Rather than struggle to find a free electrical outlet at a bookshop or cafe, people hoping to recharge their smartphones and laptops may someday just look for a nice sunny spot. That's because a new technology employed in the screens of gadgets could harness energy from any source of light, ranging from the sun to the gadget itself.
"I believe this is a game-changer invention to improve the efficiency of LCD displays," Yang Yang, a professor of materials science at the University of California in Los Angeles, said of the new "polarizing organic photovoltaic" liquid crystal display.
The LCD screens of smartphones, TVs, laptops and tablets are polarized sheets with millions of tiny liquid crystal molecules that act as light valves to let a device's backlight pass through in certain patterns. The escaping light creates the images people see on a screen, but any light absorbed by the polarizer is simply lost energy. The new, energy-harvesting polarizer can convert the backlight, ambient light or sunlight into electricity.
"In addition, these polarizers can also be used as regular solar cells to harvest indoor or outdoor light. So next time you are on the beach, you could charge your iPhone via sunlight," Yang said.
Backlights in existing gadgets can use 80 to 90 percent of their power, and as much as 75 percent of the light gets lost when absorbed by the polarizers. The polarizing organic photovoltaic LCD could recapture much of the lost energy, though not enough to completely recharge the device by itself.
Turning polarizers into the new energy-efficient version requires only a simple coating method that can easily be expanded for large-scale manufacturing, said Rui Zhu, a postdoctoral researcher at UCLA and lead author on a related paper in the online edition of the journal Advanced Materials.
The project has funding support from Intel, the world's largest computer chip maker, and the Office of Naval Research.
"The polarizing organic photovoltaic cell demonstrated by Professor Yang's research group can potentially harvest 75 percent of the wasted photons from LCD backlight and turn them back into electricity," said Youssry Boutros, program director for the Intel Labs Academic Research Office.