In the next half hour, more energy from the sun will hit our planet than the entire world’s population will consume in the next year. It’s little wonder that capturing some of that solar energy is a key part of just about any sustainable energy strategy. The problem is that this energy does not come for free. The sunlight must be captured and converted into a form of energy that can be stored until it is needed and then transported to where it is needed.
One of the most common ways to do this is to convert the light into electricity using solar cells. The problem is that most designs currently in use or in development require the use of expensive materials, such as silicon crystals or indium (used as a transparent conductor). Fortunately, new approaches make use of more common materials, such as carbon.
[Credit: Mark Shwartz, Stanford University]
Researchers at Stanford have succeeded in combining various forms of carbon to create a functioning solar cell. To capture the sunlight and convert it to electricity, they used a combination of carbon nanotubes (CNT) and “buckyballs” which are soccerball-shaped molecules of pure carbon. To transport the electricity from the cell, they constructed electrodes using graphene (sheets of carbon that are just one atom thick) and carbon nanotubes.
The problem with the initial device is that it only captures energy from the near-infrared portion of the light spectrum, which misses out on the higher energy of the shorter wavelengths in sunlight. The Stanford researchers are working with carbon materials that could capture more of the light. They also need find ways to assemble the layers of the nanomaterials better, which should also help the device be more efficient at converting the light energy.
In addition to its inexpensive materials, one of the strongest features of the all-carbon solar cell is the fact that it ultimately could be produced using simple coating methods that would allow for high-speed, low-cost manufacturing. If the devices can be made cheaply enough, they could turn out to be more cost-effective than traditional solar cells that cost much more to produce.
In the end, the same carbon that some believe is behind global warming, could turn out to be an important part of the puzzle to eliminate our use of fossil fuels.