Crystal arrangement results in more power from ferroelectric solar cells

https://www.pv-magazine.com/2021/08/04/crystal-arrangement-results-in-1000x-more-power-from-ferroelectric-solar-cells/

by vinnyglennon • 5 years ago

264 80 5 years ago

pv-magazine.com

NiceWayToDoIT5• 5 years ago

What is:

Power output per m2?

Durability (life span)?

Production cost?

At least theoretical ...

AndrewDucker• 5 years ago

The article tells you the answer to your question. Search for "1,000".

Edit: Apologies, I misread the parent's question. I thought they were saying "1,000 what?". Sorry about the unhelpful answer.

qayxc2• 5 years ago

No it doesn't. The 1000x factor refers to the photo-response of the material, not power output, not cost to produce, not durability.

All these are properties of a (prototype-)product, while this research is basic research and didn't create any prototypes. The researchers measured the photo-response by shining laser light onto a sample, they didn't build a panel and measured the power output.

boboche• 5 years ago

Not 1000x net output since we are in what now, 10-20% efficiency with current available cell technology? That would not make sense.

qayxc2• 5 years ago

Non of that can be answered just yet. This is basic research in its earliest stages.

It can't even be answered theoretically, because the researchers are in the process of developing the theory that could answer these questions.

So far they only made an observation and need to go on from there.

thehappypm• 5 years ago

This type of cheeky criticism is probably fair when you have a startup claiming crazy numbers with no prototype, but this is reporting on a paper from a research institution. No need for snark.

NiceWayToDoIT5• 5 years ago

criticism, snark ?!

What are you talking about?! All I am trying to get some numbers, if anyone has them, but it seems amount of unhelpful comments begins to be overwhelming on HN.

dylan6046• 5 years ago

For the rest of us that read no snark, please enlighten us into what words/phrasing led to your reading of snark in the parent's post. Curious minds would like to know answers to the actual questions posed by the parent, but also to what sensitivities are being upset by asking those questions.

nine_k4• 5 years ago

They don't cite power output, but cite current output: 17 mA / cm² under full sun, pretty impressive if you ask me.

The key promise of this approach is "more efficient that silicon can even theoretically be". Overcoming the Shockley limit is the key finding.

NiceWayToDoIT5• 5 years ago

Thank you, is there any way we could find out what is probable life span, is it more durable (hailing/dust/corrosion) or less than silicon crystal? From time to time it would be nice if we had AMA on HN like on Reddit for the research team.

Also mA does not says much if we do not have voltage, and I am not sure what full sun means as in Africa full sun can mean 4.5 and 6.5kWh per m2 while in Europe we can get between 1 and 2.5kWh per m2 or radiation.

jbrot• 5 years ago

From the underlying paper[1], I found this excerpt:

“The photocurrent or the short-circuit current density (JSC) extracted from BTO is around 0.415 μA/cm2. … The JSC value from SBC555 is around 11.03 μA/cm2 and is about 25 times higher than measured in BTO. The open-circuit voltage (VOC) in the case of BTO was found to be around −0.007 V, as opposed to −0.058 V in SBC555.”

Here, BTO is the existing material and SBC555 is the new material from the paper. Multiplying JSC by VOC to get power density , we see that BTO yields 2.9 nW/cm^2, while SBC555 yields 639.74 nW/cm^2.

For reference, according to [2], we have that “typical external parameters of a crystalline silicon solar cell as shown are; Jsc ≈ 35 mA/cm2, Voc up to 0.65 V.” Notice the unit difference of mA/cm^2 here vs uA/cm^2 above. Multiplying these parameters yields 22,750,000 nW/cm^2. So we see that these cells are still approximately 100,000x worse at producing power than the current crystalline silicon cells.

[1] https://advances.sciencemag.org/content/7/23/eabe4206

[2] https://ocw.tudelft.nl/wp-content/uploads/solar_energy_secti...

