银纳米线及其透明导电膜的研究进展

Research Progress of Silver Nanowires and Transparent Conductive Films

近年来,透明导电薄膜在光电器件中得到广泛的应用,是触控显示、有机发光二极管(OLED)、薄膜太阳能电池等器件的重要组成部分。目前氧化铟锡(ITO)作为透明电极在平板显示以及各种电子设备应用中处于垄断地位,但其本身存在陶瓷脆性、弯折易受损、反应温度高及易泛黄等缺点,严重阻碍了电子器件向小型化和柔性方向发展,因此迫切需要一种新的导电材料能够代替ITO,从而应用到柔性设备中。而基于银纳米线(Ag nanowires,AgNWs)的透明导电膜凭借良好的透光度、高导电性、低成本以及柔性可弯折等优点,有望成为ITO导电薄膜最具潜力的替代品。短短几年内,基于AgNWs透明导电膜的制备工艺和器件结构不断得到优化,并吸引越来越多研究者的关注。AgNWs的长径比及其分散液的粘度直接影响透明导电膜的光学和电学性能。对于高长径比的AgNWs,只需较少数量即可搭建出高导电性的AgNWs网络。这样可有效降低使用高长径比AgNWs制得的导电膜的散射,也可大幅提升其透过性。其次,分散液是影响AgNWs导电膜性能的另一个不可忽视的因素,其分散性和粘度直接影响着薄膜的均匀性及薄膜与基底的粘附性,因此获得高性能的分散液是制备AgNWs透明导电膜的关键。此外,由于AgNWs之间的接触电阻非常高,制备的导电膜的方块电阻非常大,这就需要对薄膜进行相应的后处理来降低其方阻。本文重点综述了国内外AgNWs的合成方法,总结了高透明AgNWs导电膜在导电分散液制备、薄膜制备、后处理等工艺上的研究进展,并简述了AgNWs透明导电膜在光电器件中的应用。最后,对AgNWs柔性透明导电膜在未来的发展趋势进行了展望,以期为制备高性能的AgNWs透明导电膜提供参考。

In recent years,the transparent conductive films with high conductivity are widely used in optoelectronic devices.They are the important components of touch display,organic light emitting diode(OLED),thin film solar cells and the like.At present,indium tin oxide(ITO)as a transparent electrode plays a monopoly role in flat panel display and various electronic equipment applications,however,ITO itself has some shortcomings such as brittleness of ceramics,vulnerability to bending and damage,high preparation cost,high reaction temperature and yellowing,which seriously hinder the development of electronic devices towards miniaturization and flexibility.Therefore,a new conductive material is urgently needed to replace ITO and applied to flexible devices.The transparent conductive film based on silver nanowires(AgNWs)will become the most potential substitute for ITO conductive film due to its good transmittance,high conductivity,low cost and flexible bendability.In the past few years,the fabrication process and device structure of transparent conductive films based on AgNWs have been continuously optimized,which has attracted more and more attention of researchers.The aspect ratio of the AgNWs and the viscosity of the conductive dispersion directly affect the optical and electrical properties of the transparent conductive film.For AgNWs with high aspect ratio,only a small number of AgNWs is needed to build a highly conductive AgNWs network.The scattering of the prepared film layer can be effectively reduced,and its permeability can be greatly improved.The AgNWs dispersion is another non-negligible factor affecting the AgNWs conductive film.The dispersion and viscosity of the conductive dispersion directly affects the uniformity of the film.Therefore,obtaining high performance dispersion is the key to prepare AgNWs transparent conductive film.In addition,since the contact resistance between the AgNWs is huge,causing the sheet resistance of the prepared conductive film is also extremely large,so a corresponding post-treatment process of the film is required to reduce the square resistance of the film.In this paper,the synthesis methods of AgNWs at home and abroad are summarized.The research progress of AgNWs transparent conductive silver films in dispersion preparation,film preparation and post-treatment is summarized.The application of AgNWs transparent conductive silver films in optoelectronic devices is also described.Finally,the development trend of AgNWs flexible transparent conductive film in the future is prospected in order to provide reference for the preparation of high performance AgNWs transparent conductive film.