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I Transport in PV Cells (and pn diodes)

  1. Jul 18, 2017 #1
    Hi,

    I'm having some trouble wrapping my head around some of the concepts and language of charge transport in Photovoltaic cells (and thus pn-diodes). My biggest problem is understanding the role played by the emitter region vs. the depletion region.

    In a typical PV cell the front emitter region is very small and heavily doped, where the back region is often a substrate and is thousands of times larger. It is often said that the emitter region may in fact be "dead" and thus not play a role in collecting charge (i.e. the recombination time is so fast that all electron-hole pairs excited there recombine before getting anywhere useful). However, at the same time it is often said that all charge that reaches the electric field in the depletion region is "collected".

    What I don't understand is how this can be possible. All charge that reaches the depletion region MUST PASS THROUGH the emitter region to reach a contact. So how can an emitter region be dead but all charge that reaches the depletion region be collected? This seems a clear contradiction. If recombination is so high than shouldn't the depletion region just push charges to their "death" in the emitter region and none are collected?

    Any insights are greatly appreciated. I'm a physicist so you can answer at any level of theory you like.
     
  2. jcsd
  3. Jul 23, 2017 #2
    Thanks for the thread! This is an automated courtesy bump. Sorry you aren't generating responses at the moment. Do you have any further information, come to any new conclusions or is it possible to reword the post? The more details the better.
     
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