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(Yahoo)   New solar cell generates two electrons for every photon that hits it, thumbs its nose at the 2nd law of thermodynamics   (news.yahoo.com) divider line 120
    More: Interesting, second law of thermodynamics, photons, electronics, solar cells, conversion efficiency, SciAm, quantum dots, nuclear fissions  
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7080 clicks; posted to Geek » on 19 Apr 2013 at 12:59 PM (1 year ago)   |  Favorite    |   share:  Share on Twitter share via Email Share on Facebook   more»



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2013-04-19 11:07:14 AM
25.media.tumblr.com
 
2013-04-19 11:08:06 AM
"Two electrons, one photon" HAS to be nerd pr0n, right?
 
2013-04-19 11:14:59 AM
Wibbly wobbly particlely physics stuff
 
2013-04-19 11:29:14 AM

scottydoesntknow: [25.media.tumblr.com image 500x375]


I'm glad I checked the thread before going on a search for that ;-)
 
2013-04-19 11:29:30 AM
Uncertain if want.
 
2013-04-19 11:39:08 AM
Except, no, it doesn't.

If you are ever tempted to suggest something does not obey the laws of thermodynamics, just don't. You are wrong.
 
2013-04-19 11:40:03 AM
What are you lab-coat squints flapping about now?
 
2013-04-19 11:40:29 AM
lol
nice try subby
so that was a 2nd law joke or you just dont understand the article?
 
2013-04-19 11:50:20 AM

MidnightSkulker: Except, no, it doesn't.

If you are ever tempted to suggest something does not obey the laws of thermodynamics, just don't. You are wrong.


touchy, touchy,  you know  they're not really laws, they're more like guidelines
 
2013-04-19 11:58:23 AM

MidnightSkulker: Except, no, it doesn't.

If you are ever tempted to suggest something does not obey the laws of thermodynamics, just don't. You are wrong.


Not only that, I highly doubt the solar cell has a nose, let alone a thumb.
 
2013-04-19 12:00:51 PM
The law that entropy always increases holds, I think, the supreme position among the laws of Nature. If someone points out to you that your pet theory of the universe is in disagreement with Maxwell's equations -- then so much the worse for Maxwell's equations. If it is found to be contradicted by observation -- well, these experimentalists do bungle things sometimes. But if your theory is found to be against the second law of thermodynamics I can give you no hope; there is nothing for it but to collapse in deepest humiliation.

--Sir Arthur Stanley Eddington, The Nature of the Physical World
 
2013-04-19 12:21:05 PM

BKITU: The law that entropy always increases holds, I think, the supreme position among the laws of Nature. If someone points out to you that your pet theory of the universe is in disagreement with Maxwell's equations -- then so much the worse for Maxwell's equations. If it is found to be contradicted by observation -- well, these experimentalists do bungle things sometimes. But if your theory is found to be against the second law of thermodynamics I can give you no hope; there is nothing for it but to collapse in deepest humiliation.

--Sir Arthur Stanley Eddington, The Nature of the Physical World


I love that quote.

Also, a photon doesn't "create" an electron, it moves it into the conduction band of the system. exciting two electrons with one photon does seem like a nifty trick, though.
 
2013-04-19 01:09:06 PM
The key is a phenomenon called singlet-exciton fission.

Oh yeah, I'm sure Fark knows all about singlet-exciton fission.
 
2013-04-19 01:12:17 PM
Wow, that was a massive clusterfark of scientific journalism.  Photons do not create electrons.  Under certain conditions, it excites an electron to a higher energy state.  In the useful case, the excitation reaches the level where the electron can be conducted and passed on.

I don't want to take anything away from this discovery - this could provide a very useful boost and utilize more incident photonic energy.  But for the love of Mike, get the terminology somewhat correct.  It's not that hard.
 
2013-04-19 01:15:52 PM
We're generating electrons now?  Cool!
 
2013-04-19 01:18:09 PM

JNowe: Oh yeah, I'm sure Fark knows all about singlet-exciton fission.


www.myconfinedspace.com
 
2013-04-19 01:18:51 PM

Khellendros: Photons do not create electrons.


Gamma rays would like to have a word with you.
 
2013-04-19 01:19:06 PM
Invest your bitcoins in this research today.
 
2013-04-19 01:24:54 PM

Khellendros: I don't want to take anything away from this discovery - this could provide a very useful boost and utilize more incident photonic energy.


from 25% to 30% efficiency and increase of 20%?
that is insanely huge.
of course, it will take over 9000 years for it to come to market
 
2013-04-19 01:25:34 PM

theorellior: Khellendros: Photons do not create electrons.

