Growth Mechanism of Silver Nanowires By Polyol Process and Their Application for Transparent Conductive Thin Film

Abstract

One-dimensional nanowires have attracted intense interest due to their unique photo-electric, magnetic and thermal conductive characteristics. Silver nanowire (Ag NW) based thin films have been recently used as transparent conductive films because of their high optical transparency, low sheet resistance and flexibility. Previous studies have demonstrated that polyol process, one of widely used method for Ag NWs chemical synthesis, could be used to produce Ag NWs by adding Cl- ions with appropriate concentration in the process. Besides Ag NWs, Ag particles could also be formed with addition of much higher or lower Cl- ions. However, optimal reaction time and concentration of Cl-ions for Ag NWs synthesis have rarely been reported. In this study, Ethylene Glycol (EG) solution with AgNO3was prepared and added in EG solution with Polyvinylpyrrolidone (PVP) for Ag NW formation. Mechanism of Ag NW formation was investigated by adding different amount of NaCl for different reaction time. The results show that Ag nanoparticles were initially formed and gradually turned into nanowires because of PVP addition. However, Ag NWs would gradually shorten while growing at critical length in the reaction. This interesting phenomenon could be explained by the reducing of surface energy. Furthermore, the longest Ag NWs could be obtained under condition of optimal reaction time and concentration of Cl-ions. These Ag NWs were prepared as transparent conductive thin films for optical transmittance and electrical conductivity measurements. Transparent conductive thin films with long AgNWs have better conductivity than short ones, and their stability would be further increased while coating the Polymethylmethacrylate (PMMA) as protective layer.