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Berkeley Lab Develops Technology To Make Photovoltaics Out of Any Semiconductor

samzenpus posted about 2 years ago | from the easy-solar dept.

Power 55

First time accepted submitter bigvibes writes "A technology that would enable low-cost, high efficiency solar cells to be made from virtually any semiconductor material has been developed by researchers with the U.S. Department of Energy (DOE)'s Lawrence Berkeley National Laboratory (Berkeley Lab) and the University of California (UC) Berkeley. This technology allows for plentiful, relatively inexpensive semiconductors, such as metal oxides, sulfides and phosphides that had previously been considered unsuitable for solar cells because of the difficulty in tailoring their properties by chemical means."

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55 comments

Available 5 years from now (3, Funny)

John Bokma (834313) | about 2 years ago | (#40809525)

as usual :-)

Works for me (1)

overshoot (39700) | about 2 years ago | (#40809689)

That's about when I'll be building a house from scratch.

Re:Works for me (2, Funny)

Anonymous Coward | about 2 years ago | (#40809935)

Build?
I expect to be able to print my house.
http://www.psfk.com/2012/02/3d-printing-buildings.html

Re:Works for me (0)

Anonymous Coward | about 2 years ago | (#40816695)

We thought it will be robots who will replace humans. We were wrong. It will be a printer :-)

Re:Available 5 years from now (0)

Anonymous Coward | about 2 years ago | (#40812779)

It'll probably arrive about the same time as that superhydrophobic surface treatment stuff [youtube.com] hits the consumer market. I'm still waiting for it to come out as a car wax and window treatment.

Re:Available 5 years from now (2)

Electricity Likes Me (1098643) | about 2 years ago | (#40814331)

That stuff is real today, it's just mostly used in commercial scale building construction. Any new office blocks you've seen put up recently almost certainly use it.

Re:Available 5 years from now (0)

Anonymous Coward | about 2 years ago | (#40818971)

your phone uses it too. Its just not cheap, thats all

Re:Available 5 years from now (2)

slashmydots (2189826) | about 2 years ago | (#40814041)

as usual :-)

I was thinking closer to never actually, as they've been posting stories here about vastly improved solar panels for more than 5 years. If I remember all the stories correctly, and I think my math is pretty accurate on this one, we can now build 500% efficient, spiral-shaped, multi-layer, extra thin cut, impossibly cheap, magical divine solar panels sent down from Mt Olympus to power mankind. Maybe someone should manufacture one then, huh?

Re:Available 5 years from now (4, Informative)

timeOday (582209) | about 2 years ago | (#40814899)

That is approximately true [scientificamerican.com] . A 95% reduction in price over 30 years is pretty darn impressive. Not all at once, of course, but the accumulation of dozens of such advances.

Re:Available 5 years from now (0)

Anonymous Coward | about 2 years ago | (#40816307)

Cool, semiconducting prophylactics ... sounds like fun

yay (1)

masternerdguy (2468142) | about 2 years ago | (#40809543)

progress marches on

Re:yay (0, Troll)

Teresita (982888) | about 2 years ago | (#40809717)

The greenie weenies will try to ban it because it lowers the albedo of the Earth and leads to global warming.

*yawn* (4, Informative)

sycodon (149926) | about 2 years ago | (#40809595)

call me when I can buy it in rolls or sheets at Home Depot.

Re:*yawn* (2, Funny)

turkeyfeathers (843622) | about 2 years ago | (#40809753)

Sorry, they've signed an exclusivity deal with Lowe's.

Re:*yawn* (1)

sycodon (149926) | about 2 years ago | (#40809775)

Well, they're across the street...I can deal with it.

Re:*yawn* (0)

Anonymous Coward | about 2 years ago | (#40812727)

What fucking moron mod would mod this down?

Slashdot has become some hang out for 14 year old wanna be nerds.

Re:*yawn* (3, Interesting)

timeOday (582209) | about 2 years ago | (#40814907)

So why are you reading slashdot instead of the Home Depot circular ad in the Sunday newspaper? It seems to meet your needs perfectly.

