Scientists build the first all-carbon solar cell
sciencedaily.com
sciencedaily.com
Silicon is a bitch. The equivalent doping density of silicon is something like the area of the United States, with 25 trees in it. Spread out, over the whole thing. That's what you target, and that's what we get because humans are awesome. But now we get something different. We get new materials that exhibit properties that we haven't seen before.
The nanotubes absorb IR. Awesome... transparent screens that make power (only at 1% efficiency, but it will get better). Still, there is a limit to how much power you can get if you're only able to absorb IR. So let's make it better, let's take Graphene (or nanotubes, although I'm not sure if they do it as well) and make the bandgap adjustable. It's like the "smart glass" (putting a voltage across a material 'scares' it into interacting with light differently) [1]. Now imagine we can do that with Graphene, but instead of just diffusing light, we can control when we absorb it. Put this on top of your tablet screen, when you're using the device, it is in IR mode, absorbing all the photons you can't see. When you shut it off, it starts absorbing all the visible photons, charging up your device. Put this material in your cars, keep the heat out of them in the summer while you charge your EV. On top of your house (although a plexiglas roof would be kind of scary).
The moment that we start being able to purchase the 'carbon train' is a great one. Technology is kind of a mixed feeling for me, it's so cool that we can talk to anyone, do anything (in imaginary land), but there isn't much environmental good that comes from it. Now you can use computers to do climate research or whatever, but we go out and grab the rarest materials to throw into our new fancy screens. Then we throw them away (eventually) when a newer, cooler one comes out. We are locking up all our of materials in electronic sarcophaguses that may never be separated again (at least until we get fusion and heat is free). I don't care how 'green' your laptop is, the amount of energy that went into making those teeny chips is absolutely ridiculous and I'm sure the 'energy footprint' of laptops is near the top of things we purchase. Carbon will change that though. It's plentiful. It's fast, it's new, it's sexy. It's different. We may need a little sprinkling of something special to make it really do what we want (hopefully not), but it's better in almost every way. It's going to blow our minds what the computers of tomorrow are capable of. Not because we know what's going to happen, but because the path we're headed down is going to be very, very rocky. It's time for a good electronic disruption.
Also, I can think of an excellent use of IR solar cells: turning heat into electricity. Wouldn't it be cool if you could always keep the heat in your house less than 75 degrees F, and produce electricity in the process, because your whole floor is a huge IR solar cell?
Because Silicon is similar to carbon, Silicon can do many of the things Carbon can. We know Silicon extremely, extremely well. We have been working out the kinks in it for 30 years, Intel has put billions of dollars into researching the material. We know how it works. Other materials fall off very quickly in our level of knowledge, we are still at the point in some of them that we know they work, but we don't know why. Carbon is getting a lot of attention, maybe because it's the next best step, or maybe because understanding Carbon will let us continue to push Silicon forward until years in the future when we have a better understanding of the material when we can transition nicely.
As for making heat -> You could, but the peak wavelength from the black body spectrum of the room would be about 10 microns. These solar cells are significantly shorter wavelength than that (they're absorbing ~1 micron radiation). Also, the longer the wavelength the less energy you get per photon, which wouldn't fare very well.
For heat to electricity, you need a TEG (thermoelectric generators, peltiers, something that uses the Seebeck effect) or a sterling engine of some kind. These work off temperature differentials. Unfortunately, thermodynamics is not nice about recouping energy, and they need high temperature differentials to function efficiently. Even then, the efficiency maxes at about 30% (Carnot efficiency for heat engines).
Near IR is generally up to 1400nm wavelength, where the infrared from heat isn't really a factor til you hit 4000nm.
The intensities of NIR are too low to be worthwhile.
The scientists made something that could see your remote control's LED, not your body heat.
It's a lot like the tiny paddlewheel attached to a ratchet Richard Feynman analyzed, you end up with an even dice roll 4/5 times you win but that 1/5 makes up for all those gains.
PS: Don't forget solar cells work because the sun is hot, and there is plenty of black body radiation to go around.
To make electricity the captured photons have to fall to a lower state - but if the solar cell is the same temperature the photons can't do that.
You should feel more concerned about the energy footprint of cars, it's way worse than computers. Especially electric ones with their batteries full of rare materials.
Silicon is pretty damn abundant, and they're complaining about how expensive it is -- it's the processing that matters, and right now processing cheap, abundant carbon to make defect-free layers of graphene, or uniform mixtures of carbon nanotubes (free of catalyst particles, of identical chiralities, lengths, diameters and tube number) is very hard and expensive.
Personally, I'm super interested in what Twin Creeks Technologies (http://www.twincreekstechnologies.com/solar/ -- no affiliation) is going to do. Their processing technology is completely out of left field and seems like it has huge potential.
But it seems clear that prices for these materials is dropping - and will drop much more in the future, especially with industrial demand. Interesting times!
I just had a proposal rejected by dept of energy for a composite metal/ceramic ITO replacement :)
This graph helps place, what you're talking about, in perspective.
First one came out of MIT http://web.mit.edu/newsoffice/2012/infrared-photovoltaic-062...
Might want to hold off on press releases until it hits double digits.