Study On Conductivity Of Inkjet Printing Nano-silver Ink On Flexible Substrate

As one of the typical representatives of metal nanomaterials,silver nanowires play an important role in flexible electronic products.Silver nanowires have become a hot material in the printed electronic market because of their excellent conductivity,bending resistance,flexibility and good light transmittance in transparent conductive films.The combination of ink-jet printing and silver nanowires can give full play to their advantages and complement each other.In this paper,silver nanowires were prepared by the polyol method which ethylene glycol was replaced propylene glycol as solvent reducing agent in the reaction system.After comparative experiments,it was found that propylene glycol has a greater advantage in reaction time and reaction by-products.In the process of preparing silver nanowires,the effects of the mass ratio of Ag NO₃and PVP,reaction time and temperature on the synthesis of silver nanowires were discussed.Through TEM and other detection methods,the optimal preparation conditions that the 1:2.5 mass ratio of Ag NO₃to PVP,the 140?reaction temperature and the 50min reaction time were determined,which could prepare silver nanowires for inkjet printing.Then the Purification Method combining Decantation and Solvent assisted method was discovered to achieve the Purification effect of Ultrafiltration membrane method after comparing of three different purification methods,which was better than that of centrifugal method.Based on the prepared of silver nanowires in this paper,silver nanowire ink was prepared by using PEO with deionized water as solvent and adjustable ink viscosity,PVP with adjustable ink dispersion and stability,plusing a certain amount of absolute ethanol.In order to satisfiy the conditions of inkjet printing,the influence of the amount of PEO and PVP on the performance of silver nanowire ink was explored.The results showed that the viscosity and surface tension of silver nanowire ink met the parameters of ink-jet printing ink when the mass ratio of PEO was 4%and the mass ratio of PVP was 0.5g.The prepared ink was put into an ink jet printer,and then the parameter settings of printer were adjusted to ensure that the silver nanowire ink could perform ink-jet printing evenly and smoothly.The prepared silver nanowire ink was used to conduct electrical conductivity experiments on three flexible substrates:photo paper,polyethylene terephthalate?PET?film and polyimide?PI?film.Firstly,the surface modification of PET and PI film was carried out with the measurement of contact angle as the test standard of surface modification effect.The experimental results showed that the two films treated by chemical method had obvious modification effect and complete the task of surface modification of the substrate.Then the influence of printing layer number,substrate deformation and post-treatment on conductivity was researched.When the number of layers printed by inkjet printing was four,the conductivity and the accuracy of the circuit were both at a high level.After the conductive line was treated with the Na Cl halide,the conductivity of the conductive line changed greatly.In the study of conductivity based on the deformation of the substrate,before the Na Cl halide treatment,the resistance of the conductive line increased greatly,and the corresponding conductivity decreased.But the resistance and conductivity of the conductive lines after the halide treatment did not significantly change and they were in a stable state.Therefore,the post-treatment of Na Cl halide salt has a positive effect on the conductivity of conductive lines.