Electrochromism is the reversible colour change of a material in response to an electrical stimulus. Most people have come across electrochromic technology in their cars, in the automatic dimming of the rearview mirror. In the world of printed electrochromics, the materials are taken into printable form so that they can be applied to flexible substrates. “In the context of this, the DecoChrom project aimed to elevate printed graphics products to the age of interactivity. This empowers the creative industries with the tools and innovative advanced materials to design and build aesthetically pleasing practical user interfaces to smart consumer goods and environments,” outlines Jonna Häkkilä, coordinator at the University of Lapland, Finland. The project worked to scale up the production of advanced composite materials towards three innovative electrochromic ink colours and develop manufacturing processes for different substrate materials, particularly plastic foil, high-pressure laminate and injection-moulded plastic. Project work consisted of wide dissemination activities, including numerous hands-on workshops to introduce electrochromics to designers, makers and the printing industry and the development of a toolkit to support the design process. “To explore and demonstrate the potential of the technology, the project also created functional end-user prototypes in the areas of architecture, interior design, lifestyle and sports,” explains Ashley Colley, project manager at the University of Lapland.
The age of interactivity: printed electrochromics
“The DecoChrom consortium developed printed electrochromics as the mass-producible, print industry-compatible, ultra-low power-interactive graphics solution for ambient intelligence,” confirms Häkkilä. The project’s achievements include the synthesis of multiple new red and black electrochromic polymers and the development of novel methods for their characterisation and upscaling. “Novel methods for over-moulding electrochromic displays and for embedding displays in high-pressure laminates were developed and demonstrated. Printing processes for electrochromic materials were optimised, including red ink printing by flexo, rotogravure and sheet to-sheet screen-printing, and industrial roll-to-roll printing of functional materials on paper substrates,” highlights Colley. Furthermore, the project designed and developed over 50 functional prototypes combining technology and design, which illustrated potential end-user products, utilising the developed electrochromic materials. “A key element in the project dissemination were the 25 hands-on workshops, where 340 participants learned to design and build electrochromic displays,” reports Häkkilä.
Bringing to market electrochromic displays
Based on the project’s outputs, the potential for the take-up of electrochromic displays as part of commercial products, beyond the current applications of window shading and labelling, has been demonstrated. “The prototypes developed in the project highlight opportunities for calm, aesthetic interfaces embedded into our living environments. For example, flexible displays were integrated into footwear and clothing,” describes Häkkilä. The developed red ink, which is the first red electrochromic ink suitable for screen-printing and rotogravure, extends the available colour palette to address product designer requirements. What’s more, new approaches for the integration of electrochromic displays in new materials and structures have been demonstrated through display integrations in high-pressure laminates and injection moulding, leveraging the potential for printed electronics. The project resulted in six entries in the EU’s Innovation Radar. “Through the new capabilities developed and demonstrated in the project and the increased awareness created amongst designers about the new materials, the project has paved the way for the commercial development of products including electrochromic display technology,” concludes Häkkilä.
DecoChrom, electrochromic displays, printed electrochromics, human interfaces, ambient intelligence