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Nanotechnology Boosts Solar Cell Performance
Roland Piquepaille writes "Physicists from the University of Illinois at Urbana-Champaign (UIUC) say they have improved the performance of solar cells by 60 percent. And they obtained this spectacular result by using a very simple trick. They've coated the solar cells with a film of 1-nanometer thick silicon fluorescing nanoparticles. The researchers also said that this process could be easily incorporated into the manufacturing process of solar cells with very little additional cost. Read more for additional references and a photo of a researcher holding a silicon solar cell coated with a film of silicon nanoparticles."
I wish I had access to the slashdot front page for my articles.
The nanoparticles improve efficiency by 60% in the ultraviolet spectrum. The visible light spectrum is only nominally affected.
It's still pretty cool, though.
Is it FINALLY going to be efficient enough to add solar panel edging to the trim and room of hybrid cars so they constantly recharge the battery and you can run off it almost all the time? I could see 100+ MPG on a decent liter engine that way.
Google's Super Secret Search Algorithm: SELECT @search_results FROM internet WHERE @search_results = 'good'
you had me at "hello"
The article says efficiency was boosted by 60% IN THE ULTRAVIOLET REGION. Not overall efficiency.
It only bothers me because he linkjacks it with his blog.
If he was just posting an article, with a link to the EurekAlert post, it'd be all good. Instead, he has to post about his spammy blog, as well as his (paid?) blog on ZDnet.
The ratio of decent links to spam is 1:2 in this article.
Summary:
We've just invented a new-and-improved [solar cell|battery|ultracapacitor] and it's really really great but we're not going to quote any actual absolute metrics.
We have units for expressing solar cell performance, but I didn't see any in TFA.
Also, he doesn't post the whole story (60% improvement in the UV spectrum) but rather the more sensational version (60% improvement!). That's pretty dishonest.
While at Purdue one of my friends worked on a process to increase solar cell efficiency by etching TiO2 coatings into long, thin whiskers that helped 'whisk' photons down into the surface of the material. It basically doubled the efficiency of a 3% cell in the visible range. Solar hasn't taken off.
_ by_gre_1.php uses lenses to concentrate light onto small, very efficient space-grade solar panels. Each panel (if memory serves) was on the order of 1 sqcm, allowing these very expensive but very efficient (25%+) panels to be used. The overall effect was to to take 1 m2 down to 10 sqcm of chips.. and yet have the power output be about the same. Combine that concentrator technology with higher utilization of UV bands AND ultra-efficient space grade panels and you've got a winner (concentrators work ONLY in direct sun- no clouds).
Glass typically blocks UV. Most glazings contain glass. If this only boosts (and 60%, while a large number, is still a tiny increment in efficiency) the UV efficiency then there may be limited use... unless you count concentrator applications.
The "Sun Cube" (http://www.treehugger.com/files/2007/04/sun_cube
Just some food for thought.
That is a researcher holding a silicon solar cell coated with a film of silicon nanoparticles.
-- A cat is no trade for integrity!
..that none of us probably won't see available. This is like, what, the tenth solar power technology breakthrough this year alone? And still none of it is available to anyone, private person as company alike, as breakthrough after breakthrough just keeps disappearing in thin air a while after the news has gone public.
So I RTFA, and here's the bit: "improves power performance by 60 percent in the ultraviolet range of the spectrum" and "in conventional solar cells, ultraviolet light is either filtered out or absorbed by the silicon and converted into potentially damaging heat, not electricity."
So a conventional solar cell gets ~0 energy from this part of the spectrum, but if you coat it with this special coating, it gets 60% more! And how much is that exactly?
Now if you use a different coating (2.85nm), then it improves performance "in the visible part of the spectrum" by 10%. How much energy does a conventional solar cell get from just the visible part of the spectrum? Unspecified!
Hmmm... How many other blogs and sites featured at Slashdot also have ads? Nearly ALL of them?
If you want news from today, you have to come back tomorrow.
The ratio of decent links to spam is 1:2 in this article.
More like 1:1
Dude, he provides valuable content. He distills complex scientific material into concise, pointed articles that average people can understand. My background is in accounting, not science. I'm still interested in the discoveries that are made. But I don't want to sit there and read pages and pages of scientific journals, most of which I won't understand.
But thanks to Roland, those discoveries become known to people like me. I appreciate the work that those scientists are doing, because Roland brought me word of their findings in a way that I can easily and quickly digest. That's true value, my friend. He's made me more productive and more knowledgeable by summarizing otherwise lengthy journal articles.
n/t
Blar.
