Major advance in solar cells made from cheap, easy-to-use perovskite

November 8, 2016
This first version of a new layered perovskite solar cell already achieves an efficiency of more than 20 percent, rivaling many commercial solar cells. Flexible and easy to make, it can produce more than half a volt of electricity. Credit: Onur Ergen, UC Berkeley

Solar cells made from an inexpensive and increasingly popular material called perovskite can more efficiently turn sunlight into electricity using a new technique to sandwich two types of perovskite into a single photovoltaic cell.

Perovskite are made of a mix of organic molecules and inorganic elements that together capture light and convert it into electricity, just like today's more common silicon-based solar cells. Perovskite photovoltaic devices, however, can be made more easily and cheaply than silicon and on a flexible rather than rigid substrate. The first perovskite solar cells could go on the market next year, and some have been reported to capture 20 percent of the sun's energy.

In a paper appearing online today in advance of publication in the journal Nature Materials, University of California, Berkeley, and Lawrence Berkeley National Laboratory scientists report a new design that already achieves an average steady-state efficiency of 18.4 percent, with a high of 21.7 percent and a peak efficiency of 26 percent.

"We have set the record now for different parameters of , including the efficiency," said senior author Alex Zettl, a UC Berkeley professor of physics, senior faculty member at Berkeley Lab and member of the Kavli Energy Nanosciences Institute. "The efficiency is higher than any other perovskite cell - 21.7 percent - which is a phenomenal number, considering we are at the beginning of optimizing this."

"This has a great potential to be the cheapest photovoltaic on the market, plugging into any home solar system," said Onur Ergen, the lead author of the paper and a UC Berkeley physics graduate student.

The efficiency is also better than the 10-20 percent efficiency of polycrystalline silicon solar cells used to power most electronic devices and homes. Even the purest , which are extremely expensive to produce, topped out at about 25 percent efficiency more than a decade ago.

The achievement comes thanks to a new way to combine two perovskite solar cell materials - each tuned to absorb a different wavelength or color of sunlight - into one "graded bandgap" solar cell that absorbs nearly the entire spectrum of visible light. Previous attempts to merge two have failed because the materials degrade one another's electronic performance.

"This is realizing a graded bandgap solar cell in a relatively easy-to-control and easy-to-manipulate system," Zettl said. "The nice thing about this is that it combines two very valuable features - the graded bandgap, a known approach, with perovskite, a relatively new but known material with surprisingly high efficiencies - to get the best of both worlds."

Full-spectrum solar cells

Materials like silicon and perovskite are semiconductors, which means they conduct electricity only if the electrons can absorb enough energy - from a photon of light, for example - to kick them over a forbidden energy gap or bandgap. These materials preferentially absorb light at specific energies or wavelengths - the bandgap energy - but inefficiently at other wavelengths.

"In this case, we are swiping the entire solar spectrum from infrared through the entire visible spectrum," Ergen said. "Our theoretical efficiency calculations should be much, much higher and easier to reach than for single-bandgap solar cells because we can maximize coverage of the solar spectrum."

The key to mating the two materials into a tandem solar cell is a single-atom thick layer of , which looks like a layer of chicken wire separating the perovskite layers from one other. In this case, the perovskite materials are made of the organic molecules methyl and ammonia, but one contains the metals tin and iodine, while the other contains lead and iodine doped with bromine. The former is tuned to preferentially absorb light with an energy of 1 electron volt (eV) - infrared, or heat energy - while the latter absorbs photons of energy 2 eV, or an amber color.

The monolayer of boron nitride allows the two perovskite materials to work together and make electricity from light across the whole range of colors between 1 and 2 eV.

The perovskite/boron nitride sandwich is placed atop a lightweight aerogel of graphene that promotes the growth of finer-grained perovskite crystals, serves as a moisture barrier and helps stabilize charge transport though the solar cell, Zettl said. Moisture makes perovskite fall apart.

The whole thing is capped at the bottom with a gold electrode and at the top by a gallium nitride layer that collects the electrons that are generated within the cell. The active layer of the thin-film solar cell is about 400 nanometers thick.

"Our architecture is a bit like building a quality automobile roadway," Zettl said. "The graphene aerogel acts like the firm, crushed rock bottom layer or foundation, the two perovskite layers are like finer gravel and sand layers deposited on top of that, with the hexagonal boron nitride layer acting like a thin-sheet membrane between the gravel and sand that keeps the sand from diffusing into or mixing too much with the finer gravel. The gallium nitride layer serves as the top asphalt layer."

