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Quantum Dots Could Double Solar Energy Efficiency
dptalia notes the recent publication in Science of research demonstrating a way to use hot electrons in solar cells, resulting in an overall energy conversion efficiency of 66%. Here is the abstract in Science; access to the full article requires a subscription. "A team of University of Minnesota-led researchers has cleared a major hurdle in the drive to build solar cells with potential efficiencies up to twice as high as current levels, which rarely exceed 30 percent. ... Tisdale and his colleagues demonstrated that quantum dots — made not of silicon but of another semiconductor called lead selenide — could indeed be made to surrender their 'hot' electrons before they cooled. The electrons were pulled away by titanium dioxide, another common inexpensive and abundant semiconductor material that behaves like a wire."
"The next step is to construct solar cells with quantum dots and study them. But one big problem still remains: “Hot” electrons also lose their energy in titanium dioxide. New solar cell designs will be needed to eliminate this loss, the researchers said."
You're confusing energy conversion efficiency with energy production. The main connection there is that less efficiency means more raw resources for the same result. They're certainly not the same thing.
I think what the GP was getting at is something like, "This sounds way better than past solar conversion efficiency. Can we know build viable solar power stations? What about orbital solar power satellites? Where does this leave coal and nuclear power stations? What will the overall energy production strategy be, once this comes to market, given projected energy needs WHEN it will come to market?"
That's not a set of questions you want to answer too hastily.
Read the damn paper, or at least the abstract, ok? The horsepucky all comes from the university PR flacks, amplified by the Slashdot editors.
Warning: this article may contain humor, sarcasm, parody, and perhaps even irony. Read at your own risk.
Same as fusion: Ten years from now, for all possible values of "now."
I've fallen off your lawn, and I can't get up.
It's a research paper, not a god-damned press release. Don't blame the scientists for publishing their awesome research in a prestigous journal, blame the journalists who treat every Friday as a chance to jizz out a couple of easy stories by rewriting articles in Science.
No kidding!!! What do you say at this point?
I'm no expert, but probably a lot more. Some facilitating factors:
1. PbSe is pretty easy to synthesize as nanorods. TiO2 is even easier. Lower production cost.
2. Higher efficiency (theoretically) than the 40% record achieved using triple junction cells (which have extreme costs and are likely never going to be practical) and the ~25% achievable using single-junction silicon cells (maximum theoretically about 31%).
This should lead to a great increase in the achievable power. The only thing that I'm unsure of is whether you can concentrate the light in nano-confined cells as much as you can in bulk material cells. The (I believe) issue becomes current density saturation either within the material or at the connector interface. Not altogether familiar with the R&D in this area. Since high-efficiency cells can be concentrated efficiently by a factor of ~1000x, this could be a significant effect if nano-confined cells can't be concentrated very much.
I have left slashdot and am now on Soylent News. FUCK YOU DICE.
I wrote a paper on this idea last semester, and as interesting a find as it is, I don't think it's ever going to lead to enhanced power conversion efficiencies (PCE). The "Double Solar Energy Efficiency" is actually a theoretical doubling of the thermodynamic limit on PCE, and it doesn't take non-radiative losses into account. These losses have been minimized in the record breaking silicon and multi-junction solar cells, but quantum dots bring lots of problems with them.
It's definitely worth further investigation, but currently I'm not convinced that it will ever bring improvements.
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