Device screens act as solar chargers

Posted by Kate Taylor

Soon, devices such as phones and laptops could charge themselves thanks to displays that double as solar cells.

UCLA engineers say they've been able to equip LCD screens with built-in photovoltaic polarizers, allowing them to convert ambient light, sunlight and their own backlight into electricity.

LCDs work by using two polarized sheets that let only a certain amount of a device's backlight pass through. Tiny liquid crystal molecules are sandwiched between the two polarizers, and can be switched by tiny transistors to act as light valves. Manipulating each of the screen's light valves, or pixels, lets a certain amount of the backlight escape.

Now, the UCLA team has created what it calls a polarizing organic photovoltaic, which 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.

"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."

From the point of view of energy use, current LCD polarizers are inefficient, the researchers said. 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 - and much of that could be recovered through the polarizing organic photovoltaic LCD.

"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", says Yang. "We hope this energy-saving LCD will become a mainstream technology in displays."