Post-doctoral researcher Congcong Wu, who is working in the lab of Shashank Priya, the Robert E. Hord Jr. Professor of Mechanical Engineering, holds up a layer of the flexible solar panel the group is working on. The process to adhere a thin film of titanium oxide to the panel takes less than 10 seconds using screen-printing technology. Credit: Image courtesy of Virginia Tech
A team of researchers at Virginia Tech have developed flexible solar panels to be used in wearables, window glass, wallpaper, and other products. If this technology is fully developed light energy could become the de-facto source of energy in homes and buildings.
The Virginia Tech panels were created by a screen-printing process using titanium oxide. The panels, which are roughly the size of a hand, are less than a half millimeter thick but can be arranged in patterns similar to the tiles of bathrooms. One panel can produce 75 milliwatts (mW) of power, so 60 or 70 panels could supply the power required to charge a smartphone. Another important aspect of these solar panels is the fact that they can convert any type of diffuse light such as LED output and fluorescent and incandescent light, according to lead researcher Shashank Priya, Robert E. Hord Jr. Professor of Mechanical Engineering at Virginia Tech. This is not the case with most existing standard polysilicon panels that absorb only sun light.
"There are several elements that make the technology very appealing," said Priya. "First, it can be manufactured easily at low temperature, so the equipment to fabricate the panels is relatively inexpensive and easy to operate. Second, the scalability of being able to create the panels in sheet rolls means you could wallpaper your home in these panels to run everything from your alarm system, to recharging your devices, to powering your LED lights. The properties of the panels are such that there are really few limitations in terms of light source," Priya adds. "And the fact that we are dealing with an emerging technology, means we will be able to expand the utility of the panels as we go forward."
The conversion efficiency of the Virginia Tech flexible panels is about 10 percent, compared to 13-15 percent efficiency for silicon panels, a mature technology. "Our panels right now operate around 10 percent at the panel size. At smaller, less-useful sizes, the efficiency increases, and so we can see a potential for much greater energy collection efficiencies," Priya says. When the conversion efficiency of these panels approach the existing silicon panel efficiency they can be used in products that the silicon technology can’t compete with.
"Right now we are on the cutting edge of this technology," Priya said. "Our edge is in the ability to fabricate large-area modules with high efficiency. We are actively working to integrate the product with the market and we see a wide variety of uses for the technology, from clothing to windows, to smart buildings to UAVs to mobile charging stations."