It is possible to add even more layers of perovskite separated by hexagonal boron nitride, though this may not be necessary, given the broad-spectrum efficiency they've already obtained, the researchers said.

"People have had this idea of easy-to-make, roll-to-roll photovoltaics, where you pull plastic off a roll, spray on the solar material, and roll it back up," Zettl said. "With this new material, we are in the regime of roll-to-roll mass production; it's really almost like spray painting."

Explore further: Toward 'greener,' inexpensive solar cells

More information: Graded bandgap perovskite solar cells, Nature Materials, nature.com/articles/doi:10.1038/nmat4795

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gculpex
Nov 08, 2016
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hawkingsbrother
Nov 08, 2016
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Cave_Man
3.7 / 5 (3) Nov 08, 2016
In addition, the perovskite cells suffer with poor stability, which could wipe out the savings completely.


They should be incredibly cheap compared to solar panels now, last almost as long, and be easier to recycle than Si based panels. Not sure what you're talking about though. Seems as though you don't realize that for some new technique of harvesting solar photovotaicly to be doing this well so soon, this is sure a killer investment and should outpace any advances in other PV in foreseeable future.
hawkingsbrother
Nov 08, 2016
This comment has been removed by a moderator.
rrrander
1 / 5 (6) Nov 08, 2016
Notice the envirocretins giving 1-star ratings to anything that upsets them.
hawkingsbrother
Nov 09, 2016
This comment has been removed by a moderator.
xponen
3 / 5 (2) Nov 09, 2016
Can you calculate?

I don't know, but manufacturing of perovskite is very very different than silicon... so there ought to be a massive cost saving on perovskite. The manufacturing of silicon require very high energy, to melt it and to cool it to form a crystal, but in other hand; the manufacturing of perovskite is almost done at room temperature, it's like you mixing an ingredient. This energy difference meant that you're looking at something huge like a factory with a blast furnace and huge delicate machinery to something that is small and mass produce-able, like a production line in car assembly.

If you can mass produce perovskite like I imagine it would, then it's game over for fossil fuel.
xponen
4 / 5 (4) Nov 09, 2016
Don't you guys realize that a silicon solar panel is still expensive? it cost like a car. We need the cost to be lower to the point that it's not a big deal to install a panel, you don't want to have the government talk about it or worrying about loan or something.
antialias_physorg
5 / 5 (2) Nov 09, 2016
If you look at the timeline of perovskite efficiency increases (compared to other solar panel technologies) it's pretty amazing
http://e4sv.org/w...raph.png

Can you calculate? If the cost of solar cells represents only 20%, then you can only bring 20% savings with replacement

The point you're missing here is that with very cheap solar cells it now becomes possible to incorporate them into products as an "of course it's covered in solar cells to (help) power it"..Think roof tiles, wall coverings, car roofs, sensors of all kinds, ...

Perovskite cells can also be flexible which adds anything made of cloth to the list (a jacket that powers your phone? Never again will you have to remember to go charge it)

These cells are also easy to manufacture (opening up the mid to large powerplant sector in countries that couldn't afford to do it up until now)

The potential I see for these is huge.
hawkingsbrother
Nov 09, 2016
This comment has been removed by a moderator.
tear88
1 / 5 (2) Nov 09, 2016
The point you're missing here is that with very cheap solar cells it now becomes possible to incorporate them into products as an "of course it's covered in solar cells to (help) power it"..Think roof tiles, wall coverings, car roofs, sensors of all kinds, ...

True enough, but the other components of a home system are unchanged. And energy storage, while improving, is doing so slowly. Then there's the gold and gallium nitride; those aren't exactly abundant. If this approach took off, how soon before they became an economic choke point?
antialias_physorg
4.2 / 5 (5) Nov 09, 2016
And energy storage, while improving, is doing so slowly.

Solar power has had a head start. The research into better batteries in recent years has only started to get up to speed. I think this will spike in a similar way as more and more countries are hopping on the renewables train.

Already there are some very interesting and very cheap designs in the works - from sodium-air to batteries made from scrap.
Right now it makes more sense to have photovoltaics and feed it into the grid. But in the next decade or two? I'm sure we'll see plenty of storage around. (Tesla is already selling their powerwall like hot cakes)

The price of lithium batteries is expected to drop (even with rising demand) - so even if we stick to this 'old' battery tech there comes a point when it makes sense for the average Joe to have a home storage system (e.g. instead of a gas line or an oil tank)
hawkingsbrother
Nov 09, 2016
This comment has been removed by a moderator.
Sonhouse
3.7 / 5 (3) Nov 09, 2016
It's all well and good, very good, to be talking about multiple band gap products and such and the higher efficiencies, but they did not talk about the well known problem with perovskites: moisture destroys them. So they have to solve that as a long term issue before there will be real cells on homes.
antialias_physorg
5 / 5 (4) Nov 09, 2016
Lithium price.


