Preparation And Properties Of A Leaf Vein-Like Hierarchical Silver Grids Transparent Electrode With The Application In Flexible Electrochromic Smart Windows

Electrochromism is a non-luminous technology that can control and adjust optical properties through electrical signals.They are widely used in electronic paper displays,automotive anti-glare rearview mirrors,energy-saving smart windows in buildings,sports camouflage,and smart wearable devices.At present,most electrochromic devices are manufactured on rigid ITO transparent conductive glass substrates.However,these rigid ITO conductive glasses substrates are difficult to meet the flexibility requirements of next-generation electronic devices,which has forced us to develop a new generation of flexible transparent conductive films to replace ITO conductive glass.Among the many substitutes for ITO conductive films,metal mesh conductive films have received extensive attention due to their excellent photoelectric properties and excellent bending resistance.However,the current methods of preparing metal mesh conductive films are inevitably using processes such as expensive and complicated lithography techniques,which greatly limits their future applications.Therefore,this article will look for some simple,inexpensive,large-scale methods to fabricate flexible transparent conductive electrodes with good optoelectronic properties.In this paper,the colloidal crack template was firstly prepared,and some factors affecting colloid cracking were explored.The morphology of the colloidal template after cracking is controlled by controlling the concentration of the colloidal solution,the coating amount per unit area of the colloidal solution,and the drying temperature.Then,based on the colloidal crack template,a silver metal mesh flexible transparent conductive electrode with good bending resistance and a light transmittance of 91%and a square resistance of 4.32?sq-1 was prepared.For the flexible transparent conductive electrode prepared by the colloidal crack stencil method,there are still some inevitable defects(such as cracks,cracks that are not completely cracked)in the self-forming crack template transparent conductive film.Especially in large-area films,these defects are more obvious.In this case,we designed a conductive metal grid with a leaf vein-like hierarchical structure,using the trunk conduction path to transmit the electrons collected by the branch grid over long distances.In this work,we fabricated a large-area flexible transparent conductive electrode based on a leaf vein-like hierarchical metal grid.The leaf vein-like hierarchical metal grid in the electrode consisted of a mesoscale"trunk"and a microscale"branch".The self-formed branched grids made the conducting paths distributing uniformly while the laser-etching trunk grids enabled to transport the collected electrons across long-distance.The large-area flexible transparent conductive electrode of the leaf vein-like hierarchical metal mesh not only has a high optical transmittance(?81%)but also a low sheet resistance(1.36?sq-1).The photoelectric properties of the conductive film can be optimized by adjusting the width of the grid,the gap,and the size of the TiO2 colloidal crack pattern.In addition,based on this advanced leaf vein-like layered metal grid electrode,we fabricated a flexible electrochromic device with excellent color-changing cycle performance(maintain great reversible stability after 3000 cycles at Cyclic Voltammetry test;still retaining 76.3%of initial optical contrast after 10,000 cycles).The leaf vein-like metal grid electrode with high transparency,conductivity and flexibility prepared in this paper provides a promising transparent conductive electrode for the next generation of flexible and wearable optoelectronic devices.