NiceWayToDoIT5• 5 years ago

Thank you sir!

rikkipitt2• 5 years ago

Reminds me of my masters research at university. My work was based on hybrid organic-inorganic solar devices based on boron subphthalocyanine chloride and an optimised optical spacer layer. One day, one variation of the type of cell I was producing was over double the output efficiency of what we usually expected. Was exciting until we realised the solar testing rig had been erroneously set to the equivalent output of two suns...

atonse• 5 years ago

One day… two suns. Talk about playing God. :-)

That sounds like fascinating research.

dylan6046• 5 years ago

I mean, do we really need Jupiter as is? Everything Jupiter has done for us with clearing out the trash from the solar system would have been done by a 2nd smaller sun as well.

ehsankia2• 5 years ago

There's something hilarious in adding a sun so you can improve the efficiency of your solar panels, so that you can switch to renewable energy and offset warming caused by your current single sun (and polution).

renrutal• 5 years ago

set to the equivalent output of two suns...

I didn't realize we have achieved a Kardashev Type II civilization already :)

nine_k4• 5 years ago

Achieving the effect locally for a few milliseconds has been possible for like 70 years now.

Damn hard to get a license for that nowadays, though, no matter how important your science is.

rikkipitt2• 5 years ago

Haha, very good.

In fact, we had some equipment similar to that on this site https://solarlight.com/product_category/products/solar-simul...

Basically a super bright light source with a similar spectral output to our sun. A roughly 1x1cm solar cell in a nitrogen filled chamber is wired up to check the output under the incident light. Very cool production process. I was extremely lucky to have had the opportunity to help with the research.

JoeAltmaier• 5 years ago

I thought solar conversion efficiency was a large fraction already. There's no room for 1000x improvement. Maybe 20%. What is this title talking about?

binarymax2• 5 years ago

A similar question was in the comments of the article and reply from the Author:

---

Ralph A Hutton August 6, 2021 at 1:40 am

1000 times? That means a normal size panel ,area about one square meter, that produces 200 watts , would be capable of an output of 200 kW. I look forward to that. I believe, and this needs confirming, the maximum available power from one square meter is about one kW. What have I misunderstood? Reply

---

    Ryan Kennedy
    August 6, 2021 at 1:46 am

    Our apologies for not making this clear. The photovoltaic effect was increased by 1000 times compared to previous output achieved from cells made of ferroelectric crystals, not from prevailing solar cells made of silicon or other conventional materials.**

throwaway4220• 5 years ago

Can we change title to reflect this?

czbond• 5 years ago

Can someone explain this to me like I'm 5 for me?

VMG• 5 years ago

just look for the qualifier

in this case "ferroelectric"

wlesieutre• 5 years ago

I think the confusion people are having with "Crystal arrangement results in 1,000x more power from ferroelectric solar cells" is that it doesn't have a qualifier like "more power than current ferroelectric solar cells." It only tells you what type the new ones are.

You have to infer that it's comparing new ferroelectric cells to old ferroelectric cells, and not comparing new ferroelectric cells to our typical silicon cells.

But an article doing the latter could be written with exactly the same title.

minitoar• 5 years ago

The article says “the current flow was up to 1,000 times stronger”. I don’t know what that means.

dharmab• 5 years ago

These are ferroelectric, rather than the more efficient silicon cells used for most solar energy.

binarymax2• 5 years ago

So, without a p-n junction, then we can break the Shockley–Queisser limit. Which states that in traditional photovoltaic cells you'll never get past 1/3rd efficiency. And until now I didn't even know that ferroelectric absorbers were a thing. Pretty amazing! https://www.nature.com/articles/nphoton.2016.143

k__2• 5 years ago

For those like me, who didn't get this at first.

It's about improving output from ferroelectric solar cells, a specific type of solar cells, which are easier to build than regular ones made of silicon. But they usually aren't as effective as the silicon ones.

leecarraher• 5 years ago

yup, my thoughts exactly. otherwise a 1000x increase in 30%-ish efficient pv silicon-based solar cells would be far above unity

nine_k4• 5 years ago

Depends on how you count.

If your process is 30% efficient, it wastes 70% of input. If you increase efficiency 1000x, it wastes 70% / 1000 = 0.007% of input, so it's 99.993% efficient.

nine_k4• 5 years ago

I'm not certain about the "easier" part, but with efficiency higher than a semiconductor cell can ever be, this device should draw attention, no matter how hard is it to produce currently.

k__2• 5 years ago

Ah, good to know.