It's still something, because to knock an electron out, the minimum frequency of the photon has to be at least the difference between the conduction band (where you want that electron) and the lower-energy valence band (where the electron originally is.) So you have a minimum energy cut off point. Exactly where that is, depends on the material, but generally you won't get any power out of the infrared falling on that cell.
However, the downside is that photons with higher energy than that bandgap, well, the extra energy is essentially wasted.
So basically, say, if you used Germanium at 0.67 EV bandgap, you'd catch more photons than with Silicium at 1.11 EV bandgap, but get less useful energy (i.e., electricity as opposed to heat) out of each photon.
And the higher frequency the photon, the more you waste as heat. So you won't waste more in the visible spectrum (well, unless the photon had less energy than the bandgap, in which case it's completely wasted), but in the UV spectrum you waste a lot.
So reducing the waste in the UV spectrum is really where it counts the most. Sure, it would be neat to gain everywhere, but the UV range is where we waste the most.
Their talk about fluorescent particles, makes me think they're essentially converting an UV photon into at least one lower frequency photon. The question is what they do with the extra energy. At the simplest imaginable way, you'd get at least two low energy photons from one UV photon.
On the other hand, it seems to be a bit more than that, from that short summary linked to. From their claim that they improve voltage, not just current, and that something happens at the interface between the particles and the substrate, it sounds like essentially they created a bunch of new junctions there. I.e., that it's a new way to make a multi-junction solar cell.
Multi-junction cells aren't exactly new, but traditionally they've been very expensive so far. If these guys invented a cheap way to make one, kudos to them.
On yet another hand, it will be interesting to see on exactly what existing cells can their film be applied. On silicon or other semiconductors, ok, I can see how it would form an extra junction. Would it also work on, say, Dye-sensitized Solar Cells? There essentially their particles would come on top of the dye, and I'm not sure how well that works. It'll be interesting to find out, eventually.
A polar bear is a cartesian bear after a coordinate transform.
Big difference between posting something original on a blog with ads, and paraphrasing an article on your own ad-filled blog solely for the revenue.
If I went around ripping off the AP, I'd get a nastygram from their lawyers. Why do we tolerate it more when it's a creepy-looking Frenchman?
His name link to primidi (his blog), plus his link to ZDnet (also his blog) in the article body, VS one link to the article in question.
How about something to make solar cheaper to purchase, so that the initial investment can be recouped before the expected replacement date?
A Human Right
"(I choose to use "harvest" specifically because they capture energy from the sun rather than generating from oil for example) over the expected lifetime of the panels."
And how do you think plants get their energy? By burning dinosaurs?
Wow...you are very ignorant. OPEN YOUR EYES, MAN! Thanks to Roland, 2000 babies die every year of spamosis! Thanks to Roland, AIDS is ravaging parts of Africa. And thanks to Roland, kittens will die! Open your eyes... And stop the hate.
First, we need to be careful here. A 60% improvement in the conversion among UV spectrum does not necessarily equate to a 60% increase in a given PV cell. If the particular cell is more of an infrared or visible light spectrum oriented cell, you'll see a minor, if any, improvement. So before anyone starts grabbing random solar cell outputs and starts applying a 60% increase in power and get modded "insightful" for bad information, let's get that part out there.;)
With the main advantage being in the UV spectrum, it seems to me the best application would be to UV preferential cells in orbit or on Mars, Luna, etc.. Doubly so given the difficulty in shedding excess heat in Space.
My Suburban burns less gasoline than your Prius.
That's a whole 12 characters shorter, and leaves out the important words 'in the ultraviolet spectrum', which changes the meaning completely. Also, those emitted words are 27 characters long, so if they were properly included, his summary is actually more wordy than the original source.
It's almost word for word. And it's wrong.
How many of these new cells would it take to power this I wonder? With that 60% increase of the 0% we were getting previously from the UV band, I would imagine quite a few bananas will get eaten before those monkeys actually collide!
I do not respond to cowards. Especially anonymous ones.
Big difference between posting something original on a blog with ads, and paraphrasing an article on your own ad-filled blog solely for the revenue.
Doesn't that describe slashdot pretty well?
Done with slashdot, done with nerds, getting a life.
- re
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so ...
Would a 100% efficient solar cell be black, non reflective, and cold to the touch in full sunlight?
If all the light went in the front and the only energy leaving were through wires in the back it would have to be, wouldn't it?
