Low-energy e-paper goes inverted for a full array of brilliant colors
From building facades in San Diego to road signs in Australia, we're starting to see electronic paper make its way beyond the pages of Kindles and into the world in some very interesting ways. Working to widen the applications for this promising technology are scientists at Sweden's University of Technology, whose latest electronic paper display takes on an inverted design to offer a full array of accurate and brilliant colors.
Electronic paper like that used in Kindles and other e-readers uses just a fraction of the energy of tablets and smartphones, as they require no backlight to illuminate text and images. This is because they feature reflective screens with electrically conductive polymers that reflect and absorb ambient light, mimicking the way our eyes process information on regular paper.
This allows for displays that use minimal energy, are easier on the eyes, and can be worked into thin and even flexible forms. One aspect of this technology that has proven challenging, however, is in producing electronic paper with full-color displays, or at least of the same quality as we're used to on our tablets and phones. Advances are being made with various full color screens and tablets, and right at the cutting edge of this process are the chemical engineers behind this latest study.
In 2016, the team introduced a flexible, full color e-paper that uses 10 times less energy than a Kindle, with a thickness of less than 1 micron. This display featured electrically conductive components laid over the top of a pixelated surface, and used a combination of red, green and blue pixels to produce different colors, though at sub-optimal quality.
To address this, the scientists leveraged a new porous material made of trioxide, gold and platinum and used that as their electrically conductive component. This was laid beneath the pixelated surface rather than over the top of it as before, which means the user looks directly at the pixels and obtains a much clearer view of the colors on show. So much so, the team says this new display clearly outperforms the latest commercially available e-readers in terms of color and brightness.
“For reflective screens to compete with the energy-intensive digital screens that we use today, images and colors must be reproduced with the same high quality," says Marika Gugole, Doctoral Student at Chalmers University of Technology. "That will be the real breakthrough. Our research now shows how the technology can be optimized, making it attractive for commercial use."
One area the team would like to improve on is the use of rare metals, in this case gold and platinum. Because the display is so thin, it only requires small amounts of these materials, but the scientists hope to continue refining the design so that less and less of them are needed. They say the technology could one day be used in phones, tablets, and outdoor billboard-type displays, and imagine that in the right hands, may be commercialized sooner rather than later.
“A large industrial player with the right technical competence could, in principle, start developing a product with the new technology within a couple of months,” says study author Andreas Dahlin.
The research was published in the journal Nano Letters.