This thesis illustrates synthesis process of silver nanoparticles as well as conductive silver ink that can be used for inkjet printing on cellulose film. Firstly, silver nanoparticle with size less than 50 nm was synthesized from silver nitrate, polyvinylpyrrolidone (PVP) and ethylene glycol where these chemicals acted as metal precursor, stabilizer and reducing agent, respectively. Then, a conductive silver ink was prepared with suitable solvent by adding a viscosifier, hydroxyethyl-cellulose (HEC) solution and a surfactant, diethylene glycol (DEG). The combined effect of both viscosifier and surfactant on the physical property of silver ink was analyzed by measuring contact angle of silver ink on cellulose film.
Moreover, the influences of PVP molecular weight and reaction temperature on the size of silver nanoparticle were analyzed. Before inkjet printing test, the silver ink was coated on a cellulose film by spin coating and the effects of different solvents, sintering temperature and solid content on its electrical resistivity were examined. It was found that, with 50% co-solvent of deionized water & diethylene glycol and solid content of around 50% silver ink exhibited the lowest resistivity.
This silver ink was also used in inkjet printer to print silver electrodes in micro scale on cellulose film. Finally, these electrodes were characterized by analyzing the cross-sectional SEM images and alpha-steps analysis of thickness versus width. Additionally, the electrical resistivity of printed electrodes were measured and found to be 23.5 μΩ-cm.
In summary, synthesized conductive silver ink can be used in inkjet printer to print conductive electrodes on cellulose film. Further research can be carried out to print complex electrical patterns (such as IDT pattern) on cellulose electro-active paper to fabricate flexible smart materials for flexible electronics and sensor applications.