New approach to harvesting solar energy could generate power from sunlight …

January 21, 2014 by  
Filed under Solar Energy Tips

According to a January 19 news release from MIT, researchers have developed a new way to gather solar energy with increased efficiency by using sunlight to heat a material and have its infrared radiation collected by a standard photovoltaic cell.  The researchers say that adding the extra step increases performance, because wavelengths of light that ordinarily go to waste can be used.  The complete research findings appear in this week’s issue of Nature Nanotechnology.

To overcome the limitations presented by standard silicon-based solar cells, the researchers introduced a two-layer absorber-emitter device between the sunlight and the photovoltaic cell.  This middle material collects energy from a wide spectrum of sunlight, heating up in the process.  When it heats up, the material emits light of a particular wavelength, adjusted to match the bandgap of the PV cell mounted nearby.

The two-layer material is key to this increased efficiency, as the outer layer, facing the sunlight, is an arrangement of multi-walled carbon nanotubes, which efficiently absorbs the light’s energy and turns it to heat.  This layer is fused to a layer of a photonic crystal, which is specifically engineered so that when the attached layer of nanotubes heats it, it glows with light whose peak intensity is mostly above the bandgap of the neighboring PV, ensuring that most of the energy collected by the absorber is then turned into electricity.

The researchers assert that the new solar thermophotovoltaic systems could offer the improved efficiency because of their broadband absorption of sunlight; scalability and compactness, because they are based on existing chip-manufacturing technology; and ease of energy storage.

 

 

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