CN）6]3–/[Fe（CN）6]4–.With the introduction of PFSA ion exchange resin,the optical modulation amplitude of the device at 633 nm is increased from 23.3%to 71.9%,and the color memory ability is increased from 10.1%to 67.0%after 300 s open-circuit static.This"hybrid electrolyte+electron barrier"design provides another solution to simplify the construction of EC devices. |
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