Formation of Conductive Ink Based on Copper Complexes

Yousef Farraj, Casali Center for Applied Chemistry, Institute of Chemistry and Center for Nanoscience and Nanotechnology, Hebrew University of Jerusalem, Jerusalem, Israel
Michael Grouchko, Casali Center for Applied Chemistry, Institute of Chemistry and Center for Nanoscience and Nanotechnology, Hebrew University of Jerusalem, Jerusalem, Israel
Shlomo Magdassi, Casali Center for Applied Chemistry, Institute of Chemistry and Center for Nanoscience and Nanotechnology, Hebrew University of Jerusalem, Jerusalem, Israel

Fabrication of flexible electronic devices by ink-jet printing of the conductive patterns is of growing research interest. In addition to their high conductivity, copper-based formulations is the most promising candidate to replace the the silver based formulations due to their low price (factor of ~90) and better electromigraion resistance.

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.

Here we describe the formation of 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 was found to be stable in ambient conditions for prolonged periods, without problems of losing functionality, which are usually encountered in nanoparticles inks, such as aggregation and creation of copper oxides.

The decomposition profile of the ink as well as the obtained film was investigated by various analyses including STA-MS, XPS, XRD and HR-SEM