Solar Cell 'Stickers' : 'bye to breakages

As far as we know, solar cells come as rigid panels that need a more or less flat area like a roof top to support it. This was thanks chiefly to the brittle nature of Silicon and the rigidity of the glass substrate. The cells were fragile, unless mounted to and shielded by shatter-proof glass. This limited the 'flexibility' of  their use too.

Now all that is set to change. Researchers at Stanford University have created the first 'peel-and-stick' solar cells. These cells are flexible and can be attached to a variety of surfaces. “Now you can put them on helmets, cell phones, convex windows, portable electronic devices, curved roofs, clothing – virtually anything,” says Xiaolin Zheng, the lead researcher. Most importantly, the peel-and-stick cells have the same efficiency as conventional glass-substrate devices, and they retain their performance through thousands of bending cycles. Another plus -- they can be produced using conventional, industry-standard facilities and materials.

The peel-and-stick solar cell begins life as 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.

Before sticking the cell to a surface, it is placed in a room-temperature water bath. The tape is peeled back slightly so that water seeps between the silicon dioxide/nickel interface, separating the cell from the wafer. The thermal tape is removed by heating it to 90 C (194 F) 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 other adhesive. The process is waste-free as  the Silicon wafer is undamaged and clean after removal of the solar cells, and can be reused.

The commercial realization of the process is sure to bring in highly innovative design thinking and novel applications of solar cells.

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