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  1. Standard member sonhouse
    Fast and Curious
    05 Feb '13 12:12
    http://phys.org/news/2013-02-patented-technique-key-solar-power.html

    Time will tell if this works out but it may be the development we have been waiting for. Little antenna's tuned to light frequency instead of solid state layers.

    They were impossible to fabricate before this new technique was developed.
  2. 05 Feb '13 13:46 / 2 edits
    Originally posted by sonhouse
    http://phys.org/news/2013-02-patented-technique-key-solar-power.html

    Time will tell if this works out but it may be the development we have been waiting for. Little antenna's tuned to light frequency instead of solid state layers.

    They were impossible to fabricate before this new technique was developed.
    I really hope it is as premising as it sounds!

    At first, I was confused by the bit where it says:

    “...The nano-antennas – known as "rectennas" because of their ability to both absorb and rectify solar energy from alternating current to direct current – must be capable of operating at the speed of visible light ...”

    -mainly because I did not understand where this “alternating current” originates because it doesn't make this perfectly clear.
    But then I found this which explains it:

    http://en.wikipedia.org/wiki/Nantenna
    “...Incident light on the antenna causes electrons in the antenna to move back and forth at the same frequency as the incoming light. This is caused by the oscillating electric field of the incoming electromagnetic wave. The movement of electrons is an alternating current in the antenna circuit. ...”
  3. Standard member sonhouse
    Fast and Curious
    05 Feb '13 14:21 / 1 edit
    Originally posted by humy
    I really hope it is as premising as it sounds!

    At first, I was confused by the bit where it says:

    “...The nano-antennas – known as "rectennas" because of their ability to both absorb and rectify solar energy from alternating current to direct current – must be capable of operating at the speed of visible light ...”

    -mainly because I did not understand gnetic wave. The movement of electrons is an alternating current in the antenna circuit. ...”
    Yes, its a diode the converts ac to dc but at light frequencies. You can imagine how hard it is to make a light frequency diode!

    My only question is with this ALD system, atomic layer deposition, can it be fast enough for economical production once the design gets finalized.

    If it takes an hour for a square meter, it won't be much use on the market.

    Also if it take a thousand ALD units to get a large production run where one of those machines costs in the millions, you are talking a plant costing in the billions so we will have to wait and see whether the process can be scaled up to industrial levels of production and beat the cost of regular semiconductor PV cells.
  4. 05 Feb '13 14:27
    Originally posted by humy
    I really hope it is as premising as it sounds!

    At first, I was confused by the bit where it says:

    “...The nano-antennas – known as "rectennas" because of their ability to both absorb and rectify solar energy from alternating current to direct current – must be capable of operating at the speed of visible light ...”

    -mainly because I did not understand ...[text shortened]... gnetic wave. The movement of electrons is an alternating current in the antenna circuit. ...”
    I took it that light as it is in the wave function reverses and the nano antennas must let the electron tunnel and rectify before this reversal.
  5. Standard member sonhouse
    Fast and Curious
    06 Feb '13 00:23
    Originally posted by joe beyser
    I took it that light as it is in the wave function reverses and the nano antennas must let the electron tunnel and rectify before this reversal.
    What reversal? Are you talking about the wave/particle duality? As far as I can see it is pretty much exactly as if it were radio waves and a diode rectifier turning the wave into a pulsating DC voltage. I'm sure its more complicated than that but that would be the underlying assumption.
  6. 23 Feb '13 12:48 / 10 edits
    I now have a burning question about these nanosized antenna array solar cells;
    This may be jumping the gun a bit, but:

    hypothetically, IF room temperature superconductors are possible and IF we discover room temperature superconductor that can operate at the temperature range typically experienced within a solar cell in use, could the nanosized optical rectifying antenna or 'rectenna' component of these nanosized antenna array solar cells work if the parts of the rectenna made of conductors were made of superconductors instead?
    If so, ignoring losses from electrical resistance in the leads going in and out of each rectenna, could the rectennas be designed to work with greater energy efficiency as a result of having superconductors?
    And, when such a hypothetical 'superconductor rectennas' absorbs a photon, would the electrons quantum-tunnel through the insulating-barrier part as single electrons or as cooper pairs?

    I also have another question -this time about superconductors themselves:
    when electrons are made to pass from a superconductor to an ordinary conductor (via an electric current), the cooper pairs from the superconductor must surely have to split into single electrons at the superconductor/conductor interface i.e. where the superconductor makes direct physical contact with the conductor. But it is my understanding that it takes energy just to split a cooper pair -right? -so wouldn't that mean considerable energy expenditure/inefficiency/wastage/lose at such a superconductor/conductor interface?
  7. Standard member sonhouse
    Fast and Curious
    23 Feb '13 14:33
    Originally posted by humy
    I now have a burning question about these nanosized antenna array solar cells;
    This may be jumping the gun a bit, but:

    hypothetically, IF room temperature superconductors are possible and IF we discover room temperature superconductor that can operate at the temperature range typically experienced within a solar cell in use, could the nanosized optical rect ...[text shortened]... energy expenditure/inefficiency/wastage/lose at such a superconductor/conductor interface?
    If I have it correctly, the cooper pairs are the result of a moving wave of electric fields that result from local stresses of a crystal structure, a kind of superconductor version of piezo-electric effect but on a micro scale. If the crystal relaxes the cooper pairs would split automatically, it would be more like the crystal structure going from one phase to another. In terms of thermodynamics, going from one phase to another like water to steam or ice to water there is an energy cost so maybe something like that happens to superconductors but the cost may be very low, like a fluid having a boiling point of 100 degrees kelvin or something.
  8. 24 Feb '13 07:09
    Originally posted by humy
    -so wouldn't that mean considerable energy expenditure/inefficiency/wastage/lose at such a superconductor/conductor interface?
    And energy gain when electrons enter the superconductor. Unless the super conductor is building up a charge, then they should cancel out.
  9. 24 Feb '13 09:00
    Originally posted by twhitehead
    And energy gain when electrons enter the superconductor. Unless the super conductor is building up a charge, then they should cancel out.
    Oh I think I see. So the energy going into splitting the cooper pairs as they leave the superconductor and enter the conductor can be thought of being merely 'borrowed' energy that is given back when the single electrons leave the conductor and enter the superconductor as cooper pairs reformed thus the reverse process recovers that energy and the net energy wastage is zero (or very close to zero) -I hope that is correct.