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Solar Cells Get Boost
An anonymous reader writes "Researchers from Los Alamos National Laboratory have tapped the efficiencies of nanotechnology to double solar cells' potential energy production. The key to the method is the use of lead selenium nanocrystals which can produce 2 electrons where 1 was produced before. Other optical applications can also benefit."
I have to say, this is a little picky. First of all, the article description states that the new substance "...can produce 2 electrons where 1 was produced before", so it does not imply a change in the fundamental mechanism so much as the yield. Anyone who knew how solar cells worked before reading this description would be able to make the leap that no laws of physics were being violated to produce this electron.
Second, the description does not say that the electrons are being created at all. The dictionary definition of the word produce indicates, in the first entry, that produce means "To bring forth; yield", which is good enough, but skim the third entry and its example, "To bring forth; exhibit: reached into a pocket and produced a packet of matches". I think the first is more accurate, but the second indicates just how far the definition of produce does not imply creation.
=Brian
There is nothing so good that someone, somewhere, will not hate it.
So if you really want to know what's going on you need to discover how efferent lead selenium solar cell's are and what it takes to mass produce lead selenium nanocrystals in a cheep long lasting solar cell.
Nanocrystal films would typically be grown by chemical vapour deposition (chemical constituents react as a gas at low pressure, seed crystals grow in-flight, and grow further after being deposited).
The problem is that it's very hard to produce crystals that small (they tend to keep growing after being deposited, because the source materials are still present - this is how you normally do CVD, actually). You also have difficulty producing a narrow range of sizes, because that requires that the growing environment of each crystal be identical.
Still an interesting discovery, though. The fabrication problems will eventually be solved.
What's especially interesting is looking at what happens when you fabricate oher types of semiconductor microstructure or nanostructure by more conventional techniques. As the size of a feature shrinks, you can no longer pretend it's near-infinite in extent when figuring out what the energy levels are within the crystal. This has already been used to alter the properties of silicon (fabricating LEDs in silicon, which normally emits very poorly due to having an indirect bandgap). Quantum wells, wires, and dots are an extreme case of this (dimensions comparable to a few electron wavelengths). When lithographic feature sizes start approaching this range, lots of new devices will be possible in mass-market chips that are only possible now if you have an e-beam lithography setup handy.
I simply don't know enough about the physics, but... can this be applied with the other developments like multi-band gap improvements?
:).
I'm on shaky ground here, but I think the answer is likely "no". The idea behind this technique is that you can use surplus energy from a photon absorption event to release a second electron, while the point of split bandgap cells is that you can absorb light with less surplus energy (more deposited in a useful manner into the first electron).
Ask a semiconductor physicist to get the correct answer