The age of tablets and e-readers has put a vast world of knowledge and entertainment at our fingertips and leaves many of us glued to our screen whether it be for work, education, fun or relaxation. One consequence of this is the amount of energy needed to power all those LED screens, and another is the strain on our eyes from looking at a brightly lit screen for too long. Traditional digital screens also become obscured when brought outdoors into the sunlight. A team of researchers at Chalmers University of Technology recently gave a boost to “electronic paper” technology, which solves some of these problems, by enabling thin reflective screens to display more brilliant colors than ever before.
Reflective screens use ambient light rather than the backlights used by traditional screens, mimicking the way our eyes respond to natural paper. These screens, made from specially-designed materials, use much less energy than traditional tablets, are less tiring on the eyes and can also be viewed clearly outdoors. Most electronic paper products currently on the market can only display in black and white, and previous reflective screens developed to display color did not reproduce colors with enough quality to compete with LED screens.
The Chalmers team managed to increase the quality of these colors by inverting a previous design, placing the electrochemical cell that makes the material electrically conductive underneath the pixelated nanostructure that reproduces the colors, instead of on top of it toward the viewer. The viewer can then look directly at the pixelated surface, making the colors appear much more brilliant. The new material consists of a porous platinum mirror over a layer of tungsten trioxide, with a layer of gold underneath. The research was published in Nano Letters.
“Our main goal when developing these reflective screens, or ‘electronic paper’ as it is sometimes termed, is to find sustainable, energy-saving solutions. And in this case, energy consumption is almost zero because we simply use the ambient light of the surroundings,” said research leader Andreas Dahlin.
Although the screens require rare metals like gold and platinum, the final products are thin enough that the amount of metal needed is very small. The researchers hope to further improve the design to require even less metal, and envision their technology being used in applications ranging from phones, tablets and e-readers to outdoor advertising screens.
Photo: A new design from Chalmers University of Technology could help produce e-readers, advertising signs and other digital screens with optimal color display and minimal energy consumption. Credit: Marika Gugole/Chalmers University of Technology