Acronym abuse (5, Funny)

Anonymous Coward | about 2 years ago | (#40809603)

“screening-engineered field-effect photovoltaics,” or SFPV

The two hyphenated pairs get a single letter. The single compound word gets two letter. Stop the madness!

Re:Acronym abuse (3, Informative)

Samantha Wright (1324923) | about 2 years ago | (#40809859)

There's an easy explanation for that: the second "E" disappears when you say it quickly (ess ee fee ee pee vee), and the first one would make the initialism long and unwieldy without providing pronounceability. "PV" describes the root noun and hence is more important to the meaning of the term, and makes it easier to infer what the abbreviation describes when scanning snippets of unfamiliar literature. Irregularity in such contractions is not a new thing, though—ever seen "Wm." for "William"?

Brevity, especially the minimum effort to provide disambiguation, supersedes consistency; otherwise we wouldn't use abbreviations at all. Think of it like Huffman coding. Huffman coding is the wellspring of life.

Re:Acronym abuse (1)

meekg (30651) | about 2 years ago | (#40810327)

Booyah!
Sharp as a laser beam, powerful as the diode bank that's driving it. Analogies are not my thing.
The second line should be enshrined and worshipped. Neither are accolades.
So yeah, Booyah!

Re:Acronym abuse (0)

Anonymous Coward | about 2 years ago | (#40813849)

the second "E" disappears when you say it quickly (ess ee fee ee pee vee)

Only if you have a speech impediment or are drunk.

initialism long and unwieldy without providing pronounceability

The "pronounceability of initialisms doesn't really matter like it does with acronyms, but if the reason is that they want the initialism to look good, that should be the single, consistent reason for both abridgements.

Re:Acronym abuse (1)

Samantha Wright (1324923) | about 2 years ago | (#40814227)

Wow. I have no idea how "F" came out as "fee". Clearly I've been exposed to too much Greek. I guess I'll hand the first one to you!

Regardless: five- and six- letter initialisms are heinously long; three- and four- letter abbreviations tend to be the norm. I think finding the shortest distinctive representation is more of a driving factor than aesthetics. Also perhaps there's also some innate wariness of emphasizing non-leading vowels, brought over from other abbreviation conventions.

The world will never be consistent, my friend; certainly not with something as ad hoc as abbreviations.

Re:Acronym abuse (1)

Crypto Gnome (651401) | about 2 years ago | (#40812167)

“screening-engineered field-effect photovoltaics,” or SFPV

The two hyphenated pairs get a single letter. The single compound word gets two letter. Stop the madness!

Perhaps these guys were smart enough to realize that SFP has already been abused beyond recognition for many and diverse causes [wikipedia.org] and they needed to add (at least) another letter in order to stop the madness.

Government tax dollars at work (1)

sandytaru (1158959) | about 2 years ago | (#40809985)

for once, anyway.

Re:Government tax dollars at work (1)

MasaMuneCyrus (779918) | about 2 years ago | (#40810391)

I do get a feeling that the government tax dollars will go straight to equipping a Chinese factory, however. Nearly all high tech industries are set up such that US does the research and Asia does the manufacturing and reaps the profits.

Re:Government tax dollars at work (2)

sandytaru (1158959) | about 2 years ago | (#40811881)

Well, when the US tries to encourage local companies and startups to take advantage of new technologies, and it backfires, then the government gets blamed (see the Solyndra kerfluffle.) Can't win.

Re:Government tax dollars at work (3, Insightful)

Crypto Gnome (651401) | about 2 years ago | (#40812257)

Well, when the US tries to encourage local companies and startups to take advantage of new technologies, and it backfires, then the government gets blamed (see the Solyndra kerfluffle.) Can't win.

Yes but Made In China has nothing to do with that.

Made In China: because our environmental controls are effectively nonexistent compared to yours.

Sure there's cost-of-labor (etc) factors too but in these High-Tech (ie lots of mostly toxic chemicals somewhere in the manufacturing process) industries, cost of containing (or more often than not, cleaning-up-after) pollution is prohibitive.

Someone needs to educate these companies that doing all your toxic production in a foreign country is functionally equivalent to a goldfish swimming to the other side of the bowl to take a crap.

