The Study On Transparent Electrodes For Flexible Organic Light-emitting Diode

Organic Light-Emitting Diodes(OLEDs)have attracted wide attention in recent years because of their advantages such as self-luminescence,high color saturation,high contrast ratio,large viewing angle,and fast response speed.It is setting off an application boom.In particular,it is flexible and bendable and is suitable as a wearable device.As an important part of the flexible OLED,the flexible transparent conductive electrode has also become a hot topic.The most widely used transparent conductive electrode in the OLED market today is Indium Tin Oxide(ITO).However,ITO electrodes are not a good choice for flexible OLEDs due to problems such as poor bending characteristics and short indium resources.At present,many new transparent electrode materials have been proposed to replace ITO,such as silver nanowires,PEDOT:PSS,graphene,carbon nanotubes and metal grids.Among them,silver nanowires have excellent electrical conductivity and transmittance,which is one of the research hotspots in the field of transparent conductive electrodes in recent years.In this paper,by improving the post-processing method of silver nanowires,the problem of high contact resistance between silver nanowires is solved,and the overall performance of the silver nanowire film is improved.In this paper,we have optimized the silver nanowire electrode using plasma treatment.The etching and thermal effects of plasma strengthened contact between the adjacent silver nanowires and removed the PVP thin layer on the surface of the silver nanowire at the same time.The sheet resistance of the silver nanowire film is greatly reduced,and the work function of the film is enhanced to get better hole injection.By optimizing the processing time of the plasma,we reduced the sheet resistance of the silver nanowire electrode to 7.2 ?/? while having a small effect on the transmittance.The figure of merit(FOM)of the electrode after plasma treatment is calculated to increase by 3 times compared with the original one,indicating that the photoelectric performance of the electrode has been significantly improved.Afterwards,the substrate transfer process is used to transfer the silver nanowire film into the flexible substrate NOA63.Since the silver nanowires are almost entirely embedded in the NOA63,the surface roughness of the electrode is very low,which can suit the application requirements of the OLED device.Moreover,the results of the bending test also proved that the transparent electrode can still maintain a good conductivity after multiple bendings.Afterwards,we fabricated the OLED device using the optimized silver nanowire electrode.It was found that the hole injection performance of the electrode was significantly improved by plasma treatment,and the current efficiency and lumen efficiency of the device were also increased.