Cell phone battery charging from ambient light possible: research

It might be possible one day to top up cell phone batteries from ambient light, say companies like Japan's Kyocera who have solar-powered displays in the works believe.

Material scientists at the University of Illinois at Urbana-Champaign who have developed multi-purpose LED arrays that absorbed light and turned it into electricity, and did other things besides also believed it was possible.

The LED arrays consisted of tiny nanorods arranged on a thin film made from three types of semiconductor.

The nanorods measured less than five nanometres in diameter. One of these materials both emitted and absorbed visible light, while the other two materials facilitated how electrons flowed through the first. The combination gave the LEDs the ability to emit, sense and respond to visible light.

They did this by rapidly switching between emission and detection mode, which happened so fast that it is imperceptible to the human eye, meaning that the display appeared as if it was constantly alight.

When the LEDs detects light, they absorb in much the same way as a solar cell. At the moment, this happened only on a very small scale, but the researchers are enthused by the early results and believe that they could work toward a self-powered LED display that did not compromise on performance.

''These LEDs are the beginning of enabling displays to do something completely different, moving well beyond just displaying information to be much more interactive devices,'' said Moonsub Shim, professor at the University of Illinois at Urbana-Champaign in the US.

''That can become the basis for new and interesting designs for a lot of electronics,'' said Shim.

''The way it responds to light is like a solar cell. So not only can we enhance interaction between users and devices or displays, now we can actually use the displays to harvest light,'' Shim said.