Read about oxide ones before (4, Interesting)

Grayhand (2610049) | about 2 years ago | (#40810007)

The issue was always a low output but if you can make them dirt cheap who cares if they are 5%? If you can cheaply replace the shingles on your house with cheap solar cells I'd call it a win even if you have to cover the whole roof instead of one part. Cheap and practical will always win over efficient and expensive. Even when over the long term you are better off with the more efficient cells people will actually buy the cheaper ones. It's what keeps Ikea and stores like it in business. Pressboard furniture falls apart after a couple of years but it's less than half the price of decent furniture. A good piece may last 50 years and out live 10 cheapie pieces so the cheap furniture costs 5X as much in the long run but people still go for cheap. If people could cover their roofs for $2,500 to $5,000 instead of $15,000 to $35,000 most roofs would have solar cells even if they last half as long.

Re:Read about oxide ones before (2)

Dr. Spork (142693) | about 2 years ago | (#40810311)

You're forgetting that the cost of transportation and installation is really quite high compared to the cost of the cells. Then there's all the wiring, and the expensive conversion hocus pocus that you need to safely make the power you generate come out of the socket at 120/60. These fixed costs will bite you in the ass if you skimped on the cells themselves and they're only 5% efficient and barely making a dent in your power bills. To pay back for the total installation costs, the cells really do need to have a decently high efficiency and decently long service lives.

Re:Read about oxide ones before (0)

Anonymous Coward | about 2 years ago | (#40811455)

You're correct, assuming that the new, dirt-cheap cells will have the same form factor and installation configuration of the current cells. They might not. You could imagine them getting so cheap that they can be configured to replace current building exteriors. You'd install them the way you would ordinary shingles or aluminum siding.

Re:Read about oxide ones before (1)

sandytaru (1158959) | about 2 years ago | (#40811899)

I believe it was MIT who was working on solar cells that could be stapled or nailed on a roof like shingles, with a special semiconducting tar binder that would turn the entire roof into a giant solar cell.

Re:Read about oxide ones before (1)

Anonymous Coward | about 2 years ago | (#40812439)

They have the rolls of solar cells for years now, that's not the problem. The problem is storing that energy and then using it.

I can cover my roof with solar cells, what I can't do is then afford the inverters, wire and batteries. Or the convenience parallel wiring to "green plates" e.g. you have your 117VAC "white plug cover" from pg&e or smud, and you have your "green plate covers for your solar" that's extra wiring which costs as well. There's also battery maintenance vs sealed as a choice.

The roll outs work just the same as a sharp panel or a harbor freight array, they all wear out, but they are cool.

bottom line who can spend $4000 on a single battery of which you need many, then you need several 3k watt inverters to match it all up. You want to understand your system so you can repair it as well I suppose, so being tied to one kind of product can screw you just the same as buying cheap inadequate wire.

There is a reason this is subsidized is ultimately it costs a fortune.

It's safe to play on the low end edges now.

Anyone can grab up a 50 watt kit and a battery and inverter and start learning from there. If anything you can power some communications. Get a few more watts and maybe a small trucker's fridge, coffee brewer, razor, but the best in my opinion at low watts is to replace your battery chargers with DC ones, buy a more expensive inverter with less watts but cleaner waveform.

Maybe you want to power a low watt usage router, switch and a workstation etc. That's another thing to design around. Embedded with low power cpu's work great here!

Maybe you are the mobile phone freak. Well even a cheap ass HF kit would be more than enough to deal with all those fucking USB devices.

Soon you start shopping different. You look for 117VAC/12 VDC appliances. Think this way all the way down to the battery charger. It will make life easier if all your batteries are off grid, no matter what every AAA, AA, C, D, or 9V will always be at the ready. Does your battery charger work off a 12V battery? Sure you can fire up an inverter and run it for 6 hours. But what if it ran AC/DC? Makes me want to revisit all the 1970's tech.

It all costs money though. Consider yourself very luck if you get to play.