09 F9 11 02 9D 74 E3 5B D8 41 56 C5 63 56 88 C0
Well, this is a community site, where I can spout off my opinions. So, yes, but with the addition of trolls, and editors, and other people and viewpoints.
much UV light penetrates cloud cover directly, so this enhancement may be a good boost for solar power on cloudy days, when it may be needed more.
Ben Hocking
Need a professional organizer?
It's good to finally see an article about solar cell efficiency improvements where an actual prototype has been built and tested.
He brings up a very good point. +1 Informative!
In Firehose.
Deleted
it's not dishonest. it's misleading, but not dishonest. it's like saying "4 out of 5 dentists recommend...". it could be 5 insane quack dentists. you don't t think that when you read/hear it, but it's still accurate.
It's only five years away?
Cue the Exxon-Mobil lobbyists and lawyers to try to make this illegal, or to purchase the patent outright...
At the end of the blog Roland asked why they didnt use multiple sizes of silicon nanoparticles, this was my long winded reply:
I am a graduate student working on the synthesis of silicon nanoparticles for solar cells and other applications. While silicon nanoparticles have been syntheszed for over 20 years, and their are many ways of synthesizing them, it is still very difficult to control the size of the particles. Unlike CdSe based quantum dots where the size of the particles is determined by how long your let the reaction run for, 1 min for blue 30 min for red, and various time lengths for other colors, silicon nanoparticles are more complex.
Silicon nanopariticles while they are still quantum dots, since the energy levels are somewhat quantized emit very differently as well. Silicon is an indirect band gap semiconductor, however the blue emitting silicon nanoparticles emit light with a direct band gap transisiton, where as they red emitting silicon nanoparticles are controlled by more surface effects and emit in a low energy indirect band gap transition which is slower and allows for more energy loss in other modes.
Anyways, what it comes down to, is it is difficult to make various sizes of silicon nanoparticles. I would also like to add that this technique is not very promissing for several reasons, they epense and other problems with traditional silicon etched solar cells still exist. Cost, lack of flexibility, low effeciency, heavy, glass... This method does not take full advantage of multiple exciton generation which was just proved for silicon nanoparticles in ACS journal of Nano Letters this week. PbSe quamtum dots have shown to generate 7 exciton for just one photon, which in theory could be converted to 7 electrons from 1 photon...someday. But 2.6 excitons from silicon nanoparticles is still pretty good. Especially when I have a way to get the excitons into free electrons And silicon is a non-toxic cheaper alternative to the PbSe quantum dots.
The cost of solar panels today is completely recouped in areas where electricity is expensive.
Here in Southern California, panels pay for themselves in about ten years, but will last at least 25 years with 85% efficiency. Guaranteed.
Even if you figure the life as 30 years, and factor out the state rebate, the panels are still generating twice as much "money" as they cost. If you're one of the poor saps in the fourth or fifth "tier" over-baseline, you can recoup the cost of a small residential PV in five to eight years!
And if you think electricity won't get more expensive over the next 25 years, well...
So now I can use my calculator with my black light......groovy!
If we could shed about 60% of the solar panels on our space vehicles, that would be a tremendous boost in our ability to launch neat stuff cheaper. The question that comes up though is, how well will this new coating survive the rigors of the space environment? If it degrades faster than our current choice then we probably cannot qualify it as a replacement for our current cells. Until that question is addressed, flown and tested, this remains as only a neat future potential. Space drives the race.
The whole stupid FA never once gives the percentage improvement when exposed to a sunlight spectrum. Not cool. Not cool at all. I'm sure it was an easy oversight. Sunlight is an obscure point of reference in this debate. After all, sunlight is nowhere near as common as water or air.
I've asked that question after every Gerard Depardieu movie.
Find environmentally and socially responsible products on http://buy-right.net
Because if we don't, he will fart in our general direction, you silly English kiniggit!
(Sorry, I couldn't resist the two-fer.)
Find environmentally and socially responsible products on http://buy-right.net
In this house, we obey the laws of thermodynamics!
Perscriptio in manibus tabellariorum est.
Now I realize it's because I'm running Firefox with adblock (and noscript). I'm so used to a net without ads I had pretty much forgotten their existence. Which leads me to wonder - why is a typical Slashdot reader (you're typical, right?) seeing ads? Why are you not running Firefox with adblock (and maybe noscript)?
The stuff people put up with willingly or out of conservativism (the little 'c' kind, the kind that makes you averse to change)... I just don't get it.
This space available.
They are using the fairly superior Internet explorer 7.
