Above: A sample of the polarizing organic photovoltaic film.

It's always a bummer when your phone starts to lose power and you aren't near an outlet. But some folks at UCLA might have that problem solved.

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LCDs use two polarized sheets that control how much of the backlight gets through. Images are created by the changes in current through liquid crystal molecules sandwiched between the two sheets.

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The UCLA engineers led by Yang Yang, a professor of materials science have made the polarized sheets into built-in photovoltaic cells, allowing them to convert ambient light, sunlight and their own backlight into electricity. It's called a polarizing organic photovoltaic, which can work as a polarizer, a photovoltaic device and an ambient light or sunlight photovoltaic panel at the same time.

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You can't use it for free energy — no hooking up your phone as a power source by itself — but it does mean that the batteries will last a lot longer, and the energy generated by the backlight's own glow isn't wasted. (The backlight is often the biggest energy hog in your phone). It an also allow the phone to charge a bit with ambient light.