‘Electronic paper’ displays colours at a fraction of the energy cost

Traditional digital screens use a backlight to illuminate the text or images displayed upon them. While this is fine indoors, it can be difficult to see when in direct sunlight.

The reflective screens, developed by researchers from Chalmers University of Technology in Sweden, attempt to use the ambient light to mimic the way our eyes respond to natural paper.

“For reflective screens to compete with the energy-intensive digital screens that we use today, images and colours must be reproduced with the same high quality. That will be the real breakthrough. Our research now shows how the technology can be optimised, making it attractive for commercial use,” said researcher Marika Gugole.

The researchers had already previously succeeded in developing an ultra-thin, flexible material that reproduces all the colours an LED screen can display, while requiring only a tenth of the energy that a standard tablet consumes. However, in the earlier design the colours on the reflective screen did not display with optimal quality.

The new version uses a previously researched, porous and nanostructured material, containing tungsten trioxide, gold and platinum. It inverts the design in such a way as to allow the colours to appear much more accurately on the screen.

The researchers placed the component which makes the material electrically conductive underneath the pixelated nanostructure that reproduces the colours, instead of above it as was previously the case. This new design means a user looks directly at the pixelated surface, therefore seeing the colours much more clearly.

In addition to the minimal energy consumption, reflective screens have other advantages. For example, they are much less tiring for the eyes compared to looking at a regular screen; many people have already experienced these benefits through e-reader technology such as Amazon’s Kindle devices.

While certain rare metals are required to make the screens, such as the gold and platinum, the researchers said that only tiny amounts are needed because the final product is so thin. They also hope that they will be able to significantly reduce the quantities needed for production in the future.

“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.

Reflective screens are already available in some tablets today, but they only display the colours black and white well, limiting their use.

“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,” Dahlin added.