Solar cells, printed on paper, may someday decorate your walls

Imagine decorating your sunny bedroom with wallpaper that generates electricity.

That’s the tantalizing possibility thrown up by the development of solar cells that can be printed on paper. Researchers at the Massachusetts Institute of Technology printed them on untreated copy paper using a technique that could help slash the cost of producing solar cells.

Solar cells’ glass or plastic backings typically account for 25 to 60 percent of the total cost for materials, so lighter, paper-based cells could significantly reduce the overall cost of producing, transporting and installing photovoltaic systems.

A team led by Vladimir Bulovic and Karen Gleason changed an ingredient in the sandwich of materials that makes up a solar cell. They used a flexible conducting polymer as the bottom electrode in the sandwich instead of a transparent metal oxide.

The researchers constructed the solar cell by depositing each layer as a vapor dispersed in a vacuum: first the polymer electrode, then three energy-collecting materials, and finally the metal electrode at the top of the sandwich. Because the vapor was deposited at a relatively low temperature, the technique allows solar cells to be created on fabric, tissue paper and even newspaper.

At the moment, these paper solar cells are only about 1 percent efficient. But that’s enough to run small electronics such as alarm clocks. A lightweight solar cell could be used for wallpaper or window shades and simply installed using staples or glue.