Gamma rays would like to have a word with you.


wellllllll
dont they create electron and positron pairs?
technically?
 
2013-04-19 01:31:18 PM

Khellendros: Wow, that was a massive clusterfark of scientific journalism.  Photons do not create electrons.  Under certain conditions, it excites an electron to a higher energy state.  In the useful case, the excitation reaches the level where the electron can be conducted and passed on.

I don't want to take anything away from this discovery - this could provide a very useful boost and utilize more incident photonic energy.  But for the love of Mike, get the terminology somewhat correct.  It's not that hard.


Ctrl-F create

Found one instance which has nothing to do with your objection.

On the other hand, I see "generate" in the headline and TFA, and "an arriving photon generates two "excitons" (excited states) that can be made to yield two electrons". Seems they got the terminology exactly correct, but you seem to have trouble reading.
 
2013-04-19 01:38:59 PM
That's a large boost in efficiency and is a big deal if the dye isn't broken down by this process then this could be a major development. The economics of PV energy is getting very close to a tipping point already with the rising costs of fossil fuels. Once mass production begins to scale up expect major price drops which will accelerate adoption.

Now if only somebody could invent a better battery. Pumping water uphill is lossy but still an effective mass energy storage strategy if terrain permits it.
 
2013-04-19 01:39:26 PM
One high energy photon generating two lower energy electrons.  No laws broken or nose thumbed.

Still, it's a big deal--what we have now is one high energy photon generating one lower energy electron plus waste heat.  So this would be progress away from the step function we have now in which only the photons with an energy exactly that of the band gap are 100 percent efficiently converted (exotic cells can also fake it somewhat with multi-junction architecture).

Of course, like usual, the question will be, can it be manufactured in high volumes at low cost?  It's pretty hard to compete with the standard Silicon PV that is currently selling for about 90 cents per watt peak.
 
2013-04-19 01:40:55 PM
But not the 4th law, right?

www.toothpastefordinner.com
 
2013-04-19 01:44:49 PM
Any increases in efficiency is always welcome, but the issue has never really been about efficiency, it's about cost-per-watt.

Who cares if you can install a 30% efficient solar panel, when the cost is ~10x's that "standard" 15% efficient panels. The average American rooftop has more than enough space to install enough 15% efficiency panels to power the home.

What most people don't realize is that we already have a revolution in solar power going on right now. The prices of solar panels today were almost unimaginable 10 years ago.

Solar panel cost per watt:
1980: $24
1990: $10
2000: $5
2010: $2.35
2013: $0.65

Solar panels are dirt cheap these days.
 
2013-04-19 01:45:04 PM

DarwiOdrade: Khellendros: Wow, that was a massive clusterfark of scientific journalism.  Photons do not create electrons.  Under certain conditions, it excites an electron to a higher energy state.  In the useful case, the excitation reaches the level where the electron can be conducted and passed on.

I don't want to take anything away from this discovery - this could provide a very useful boost and utilize more incident photonic energy.  But for the love of Mike, get the terminology somewhat correct.  It's not that hard.

Ctrl-F create

Found one instance which has nothing to do with your objection.

On the other hand, I see "generate" in the headline and TFA, and "an arriving photon generates two "excitons" (excited states) that can be made to yield two electrons". Seems they got the terminology exactly correct, but you seem to have trouble reading.


In fairness to the pedants on both sides, judging by the comments on TFA, I suspect that the article has been corrected to replace "create" with "generate".

Apart  from that, it's a pretty average piece of science journalism, not exceptionally bad. There are far worse write-ups of this paper.
 
2013-04-19 01:45:42 PM
Next they're going to say that for every one neutron that breaks a U-235 atom, we get three back.
 
2013-04-19 01:49:14 PM

namatad: wellllllll
dont they create electron and positron pairs?
technically?


Yes, which is creating an electron. : )
 
2013-04-19 01:53:39 PM

MrSteve007: Any increases in efficiency is always welcome, but the issue has never really been about efficiency, it's about cost-per-watt.

Who cares if you can install a 30% efficient solar panel, when the cost is ~10x's that "standard" 15% efficient panels. The average American rooftop has more than enough space to install enough 15% efficiency panels to power the home.

What most people don't realize is that we already have a revolution in solar power going on right now. The prices of solar panels today were almost unimaginable 10 years ago.

Solar panel cost per watt:
1980: $24
1990: $10
2000: $5
2010: $2.35
2013: $0.65

Solar panels are dirt cheap these days.


um
WHAT happened between 2010 and 2013?!!!
And yah, cheap is NOW.
 
2013-04-19 02:03:02 PM

theorellior: Khellendros: Photons do not create electrons.

