Studies On Fabrication Of Stretchable Cu Nano-meshes By Crack Template Method And Their Transparent Conductive Performances

Due to the continuous development of electronic equipment,flexible electronic equipment has received widespread attention.With the advent of flexible electronic devices such as electronic skins,implantable medical devices,and flexible stretchable displays,people have put forward new requirements for electrodes: not only to have good optoelectronic performance but also to have flexibility and stretchability.However,traditional metal oxide transparent conductive materials(ITO,FTO,AZO)have shortcomings such as high brittleness,high growth temperature,and high manufacturing cost.These shortcomings limit their application in flexible optoelectronic devices.Therefore,people are constantly looking for new materials to replace metal oxide electrodes.Among the many candidate materials,the metal network has the advantages of high conductivity and high transmittance.These advantages make the metal network become one of the most promising materials to replace traditional transparent electrodes.The preparation methods of the metal network mainly include the photolithography template method,the nanofiber template method and the crack template method.Among them,the preparation process of the crack template method is simple.The crack film prepared by scraping or spin coating is used as a template,and the metal is deposited in the gap of the template by a vacuum evaporation method.However,the crack template method has the problems of small template crack density and uneven width distribution.At the same time,large vacuum equipment needs to be used during the metal deposition process,and the metal utilization rate is low.These problems lead to high preparation costs of the metal network.In response to the above problems,this article uses plasma treatment to increase the surface energy of the substrate to achieve the control of the crack width and density and uniformity of the crack template;the method of electroplating is used to reduce the preparation cost of the metal network and shorten the preparation cycle;finally,the copper The network is embedded in the polymer PDMS to reduce the area of the copper network in contact with the air and improve the stability of the metal network.At the same time,with the help of the elastomer PDMS,a transparent and flexible copper network transparent electrode is prepared.The main research contents are as follows:1.Optimize the morphology of the crack template by plasma treatment.We use oxygen plasma to bombard the surface of the substrate to change its surface energy,thereby adjusting the crack width and density of the crack template.The contact angle test and SEM results show that the surface energy of the substrate gradually increases to saturation as the plasma treatment time increases,while the width of the crack on the template gradually decreases,and the density and uniformity gradually increase.On the basis of the cracked template,the transparent conductive film of the metal network was obtained by vacuum evaporation.After oxygen plasma treatment,the quality factor of the metal network is increased by 3.4 times.2.The use of electroplating to achieve low cost,high efficiency,high performance transparent electrode preparation.The SEM and AFM tests showed that the plasma treatment method can increase the adhesion between the substrate and the template,and avoid the penetration of the plating solution into the template,and the plasma treatment method can also improve the wettability of the surface of the substrate,facilitate the deposition of the metal,this method can improve the quality factor of metal network structure nearly 20 times.The influence of plating time and current is also studied.With the increase of plating time and plating current,the thickness of metal gradually becomes thicker and the conductivity is enhanced,but the thickness of metal is not easy to exceed the thickness of cracking template.By optimizing the plating conditions,we finally obtained a film with the sheet resistance of 0.14 ohm/? and the transmittance of 76%(wavelength of 550 nm).3.Tensile stability and chemical stability are essential properties of a flexible stretchable metal network structure.The copper network structure was embedded in the PDMS substrate,and the flexible stretchable PDMS/Cu/PDMS film was prepared by the elastic PDMS.After stretching for 1000 times in the state of stretching 10%,the film surface resistance was almost maintained.Analysis by in-situ microscopy,the tensile stability of the film is mainly through the deformation of the metal network to release stress,when the original length is restored,the deformation is restored.In addition,the embedded structure isolates the metal network from oxygen molecules and improves its chemical stability.The copper network not embedded in the substrate is aged at 85 ? and 85% humidity for 10 hours,and the resistance surface resistance is increased by 140 times,and the copper network embedded in PDMS is aged for 20 hours under the same aging conditions,the sheet resistance is only increased by 20 times.