Xiaolin Zheng’s research team at Stanford is reimagining solar panels:
Because conventional thin-film solar cells are manufactured on glass or silicon wafers, they are rigid, heavy, and quite limited in how and where they can be used. Plastic or paper would be far more flexible, but it cannot withstand the high temperatures and chemicals required for fabrication.
“Our new technique lets us treat the solar cells like a pizza,” explains Zheng. “When you bake pizza, you use a metal pan that can tolerate high temperatures. But when it’s time to distribute the pizza economically, it’s placed in a paper box.”
Working with her students, Zheng set out to fabricate solar cells on a silicone or glass surface as usual, but she inserted a metallic layer between the cell and the surface. After some trial and error, the team was finally able to peel away the metallic layer from the surface after soaking the whole structure in water for just a few seconds.
The result was an active solar cell that is only a couple of microns thick—about one-tenth the thickness of plastic wrap, Zheng says. “It’s extremely flexible, so it can be attached to any surface—the back of a mobile phone, a skylight, a wall, a curved column.”
The skinny, bendable cells can produce the same amount of electricity as rigid ones, and they offer cost benefits as well, according to Zheng. “The silicon wafers come through the process clean and shiny,” she says. “So just like a pizza pan, they can be used again and again, which translates to savings.” And because the solar stickers are lighter than conventional panels, they will be easier and less expensive to install.
The stickers might be able to reduce manufacturing costs too, Zheng says. In traditional solar-cell production, the foundation materials account for 25 percent of the cost. The new method will enable that base layer to be removed or replaced with a cheaper material. For example, the windows of a building provide a ready-made base layer, so all that’s needed is the solar cell itself. A cell that could simply be peeled and applied enables that economical shortcut.