Preparation And Properties Of Silver Nanowire-graphene Oxide Composite Transparent Conductive Films

With the rapid development of flexible electronic devices,flexible and foldable requirements have been put forward for their transparent electrode materials.Silver nanowires have high aspect ratio,good electrical conductivity,and high transmittance,and are considered to be the most ideal substitute for traditional indium tin oxide(ITO)electrodes.However,the poor oxidation resistance,low mechanical properties,and large surface roughness of silver nanowires have severely limited their application in flexible electronic devices.Improving photoelectric performance,flatness and stability has become the main research direction of silver nanowire transparent conductive thin film electrodes.Based on the current research status of silver nanowire transparent thin film electrodes,silver nanowire-graphene oxide composite transparent conductive thin film materials were prepared by Meyer bar coating method and spin coating method,respectively.The microstructure,surface characteristics and optoelectronic properties of the composite transparent thin-film electrode material were analyzed.The thermal and mechanical stability of the composite transparent thin-film electrode material were investigated.The OLED light-emitting devices and thin-film heating devices were also designed and fabricated.The resultant silver nanowire-based composite transparent conductive thin-film electrode materials are promising to replace ITO films for flexible electronic devices.The main research contents are as follows:(1)Preparation of silver nanowire-graphene oxide flexible transparent conductive film by Meyer rod method.AgNWs-GO composite transparent conductive thin film was prepared by a layered manner using a Meyer bar coating method with silver nanowire(AgNWs)and graphene oxide(GO)inks as raw materials and PET as a substrate.The as-prepared composite film has excellent photoelectric performances,and the square resistance is 25?/sq under the premise of maintaining a transmittance of 550 nm at 87.6%.Its root-mean-square roughness(RMS)is 4.86 nm,which is 20.7%lower than that of AgNWs film,and the surface wettability is improved(CA=43°).GO is used as a protective layer to improve the oxidation resistance of the AgNWs film.The composite film remains under the conditions of 80°C and 75%RH for 16 days without significant oxidation phenomenon,and the composite film has good mechanical stability and can resist 2200 mechanical stability tests.(2)Preparation of silver nanowire-graphene oxide flexible transparent conductive film by spin coating method.The AgNWs-GO composite transparent conductive thin film material was prepared by coating silver nanowires and graphene oxide dispersions on the surface of a glass substrate in a spin coating process.The number of GO layers has a great influence on the photoelectric properties of AgNWs films.The square resistance of AgNWs film is obviously reduced after GO compounding.The single layer GO compounding reduces the square resistance of AgNWs film from 27 to 18?/sq.As the number of GO layer increases,the square resistance gradually increases.The composition of GO layer and increase in the number of layers will slowly increase the haze of the AgNWs film,while the transmittance remains basically unchanged.After GO compounding,the surface water contact angle of the AgNWs film reduces from 40.9°to 35.6°,and the work function increases by 10.5%,thereby realizing the controllable work function.(3)Designature and fabrication of flexible electronic devices.Using as-prepared silver nanowire-based transparent film as an electrode material,two kinds of flexible electronic devices,namely an organic light emitting diode(OLED)and a thin film heater,were designed and fabricated.AgNWs-GO composite thin film based flexible OLED devices can achieve a luminous efficiency of 1200 cd/m~2 at a voltage of 12 V,its external quantum efficiency can reach up to 25%,and the concentration of graphene oxide will affect the luminous efficiency of OLED.The AgNWs film and the AgNWs-GO composite film are used to prepare a thin film heating device respectively.The maximum withstand voltage of the AgNWs film heater is 7 V and the maximum heating temperature is 100°C,which shows uneven heating.The maximum withstand voltage is 11 V,the maximum heating temperature is 112°C,and the heating is more uniform.