Fabrication And Performance Research Of Flexible Transparent Conductive Films Based On Silver Nanowires And Graphene

Transparent conductive films are one of the key components which dicide performance quality of organic light-emitting diodes, solar cells and other organic optoelectronic devices. As electronic devices develop toward the direction of miniaturization, flexiblility and multi-function, flexible transparent conductive films and materials have become hot research spots at home and abroad. Traditional transparent conductive material such as tin indium oxide is too expensive and fragile, not suitable as flexible transparent conductive material. Therefore, people began to find new alternative materials, for instance, carbon nanotubes, graphene, metal mesh, metal nanowires and conducting polymers. Among them, one-dimensional silver nanowire possess good bending resistance, high transparency, high electronic conductivity and thermal conductivity, etc., two-dimensional graphene has unique crystal structure and excellent performance in optical, thermal, electrical and mechanical properties. Both of them have broad application prospects in the flexible transparent conductive film material field. This paper summarized the research background, introduced research status of silver nanowire flexible transparent conductive films and latest progress of graphene composite films, then synthesised silver nanowires with different inducing agents and experiment conditions.We prepared graphene oxide by Hummers method and achieved its reduction with hydrazine hydrate. Next, wo explored the effect on electrical and optical properties of different morphology silver nanowires based flexible transparent conductive films, substrates, binder and treatment process. The adhesion and flexibility of silver nanowire based films were measured and applied to LED lamp. Finally, we prepared silver nanowire and graphene compound flexible transparent conductive films and studied the influence of silver nanowire, graphene and composite structure on photoelectronic properties, then we further explored the films’ adhesion and flexibility performance. The main contents are as follows:(1) We studied the effect of type and content of inducing agents, the content of PVP, reaction time and subsequent heat treatment temperature on the formed silver nanowires morphology, With SEM and DSC we analysed the thermal behavior of silver nanowires at certain temperature. Studies showed that thinner and shorter silver nanowires can be easily achieved with ferric chloride while longer and thicker silver nanowires can be easily synthesised with sodium sulfide as inducing agent. The diameter of formed silver nanowires can be reduced by increasing the content of PVP appropriately. Extending the reaction time will reduce the length of silver nanowires and has no significant influence on the diameter of silver nanowires. The melting point of synthesised siver nanowires is 374 ℃, lower than silver melting point of 960.5 ℃.(2) We prepared graphene oxide by Hummers method and reduced it with strong hydrazine hydrate at room temperature. With X-ray diffraction(XRD), we can see that the layer spacing of graphene oxide is 0.83 nm, far higher than that of graphite sheet 0.339 nm. In the meantime, the crystal plane spacing of reduced graphene oxide is 0.73 nm, the experimental prepared reduced graphene oxide was deposited on pet and can be conductive, sheet resistance of which was 780 Ω·□-1. The graphene oxide and reduced graphene oxide were successfully obtained.(3) We explored the effect on films’ electrical and optical properties of morphology of silver nanowiress, substrates, binder, graphene compound, subsequent treatment process and different film forming process. Moreover, we integrated the adhesion and flexibility of silver nanowire based flexible transparent conductive films. The resluts showed that the optoelectronic performance of longer silver nanowire based films are more superior. We can obtain silver nanowire based films with better uniformity, integrity and attachment. The subsequent pressure treatment can effectly improve film conductivity. Transparent conductive films with thinner silver nanowires on MCE substrates can obtain better adhesion performance.(4) We investigated the influence on flexible transparent films’ optoelectronic performance of silver nanowire, graphene and different compound structure.Results showed that we can obtain composite films with mean sheet resistance of 14.49 Ω·□-1 and transmittance of 78.38% at 550 nm when silver nanowire deposition density reach 220 mg·m-2 and graphene deposition density of 55 mg·m-2. Trace of graphene can further improve the conductivity of silver nanowire based films and has little influence on transmittance. The change of composite structure has little affect on composite films’ photoelectronic properties. The compound of reduced graphene oxide can improve the flexibility of silver nanowire based transparent conductive films.