Tuesday, 24 July 2012 10:48
July 24, 2012
Over the past few years, the U.S. has already become a growing player in the solar energy industry, with states like New Jersey and California seeing solar panels cropping up on rooftops from houses to warehouses.
Researchers at the University of California at Los Angeles are hoping to bring this revolutionary new power source down off the roofs specifically to where people will not see them - windows.
Seeing through solar
The UCLA group, led by professor of materials science and engineering Yang Yang, has further developed a new breed of solar technology known as polymer solar cells, which rely on complex large molecules to absorb light and transform it into an electrical charge.
Polymer solar cells offer a variety of interesting potential advantages over traditional crystalline silicon solar cells, or even thin-film solar cells made from elements like gallium or amorphous silicon.
Chief among these advantages is that polymers, a broad category of molecules that encompasses plastics and a range of other natural and synthetic substances, can be specifically tailored to target certain attractive traits.
In general, this has meant creating lighter-weight, more flexible solar cells than the heavy, rigid crystalline silicon allows. But Yang's team also focused on creating polymers that would pointedly target infrared light instead of the visible spectrum that gets absorbed by most traditional solar panels.
What resulted was a thin film that incorporates transparent polymers capable of absorbing entirely invisible parts of sunlight along with a mesh of fine silver nanowire that serves as the one electrode for the device and a layer of titanium dioxide as another. According to Bloomberg, these wires are only around 0.1 micrometers thick.
Spreading solar as far as possible
This new type of solar cell offers a wide range of interesting possibilities for the future of solar power, highlighted first and foremost by the idea that every building could be designed with south-facing windows that would absorb some amount of electricity without impeding peoples' views.
If the process were made cheap or ubiquitous enough, such windows could conceivably be installed throughout a building, absorbing infrared from the surrounding landscape.
These types of applications would not necessarily require huge renovations either, simply requiring owners to apply the film on top of the existing glass window.
"It’s my dream that everyone’s window can be a solar panel in the future," Yang told Bloomberg. "It could be potentially very cheap."
However, windows are not the only possible application for this technology. Transparent solar cells could also be applied to all sorts of consumer electronics, helping to recharge batteries with wasted energy from the backlight even as the devices are in use.
"These results open the potential for visibly transparent polymer solar cells as add-on components of portable electronics, smart windows and building-integrated photovoltaics and in other applications," said Yang.
Improving cost-benefit picture
One of the biggest knocks against solar power is that it is generally not cost-effective at current electricity prices, but that picture has been steadily improving as the technology improves and efficiencies rise.
By emphasizing making these solar cells transparent, the UCLA team took a step back on efficiency going from between 10 and 20 percent for most on-market technologies, depending on which technology customers choose, to around 4 percent.
However, the group has already tested similar technologies that could bring that number as high as 11 percent, in the range currently on the market. Yang told Bloomberg he hopes to eventually reach a cost of between $10 and $15 per window, with even cheaper spray-on applications possible for large-scale manufacturing.
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