Light funnels – a new way to concentrate solar power

Solar Funnel
Solar Funnel created by MIT researchers. This filament contains about 30 million carbon nanotubes.
An MIT research team has found a way to concentrate light using carbon nanotubes that could lead to greatly improved solar cells.   Using the carbon nanotubes, the team was able to concentrate solar energy 100 times more than a regular photovoltaic cells.   The researchers believe that their nanotubes could form antennas to capture light, which would then be used to create smaller and much more powerful solar arrays.  “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,” says Michael Strano, the Charles and Hilda Roddey Associate Professor of Chemical Engineering and leader of the research team.

The new carbon nanotube antenna, called a “solar funnel”, consists of a fibrous rope about 10 micrometers long and four micrometers thick.   The fiber is made up of two different layers of nanotubes, with each layer having a different electrical property, or bandgap.  When light hits the outside layer with higher bandgap (the bandgap is the difference in energy between the electron at rest and the electron after its hit by a photon), it’s funneled from that layer to the inside layer where the bandgap is lower, which concentrates the energy.    The team has successfully demonstrated the nanotube antenna funnel – their next step is to construct a functioning solar cell by building an antenna around a core of semiconducting material.

Via: Science Daily

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