MIT researchers have achieved a breakthrough success in creating an all carbon solar cell that will be able to harness energy from solar rays that lie in infrared region of spectrum, and which silicon cells were unable to harness previously. About 40% of the energy that reaches earth’s surface lies in the infrared region and a great amount of energy was ignored by silicon solar cells, but now the new device, which is a combination of two forms, silicon and carbon nanotube, can harness more energy from sun. In the new cell, a layer of single walled, pure nanotubes is attached on the silicon surface without creating any hindrance for silicon part. This makes it possible to harness energy from both regions.

There have been a few previous attempts to harness the untapped energy of infrared range. However, the need of polymer to hold the carbon nanotubes in position made it unstable to sustain in the open air and added to the extra production costs, as extra coatings to prevent degradation were required. The layer of present material is transparent and can be easily stacked on conventional solar cells. As an early proof, the present device was tested to find out the energy conversion efficiency and it was found to be 0.1%. Further, the nanoscale carbon material used offers great efficiency and therefore less material would be required, thus leaving us with a light weighed photovoltaic cell.



The carbon-based cell is most effective at capturing energy in the near-infrared region. Because the material is transparent to visible light, such cells could be overlaid on conventional solar cells, creating a tandem device that could harness most of the energy from sunlight.

The haven’t yet finished the project completely, but still, the use of carbon nanotubes without polymer layers means a dream come true for the renewable energy world. With these cells the possibility of light and coast effective solar cells has increased. However, there are still inefficiencies in the device and researchers are looking to identify and solve them. Fact that heterogeneous mixtures of carbon nanotubes are much less efficient as compared to the homogeneous formulations has been a known problem to various other researchers working this field.

But, if the researchers could provide us with less efficient all carbon solar cells, even then it’ll be an advantage as the infrared region has never been harnessed and even a solar cell with low efficiency would add to the total amount of energy converted. To make it more comprehensive, you must go through the following statement given by Michael Arnold, an assistant professor of materials science and engineering at the University of Wisconsin at Madison:

Carbon nanotubes offer tantalizing possibilities for increasing the efficiency of solar cells and are kind of like photovoltaic polymers on steroids.” This work is exciting because it demonstrates photovoltaic power conversion using an active layer that is entirely made from carbon. This seems like a very promising direction that will eventually allow for nanotubes’ promise to be more fully harnessed.

MITNews