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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."
Meanwhile, partially as a result of various breakthroughs in solar cell technology, solar cell prices are finally dropping despite unprecedented demand.
Finally! A year of moderation! Ready for 2019?
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.
In my experience, rules set by regulatory bodies are never that useful, and generally only become so when their proposed regulations threaten the bottom line of someone with a lot of money. Unfortunately in that case, they often get diluted to worthlessness...