Studies On The Preparation And Electromagnetic Interference Shielding Properties Of Graphene/Silver Nanowire Composite Network

Transparent conductive materials are important components of optoelectronic devices such as solar cells,transparent electrical heater and electromagnetic interference shielding windows,which directly affect the cost,performance and life of the devices.With the development of flexible optoelectronic devices such as organic electroluminescence display(OLED),new requirements for the flexibility of transparent conductive materials have been put forward.At present,tin-doped indium oxide(ITO),which occupies the main position in the market,has the inherent brittleness,high price and poor chemical stability,limiting the practical application of flexible optoelectronic devices.Therefore,searching for its substitute material has become a research hotspot in the recent decade.Metal nanowire networks have the advantages of good bending resistance,high electrical conductivity and high full spectral transmittance,and are considered as one of the ideal flexible transparent conductive materials to replace ITO.However,the chemical activity of metal nanowires is high,and the stability of metal nanowires in high temperature and oxygen environment needs to be improved.In the work,a graphene/silver nanowire composite network flexible transparent conductive material was fabricated by electrodeposition and a subsequent pulsed laser irradiation process.The effects of graphene layer on the photoelectric properties,chemical and mechanical stability,and electromagnetic interference shielding properties of the silver nanowire networks were investigated.Main results are as follows:1.Preparation and optimization of the photoelectric properties of graphene/silver nanowire composite networks.First,the graphene oxide was selectively wrapping of silver nanowire networks by electrodeposition.The thickness of graphene oxide can be effectively controlled(3-31 nm)by adjusting the current.Secondly,the graphene oxide wrapped silver nanowires were irradiated by pulsed laser to reduce the graphene oxide,and the silver nanowires were welded by the photothermal effect of surface plasmon resonance to improve the electrical conductivity of the composite networks,the graphene/silver nanowire composite network exhibits the average transmittance of 91%,low sheet resistance of 3.3 ohm/sq.2.Study on the chemical and mechanical stabilities of graphene/silver nanowire composite networks.The graphene can not only effectively block the contact between the silver nanowires and the external oxygen and water molecules,but also provide a conductive pathway,which enables the graphene/silver nanowire composite networks to remain stable electrical heating temperature above 200°C.The graphene/silver nanowire composite networks maintained good mechanical stability through reversible rearrangement and slippage by bending tests with a bending radius of 3 mm and tensile tests with a deformation of 40%.3.Study on electromagnetic interference shielding properties of graphene/silver nanowire composite networks.The electromagnetic interference shielding properties of the silver nanowire networks and the graphene/silver nanowire composite networks in the frequency range of 8.2-12.4 GHz were measured by the waveguide method.The results show that the graphene shell can improve the electromagnetic interference shielding effectiveness of the silver nanowire networks by 50%.By comparing the dielectric constants of different graphene thicknesses and silver nanowire densities,it is found that the multiple reflection,dielectric polarization,conduction loss and other physical processes in the graphene /silver nanowire composite networks are the main reasons for the high electromagnetic interference shielding effectiveness.