CAJ #7 - Potential use of graphene in solar cells

Solar cells are devices that convert the sun’s energy directly into electricity. They rely on the photoelectric effect - the ability of matter to emit electrons when a light is shone on it. Most of today’s solar cells are made out of silicon. However, silicon is very expensive because it is generally highly purified and then made into crystals that are sliced thin. Researchers have been trying to find an alternative that would be cheaper than silicon but have the same quality. Some believe the solution is inidium tin oxide, whereas others, namely MIT researchers, believe the answer is graphene. 

Silvija Gradček and eight other researchers at the  MIT, produced new graphene-based solar cells that are more flexible, lighter, and have a higher mechanical strength. The photovoltaic cell is based on sheets of flexible graphene coated with a layer of nanowires. This could lead to low-cost, transparent and flexible solar cells that could be set up on windows, roofs and other surfaces because of its low weight, mechanical strength and chemical robustness. This could potentially lead to the production of solar cells for households.

  

Graphene has a stable and inert structure, thus building a semiconducting nanostructure directly on its surface without damaging its electrical and structural properties has been a real challenge for researchers. They used a series of polymer coatings to modify its properties which allowed them to bond a layer of zinc oxide nanowires to it. Next they added an overlay of materials that respond to light waves. Throughout the whole process, graphene’s elemental properties remained intact.

1)  a flexible layer of graphene

2) a layer of polymer 

3) a layer of zinc-oxide nano wires (magenta color)

4) a layer of material that can extract energy from sunlight

The new graphene solar cells are not as efficient as certain types of silicon solar cells. Nonetheless, they are not far off the mark. Researchers will keep working on them in order to make them better and more efficient.  
So far the MIT research team has produced the graphene solar cell the size of only half an inch. It has not been proven yet that the technique can be used to create larger solar cells. Gradček says that it is only a matter of time when they will overcome this obstacle. She does not see that as a problem. Gradček claims that this technology could come on the market within the next couple of years. She hopes that this will make solar cells and solar power cheaper and available to the general public. 

XOXO A.