Research On Preparation And Application Of Graphene/Ag Nanowires Transparent Electrode

With the rapid development of intelligent electronic devices,flexible,cheap and excellent performance transparent electrode have attracted many researchers' attention.Currently,ITO occupies a dominant position in the field of photoelectronics markets for several decades where stretching,twisting,or serious bending is required.However,ITO is fragile and is made of indium that is rare and expensive.These two defects limited its application in the flexible electronics.To find a new replaceable material for ITO has become a hot research area.Many researchers pay much attention to the carbon nanotubes and nanowires.Metals are always opaque,but when there are very thin or properly arranged on the nanoscale,metals become transparent and flexible.In this thesis,we fabricate Ag nanowires flexible transparent by spin-coating to the flexible polyethylene terephthalate(PET)substrate to form a random Ag NWs network.In many cases,such a network has a large resistance due to large wire–wire junction resistance,even reaches M? magnitude.we demonstrate a facile method to dramatically reduce large wire–wire junction resistance by 1-2 second microwave annealing.When microwave radiate to the surface of a block metal,most of the energy is reflected according to the Maxwell's electromagnetic theory.The other part decays in the metal internal rapidly.But when the metal is minimized to micrometer or nanometer,the skin depth and the mental size are almost stay in the same magnitude or with little difference.In this case,the consumption of microwave energy in the nanowires will lead to a big temperature change.The extreme sensitivity of the heating efficiency on the junction geometry causes a much better contact between nanowires.Resistance drops by more than three orders of magnitude after microwave annealing but the transmittance almost remains the same and partial junctions are welded together.As a result of the existence of surface current,make the temperature of the nanowires higher than that of substrate so as to protect the heat sensitive substrate within the short time.But this type of metal network transparent electrode usually have too many holes and the oxidation will take place on the surface.Graphene films has many good properties.By combing the graphene films with Ag NWs network,we can settle the above problem.Graphene films on copper foils are synthesized by chemical vapor deposition.After high temperature annealing,oxide particles are removed so that the surface of copper foil become more smooth.During the growth process,carbon source such as methane is decomposed into hydrogen and carbon atmos.after a recombination between of carbon atmos,large-area graphene films deposit on the copper foil.As the solubility of C in Cu is very low,the growth is self-limited.We demonstrate two different ways to transfer the graphene films on the copper foil to the target substrate before we measure its photoelectric properties.We also perform some experiment proving that the graphene film is a very good anti-oxidation protection layer.By transferring the graphene to the Ag NWs network,we obtain the graphene/ Ag NWs transparent electrodes.We apply it to organic light-emitting diodes(OLED)then observe its performance This thesis mainly concentrate on the preparation,properties and application based on graphene/ Ag NWs transparent electrodes.