Dismiss Notice
Join Physics Forums Today!
The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

Relevant informations about photovoltaic cells

  1. Jun 11, 2014 #1
    it's good to aim for something impossible.
    so.... recently, i have alot of free time (oh, i'm only in my teens), and i would like aim to be someone who makes solar cells cheap and available, that kinda thing
    i know physics, like general relativity, and some quantum mechanics, recently i'm hooked into quatum computing and am reading this pdf
    and i would like to research concurrently into energy solutions, just cause.
    so, what kinda thing do i need to research in to understanding almost EVERYTHING of a photovoltaic cell and why is it so inefficient? what laws of thermodynamics?
    i have time, like alot.
    may i ask for some leads?
  2. jcsd
  3. Jun 11, 2014 #2
    2 big reasons.

    First is the bandgap. Photons hitting the semiconductor need to have a minimum energy to force a electron out of its orbit. Anything below this energy does nothing. I believe anything above this energy is wasted (not 100% sure, been awhile). Shine some red LEDs at a PV cell, nothing happens no matter the number or size of the LEDs. Shine a blue light on it, it works. Shine a violet light on it the same size as the blue one, you get the same energy even though violet photons are more energetic.

    2nd has to do with the depletion region. The depletion region is the area surrounding the border between two alternately doped semiconductors. This is where the magic happens in semiconductor physics. The energy from the photon is converted here, but it has to get here first. Unfortunately, the depletion region does not extend all the way through the top layer, so the photon needs to penetrate some distance through top layer to be useful. The top layer is made as thin as possible to accommodate this, given manufacturing restrictions. This also means that the PV needs to be angled toward the sun for max power, not only to increase surface area but also because the distance photons have to travel through that top layer increases as it tilts away, like the atmosphere does with a rising/setting sun.

    So, to really understand PVs, understand the band gap and the depletion region.

    http://www.pveducation.org/pvcdrom is a really good resource for PV stuff.
    Last edited: Jun 11, 2014
Share this great discussion with others via Reddit, Google+, Twitter, or Facebook