Researchers at the Massachusetts Institute of Technology are proposing a new material that could make the use of organic solar cells more feasible and cost-effective.
Organic solar cells are seen as inexpensive alternatives to silicon solar cells as they use carbon-containing compounds instead of highly purified silicon.
However, scientists have had a difficult time of coming up with inexpensive materials for the cells’ electrodes to carry the current to and from the cells.
The standard material used for the electrodes is indium-tin-oxide, which is expensive and rare. Thus, the M.I.T. researchers proposed an alternative made of carbon, specifically graphene.
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Graphene is a form of carbon in which the atoms form a flat sheet just one atom thick, arranged in a formation that resembles chicken wire.
The specific characteristics of the graphene electrode differ from those of indium-tin-oxide, but its overall performance in a solar cell is very similar.
Graphene is transparent, so electrodes made from the material can be applied to transparent solar cells without blocking the light. It is also flexible, allowing the organic solar cell to follow the contour of a structure for easier building integration.
Solar panels could also be stacked one on top of the other, increasing the amount of power generated from a given area.
However, one hurdle the researchers came across was how to get the material to adhere to the panel. Graphene repels water, so conventional procedures for producing an electrode by depositing the material from a solution do not work.
To solve this problem, the team introduced a set of impurities into the surface of the graphene to change its behavior and allow it to bond tightly. The new technique also improved the material’s electrical conductivity.
The team is now working to adapt graphene to replace two of the electrodes on a solar panel and is seeking to develop new techniques for large-scale manufacturing of graphene. The ongoing work has been funded by the Eni-MIT Alliance Solar Frontiers Center and an NSF research fellowship.