It has all the wanted features of firefox and other popular browsers that have been making headway on Microsoft's browser lock in market.
Ehh. the real reason is marketing speak. Someone has tricked the drugstore geek.
The nanoparticles improve efficiency by 60% in the ultraviolet spectrum. The visible light spectrum is only nominally affected.
.90s could be a whole heck of a lot better than even the experimenters were originally chasing. So it's no wonder they published now, with only two sizes of particles tested.
It's still pretty cool, though.
This whole series of "only 60% of the UV part" threads is missing the rest of the article. That was just for ONE size of naonparticle, suitable for converting light to the middle of the visible range. They ran the tests for another size, suitable for converting to visible red, and got a higher conversion result, as expected.
Solar cells completely miss photons below the bandgap energy and only peel off the bandgap energy from those above it. They have a bandgap in the infrared so they get most photons, but only take that first 0.6 electron-volt chunk of their energy and lose the rest as heat. That's great if you have an infrared photon at 0.603 eV, not so hot for visible light photons at 1.8-3.1 eV, and pretty crummy for UV photons at 3.1 to 12 or so eV.
Films of nanoparticles have an interesting property: They absorb photons of various wavelengths and emit photons of particular wavelengths related to their size. But they don't do that in the solar-cell style of chopping the right-sized hunk off a more energetic photon and throwing the rest away. Instead they are able to combine energy from multiple lower-energy photons to generate one of the desired energy, chop several desired energy photons out of a high-energy one (and keep the leftover shavings to combine with others to make more desired-energy photons), and trade energy among their neighboring particles.
So it was expected that a film of nanoparticles on a solar cell would grab the energy from photons all over the spectrum, convert it to the energy characteristic of the nanoparticle size, and re-emit that. The improvement from efficiently salami-slicing and stacking photons should be better than losses from such things as emitting the photon in the wrong direction, giving a big boost to the cell.
And to some extent that was happening: Feed UV photons to nanoparticles that chunk 'em into something in the 3 eV range and you get more out of the UV hitting the cell than you would without the film - without appreciably affecting the output from the visible light. You're averaging about 1 2/3 IR photons worth of energy, instead of 1, for each incoming photon. Feed it to nanoparticles that chunk it up finer, down to 2 eV or so, and you get more out of your UV and also start improving on even visible light.
That's a good sign for doing what you really wanted to do: Use nanoparticles that emit just a tiny squidge above the solar-cell's bandgap, chunking all the photons into the right size for the cell and wasting very little of their energy. (But maybe still losing a bunch by emitting them in the wrong direction. That might be improved by putting the nanoparticles at the bottom of wells in the cell rather than on a flat surface.)
But the experiment produced a surprise: The VOLTAGE went up! WTF?
That means one of two things:
a) The nanoparticles affected the bandgap.
b) The nanoparticles coupled directly into the cell's "circuitry" in some non-obvious way.
b) might lead to something even better: Nanoparticles that capture the photons, chunk and stack them into some desired size (voltage), and deliver them directly to the wiring. That could get virtually ALL the incoming energy into your wires.
A solar cell with efficiencies in the
Hot DAMN!
Bantam Dominique roosters crow a four-note song. Once you've heard it as "Happy BIRTHday" you can't NOT hear it that way
> it's not dishonest. it's misleading, but not dishonest.
Honest people don't mislead others. Natch.
Hmmm...How many other blogs and sites featured at Slashdot with ads is "featured" on a weekly basis with low signal to noise ratios? One, Piqy's blog.
Yes, you are too late to send your letter to the Prussian consulate via the 4:30 autogyro to Siam.
When our name is on the back of your car, we're behind you all the way!
To
'Doesn't that describe slashdot pretty well?'
Yeah but the Slashdot editors don't submit the slashdot version of the articles to other sites.
100%? Actually, yes it would be.
Imagine coming across such a solar cell. It would be weird to touch something that's a solid black in full sunlight and have it feel cool to the touch.
Also, the cell would be COMPLETELY black. Absolutely no reflected light. It would basically look like a perfect shadow.
if it's not blocking the ads, then it doesn't have all of the wanted features.
This space available.
Your friendly neighborhood Grammar Nazi
I would suspect that improving the UV spectrum has the most benefit in spaceflight where there is no ozone layer filtering UV rays. The power/mass ratio of solar PV could be one of the driving factors in what sort of propulsion takes us beyond the Earth-Moon system.
