According to a July 18, 2007 press release, the folks over at the New Jersey Institute of Technology (NJIT) have come up with an inexpensive solar cell technology that can be painted or printed on flexible plastic sheets. Lead researcher and acting chair of NJIT's Department of Chemistry and Environmental Sciences, Somenath Mitra, PHD, predicts a scalability that will allow for inexpensive home-based inkjet printers.
The Royal Society of Chemistry's Journal of Materials Chemistry published the process in a June 21, 2007 cover story.
The new process uses carbon nanotubes (molecular configuration of carbon in a cylindar shape). The tiny nontube is estimated at 50,000 times smaller than human hair. The nanotubes are combined with fullerenes (called Buckyballs and which are like the tubes, but carbon in the shape of a sphere). The balls trabe the electrons, but need the sunlight to excite the polymers to create the electron flow through the tubes, which are better conductors than copper.
Current solar cells are made with purified silicon. When sunlight hits the solar cell, positive and negative charges are created. In order to generate a current, the charges must be separated. A traditional solar cell is made up of two types of silicon, postive-type silicon (p-type, which has slightly too few electrons, or free holes) and negative-type silicon (n-type, which has too many electrons, or free electrons). In order to create these two types from the normal pure crystalline structure of silicon (which wouldn't have the free electrons or the required holes) either boron (for p-type) or phosphorous (for n-type) is added to create the desired atmosphere where the mismatched electron scenario occurs.
When the p-type and n-type are combined, the n-type free electrons rush to fill the holes on the p-type side. At the junction, a one way barrier is formed as an equilibrium is reached (electric field), but there remain free electrons and holes.
Light (photons) knock electrons free (and thus create holes), which are driven by the electric field from the lower level to the upper level (n-type) while the holes are now on the lower lever (p-type). The provided circuit allows the lost free electrons a path back to the p-type side to reunite with their long lost holes. The electron flow = current. The electric field = voltage. Combining the two results in power!
Just slap an antireflective coating over the doped silicone (doping was the process we used to add the boron and phosphorous) so the sneaky photons can't get away, then cover the mess with a protective sheet of glass and we are ready to go. Surely the average Joe can do that at home?
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