Avalanche Effect Demonstrated In Solar Cells

esocid writes "Researchers at TU Delft (Netherlands) and the FOM (Foundation for Fundamental Research on Matter) have found irrefutable proof that the so-called avalanche effect by electrons occurs in specific semiconducting crystals of nanometer dimensions. This physical effect could pave the way for cheap, high-output solar cells. Solar cells currently have relatively low output, typically 15%, and high manufacturing costs. One possible improvement could derive from a new type of solar cell made of semiconducting nanocrystals and could theoretically lead to a maximum output of 44%, with the added benefit of reducing manufacturing costs. In conventional solar cells, one photon can release precisely one electron. However, in some semiconducting nanocrystals, one photon can release two or three electrons, hence the term 'avalanche effect.' This effect was first measured by researchers at the Los Alamos National Laboratories in 2004, and since then the scientific world had raised doubts about the value of these measurements. This current research does in fact demonstrate that the avalanche effect can occur."

Comments

Thermaldynamics?

[mlts]

Without violating thermaldynamic laws, I wonder how much electricity output this will add. I don't think it would double the current flow with 2-3 electrons popping out for each photon that strikes the array, but I know this should add a significant amount of efficiency.

I just hope all these advances, especially ones that make solar cells cheaper to manufacture go into production. There are huge chunks of the world that are lifeless desert, and would be perfect for large solar and wind arrays, assuming one could find a way to transport the generated electricity to cities without too much current loss. Perhaps some chemical reaction that pulls carbon from the air directly to make ethane, then another reaction that converts the ethane to ethanol to be piped to places that can burn the ethanol for electricity. Yes, the chemical reactions to pull carbon from the air, and get it into ethanol are wasteful, but for very long distance transfer of energy (100-200+ miles), it would be less wasteful to do that, than to use standard power transmission lines. Even though the ethanol electricity generating plants would be adding carbon into the air, it would be carbon neutral due to the carbon being extracted at the solar/wind site.

Re:Thermaldynamics?

[Yetihehe]

Perhaps some chemical reaction that pulls carbon from the air directly to make ethane, then another reaction that converts the ethane to ethanol to be piped to places that can burn the ethanol for electricity.

Would methane be ok? If so, it is already done with CO2 and sunlight.

Re:Isn't price the key?

[syphax]

Efficiency matters, for a few reasons, including:

1. Indirect costs (installation labor, racks, mounts, etc.) scale with the area of the array. The area of array required for a given power output goes with the inverse of efficiency. These costs are pretty significant, so efficiency has a direct impact on installed costs.

2. There's lots of area available for solar panels, but solar energy is pretty diffuse, so you need a lot of area anyway. If a 1% efficient system cost a dime per watt installed, great, but you'd have to cover huge areas to generate significant amounts of electricity. There are practical limits. Even at 10-20% efficiency, you're still looking at large areas to generate a meaningful amount of juice.