Traditionally, thin-film solar cells are made with rigid glass substrates, limiting their potential applications. Flexible versions do exist, although they require special production techniques and/or materials. Now, however, scientists from Stanford University have created thin, flexible solar cells that are made from standard materials – and they can applied to just about any surface, like a sticker.
To make the peel-and-stick cells, the researchers started by applying a 300-nanometer layer of nickel onto a rigid silicon/silicon dioxide wafer. Using standard fabrication techniques, thin-film solar cells were then deposited onto the nickel. A protective polymer was then applied over the cells, followed by a layer of thermal release tape being applied over it.
The resulting sandwich of material was then submerged in room-temperature water and one edge of the tape was peeled back, letting water seep in between the nickel layer and the wafer. Once the nickel completely separated from the wafer, the researchers were left with a bare wafer, and the tape with everything else still clinging to it.
The tape and its contents were then heated to 90ºC (194ºF) for several seconds, adhesive was applied to the non-tape side, and the whole thing was applied to a chosen surface. When the tape was subsequently peeled off, all that was left were the polymer-covered cells, adhered like a decal.
The cells have been successfully applied to a variety of both flat and curved surfaces – including glass, plastic and paper – without any loss of efficiency.
Not only does the new process allow for solar cells to applied to things like mobile devices, helmets, dashboards or windows, but the stickers are reportedly both lighter and less costly to make than equivalent-sized traditional photovoltaic panels. There’s also no waste involved, as the silicon/silicon dioxide wafers can be reused.
According to assistant professor of mechanical engineering Xiaolin Zheng, the process could likely also be used to create peel-and-stick thin-film electronics, such as printed circuits or LCDs.
“Obviously, a lot of new products – from 'smart' clothing to new aerospace systems – might be possible by combining both thin-film electronics and thin-film solar cells,” she said. “And for that matter, we may be just at the beginning of this technology. The peel-and-stick qualities we're researching probably aren't restricted to Ni/SiO2 [nickel/silicon dioxide]. It's likely many other material interfaces demonstrate similar qualities, and they may have certain advantages for specific applications. We have a lot left to investigate.”
A paper on the research was published this Thursday in the journal Scientific Reports.
Source: Stanford University
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