Growth Processes Of Silver Nanowires Assisted By Iron Ions And Preparation And Properties Flexible Transparent Conductive Films Based On Silver Nanowires

With the development of electronic devices towards the direction of movable,portable and bending deformation,new flexible transparent conductive thin film materials have been developed rapidly.Compared with traditional hard conductive materials,new flexible transparent conductive thin films not only have excellent optical transparency and low surface resistance,but also can be used in bending state.The flexible transparent conductive thin films based on silver nanowires have become a hot research area in recent decades because of their excellent properties and low preparation cost among all kinds of flexible transparent conductive thin film materials.There are many methods for the preparation of silver nanowires,among which polyol reduction is the most commonly used method to prepare siliver nanowires.While,polyol reduction method is necessary to control the growth of silver nanowires by adding polyvinylpyrrolidone(PVP)to prepare silver nanowires.We have creatively proposed the use of ionic additives as a growth control agent to prepare silver nanowires,and focused on the growth process of silver nanowires.The results show that the growth of iron ion assisted silver nanowires mainly goes through three stages.In the first stage,the silver ions are reduced to form crystal seeds.The second stage,crystal seeds grow into primary crystals.In the third stage,iron ions are coated on the specific surface of silver nanocrystals,which promotes the primary crystals grow into silver nanorods,and eventually silver nanorods grow into silver nanowires.When the ends of two grown silver nanowires are in contact with each other,it is possible to "self join" to form a silver nanowire with obtuse angle.The effects of different cation growth control agents(copper ions,iron ions,and ferrous ions)were compared.It was found that only iron ions can effectively promote the formation ofsilver nanowires.Compared with PVP-assisted silver nanowires,the silver nanowires prepared with iron ions have a smooth surface and no organic coating.Silver nanowires prepared by iron ion assisted have better electrical conductivity.,and the purity of silver nanowires gradually increases with the increase of iron ion concentrationBased on the above research,three kinds of flexible transparent conductive films were prepared by spin coating、Meyer-rod coating and vacuum filtration based on silver nanowires prepared by iron ion.The technological parameters of three methods and the performance of three kinds of flexible transparent conductive films are investigated systematically,and the advantages and disadvantages of the three methods are also compared.The results show that: the spin coating method and Meyer-rod coating method are simple in operation.In addition,the transparent conductive films prepared by these two methods have high transparency,excellent conductivity and good flexibility,but the adhesion of silver nanowires is poor.The transparent conductive film prepared by vacuum filtration method has high transparency,excellent conductivity,good flexibility,high adhesion of silver nanowires,but poor uniformity of conductivity and complex preparation process.Based on the advantages and disadvantages of the above methods,we first proposed a new method for preparing flexible transparent conductive films by Meyer rod coating and transfer method.We studied the optical properties,electrical properties and thermal effects of this conductive film and applied it to the preparation of a simulate flexible touch screen and its performance.The results show that the flexible transparent conductive thin films with uniform conductivity and high adhesion of silver nanowire can be prepared by the Meyer rod coating and transfer method.