Study On Shape-controlled Preparation Of Nanosilver And Conductive Ink Applications

Due to the excellent electrical properties,chemical stability,thermal properties,and antibacterial properties,nanosilver is widely used in the fields of electronics,antibacterial,surface Raman enhancement and so on.The application performance of its specific aspects can be effectively enhance by adjusting its shape,size and other parameters.However,there are still many challenges to the synthesis and regulation of nanosilver so far,especially the preparation of high-aspect-ratio silver nanowires and small-diameter silver nanoparticles.In response to these problems,the thesis deeply studies the growth mechanism and regulation mechanism of silver nanowire and silver nanoparticles.A method for synthesizing small-sized silver nanoparticles with simple method,good reproducibility and large-scale preparation,and a method for preparing silver nanowires with high aspect ratio,uniform height and adjustable size are obtained,respectively.The inkjet printing and sintering properties of silver nanoparticle inks and the application of silver nanowires in the field of transparent conductive films are also studied.The main findings are as follows:(1)Silver nanoparticles were synthesized by using liquid-phase reduction method with polyacrylic acid and sodium citrate as the joint protective agents.The effects of reaction temperature,holding time,packing method,stirring speed and ultrasonication on the morphology and size of silver particles were thoroughly investigated.By adjusting these factors,uniform silver nanoparticles of 10 nm could be obtained in batches.(2)Silver nanowires were synthesized using the polyol method with Cl^-,Br^-and Fe³⁺as control agents,and the individual and synergistic effects of these control agents were studied in depth.The research shows that both Cl^-and Br^-can promote the formation of small-diameter silver nanowires,and the regulation effect of Br^-is stronger than Cl^-;In addition to improving the uniformity of silver nanowires,Fe³⁺is also beneficial to obtain silver nanowires with high aspect ratio.By adjusting the type and concentration of the control agent,a highly uniform silver nanowire with a diameter of less than 30 nm and a length of more than 90?m can be obtained.(3)Based on the obtained silver nanoparticles,the silver conductive ink is configured.The effects of organic solvents such as dispersants and stabilizers on its stability and inkjet printing performance are explored and printed lines with a width of less than 20?m were obtained.In addition,the ink pretreatment method and sintering process were optimized.The sintering was performed at 150°C for 1 h under the action of HCl electrolyte.The silver layer was dense and uniform,with a square resistance as low as 4??·cm.(4)Transparent conductive films were prepared based on the synthesized silver nanowire,and the influence of the length-diameter ratio of the silver wire on its performance was compared.Without any post-treatment,the sheet resistance is only 4.7?·sq^-,the haze is as low as 1.08%,the light transmittance is as high as 95.2%(at 550nm).In addition,the transparent conductive film shows excellent flexibility,and the resistance remains almost unchanged after 2500 repeated bends.