Now, reporting their results in the journal Nanotechnology, Hak-Sung Kim, Hyun-Jun Hwang and Wan-Ho Chung based at Hanyang University in South Korea have made a great stride towards the realization of low-cost copper nanoparticle ink. The team has developed a process that enables commercially available Cu/Cu2O nanoparticles to be used in printed electronics.

The production of pure Cu nanoparticles is difficult because they oxidize easily on contact with air. Most commercial Cu nanoparticles are covered with a thin Cu2O shell and cannot be transformed into conducting lines/films through traditional thermal sintering. To alleviate these problems, Hak-Sung Kim’s group has developed a two-step process.

IPL sintering

The first step is to functionalize the Cu/Cu2O nanoparticles to induce reduction during sintering. The next step is to use intense pulsed light (IPL) to shorten the sintering time to 20 or so milliseconds. The sintered lines/films exhibit a conductivity that is just a few times lower than the value for bulk copper.

In addition, the researchers optimized the IPL sintering process via in situ monitoring of oxide reduction/sintering phenomena to minimize the re-oxidation phenomena of copper nanoparticles during IPL sintering process (see movie).

The synergistic combination of functionalized Cu nanoparticles and IPL sintering can realize low-cost nanoink and enable instant sintering at room temperature and under ambient conditions for printed electronics.

Back in the lab, the group is working on various other types of nanoparticles and pre-cursor inks for printed electronics and energy harvesting/storage devices in combination with the IPL process.

Additional information can be found in the journal Nanotechnology.