A new type of reflective screen — sometimes described as electronic paper — was developed that offers optimal color display, while using ambient light to keep energy consumption to a minimum.
Traditional digital screens use a backlight to illuminate the text or images displayed upon them. This is fine indoors but creates difficulties in viewing such screens in bright sunshine. Reflective screens, however, attempt to use the ambient light, mimicking the way our eyes respond to natural paper.
The researchers previously developed an ultra-thin, flexible material that reproduces all the colors an LED screen can display, while requiring only a tenth of the energy that a standard tablet consumes. But in the earlier design, the colors on the reflective screen did not display with optimal quality. Using a porous and nanostructured material containing tungsten trioxide, gold, and platinum, the team tried a new tactic — inverting the design in such a way as to allow the colors to appear much more accurately on the screen.
The team placed the component that makes the material electrically conductive underneath the pixelated nanostructure that reproduces the colors instead of above it, as was previously the case. This new design means one looks directly at the pixelated surface, seeing the colors much more clearly.
To make these reflective screens, certain rare metals are required — such as the gold and platinum — but because the final product is so thin, the amounts needed are very small. The researchers hope that eventually, it will be possible to significantly reduce the quantities needed for production.
Reflective screens are already available in some tablets today but they only display the colors black and white well, which limits their use.
In addition to smartphones and tablets, the technology could also be useful for outdoor advertising, offering energy and resource savings compared with both printed posters or moving digital screens.
For more information, contact Professor Andreas Dahlin at