Folded Solar

Solar electrical is pretty exciting right now, I must say. After my previous post on some of the cool stuff coming up in photovoltaics I let it slide for a while and chased other cool news, but this new thing from late December really caught my attention.

I mean, solar panel stickers? Which you can apply to fabric or paper, bend them, and have them still work?

The researchers say that this technique isn't only good for solar panels but also possibly for electronic circuits, transistors, and even LCDs as well. Maybe you really could have a solar powered, electronically active jacket, including flexible display, one day. Imagine, a self-powered jacket that could show you a map of where you are, among other things.

They tested the solar panels to a bend radius of 7mm without any damage. I don't know if it would handle a crease (if on paper) very well, or crumpled-clothes type bends. From the paper, it doesn't look like they tested its bending abilities to failure.

However, even this is pretty impressive:

[Photo from "peel and stick" article, via]

especially when you compare it to the normal type of solar panel:

One of the neat things I noticed while reading the paper was that this bendiness isn't actually due to the researchers making the solar panels in a substantially different way. It turns out this is a natural property of the materials used in normal thin-film solar cells. The new part, which makes the solar cells bendable, is that they've been removed from the rigid backing that they're made on.

Thin-film, flexible electronics and transistors have been under development for quite a few years. Google Scholar found papers and patents going back over ten years covering electronics in general, transistors, even computer memory, processing, and display, all thin and flexible.

And that last link is about an actual product, not basic research. This stuff isn't all that far off.

The key to getting the solar cell off of its production support looks simple, but probably took them a while to figure out, because that's how these things go. What they had to do was put a thin layer of nickel on the silicon support prior to making the thin film solar cell in the usual way. It turns out that nickel doesn't bond very tightly to a-Si:H while it does to silicon dioxide crystals, which the backing wafer is made from. Not only does nickel not bond very tightly, it releases its bonds to the solar cell material, but not the support wafer, when dunked in water.

That surprised me with how easy it looks. Not only that, but the nickel layer stays on the support wafer, and it can be sent back to the start of production and re-used. I'm all for re-using things.

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