   

Re:Read about oxide ones before (0)

Anonymous Coward | about 2 years ago | (#40812601)

able to run a fucking cheap $99 tile cutter on 12 x 12 marble tile with only a 45 watt harbor freight kit, inverter and a 22 AH battery

Go play on the low end. It's worth it, knowing you can run a pump, drill, lights in the winter with a blackout. It's low end prepping, and if you tinker, you can have a pretty mean system after a few years. Live in a flood zone, nice to know you can saw through your roof and launch a blow up (12V air compressor) raft even kittah's and Goggies can have their cages float in an emergency!

Ham shack. I'm tellin ya, fun fun fun.

Fuck the green ness carbon tax ne$$ UN Agenda 21 ne$S, think of the off grid ness good ness
think, fuck all this shit.

There is maintenance.
Be ready to wash panels, lift out bad batteries / hazardous bullshit, cut, solder, pot, dress and seal wires, replace fuses with freaky fucking bullshit happening. You are responsible for your own electric company. If it catches fire, your responsible, if it kills your responsible.

There is responsibility
In tight "homeowners associations" Measure your sunlight four times a year and adjust locations until you find the best spots, where do you garden, how much sun can you sacrifice to light for energy vs garden growing / propagation energy.

It takes DIY skills and advanced troubleshooting skills to be completely off grid, got a degree, so what.

Re:Read about oxide ones before (1)

mattack2 (1165421) | about 2 years ago | (#40822297)

But you save a lot of money if you use grid-connected solar, and do without the batteries.

Re:Read about oxide ones before (1)

cjsm (804001) | about 2 years ago | (#40812031)

Another factor is PV is getting cheaper and better all the time. So buy the cheap stuff now, and upgrade in a few years to PV that's significantly better and cheaper than the high end PV was when you did the original installation.

Re:Read about oxide ones before (1)

fast turtle (1118037) | about 2 years ago | (#40812263)

yah don say! In regards to the cost of real furniture, I can find good quality real wood made in the USA for the same price as the crap pressboard sold by HomeDepot/Lowes and Walmart. What's that? Yep, there's quite a few places, most are local or within driving distance that make furniture from Pine and such and that's what I buy as it's better quality for the same damn price

Re:Read about oxide ones before (0)

Anonymous Coward | about 2 years ago | (#40812337)

To be fair, everyone I know just buys furniture from Ikea because they are livinig in apartments that they know they will be living in for only a few years, so there's no point in spending a lot of money making it nice. Solar panels at least increase the resale value of a house by a non-trivial amount, so installing nicer solar panels might be easier to justify. Of course, if you need credit to afford them and there's no way to get the credit, you'll buy the cheap ones.

Re:Read about oxide ones before (1)

ThatsNotPudding (1045640) | about 2 years ago | (#40816233)

If you can cheaply replace the shingles on your house with cheap solar cells I'd call it a win even if you have to cover the whole roof instead of one part.

Hail decides who wins.

Re:Read about oxide ones before (0)

Anonymous Coward | about 2 years ago | (#40825087)

Making cells into modules is expensive. Tempered glass, etc. For CdTe (First Solar), the glass is a substantial part of the total cost.

Installation costs aren't going to change very much, either.

Attempt at layman explanation (5, Informative)

LourensV (856614) | about 2 years ago | (#40810529)

I read the article (I know! But there were no comments yet, so what am I to do?) and, not having understood much of it, did some reading to try and understand what's going on here. I think I've more or less figured it out, so I'm attempting a simple explanation here. Semiconducting physics nerds, please fix this for me as appropriate.

Atoms consist of a positively charged nucleus, surrounded by one or more shells of electrons. Electrons farther away from the nucleus have more energy than ones closer in. Put a bunch of those atoms together, and there are two things that can happen. In some materials, the electrons in the higher energy states are so "far away" from the nucleus in energetic terms, that they can easily move from one atom to the next. These materials are conductors. In other materials, there is a big gap (the band gap) between the highest "bound" (valence band) energy state, and the minimum energy state (the conduction band) needed to move between atoms. So, the electrons can't move away from their nuclei, and these materials are electrical insulators. Then there are some materials that have an intermediate sized gap between stuck valence states and free-to-move conduction states, and these are called semiconductors.

