Combined Chemical and Thermal Sintering for High Conductivity Inkjet-printed Silver Nanoink on Flexible Substrates

Abstract

Electrical conductivity is a key factor in measuring performance of printed electronics,<br /> but the conductivity of inkjet-printed silver nanoinks greatly depends on post-fabrication<br /> sintering. In this work, two different conductive silver nanoinks, in which the silver nanoparticles were stabilized by two different capping agents – Poly(acrylic acid) (PAA) and Poly(methacrylic acid) (PMA) – were synthesized. The inks were inkjet-printed on flexible PET substrates, coated with an additional polycation layer, which facilitated<br /> chemical sintering. The printed features were then exposed to moderately elevated<br /> temperatures to evaluate the effect of combined chemical and thermal sintering. Both<br /> inks produced conductive features at room temperature, and the conductivity increased<br /> with both temperature and duration of sintering. At temperatures above 100 °C, the choice of capping agent had no pronounced effect on conductivity, which approached very high values of 50 % of bulk silver in all cases. The lowest resistivity (2.24 μΩ cm) was obtained after sintering at 120 °C for 180 min. By combining chemical and conventional thermal sintering, we have produced remarkably conductive silver electrodes on flexible substrates, while using low-cost and simple processes.