Nanoparticle inks for reel to reel flexible electronics manufacture
Researchers from the Leibniz Institute for New Materials (INM) have developed nanoparticle inks featuring transparent, conductive oxides (TCOs) and claim the transparent lines and patterns, which can be created by direct gravure printing on thin plastic foils remain electrically conductive even after bending.
According to the team, conductive TCO coatings are usually applied using high vacuum techniques, such as sputtering. Patterning TCO coatings requires additional process steps, including photolithography and etching. These are more costly than the one step printing process enabled by the TCO inks.
“We use TCOs to produce nanoparticles with special properties”, said Peter William de Oliveira, head of the Optical Materials Program Division. “The TCO ink is created by adding a solvent and a special binder to the TCO particles.” The binder performs several tasks: it not only makes the TCO nanoparticles adhere well on the film, it also increases the flexibility of the TCO coating. After curing under UV light at temperatures of less than 130°C, the coating is ready.
The transparent electronic inks are said to allow conductor tracks to be produced using a reel to reel process. The team says initial trials have been promising and it adds that the use of structured rollers will allow larger structured conductive surfaces to be printed at high throughput and low cost.
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