Gamma rays would like to have a word with you.


You're correct. Pardon me - within the confines of the engineering space the article was referring to, this new feat has nothing to do with creating electrons, just exciting them.  Yes, there are methods of electron creation with extremely high photon energy, but they're not terribly relevant to the energy utilization of bulk solar cells.
 
2013-04-19 02:03:18 PM

Egoy3k: Now if only somebody could invent a better battery. Pumping water uphill is lossy but still an effective mass energy storage strategy if terrain permits it.


Better battery used to be all about chemistry. Which had limits.
But with the insane advances of nanotech, the rules have changed a bit.

What about when this tech gets to the home market?
http://en.wikipedia.org/wiki/Electromagnetic_Aircraft_Launch_System# En ergy_storage_subsystem
In the end, ALL storage is lossy. And the more dense the storage, the greater the risk of catastrophe when they system fails, accidently or intentionally.
At some threshold, you care less about storage loss. As long as you have enough storage capacity to meet off-hour demands.

Using power companies buying back your surplus and getting power directly from them is probably the most efficient way to "store" excess.
At what point do public utilities become massive distributed energy storage farms, with the electricity being produced ubiquitously?

We certainly live in interesting times.
/Now back to the next gun/explosion/nut with a knife story.
 
2013-04-19 02:06:45 PM

MidnightSkulker: Except, no, it doesn't.

If you are ever tempted to suggest something does not obey the laws of thermodynamics, just don't. You are wrong.


It seems to me that anything that involves the Casmir effect or

MrSteve007: Any increases in efficiency is always welcome, but the issue has never really been about efficiency, it's about cost-per-watt.

Who cares if you can install a 30% efficient solar panel, when the cost is ~10x's that "standard" 15% efficient panels. The average American rooftop has more than enough space to install enough 15% efficiency panels to power the home.

What most people don't realize is that we already have a revolution in solar power going on right now. The prices of solar panels today were almost unimaginable 10 years ago.

Solar panel cost per watt:
1980: $24
1990: $10
2000: $5
2010: $2.35
2013: $0.65

Solar panels are dirt cheap these days.


Let me do some math...

$0.65 is $650,000 per megawatt in upfront capital cost.

Existing coal generation is about $25/megawatt hour.

That means that the PV array has to run at 100% of rated capacity for 26,000 hours.

Let's be generous and say you get the equivalent of 10 hours a day at 100% which means it takes 2600 days to pay back the capital cost.

That's a payback on the PV array of 7 to 7.5 years which is pretty good.

Add in the construction, storage battery and inverter costs and you've probably doubled that, at which point you may be pushing up against the lifespan of much of the equipment.

PV is getting there, but isn't quite there yet.  In a couple of years though.
 
2013-04-19 02:08:32 PM

Khellendros: Wow, that was a massive clusterfark of scientific journalism.  Photons do not create electrons.  Under certain conditions, it excites an electron to a higher energy state.  In the useful case, the excitation reaches the level where the electron can be conducted and passed on.

I don't want to take anything away from this discovery - this could provide a very useful boost and utilize more incident photonic energy.  But for the love of Mike, get the terminology somewhat correct.  It's not that hard.


So they went from A to D rather than A-B-C-D.  Not all the masses have doctorates.  It was well enough explained.  And this is coming from someone who did that exact particular research.

namatad: theorellior: Khellendros: Photons do not create electrons.

Gamma rays would like to have a word with you.

wellllllll
dont they create electron and positron pairs?
technically?


No, electron and hole pairs.  Hence the name exciton.
 
2013-04-19 02:16:00 PM

nmrsnr: Also, a photon doesn't "create" an electron, it moves it into the conduction band of the system. exciting two electrons with one photon does seem like a nifty trick, though.


Does the analogy of hitting a double in baseball work here? I'm a little weak on quantum mechanics, but couldn't one electron be excited enough to displace another one?

Maybe a billiards analogy would work better...or the analogy where one dog is humping the other dog that is already humping your leg?
 
2013-04-19 02:18:41 PM

Mr. Eugenides: That's a payback on the PV array of 7 to 7.5 years which is pretty good.

Add in the construction, storage battery and inverter costs and you've probably doubled that, at which point you may be pushing up against the lifespan of much of the equipment.

PV is getting there, but isn't quite there yet. In a couple of years though.


The warranted life of solar panels are typically between 25 and 30 years of operation - and just because the warranty runs out doesn't mean it quits working (does your car die at 3-year/36,000 miles?)

If you price them & into account the historical average annual inflation of electricity prices of ~6% plus a *minimum* operating life of 30-years, the math starts to look ridiculously in favor of rooftop PV. They'll pay for themselves over, and over, and over again.
 
