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Ynvisible Ventures Brings New Electrochromic Colors to Life

April 30, 2021
Ynvisible Ventures, the umbrella for Ynvisible’s ambitious R&D efforts and partnerships, presents the latest breakthroughs in developing new electrochromic colors as well as integrating a range of colors into low-cost ITO-free devices.

Electrochromic Colors Enable New Applications

This is the “Smart Thermos Flask”, a recent prototype integrated with electrochromic (EC)technology. Namely this is a vertically stacked electrochromic display (ECD) combining PET-ITO electrodes coated with PEDOT:PSS, a well-known electrochromic polymer “blue", and the newly developed EC polymer “Red”.  The cap of the flask is integrated with the ECD (visual indicator) connected to a temperature sensor, powered by a cell coin battery. The color combination of the blue and the red are useful to signal temperature perception applications, for example to indicate if the contents of the flask are cold (blue) or hot (red).

The combination of these EC materials in multi-colored devices is a significant advance in the increase of color change between the switching states, compared to the current available devices that rely on monochromatic blue-transparent and other monochromatic color combinations. In collaboration with industrial and academic partners, Ynvisble is working to expand the range of EC color choices available to designer, creatives, and commercial businesses.

Shades of red EC polymers. Credit: A. Stopin, University of Wien

During this process different polythiophene based polymer with tones targeting the red color have been designed and synthesized, aiming at 10000 – 100000 cycles and 1-3 s switching speed. Currently, Ynvisible is developing a formulation of the Red EC ink for industrial printing applications. The next step will be the scale up production of the obtained ink products. This is expected to be accomplished by June 2022.

Miriam Sousa, Project Development Specialist at Ynvisible’s R&D center in Freiburg, Germany, is one of the main contributors to the recent advancements in the colorful electrochromic displays.

This innovative work has been developed under the Decochrom project, a European Union’s Horizon 2020 research and innovation program. The development and synthesis of the Red EC material were carried out by A. Stopin from the D. Bonifazi group  at the University of Wien and the “Smart Thermos Flask” was developed by the A. Colley group from the University of Lapland. Both are partners in the project. The manufacture of the displays and the development of new EC inks has been performed by Ynvisible.

Cost-Effective Colorful Dynamic Displays without ITO

One of the key components of an electrochromic display is the underlying conductive substrate. This layer transfers electrons from the electrical contacts into the electrochromic polymer, allowing the polymer to undergo its characteristic color change. The most widely used conductive substrate is ITO, or Indium Tin Oxide. While ITO has desirable optical and electrical properties, the cost and scarcity of the material can be cost prohibitive for mass production.

In collaboration with researchers from the Reynolds Group at the Georgia Institute of Technology, Ynvisible has been working on a project targeting colorful electrochromic displays that do not require an underlying conductive substrate.

The conductivity of an electrochromic polymer film is dependent on several factors including the chemical composition, oxidation state, processing parameters, and additives in the material. Some electrochromic materials, for example the widely used blue PEDOT:PSS, have enough inherent conductivity to function without the support of an underlying conductive substrate. In this project, the team studied the performance a series of dioxythiophene based polymers with a range of conductivities and colors to investigate their performance without a supporting underlying conductor.

One primary outcome in the study was defining the conductivity threshold for a polymer to function without an underlying conductive substrate. The study further characterized how the conductivity relates to critical operating features such as the switching rate and cyclability in devices. The team then engineered a device layout to optimize the performance of these polymers in ITO-free devices.

The conclusions from this research project generate exciting new possibilities for incorporating more colors, such as green, magenta and orange, into low-cost labels.

Elin Howard is working as a Project Development Specialist at Ynvisible and is the main author in publication on this topic together with researchers Anna Österholm, Eric Shen, Prerana Panchumarti, and John R. Reynolds from the Georgia Institute of Technology. Read the full article here “Cost-Effective, Flexible, and Colorful Dynamic Displays: Removing Underlying Conducting Layers from Polymer-Based Electrochromic Devices”

Ynvisible Ventures – Center of Expertise

We believe in a vibrant and sustainable future! Ynvisible Ventures and its technology team focus on the next generation of electrochromic display technologies to deliver new functions and sustainable solutions. In co-operation with our extensive network of academic and industrial partners we help our customers to shorten the journey from discovery to product development.

Ynvisible’s innovation is based on 3 fundamental pillars:  new functional materials, device engineering and process integration & sustainability. The voice of the customer and market trends define our development goals, we are also conscious of our responsibility to put technology at the service of society. We find solutions for problems that are not addressed with existing technologies exploiting the unique features of electrochromics. We invite companies to join our innovation programs so that their custom needs will influence the development targets and benefit from custom solutions.

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