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Fermi level solar cells

  1. Jan 28, 2010 #1

    Im working on a paper on solar cells and i came across the term "Fermi level". What exactly is the Fermi level in this context:

    "The working voltage produced by the device is the difference
    between the chemical potential of the titanium dioxide (Fermi
    level) and the redox potential of the mediator (I-/I3-)."

    Thank you!

    Max Planck
  2. jcsd
  3. Jan 28, 2010 #2


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    Gold Member

    Re: Fermi_level

    "in this context"?
    Is there are any particular reason why you think they are refering to anything but the "normal" Fermi level?
  4. Jan 29, 2010 #3
    Re: Fermi_level


    I already read this topic: https://www.physicsforums.com/showthread.php?t=239923

    The first reply states that there are 2 definitions of fermi level.
    Its a bit confusing, can anyone explain?
  5. Jan 29, 2010 #4


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    Re: Fermi_level

    Chemical potential and Fermi level are synonyms.
  6. Jan 29, 2010 #5
    Re: Fermi_level

    What exactly is the chemical potential?
  7. Jan 30, 2010 #6
    Re: Fermi_level

    I read that the chemical potential of a semiconductor is in the middle of the band gap, is this true?
  8. Jan 30, 2010 #7


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    Re: Fermi_level

    No, generally not.
    Its the derivative of e.g. energy U with respect to particle number (here of electrons) at fixed S and V or of G at fixed T and p. In a semiconductor it is usually somewhere inside the gap, but seldomly in the middle. In a metal at absolute zero it is the borderline between the occupied levels and the empty energy levels.
    Have a look at a book on thermodynamics or solid state physics.
  9. Feb 1, 2010 #8
    Re: Fermi_level

    In general the Fermi level and the (electro)chemical potential are not the same, but in a semiconductor we regard them as being synonymous.
  10. Feb 1, 2010 #9
    Re: Fermi_level

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