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A way to increase photovoltaic efficiency using fiber optics?

One of the claimed inhibitors of efficiency was the band gap of materials which contrasts to that of a photon. My idea is a way to possibly mitigate this loss by increasing the frequency of the electricity being generated(?) and taking it directly to coil.

In a glass fiber from fiber optics, light bounces back and forth many times before finally exiting out the other end of the fiber optic thread.

What if you were to manufacture a fiber optic thread so that it has a thin copper coil embedded in it that would have a staggered patterned coating on bare copper of n type and p type silicon? Think n,p,n,p,n,p etc for the nano coating facing the light source. The copper winding would be encapsulated at this point to prevent energy leakage. The copper coil would not be tightly wound and would leave space for some of the light to reflect to the other parts of coil. The nano silicon of p and n types would directly transfer the photovoltaic charge to the copper coil and it would remain homogenous to the coil. A secondary coil would be used (not coated with anything save for an insulator) to transfer the energy elsewhere. So basically this is induction.

Would the back and forth motion of electrical charges be sufficient for this to work?

Would the induction frequency occur near the speed of light?

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Stevan White
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2 Answers2

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Your device is hard to visualize, it would help if you drew a picture so we can see exactly how it works in theory. I'm not sure if your device would work, but I can explain some additional concepts that may help you put together something that will.

Lossy band gaps...

When a photon is absorbed by a semiconductor, you can see loss of energy if the photon has a little too much energy than required, and the electron decides not to use it all. For example, Silicon has a band gap of about 1.1eV, if you shoot a 1.2eV photon at it, the electron will be excited to a state with energy of 1.1eV to 1.2eV higher than the state it was in in the valence band. A new photon will be created with the unused energy.

Cure: Tandem Solar Cells.

If the photon does not have enough energy to be absorbed via band gap, it will go straight through the material. One can design a stack of photo-voltaic cells that first absorbs only high-energy light, then slightly lower photon energies until you reach the photovoltaic cell which can excite electrons from low-energy light. This way, the high-energy photons are absorbed first with high efficiency, then the next highest energy photons are absorbed and so on.

Reference: Semiconductor Devices: Physics and Technology by S.M.Sze and M.K.Lee

PaulisDontExcludeMe
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  • Hi Paul I added a photo I’m not the best of artists though hopefully it’s sufficient. – Stevan White Mar 30 '18 at 21:39
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    I think I've got the gist. The idea you have is that the light will be absorbed along the p-n junctions and create AC current as the electrons jump between the doped materials? This is a really unique idea. Unfortunately I don't think it would work the way you've got it laid out right now. The light bouncing inside the fiber-optic, exciting electrons through the junctions, would do excite the electrons in a random direction. Since there is no net displacement of the electrons, any current generated would be quickly extinguished by current in the opposite direction. – PaulisDontExcludeMe Mar 31 '18 at 02:49
  • Thought it may be that way but since light travels so fast would the difference in time between photons hitting different parts be negligible and not really matter? – Stevan White Mar 31 '18 at 20:31
  • Or maybe a better idea would be to have two copper wires in the primary coil where one was for the positive and the other negative tie them together at certain points? Add diodes? – Stevan White Mar 31 '18 at 20:35
  • I can't really say whether or not that would work. The problem with adding diodes and pn junctions is that they come at a cost as well. The forwards bias required to push electrons through is at about 0.7V in a typical diode, which translates to lost potential energy. I would try to simplify the design, then reduce the amount of geometry to maximize the light collected. There remain a bigger problems with this as well. When the light is absorbed into the fiber-optic, the glass will absorb anything larger than 9eV. Also, I don't think the internal bounces will not add to the energy generated. – PaulisDontExcludeMe Apr 01 '18 at 23:27
  • Thanks for your wisdom on this. I believe it is an interesting idea that may hold some promise but with anything needs refinement. – Stevan White Apr 03 '18 at 17:22
  • You're welcome! I'm glad that you're interested in semiconductor physics. It is a really interesting field, and some beautiful physics in involved. – PaulisDontExcludeMe Apr 03 '18 at 20:50
  • @StevanWhite you might be interested in this idea because of the AC component in your idea https://en.m.wikipedia.org/wiki/Optical_rectenna – boyfarrell May 29 '18 at 11:35
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What you looking for is cooper pairing https://en.wikipedia.org/wiki/Cooper_pair Means that a single photon trapped can atract electrons from the walls of the tube and create enegy (better creating heat) ? Is that what you looking for?

user38657
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  • Please be so kind as to expand your answer to be self-contained and not rely extensively on an outside link. – ZeroTheHero May 29 '18 at 13:12
  • What he's searching for is to break the conservation laws which is impossible. In his case the photon would be wasted quickly and would need replacing it. – user38657 May 29 '18 at 17:31