SELF-REDUCTION OF COPPER COMPLEXES INDUCED BY THERMAL DECOMPOSITION FOR FLEXIBLE PRINTED ELECTRONICS

Direct deposition of metallic inks for obtaining printed flexible electronic devices is of high research interest. Due to the high conductivity of copper and it’s low cost compared to silver, copper-based inks are the most promising candidates to replace the commonly used silver based inks.

However, copper nanoparticles tend to oxidize before and after printing, and therefore leads to poorly conductive patterns. Moreover, after printing the copper nanoparticles require a high temperature sintering process (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 undergo 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 deterioration in its functionality, compared to what is usually encountered in nanoparticles inks, such as aggregation and creation of copper oxides.

The decomposition mechanism of the complexes in the ink as well as in the obtained printed pattern was investigated by various approaches including STA-MS, XRD and HR-SEM.