I have noticed he isn't the only one doing it and it really pisses me off when you read some blog and want the original article, only links is to other blogs and you just keep going in circles never actually being able to see what the original source was.
by simply covering the article with a thin layer of bullshit.
Boffoonery - downloadable Comedy Benefit for Bletchley Park
Sorry about that, I switched to dvorak and have been mixing O, E, and A up. It was strictly a typo.
I do use these things, but as someone who'd like to someday make money off of writing things, linkjackers really bother me a lot.
I've already found one of my articles linkjacked, actually, just ripped off. It's not a happy feeling.
well, that's the internet for ya.
This space available.
I'm afraid Content is not King.
There are places where the networks are not touching,and there are places where they are-Boeing's Lori Gunter
I guess you missed the joke. It was only superior in the marketing speak.
Everybody else has had it for 2 weeks already by then.
I believe it would be the same temperature as the surrounding air. To actually be cold, it would have to be turning thermal energy into electricity as well.
You want the truthiness? You can't handle the truthiness!
Voltage by itself is meaningless, we need POWER, which is voltage times current. No mention of the current in the article.
If they're getting the extra voltage by putting these nanoparticles in series with the regular cell, then the nanoparticle layer current will be the limiting factor. And IIRC there's far fewer ultraviolet photons than visible or infrared ones.
So it's not clear how much of a win, if any, this new development is.
And as solar cells are still several powers of ten less economical than anything else, it may be a net loss if the gain is overshadowed by increased cost or decreased durability.
I have read hundreds of articles which claim improvements of 50-100% over all previous solar cells. Based on my understanding, a single solar cell (2 inches by 2 inches) should be enough to light up the entire world. Somehow, I get a feeling that we are still mostly using other non-renewable forms of energy. I wonder why!!
O this learning! What a thing it is - William Shakespeare
Not to mention that the words had to disappear to somewhere, and I'm guessing they were emitted out of his ass like the rest, but somehow came to rest in a different location than his bLoggings.
which is totally what she said
oh.. wait! uh.. nevermind...
I'm going to post this exact same text on every article about fuel cells, batteries, bio-fuels, wind power, solar cells, wave energy, geothermal, nuclear, tidal action, and all the other silly articles about imminent energy breakthroughs that never seem to amount to anything substantial in any amount of time. This one won't either.
This arguement keeps coming up. For some reason a group of people seem totally convinced that Solar Cells are a uselss investment as they will never pay for them selves.
p an/pvpayback.htm
First of all, this is obviously a flawed arguement. Afterall, as PV effeciencies rise (and they have been rising for many years) and manufacturing techniques improve, they will inevitably reach the point where PV start to pay for themselves (both in $$ and in energy) will continue to get shorter and shorter!
And secondly, the point is totally wrong!! As many other posters have also pointed out, Solar Panels are usually guaranteed for 20 years of operation and even the worst estimates put them at a break even date of 8-12 years.
Here is an example of the numbers you've requested.
http://www.csudh.edu/oliver/smt310-handouts/solar
And lastly, the argument is self-defeating! If you're worried about the amount of non-renewable energy we as a race are using, shouldn't you be celebrating improvements in efficiency and production?
Afterall this makes it more likely that your dreams of 100% renewable energy is more likely to come true. By complaining that all the most promising enrgy break throughs in recent times are not "net efficient" you are discouraging others from doing further work in those areas. That leaves us only with the areas which we already know are unsustainable!
Is that what you'd prefer?
Quantum Physics a.k.a. sub-molecular statistics
I don't resent ads fundamentally. I only have a problem when the advertisement steps across the line of my personal tastes. Pop-ups, Flash-scrolling across the screen, loud, flashing .gifs, all of which cause me to block the source. I have adblock installed, I just don't use any of the suscriptions.
I understand what ads are, what role they serve, and how they be beneficial or detrimental.
Penny Arcade serves up ads that I'm interested in, original ads using the webcomic's art style, and they screen them so that they'll only show products that they themselves find interesting. My opinions often coincide with theirs, so I find that these ads are targeted to me very well. I'll click on ads I'm interested in. I'll ignore ads I'm not interested in. I adblock ads that annoy or upset me.
A 100% efficient solar cell would be HOT, man! It would heat up the solar market to a blazing furnace of fiscal activity, that's what it would bring.
Physically, it would probably actually be warm to the touch, because the 100% efficient material is under a protective layer of glass, which will retain some heat. Plus, exposed frame and roof will raise the temperature as well.
Nice pipe dream, though!
Give a man a fish, he'll eat for a day, but teach a man to phish...