New research suggests that more effective colour displays could be coming to eBook readers and other electronic paper devices in future. 

If you've got an Amazon Kindle or similar, you'll know that it's very much a black and white experience, while commercially available colour readers are expensive. 

Researchers working at the Chalmers University of Technology in Sweden have published research in the Nano Letters journal around a paper-thin screen that can also show colour. Crucially, the display should be very energy efficient since it uses ambient light rather than a backlight to show text and images while also showing colour accurate images. 

The display uses tungsten trioxide as it is able to regulate how light is absorbed and reflected, say the researchers. They tried using a combination of tungsten trioxide, gold and platinum. 

The researchers say these reflective rather than backlit displays are also easier on the eyes, too. 

"In this work, we show a new design for inorganic electrochromic nanostructures which circumvents the problem of low reflectance while still providing an excellent colour range" say the researchers. This is achieved by selecting the right metals and reversing the thin film layers, enabling all electrical components to be “hidden” behind the reflective surface.

"We show that our nanostructures clearly outperform the latest commercial colour e-reader in terms of both color range and brightness," they add.