Ah..But the lithium price isn't the only thing that drives lithium battery prices. The figure of merit is $/kWh. Lithium batteries are being improved (getting more kWh with the same amount of Lithium), economics of scale are coming into play with Gigafactories (not just from Tesla, but some asian players as well)
...to the point where lithium battery prices have dropped by 70% over the last 18 months:
https://www.green...8-months

And as noted: Lithium isn't the only player in the battery market. Basically you can make a battery from any two elements (you _can_...from some you probably shouldn't), The number of possibilities still unexplored is almost endless.
hawkingsbrother
Nov 09, 2016
This comment has been removed by a moderator.
antialias_physorg
4 / 5 (4) Nov 09, 2016
Why the rechargeable batteries are still so expensive, after then?

Because up until now there wasn't really a large scale use case for them. Energy production from oil and gas was cheap - so energy storage wasn't an issue for anyone (and the storage that was needed for short term load balancing was easily handled by cheap hydropower).

For the same reason we have had fossil fuel powered cars. In the beginning of car manufacture there already were battery powered cars being sold - but oil was just too cheap for them to survive. With the prices as they are now EVs are - seen over their lifecycle - cheaper than the old kind of cars. So "too expensive" isn't the issue. It's that even with low gas prices the batteries are now at the break-even point (even if we ignore the elephant in the room for a moment: climate change)

No use case no (money for) research. Right now there are attractive use cases so there's suddenly a lot of research going that way.
Zzzzzzzz
2.2 / 5 (5) Nov 09, 2016
Notice the envirocretins giving 1-star ratings to anything that upsets them.

just keep on deluding yourself, worthless asshole
Zzzzzzzz
2 / 5 (4) Nov 09, 2016
Can you calculate? If the cost of solar cells represents http://energyinfo...st1.png, then you can only bring 20% savings with replacement of solar cell material. And the cost of silicone material represents only minute portion of the cost of solar cells, because the most expensive part today represents the transparent indium electrode. Silicone in general is quite cheap material, which requires only sand, energy and water to produce. So your savings will be even less than 20%, probably bellow 10%. Is it worth of research? Why just the scientists are so bad in economics?

You misread your linked site. First, it says the panel cost is 30%, not 20%. Permits & inspection fees are more than absorbed currently by incentives. Operational costs? figured at 20%? I'd like to see supporting data. And these are not upfront installation costs. Labor costs also reduce with new technology.
Your misrepresentation shows you cannot calculate.
hawkingsbrother
Nov 09, 2016
This comment has been removed by a moderator.
Edenlegaia
3.7 / 5 (3) Nov 10, 2016
I'm just explaining, why perovskite cells will never reach solar market (which still runs on classical silicon last thirty years). The proponents of mainstream science cannot do economy, because they get everything for free and they're just motivated on further job - I mean grants and research.


Of course, trying to know more about how to make perovskite both competitive, efficient AND durable is pointless because "we already have good things duh".
Better is the worst. Let's get rid of cars and go back to horses: those were good enough.
antialias_physorg
5 / 5 (5) Nov 10, 2016
I'm just explaining, why perovskite cells will never reach solar market

I think you're missing quite a few points (some I already mentioned)...but another one is that the installation cost or the cost to the end user doesn't matter at all in whether a solar cell technology comes to market or not.

The _only_ thing that matters in whether something comes to market is the profit margin for the company making it. The end user doesn't care whether he has technology A or B on the roof as long as he pays the same $/kW installed capacity. And perovskite cells are cheaper to manufacture than Si cells - so, if sold at the same price: more profit.

Up until now they couldn't sell these because of durability issues and inferior efficiency. That has changed now. The only thing that stands in the way is the tooling cost of changing factories over from Si to perovskite (which is substantial and will drag out the changeover a bit until the first company does it or a new one starts up).
hawkingsbrother
Nov 10, 2016
This comment has been removed by a moderator.
TheGhostofOtto1923
3 / 5 (4) Nov 10, 2016
The end user doesn't care whether he has technology A or B on the roof as long as he pays the same $/kW installed capacity. And perovskite cells are cheaper to manufacture than Si cells - so, if sold at the same price: more profit
-You mean after subsidies and rebates and tax breaks and the relative value of fashion statements, yes?

