Fabrication of flexible electronic devices by ink-jet printing of the conductive patterns is of growing research interest. Ink formulations based on copper has the potential to replace the silver due to its low price and high conductivity.
However, it is difficult to prevent the oxidation of copper nanoparticles, before and after printing, which leads to poorly conductive patterns. Moreover, after printing the copper nanoparticles require a high temperature curing (usually above 200 °C) which prevents their application in low cost, heat sensitive plastic substrates.
To address these challenges, we developed a metal organic decomposition (MOD) ink based on copper amine complexes that undergoes pyrolysis to copper metallic nanoparticles at low temperatures (below 150 °C), and therefore enables printing conductors on heat sensitive plastic substrate (PET and PEN). The ink is stable in air for prolonged periods, without problems of losing functionality which are usually encountered in nanoparticles inks, such as aggregation and creation of copper oxides.
Our observations showed that controlling copper particle size following complex decomposition is possible by controlling the process temperature. The range of particles size obtained was between 10 nm and 2 µm.
yousef.farraj@mail.huji.ac.il