A solar cell works by the photoelectric effect: when an incoming photon (e.g. sunlight) hits an electron in a semiconductor, the electron absorbs the photon and its energy increases. If the photon is energetic enough, this will move the electron from the valence band to the conduction band. This also creates a positively charged "hole", where the electron was before. The electron and the hole attract each other because they have opposite charge. Left to their own devices, they'll just recombine, so in a solar cell, an electric field is applied. This moves the electron in one direction, and the hole in the opposite direction (because of the opposite charge). This moving electrical charge is otherwise known as current flow, and so we have a working solar cell.

So how do we make an electric field? In normal photovoltaic cells, this is done by doping (adding small impurities, typically boron and phosphorus to) the semiconductor. Since these have less or more electrons in their outer shells, they create areas in the semiconductor with more electrons or more holes, which creates a charge difference between them (a P-N junction). This charge difference creates an electric field, which will whisk away any electrons and holes created within it. Apparently, this doping process only works for relatively expensive semiconductors however.

So, if I understand correctly, what these researchers have done is to apply an external electric field, by applying a small voltage across the whole thing. This puts a charge on the contacts on each side of the cell, which draws electrons in the semiconductor one way and holes the other way, thus creating a P-N junction without doping. The problem is that normally the construction of the contacts keeps their electric field from propagating into the semiconductor, so that it doesn't generate a good P-N junction. Apparently they've overcome this by changing the geometry of one of them, in two different ways for two different alternative semiconductors. And then they have a version in which the external voltage is supplied by the cell itself, making it self-contained.

So is this useful? Well, conspicuously absent from the article is any mention of efficiency. So I'd speculate that this mainly allows the production of low-efficiency solar cells at lower prices than before, rather than getting more output from your roof. But if this makes solar cells cheap enough to just blanket anything and everything with them, that could still be useful of course.

Re:Attempt at layman explanation (4, Insightful)

Anonymous Coward | about 2 years ago | (#40810671)

Pretty good summary! The journal article (http://pubs.acs.org/doi/full/10.1021/nl3020022) discusses efficiencies for silicon, a well understood semiconductor used as a test case. The effect can improve silicon Schottky barrier cells from 8% to almost 20% efficiency. (Note that Schottky cells are a metal-semiconductor junction, not the typical commercial chemically-doped silicon that gets around 20-25%.)

The exciting thing about this technique is that you can now take low-efficiency (10%) Schottky or heterojunction cells made with (literally) dirt-cheap materials (rust, sulfides, etc) and convert them into low-cost, high-efficiency (perhaps ~15-20%) cells. Then the module cost is low, and the installation costs can be low too (as you don't need to buy as many panels and cover as much ground for a certain amount of generated power).

Re:Attempt at layman explanation (0)

Anonymous Coward | about 2 years ago | (#40825075)

Too bad you can get 17.6 with silicon/native oxide/aluminum (Green, Appl. Phys. Lett, 1976, 34, 790), and this was in 1979! The article doesn't list numbers anywhere near what you quoted.

Hezel's group has gotten up to 21% (maybe only 20%?) with silicon/native oxide/aluminum Schottky, using trapped cesium charges acting in the same way as a gate. This works on p-type Schottky since you typically only trap positive ions in oxides/nitrides. Basically, the trapped charges work the same way as the gate (i.e. attracting electrons), without having to apply a constant potential.

Also, without some kind of electron/hole blocking layer, you get a lot of dark current (i.e. current that goes in the wrong direction). This is what the native oxide does, and a lot of people screw around with polymers/etc to replace the native oxide on other materials.

The main problem with silicon is thickness (need it 10-20 um only), as Si is expensive. There are a lot of good materials out there (Cu2O, some sulfides, Zn3P2) that have good bandgaps to make 2-junction cells with silicon, but efficiencies are dreadful. Also, some of the oxides/sulfides react with the metals that you're trying to form a Schottky barrier with, forming other metal oxides/sulfides, which limits the efficiency. Gating really can't help there.

Also, making the module (from cells) is 1/3 of the cost of a solar panel (typically, with making wafer and making cells each ~1/3); installation is also expensive. Unless you can make it much cheaper than silicon, with comparable efficiency, it just can't compete (i.e. it takes longer to recoup the investment).