I wonder what our new fearless leader will have to say about these costly incentives?

I wonder... the establishment's response to the impending mortgage bubble was to exacerbate it and spread it worldwide. I wonder if the national debt bubble is not being exacerbated with entitlements and incentives for the same reason?

What is debt when everybody owes everybody everything?
TheGhostofOtto1923
3 / 5 (4) Nov 10, 2016
"11 For as high as the heavens are above the earth,
so great is his love for those who fear him;
12 as far as the east is from the west,
so far has he removed our transgressions from us." Psm103

-So I guess all we have to do is pray, right?
gkam
1 / 5 (5) Nov 10, 2016
"And the cost of silicone material"
--------------------------------

It's SILICON, not silicone.
gkam
1 / 5 (5) Nov 10, 2016
BTW, why the negative views of alternative energy? Have funds invested in nukes? Love coal pollution?

I think perovskites will be used and other technologies as well. Your days of nukes and coal and Big Power are over, now that we can make our own.

And mine is clean. How about yours?
antialias_physorg
5 / 5 (3) Nov 10, 2016
For example, whole the introductory material is cheaper, because the silicon or quartz is one of the most widespread materials at the Earth.

Perovskite is roll-to-roll feasible. Do you have any idea how huge that advantage is when it comes to manufacturing? Obviously not. The shere volume of stuff you can produce with such a process as opposed to serial (even fully robotic) assembly just staggers the mind. And that speed of manufacturing directly translates into cost savings for the manufacturer.
hawkingsbrother
Nov 10, 2016
This comment has been removed by a moderator.
antialias_physorg
4.2 / 5 (5) Nov 10, 2016
Amorphous silicon gets nowhere near 20% efficiency (from what i read they don't even get 14%)

Elon Musk's solar roof tiles utilize roll-to-roll? If not, why not?

Because they have 22-24% efficiency. I.e. they are not amorphous silicon. Duh.
TheGhostofOtto1923
5 / 5 (3) Nov 11, 2016
BTW, why the negative views of alternative energy? Have funds invested in nukes? Love coal pollution?
Perhaps you're misconstruing negative views of lying cheating psychopaths again? Because in your mind who could doubt the obvious wisdom of george kamburoff?
Edenlegaia
5 / 5 (3) Nov 12, 2016
BTW, why the negative views of alternative energy? Have funds invested in nukes? Love coal pollution?


I doubt anyone personally invested in nukes and loves pollution....any kind of it. And i doubt anyone accepts the constant ego level supernova you emit nearly each time it comes to renewables.
So it comes to this: your presence equals 1 stars rating. Damn, you could talk about sushis, the situation wouldn't change.
Gloating about how clean you are with energy and all is....tiring, even if it's good for the Earth. Probably. But are you REALLY clean on how people reacts to you?
snerdguy
1 / 5 (1) Nov 14, 2016
New technologies have to start somewhere. This particular solar cell design may never make into mass production. But, it proves that perovskite solar cells can be made to operate efficiently. A lot more work has to be done to create a cheap and easy to mass produce version and, by that time, it may not even need lithium. There will eventually be a day when solar cells will be a common component in building construction. This is another step in that direction.
EnergySolutions
1 / 5 (1) Nov 14, 2016
Your going to use LEAD and "spray paint" --- THINK AGAIN
gkam
1 / 5 (5) Nov 14, 2016
"Gloating about how clean you are with energy and all is....tiring, even if it's good for the Earth. Probably. But are you REALLY clean on how people reacts to you?"
---------------------------------------

Gloating? I am 72 and cashed in some investments, (which had to be cashed in anyway), and paid for my energy in advance. I did it because it was the right thing to do. It is what I believe in. I am a former utility engineer with a degree in ecoscience.

If you cannot do it, do not criticize those of us who can clean up what we consume.

My point has been that it is now not just possible but practical to make our own power, and use the grid for trading it back and forth. We can be independent if we want, of Big Oil, and the power company if you choose.

Get your ego out of the way and see the future you can have now.
TheGhostofOtto1923
4 / 5 (4) Nov 15, 2016
Gloating? I am 72 and cashed in some investments, (which had to be cashed in anyway)
By cashed in do you mean forced your poor wife to liquidate her bank account and 401k?
and paid for my energy in advance. I did it because it was the right thing to do
-Never 'we'. Theres george and then theres all the poor victims he feeds on including wife and family.

