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Plugged in to the Sun?


Published Aug 23, 2011 12:00 AM


Designed by Joseph Maddela

We've all worried about the charge on our smartphones or laptops running down when we’re not near an electrical outlet. But new technology developed at UCLA could help solve that problem.

Researchers at the UCLA Henry Samueli School of Engineering and Applied Science have created a concept for enabling electronic devices to convert ambient light, sunlight and their own backlight into electricity. This would be achieved by equipping the devices' LCD (liquid crystal display) screens with built-in photovoltaic polarizers.

LCDs, used in many electronic devices, contain two polarized sheets with liquid crystal molecules sandwiched between them. The two polarizers limit how much of a device's backlight can pass through. Tiny transistors can switch the liquid crystal molecules to act as light valves. Manipulating each light valve, or pixel, allows a certain amount of the backlight to escape; millions of pixels combine to create images on LCDs.

The UCLA team created a new type of energy-harvesting polarizer for LCDs called a polarizing organic photovoltaic. It can potentially boost the function of an LCD by working simultaneously as a polarizer, a photovoltaic device and an ambient light or sunlight photovoltaic panel.

"I believe this is a game-changer invention to improve the efficiency of LCD displays," says Yang Yang, a professor of materials science at UCLA Engineering and principal investigator on the research. "In addition, these polarizers can 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."

Current LCD polarizers are inefficient energy users, the researchers say. A device's backlight can consume 80 to 90 percent of the device's power. But as much as 75 percent of the light generated is lost through the polarizers. A polarizing organic photovoltaic LCD could recover much of that unused energy.

"In the near future, we would like to increase the efficiency of the polarizing organic photovoltaics, and eventually we hope to work with electronic manufacturers to integrate our technology into real products," Yang says. "We hope this energy-saving LCD will become a mainstream technology in displays."

"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," says Youssry Botros, program director for the Intel Labs Academic Research Office, which supported the research. "The strong collaboration between this group at UCLA Engineering and other top groups has led to higher cell efficiencies, increasing the potential for harvesting energy.”

The research was supported by Intel through a gift to UCLA, and by the Office of Naval Research.

Edited by Mary Daily and written by Matthew Chin and Wileen Wong Kromhout. This article originally appeared online at UCLA Newsroom, August 09, 2011.



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