Preparation And Properties Of Flexible,Transparent Hybrid Electrode With The Application Of Wearable Electrochromic Devices

Electrochromic devices?ECD?have broad application prospects in temperature-controlled smart windows,new displays,e-papers and smart wearable devices due to their diversified colors,high controllability and low energy consumption.Flexible ECD have received extensive attention,with the progress of miniature,flexible and lightweight electronic devices in recent years.However,the most widely used indium tin oxide?ITO?conducting films exhibit disadvantages such as high cost,fragility,poor bending resistibility,which seriously restrained the development of flexible ECD.Among the numerous alternatives for ITO,the metallic nanogrids conducting films become a focus owing to their excellent mechanical flexibility and photoelectric performance,but their vulnerability resulting corrosion to environmental influences such as atmosphere and temperature limiting their application of flexible ECD.Based on this,this work has developed ultra-thin,highly flexible and high-performance ECD from two aspects.First,electrostatic spinning and vacuum sputtering are utilized to fabricate conductive silver nanotrough networks?Ag NN?,which greatly optimize the endurance of bending and stretching of the conducting films by the unique hollow groove-like structure.Meanwhile,the Ag NN with high length-diameter ratios significantly decrease the number of wire-wire junctions and ultimately improve the conductivity of the films.Second,this work has built a WO₃/Ag NN/PEDOT:PSS "sandwich-structured"hybrid flexible ECD electrode,which enhance the adhesion and chemical stability of the Ag NN films with the effect of WO₃-bottom layer and PEDOT:PSS-top coating,respectively.After optimization,the "sandwich-structured" hybrid ECD electrodes display excellent photoelectric properties,the sheet resistance is as low as 7.9 ? sq-1 meanwhile an average transmittance of 88.8%.The sheet resistance only increases 1.77? sq-1 during bent 5000 times at a curvature radius of 5 mm;a 7.04 ? sq-1 increasing at 100%tensile strain;good conductivity maintains when is twisted at 720°.In the application of ECD,the hybrid WO₃/Ag NN/PEDOT:PSS/WO₃ electrochromic films maintain great reversible stability after 3000 cycles at Cyclic Voltammetry test;the switching time is as rapid as 0.75 s/1.82 s for bleaching/coloring,respectively;a high cyclic performance are also simultaneously obtained,86%retention of the initial optical contrast after cycling for 30000 s at a three-electrode system.The hybrid electrodes are successfully fabricated on various flexible sustrates,such as PET,PE,PDMS and Ecoflex,which shows the adaptability of the hybrid electrode to the different flexible substrate.Finally,the flexible ECD can be used as capacitors for energy storage,which represent good electrochemical stability and specific capacitance of the Pseudocapacitance in the Galvanostatic charging/discharging test.