Study On Preparation And Properties Of Graphene Conductive Film

Commercial indium tin oxide(ITO)film has always been the most common material in the market of conductive film and it has a firm grip on the major market share.With the progress of science and technology,people look forward to higher requests of conductive film materials,hoping that the next generation of materials can maintain the high performance as well as excellent flexibility to meet the development of wearable intelligent devices.While traditional ITO cannot meet these requirements.And at the same time the excessive cost of fabrication further restricts the breakthrough of ITO in the future optoelectronic field.Graphene is a kind of two-dimensional material with high performance,such as excellent photoelectric properties and good mechanical properties.It is one of the substitutes to replace ITO film.In this work,graphene oxide(GO-E)with large scale was fabricated by a two-step way:electrochemical intercalation first and then further oxidation.GO-E was characterized by SEM,FT-IR,XPS,XRD tests to determine the structure.GO-E was also compared with GO-C(prepared by Hummers way).Then GO film was prepared by spinning coating through liquid phase.The reduction of GO films was applied by chemical reduction and high-heat treatment to restore its performance.Results showed that reduction by hydroiodic acid was better than ascorbic acid.And during the high-heat treatment,higher temperature made for the better electroconductivity of GO films.With the synergistic effect of chemical reduction and high-heat treatment(1000?),the best performance of graphene conductive film was prepared,with the transmittance and sheet resistance of 76.7%(550nm)and 2711?/sq,respectively.Then we synthesized silver nanowires with high length-diameter(which can reach 1000)by polyol method.Silver nanowires dispersion liquid with different concentrations was prepared by dispersing AgNWs in ethanol.When the concentration was 2mg/mL for spinning coating,the AgNWs film exhibited 494 ?/sq sheet resistance with 94.2%transparency at 550nm.Although the sheet resistance is high,the transmittance was good enough for the combination with graphene.After that,AgNWs/graphene films were prepared by combining silver nanowires(2mg/mL)and graphene oxide with different size and then reduced by VC.The effects of structure of the composite films on the performance of the conductive films were also investigated.It turned out that the introduction of graphene oxide can reduce the contact resistance between silver nanowires as well as the surface roughness of silver nanowires.The results showed that the conductive film in rGO/Ag/rGO structure exhibited the lowest sheet resistance(about 44 ?/sq),and the corresponding transmittance at 550nm was 86.5%.While GO-E/Ag/GO-E owned the highest performance parameter FOM,which value was 88.4.The corresponding sheet resistance and light transmittance were about 53 ?/sq and 92.4%,respectively.The graphene with large-size improved the flexibility and stability of the composite films.And GO-E composite films showed better performance than GO-C composite film.Although the transmittance of the three-layer composite film is lower than that of the double-layer composite film,the structure led to the improvement of conductivity,bending resistance and oxidation resistance.The reduction of films promoted the conductivity while the transmittance decreased.In order to further improve the composite film with better properties,conductive polymer PEDOT:PSS was introduced into the composite films to fill the gaps between the silver nanowires network.PEDOT:PSS was purchased and diluted into a series of concentration gradients to explore its best composite mass fraction with silver nanowires and graphene.In Ag/PEDOT,GO/Ag/PEDOT and rGO/Ag/PEDOT composite films,all films showed the lowest sheet resistance when the mass fraction of PEDOT:PSS was 0.30wt%,at which PEDOT:PSS and silver nanowires had the best composite performance.Finally,the composite film with the highest FOM was GO/Ag/PEDOT-0.30 film,which was 140.6.The introduction of PEDOT:PSS further improved the bending resistance and oxidation resistance of the composite film.