by Melissae Fellet
reporter

12 July 2011
from NewScientist Website

Imagine decorating your bedroom walls with paper made from the same solar cells that now power your home.

That's the tantalizing possibility thrown up by the development of lightweight solar cells that can be printed on paper, be scrunched up like an accordion and still conduct electricity.

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.
 

The glass or plastic backing typically used for solar cells accounts for 25 to 60 per cent of the total cost for materials and so lightweight paper-based cells could significantly reduce photovoltaic production, transportation and installation costs.

A team led by Vladimir Bulović and Karen Gleason changed an ingredient in the material sandwich 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 using a dry fabrication process, depositing each layer as a vapor dispersed in a vacuum.

A thin mask patterned with holes restricted the placement of the five separate layers of material into cells:

the polymer electrode, three energy-collecting materials and the metal electrode at the top of the sandwich.

The fact that the vapor was deposited at a relatively low temperature means that the technique allows solar cells to be created on fabric, plastic, tissue paper and even printed newspaper.

At the moment, these paper solar cells are only about 1 per cent efficient. But that's still enough to run small electronics like an alarm clock.

A lightweight solar cell could be used for wallpaper or window shades and simply installed using staples or glue.