Researchers at Stanford University have created the first peel-and-stick solar cells. These cells are flexible, can be attached to a variety of surfaces (windows, business cards, clothing), and most importantly they can be produced using conventional, industry-standard facilities and materials. Furthermore, it should be possible to use Stanford’s new process to create peel-and-stick computer chips and LCD displays.

To make a peel-and-stick solar cell, Stanford begins with a standard silicon wafer that has had a layer of silicon dioxide grown on it. A 300nm (0.3 micron) layer of nickel is deposited on the wafer, and then a conventional, hydrogenated amorphous silicon thin-film solar cell (TFSC) is deposited on top of that. The whole thing is covered in a protective polymer (plastic), and finally a piece of thermal release tape is attached to the top of the solar cell (think of it as normal adhesive tape that can be removed with heat).

You now have a peel-and-stick solar cell. To actually affix it to something, the cell is placed in a room-temperature water bath. The tape is peeled back slightly, which allows water to flow between the silicon dioxide/nickel interface, separating the cell from the wafer. The thermal tape is removed by heating it to 90C (194F) for a few seconds, and then it’s simply a matter of affixing the flexible solar cell to any surface you like — with double-sided tape, glue, or any other adhesive that tickles your fancy.

In testing, the peel-and-stick process leaves the thin-film solar cell completely in tact. The peel-and-stick TFSC has the same efficiency as a conventional glass-substrate TFSC (7.5%), and it retains its performance through thousands of bending cycles. Xiaolin Zheng, the lead researcher, even says that the process is waste-free: “The (Si) wafer is typically undamaged and clean after removal of the solar cells, and can be reused.”



Historically, by virtue of silicon’s brittleness and the rigidity of the glass substrate, solar cells are about as inflexible as it gets. This limits their use to large, flat expanses, such as deserts and rooftops. “Now you can put them on helmets, cell phones, convex windows, portable electronic devices, curved roofs, clothing – virtually anything,” says Zheng. The research team also believes that the same process can be used to create peel-and-stick LCD displays and printed circuits — which makes sense, given that all of these technologies are ultimately based on silicon.

Just last week we wrote about flexible, fiber-optic solar cells that can be woven into clothes — and only two days ago MIT announced that it had produced flexible solar cells from graphene. It’s a fairly big step from wearable solar cells to wearable computers, but it’s now only a matter of time until we at least have clothing that can recharge our smartphone while we walk around, solar-powered LCD display business cards, and of course hilarious, programmable t-shirts and caps.

Now read: LG produces the first flexible cable-type lithium-ion battery

Research paper: doi:10.1038/srep01000 – “Peel-and-Stick: Fabricating Thin Film Solar Cell on Universal Substrates”