Re:Attempt at layman explanation (0)

Anonymous Coward | about 2 years ago | (#40811585)

Great summary. I found it very helpful.

So I was thinking, "where would the initial electric field come from?" If the panel needs an external voltage applied to it in order to start it up, that might make it less useful in situations where there isn't a tie-in to the grid. The best thing I can think of is to add a small patch of original-style solar panel on each of the new panels.

Re:Attempt at layman explanation (0)

Ryanrule (1657199) | about 2 years ago | (#40812189)

Oh noes, all the college is coming back to me. Why didn't I bang that one chick, who cares she had a bf.

Re:Attempt at layman explanation (4, Insightful)

gaelfx (1111115) | about 2 years ago | (#40813505)

You know, reading this gave me an idea. /. should have something like this for every article (or at least articles such as this that require some explanation). they could make a competition out of it, and feature the winning comment in some way that makes it easy for us laymen to see when we choose to view the comments. Just a thought.

Nice explanation, btw. I never really understood what an electric field was before!

Re:Attempt at layman explanation (1)

nbsr (2343058) | about 2 years ago | (#40817463)

I agree. A comment section with a scoring system would be fantastic.

Re:Attempt at layman explanation (0)

Anonymous Coward | about 2 years ago | (#40813771)

when an incoming photon (e.g. sunlight) hits an atom in a semiconductor, the atom (Nucleus) absorbs the photon and its energy increases ,momentarily, exciting electrons into a higher state*.

FTFY

* Photo Absorption" [wikipedia.org]

Re:Attempt at layman explanation (1)

purpledinoz (573045) | about 2 years ago | (#40814843)

To summarize the summary, the researchers managed to create a PN junction by applying an electric charge rather than doping.

Quote (2)

gaelfx (1111115) | about 2 years ago | (#40813363)

To quote Bart Simpson: "I can't believe it! You actually found a practical use for geometry!"

vaporware (0)

swell (195815) | about 2 years ago | (#40814911)

Have we forgotten the term 'vaporware'? Has it evaporated along with the products we used to laugh at?

I've been reading about 'exciting new developments' in photovoltaics for forty years, along with the flying car that's just around the corner and similar fantasies perpetuated by Popular Science & Popular Mechanics magazines.

Show me the cheap efficient PV product I can buy today or just shut up.

Re:vaporware (1)

Anonymous Coward | about 2 years ago | (#40815301)

Not how science works, buddy -- research is hard and long term and needs occasional puff pieces to remind people it's worthy of funding. Photovoltaics is a tough nut to crack -- it's essentially competing with solar energy that's been accumulating and concentrating for millions of years (fossil fuels). Practical photovoltaics have only been around since the 1950s -- that fact that we're already close to grid parity in only a lifetime of research is a miracle.
Reminiscent of this: http://www.youtube.com/watch?v=8r1CZTLk-Gk&feature=player_detailpage#t=22s

Panels Above the Trees (1)

Doc Ruby (173196) | about 2 years ago | (#40815051)

Solar panels are already cheap enough for me. In NYC, Con Ed charges $0.20+ per KWh, so installed panels at about $3:Wp pay off in under 7 years: a 14% ROI, better than the stock market ever gets (so I almost wish they cost more :).

My problem is that my roof is largely covered by trees, so I get only about 20% of the sunshine past them. So I've been considering building a platform above the roof, above the trees, though that's going to be something like 10m above the roof, which is about 7m above the ground. I don't know if it will be stable, or how many years of solar power it will cost to pay back the extra infrastructure costs. We don't have enough wind to make turbines on the platform worth their investment.

Where can I research whether a raised platform is feasible?

Re:Panels Above the Trees (1)

flyingfsck (986395) | about 2 years ago | (#40815693)

Won't it be easier and cheaper to prune the trees?

Re:Panels Above the Trees (1)

Doc Ruby (173196) | about 2 years ago | (#40828829)

It would be a lot of trimming. I like the trees, and the shade.

Plus, I might get a lookout tower out of the deal.

I want it all!

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