""Do what thou wilt shall be the whole of the Law." -the credo of the psychopath.
It is what I believe in
You believe in george kamburoff and anything you can grab, cheat, and steal to get for him.
I am a former utility engineer
We have confirmed this is a lie.
with a degree in ecoscience
We have confirmed this is also a lie.
If you cannot do it, do not criticize those of us who can clean up what we consume
We criticize serial liars and psychopaths who pretend to be things they arent.
gkam
1 / 5 (5) Nov 15, 2016
Outgrow it. Your hate just betrays your corroded character.

What did it to you? Nasty Mom? Abusive Dad? Kids make fun of you in school?

Is that why you hide from real life, there in internet anonymity? From what, whom, you cower?
TheGhostofOtto1923
4 / 5 (4) Nov 15, 2016
What did it to you? Nasty Mom?
Most married people use the term 'we'. You say 'I' all the time. How come? Is your poor wife just furniture to you?

More inadvertent exposure of the true nature of a lying cheating (and bumbling) psychopath.
gkam
1 / 5 (5) Nov 16, 2016
Those of us who already have PV systems powering our homes and electric automobiles are using them to save up for more of the same.

And we often resent having to drive behind stinking noisy, polluting Diesels and their insensitive owners.
Edenlegaia
3.4 / 5 (5) Nov 16, 2016
And we often resent having to drive behind stinking noisy, polluting Diesels and their insensitive owners.


Probably as much as those "stinking noisy, polluting Diesels owners" resent lesson givers and you may be the reason why some are starting to consider joining the army of those who clearly gives no damn about the environment because fuck it, not because they care little, but because it would annoy the "green saints". Yep, that'd be plain stupid, but it could have been -still can be- avoided. It only requires humility. Humility to recognize NOT EVERYONE is in a situation to "choose". In a situation to "change".
What i criticize is your attitude. You passively criticize every person not being, thinking, heck almost LIVING like you.
You know nothing of other people's lives and the reasons of their "choices" and poke on them because it seems to please you. Often, it's just annoying. Sometimes, it's despicable and serves no purpose.
There you have your answer.
gkam
1 / 5 (6) Nov 16, 2016
Get over your adolescent emotion and get real. I am just showing you it can be done, then defending myself from the anonymous snipers like you. Yeah, I live in a situation made for that decision, and am able to do the projects. It is an example, a demonstration. Outgrow your petty irritation.

Do YOU like driving behind a stinking Diesel? Long before I was able to get an EV, I wanted a law to put the tailpipes of Diesels in front of the cars, so the owners would be the first ones to enjoy what they were doing to others.
gkam
1 / 5 (6) Nov 16, 2016
"Humility to recognize NOT EVERYONE is in a situation to "choose". In a situation to "change"."
--------------------------------------

I made that clear many times. My example was an early adoption of technology in a geographical area conducive to it. As a former utility engineer with a degree in Ecoscience, it was a natural thing to do as soon as we were able. It is not only possible now, but practical.

My strong words are for the ottos and Iras and Stumpys of the forum, who have some kind of personal need to attack and demean. It carries over to the rest of the posts, apparently. Sorry.

Let's get rid of the snipers, and we can have a forum of professionals and grownups.
TheGhostofOtto1923
3.7 / 5 (3) Nov 16, 2016
I made that clear many times. My example was an early adoption of technology in a geographical area conducive to it. As a former utility engineer with a degree in Ecoscience
George. Everybody here knows you lie about being an engineer and you lie about your degree. Who do you think youre kidding? Why do insist on continuing to make an ass out of yourself?
My strong words are for the ottos and Iras and Stumpys of the forum, who have some kind of personal need to attack and demean
Youre a lying cheating psychopath. Strong words are necessary to describe the sort of scum you are.
Uncle Ira
4 / 5 (4) Nov 16, 2016
Let's get rid of the snipers, and we can have a forum of professionals and grownups.
Where you go then Cher? All those other places either cut you off entire or put a restriction on how many goofy postums you can make in the same day.
gkam
1 / 5 (5) Nov 17, 2016
"Goofy postums"?

This is a science site, not a comics comment board.

More efficient PV will change the world. Silly comments will not.
TheGhostofOtto1923
3.7 / 5 (3) Nov 17, 2016
This is a science site, not a comics comment board.

More efficient PV will change the world. Silly comments will not
You mean like claiming to have an MS in 'ecoscience' while not knowing what CFR is? Garbage like that is good for a laugh yes?
https://www.youtu...7hVx0fwE

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