This filament containing about 30 million carbon nanotubes absorbs energy from the sun as photons and then re-emits photons of lower energy, creating the fluorescence seen here. The red regions indicate highest energy intensity, and green and blue are lower intensity. (Credit: Geraldine Paulus/MIT.)
MIT News reports that chemical engineers have devised a way to collect solar energy 100 times more concentrated than a traditional photovoltaic cell. The solar funnel could alter how solar energy is collected by removing the need for large solar arrays.
The researchers, led by MIT’s Michael Strano, used carbon nanotubes as the primary instrument in capturing and focusing light energy, allowing for not just smaller, but more powerful solar arrays. The antenna consists of a fibrous rope about 10 micrometers long and four micrometers thick, containing about 30 million carbon nanotubes.
The inner layer of the antenna contains nanotubes with a small bandgap, and nanotubes in the outer layer have a higher bandgap. When light strikes the antenna, all of the excitons flow to the center of the antenna where they are concentrated and the photons are converted to an electrical current.
Strano says, “Instead of having your whole roof be a photovoltaic cell, you could have little spots that were tiny photovoltaic cells, with antennas that would drive photons into them.”
The solar funnels could be used in applications where light needs to be concentrated – such as telescopes or night-vision goggles. The nanotube antenna boosts the number of photons that can be transformed into energy, but in a similar process to that of tradition solar cells.
The research was published in the latest online Nature Materials.