Credit: Zimu Zhao
With batteries stubbornly refusing to get more efficient, researchers continue to hunt for new ways to power our gadgets. Recently, a cover story for the journal Advanced Optical Materials described how researchers at Michigan State University developed a transparent plastic they believe could double as both the screen for your devices and a solar power center.
Richard Lunt lead the team and says the material is intended for any surface where you want to maintain the underlying aesthetic -- be it an app on a glass screen, or a sunset out the window.
"It could be integrated [into] the touchscreen of a tablet or an e-reader," he told CITEworld. "We've designed it so you can retrofit it to your surface, like one of the protective films to prevent scratching."
The material is still being perfected -- right now, it has an energy conversion rate of less than one percent. So while it won't power Windows devices yet, the research team's central focus was using windows -- the glass kind -- as devices of power.
Photovoltaic cells often go on the roof to lighten the bills, but a building's yawning panes of glass on the walls leave a lot of unused real estate for power generation. As panels have gotten more efficient and less expensive, the concept of "building-integrated photovoltaics" (BIPV), an idea that's been around since the 1970's, has taken off. Researchers and designers alike continually look for ways to integrate the power generators into roofs and walls.
But it's proven slightly harder for windows to reap those same power rewards while maintaining adequate visibility. Pythagoras Solar builds windows made of two panes of glass and an air cavity in between. Optics direct the sunlight flooding through the window to solar voltaic cells that look akin to window blinds and generate power. Other efforts inject a luminescent dye into the glass which channels the solar energy to panels on the rim of the pane.
This is where Lunt hopes his research stands out. Those dyes color the material -- he reports their prototype models exhibit a transparency of about 86 percent, not too far from clear glass. The reason they don't need to obstruct visible light, which contains a lot of power, is they're not using it.
The material captures infrared light which we can't see. Small organic molecules absorb those rays and trap them in the window. Using principles similar to fiber optic cables the material guides the light energy to the edge where a solar cell absorbs the energy.
But again, this is still early days. Lunt has founded a company to develop the product but OEMs still have strict requirements about the materials used as screens, especially with respect to touch, thickness and transparency. Not to mention Lunt's group is still a ways off of their target efficiency of five percent.
We'll need to rely on those stubborn batteries a bit longer.
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