Oregon State University’s College of Engineering is on a mission to help manufacturers speed up the production of advanced, flexible electronics based on its research in photonic sintering of silver nanoparticle films—the use of intense pulsed light, or IPL, to rapidly fuse functional conductive nanoparticles.

According to OSU, scientists have uncovered a relationship between film temperature and densification. Densification in IPL increases the density of a nanoparticle thin-film or pattern, with greater density leading to functional improvements such as greater electrical conductivity.

The engineers found a temperature turning point in IPL despite no change in pulsing energy, and discovered that this turning point appears because densification during IPL reduces the nanoparticles' ability to absorb further energy from the light.

This previously unknown interaction between optical absorption and densification creates a new understanding of why densification levels off after the temperature turning point in IPL, according to OSU, and further enables large-area, high-speed IPL to realize its full potential as a scalable and efficient manufacturing process.

Intense pulsed light sintering allows for faster densification—in a matter of seconds—over larger areas compared to conventional sintering processes such as oven-based and laser-based. IPL can potentially be used to sinter nanoparticles for applications in printed electronics, solar cells, gas sensing, and photocatalysis.

Products that could evolve from the research include radiofrequency identification tags, a wide range of flexible electronics, wearable biomedical sensors, and sensing devices for environmental applications, according to OSU.

Rajiv Malhotra, assistant professor of mechanical engineering at OSU, and graduate student Shalu Bansal conducted the research. "For some applications we want to have maximum density possible. For some we don't. It becomes important to control the densification of the material," Malhotra said.

“Since densification in IPL depends significantly on the temperature, it is important to understand and control temperature evolution during the process.” Malhotra said. “This research can lead to much better process control and equipment design in IPL."