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2251 Views 1 Reply Latest reply: May 29, 2014 11:37 AM by mrtibbs RSS
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May 26, 2014 10:03 PM

Photo/Fuel Cells

I've always wondered on how photo cells work. How would it generate electricity? And these chargers and light fixtures are so common nowadays, how efficient are these things anyway?

 

And how about Fuel Cells? how do they generate electricity? What sort of fuel does it use? and where are they best used?

 

Thanks for the answers!

  • mrtibbs Novice 13 posts since
    May 21, 2014
    Currently Being Moderated
    May 29, 2014 11:37 AM (in response to Riley)
    Photo/Fuel Cells

    In order to understand photo cells you first need to understand the fabrication process of said photo cell.  Photo-cells are generally made from silicon and some other doping agent.  The doping agent generates holes (a space that lacks and electron) or excess electrons.

     

    The electrons and holes live in two different levels of electric conductivity, the valence band and the conduction band.  When you shine light onto a photo diode for example, you are actually bombarding it with photons!  Photons are absorbed by the material and force electrons from the valence band to the conduction band.

     

    Electrons that are in the conduction band are then free to move around, when an electric field is placed across the diode, the electrons in the conduction band begin to move toward the positive signal.

     

    There is a whole lot of physics that determines how many free electrons there are in a material and how much photon energy the band gap can absorb.  This is just a very brief example.

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