2013-04-19 02:18:43 PM
SewerSquirrels: nmrsnr: Also, a photon doesn't "create" an electron, it moves it into the conduction band of the system. exciting two electrons with one photon does seem like a nifty trick, though.
 
Does the analogy of hitting a double in baseball work here? I'm a little weak on quantum mechanics, but couldn't one electron be excited enough to displace another one?

Maybe a billiards analogy would work better...or the analogy where one dog is humping the other dog that is already humping your leg?



Let me dispel the god-like adoration of multi-exciton generation.

MEG is like a footlong sandwich from Subway.  Cut it in half and your feeding efficiency is now 200%.  It doesn't mean you have 2 farking footlongs now.
 
2013-04-19 02:22:01 PM

SumFrequency: Gamma rays would like to have a word with you.

wellllllll
dont they create electron and positron pairs?
technically?

No, electron and hole pairs.  Hence the name exciton.


CUTE
but I thought it was pair-production in a vacuum.
we were talking about gamma rays, not the article.
http://en.wikipedia.org/wiki/Pair_production

but go on
 
2013-04-19 02:22:30 PM

namatad: WHAT happened between 2010 and 2013?!!!
And yah, cheap is NOW.


1. As PV entered the phase in which it was lucrative with subsidies, and began to approach the point where it would be lucrative without, a huge number of companies saw the writing on the wall and entered the manufacturing market.  China, in an attempt to corner the market, dumped massive subsidies into huge capacity increases, exporting almost all of it.

2. The worldwide recession knocked the subsidies out a few years before they were supposed to, particularly in Europe.  Meanwhile, capital dried up.  China had gone too far in production as well.  The net result was massive oversupply, tanking prices rapidly.

3. The new companies could not survive in such a market, and they began going bankrupt in 2011.  Their massive inventories were sold at firesale prices by liquidators, dropping prices even farther.

4. The firesale liquidations caused all PV manufacturers to have to sell at a loss for extended periods of time.  Since the manufacturing model relies on economies of scale, cutting output back wasn't a good option.  Even well established companies began to go out of business, keeping firesale product on the market.

5. 2012 was when this process peaked.  In the meantime, surviving companies have poured in all their efforts into reducing costs.  At this point, prices have begun to stabilize.  They aren't going to go back up, probably, so anyone who wants to stay in the business will have to get their production costs down to the point at which they can sell for a profit at around 70 cents per watt.  The industry believes that prices will stay flat for a year or two before they start falling again at a sustainable rate.  In the next five years or so, PV will reach the point where it is lucrative without subsidies, and the market will begin to rapidly expand, this time permanently.


That's what happened between 2010 and 2013
 
2013-04-19 02:24:13 PM

namatad: SumFrequency: Gamma rays would like to have a word with you.

wellllllll
dont they create electron and positron pairs?
technically?

No, electron and hole pairs.  Hence the name exciton.

CUTE
but I thought it was pair-production in a vacuum.
we were talking about gamma rays, not the article.
http://en.wikipedia.org/wiki/Pair_production

but go on


I'm not being cute.  An exciton really is an electron-hole pair.  Otherwise the papers I published on them wouldn't have been accepted.

The more you know.
 
2013-04-19 02:25:07 PM

SumFrequency: MEG is like a footlong sandwich from Subway.  Cut it in half and your feeding efficiency is now 200%.  It doesn't mean you have 2 farking footlongs now.


Right, but without it, you have a footlong, cut it in half and throw the other half away.  So you are getting 2 six inch subs from a footlong instead of one six inch sub plus some trash from a footlong.
 
2013-04-19 02:26:21 PM

Mr. Eugenides: Let me do some math...

$0.65 is $650,000 per megawatt in upfront capital cost.

Existing coal generation is about $25/megawatt hour.

That means that the PV array has to run at 100% of rated capacity for 26,000 hours.

Let's be generous and say you get the equivalent of 10 hours a day at 100% which means it takes 2600 days to pay back the capital cost.

That's a payback on the PV array of 7 to 7.5 years which is pretty good.

Add in the construction, storage battery and inverter costs and you've probably doubled that, at which point you may be pushing up against the lifespan of much of the equipment.

PV is getting there, but isn't quite there yet. In a couple of years though.


I wonder how the math would look if we actually factored in all of the costs, not just fuel extraction and material production.  With fossil fuels, we leave out the costs of spills and CO2 emission.  With PV I don't hear much about the lifespan of the solar cells, and how much environmental cost there is to their production (subject I admittedly know little to nothing about).

