Printed Electronics Goes Green with Water-Based, Fully Recyclable Technology

Engineers at 美国杜克大学 have produced the world's first fully recyclable printed electronics that replace the use of chemicals with water in the fabrication process. By bypassing the need for hazardous chemicals, the demonstration points down a path industry could follow to reduce its environmental footprint and human health risks.

On February 28, Nano Letters published a study led by Aaron Franklin, the Addy Professor of Electrical and Computer Engineering at Duke University, addressing the challenge of securing multiple layers of components on top of each other in electronics manufacturing. This is especially difficult in printed electronics, as getting the layers to stick together can be a frustrating process.

Franklin and his group previously developed the first fully recyclable printed electronics, using three carbon-based inks: semiconducting carbon nanotubes, conductive graphene, and insulating nanocellulose. In their recent study, they attempted to adapt the original process to only use water, but encountered difficulties with the carbon nanotubes.

To create a water-based ink with carbon nanotubes that don't clump together and spread evenly, a surfactant similar to detergent is added. However, this results in an ink that doesn't create a layer of carbon nanotubes dense enough for a high current of electrons to travel across. Furthermore, the surfactant used to keep the carbon nanotubes from clumping also prevents additional layers from adhering to the first.

Franklin and his group developed a cyclical process in which the device is rinsed with water, dried in relatively low heat, and printed on again. They also tuned down the amount of surfactant used in the ink. The result is fully functional, fully recyclable, and fully water-based transistors.

While the performance of these thin-film transistors doesn't match the best currently being manufactured, they're competitive enough to show the research community that they should all be doing more work to make these processes more environmentally friendly. The approach could be used in the manufacturing of other electronic components like screens and displays, which currently rely on high-energy fabrication technology that uses hazardous chemicals and toxic gasses.

Read more here https://www.nature.com/articles/s41928-021-00574-0