Typical roll-to-roll manufacturing processes utilize solution based inks or pastes followed by a  post-deposition thermal step, primarily to evaporate solvents but also to initiate chemical reactions and anneal/sintering at high temperatures. The residence times required to complete these post deposition processes is considerably longer than the actual deposition and hence the ovens dominate the production line. Although this is accepted protocol and has been established over decades of operations, it does incur inefficiencies, downtime, yield issues and can be a major impediment to advanced substrates. Intense pulsed light can reduce the habitual reliance on large scale ovens and will improve the energy efficiency of roll-to-roll manufacturing, and open up to a larger range of substrates and devices on flexible substrates.

Our group has been conducting research using the intense pulsed light process for several thin films with applications in:

• conductive films for printed electronics,
• wide area semiconducting films for photovoltaics,
• optical thin films for engineered surfaces, and
• graphene oxides.
  

Intense pulsed light is a localized heating technique that uses a broad spectrum of light delivered by a high energy xenon bulb over a wide area. Thin films with high absorbance within the visible light spectrum absorb this light energy and it is quickly released as thermal energy. The induced temperatures can reach up to several hundred degrees centigrade which are sufficient to induce thermomechanical and thermochemical responses. The process is extremely fast and as such these temperatures within the film are not transmitted into the substrate. Thus it is possible to employ the method on delicate substrates such as plastics and thin film membranes, and the speed of the process reduces handling long unsupported webs.