/non-agenda post, I'd just like to see a more complete analysis of costs for all energy sources
 
2013-04-19 02:26:24 PM

Mr. Eugenides: That's a payback on the PV array of 7 to 7.5 years which is pretty good.

Add in the construction, storage battery and inverter costs and you've probably doubled that, at which point you may be pushing up against the lifespan of much of the equipment.

PV is getting there, but isn't quite there yet.  In a couple of years though.


This is all assuming retrofitting after the fact. At what point does new construction include all of this from day one?
The incremental cost to the cost of house at the point of construction would be lowest, with the highest possible return on investment.

Plus, from a resale point of view, given two identical choices, you would probably pick the one with installed PV system.
/I wish my high-rise would think about something like this. Or a roof deck. lol
 
2013-04-19 02:26:50 PM

namatad: SumFrequency: Gamma rays would like to have a word with you.

wellllllll
dont they create electron and positron pairs?
technically?

No, electron and hole pairs.  Hence the name exciton.

CUTE
but I thought it was pair-production in a vacuum.
we were talking about gamma rays, not the article.
http://en.wikipedia.org/wiki/Pair_production

but go on


Completely different things.  Hole != positron.  We are talking energy states in a lattice, not matter and energy converting between each other.
 
2013-04-19 02:27:06 PM

SumFrequency: Khellendros: Wow, that was a massive clusterfark of scientific journalism.  Photons do not create electrons.  Under certain conditions, it excites an electron to a higher energy state.  In the useful case, the excitation reaches the level where the electron can be conducted and passed on.

I don't want to take anything away from this discovery - this could provide a very useful boost and utilize more incident photonic energy.  But for the love of Mike, get the terminology somewhat correct.  It's not that hard.

So they went from A to D rather than A-B-C-D.  Not all the masses have doctorates.  It was well enough explained.  And this is coming from someone who did that exact particular research.


No, they didn't.  There is no path in that article that gets you from base facts to conclusion that includes "creation of electrons".  That's not a doctorate level discussion.  That's second-semester physics you learn at the beginning of your E&M chapter.  You don't need to understand the research to report this correctly.  You need the amount of physics that any college STEM B.S. learned in their first year.  Without it, you end up reporting something that says that photons are creating electrons, which is terribly misinformed at its very core.  It contributes to ignorance of basic facts, which is kinda what journalism should be striving against.

In November, the American populace didn't "craft a president".  Ford doesn't "grow automobiles".  Photons hitting solar cells don't "create electrons".  The first two are obvious and absurd.  The third is problematic, because a large portion of people don't understand enough of the basics to get what they're reading.  But it's just as basic in a critical subject.

Yes, I'm ranting, and maybe even being a it pedantic.  But this is basic shiat that the average person should get right.  No insult to you intended.  I'm just being crotchety, I guess.
 
2013-04-19 02:31:22 PM

SumFrequency: I'm not being cute.  An exciton really is an electron-hole pair.  Otherwise the papers I published on them wouldn't have been accepted.

The more you know.


1) super jealous of your research project. we barely had electrons when I was in college.
2) yes, I know, excitons are both super cool and not electron-positron pair production.
3) we weren't talking about excitons. we were talking about gamma rays.

/it has been amazing watching the future unfold. from reading about nanotech to we now have nanotech.
/still waiting for room temp superconductors
 
2013-04-19 02:31:25 PM

BKITU: The law that entropy always increases holds, I think, the supreme position among the laws of Nature. -- Sir Arthur Stanley Eddington, The Nature of the Physical World


So evolution is false and God created the universe and everything in it.
QED
 
2013-04-19 02:36:53 PM

Khellendros: Yes, I'm ranting, and maybe even being a it pedantic.  But this is basic shiat that the average person should get right.  No insult to you intended.  I'm just being crotchety, I guess.


marching morons
and yet, we can never have a test for voting rights.
 
2013-04-19 02:38:03 PM
So this cell is not following the laws? Here come the background checks.
 
2013-04-19 02:38:14 PM

Hollie Maea: SumFrequency: MEG is like a footlong sandwich from Subway.  Cut it in half and your feeding efficiency is now 200%.  It doesn't mean you have 2 farking footlongs now.

Right, but without it, you have a footlong, cut it in half and throw the other half away.  So you are getting 2 six inch five and a half inch subs from a footlong instead of one six inch five and a half inch

 sub plus some trash from a footlong.

FTFY
 
2013-04-19 02:43:44 PM

Magorn: MidnightSkulker: Except, no, it doesn't.

If you are ever tempted to suggest something does not obey the laws of thermodynamics, just don't. You are wrong.

touchy, touchy,  you know  they're not really laws, they're more like guidelines


It's spelled touché
 
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