Yes, easier might be not right here, but it sounded like overall they are less complex.

smolder• 5 years ago

Reading the article and the comments... No, these are not more efficient than silicon cells. They took an inefficient, simpler to produce PV material and found a way to dramatically increase its efficiency on certain wavelengths of light. It's still worse than silicon panels overall.

wishawa2• 5 years ago

I did a quick Google for the Power Conversion Efficiency of Barium Titanate based solar cells and they are currently mostly in single-digit percentages [1]. A thousandfold increase would be over 1000%. Unless I'm missing something important, they probably mean 1000x over a super basic BaTiO3 system, not 1000x over the current state of the art.

[1] For example, this 5.13% PCE from "hierarchical barium titanate micro flowers": https://iopscience.iop.org/article/10.1088/2053-1591/aace86

ghastmaster• 5 years ago

From the comments section of the article:

Our apologies for not making this clear. The photovoltaic effect was increased by 1000 times compared to previous output achieved from cells made of ferroelectric crystals, not from prevailing solar cells made of silicon or other conventional materials.

phkahler• 5 years ago

In other words they made something work that really didn't before.

Even if they made the best theoretically possible solar cell, the starting point of 1/1000th of that would not have been considered useful for anything.

VygmraMGVl• 5 years ago

To get the 1000x figure, the research is comparing photocurrents from bulk BTO and their special crystal-aligned BTO at a specific wavelength of incident light (306nm).

They also compare photocurrents under a solar simulator and achieve 100x increase vs bulk BTO.

At no point do they make comparison to state of the art BTO cells, which almost certainly aren't just bulk BTO but are likely doped, nanostructured, or have some other novelty.

wishawa2• 5 years ago

That is true. The research is good. But the headline, the article itself, and especially this comment by the author

Our apologies for not making this clear. The photovoltaic effect was increased by 1000 times compared to previous output achieved from cells made of ferroelectric crystals, not from prevailing solar cells made of silicon or other conventional materials.

misleadingly make it seem like they made 1000x progress from the current best.

kilroy123• 5 years ago

The other day, I watched this documentary on a huge off-shore wind project off the coast of the UK. It uses some of the largest windmills ever created.

This project has a mind-boggling amount of complexities and involved a special large ship, one of the only kinds of its type, to move things around—very impressive project.

It made me realize just how revolutionary solar is. Also, why it can compete and be so cheap compared to other forms of energy production.

You just put this almost magical thing on your roof, and it silently creates green renewable energy for decades. Power plants can be complex and expensive buildings. Solar is just stupidly simply.

jvanderbot• 5 years ago

I was told that an offshore oil exploration drilling operation costs as much as the most recent Mars rover mission ever will. When it comes to keeping the world moving, there's room for ungodly amounts of complexity.

Solar cell installation is pretty easy, but there is some non-negligible complexity in producing them.

LeifCarrotson• 5 years ago

The 1000x efficiency headline is from Figure 4 of the source PDF:

https://advances.sciencemag.org/content/advances/7/23/eabe42...

Units are Amps per miliwatt on the Y axis and electron volts on the X axis. The black BTO line has a minimum of around 1x10^-10 at 2.8 eV, which is the energy of a photon in 450 nm blue light, and the red SBC222 line has a minimum of around 1x10^-7. Yes, the difference between 10^-10 and 10^-7 is 1000x; good job, headline! But no, that's not the key takeaway from the article.

Solar cells have an efficiency curve based on their bandgap and the energy in the incident light. It's theoretically a straight line, and regular silicon cells get pretty close to it, see the figure here:

https://www.pveducation.org/pvcdrom/solar-cell-operation/spe...

Note the units in A/W, not A/mW, also, the research is at a temperature of 77k, the boiling point of liquid nitrogen, while the above plot is close to room temperature. At 450 nm = 2.a silicon cell produces about 0.35 x 10^-3 A/mW, which represents an efficiency of something like 30% in the real world.

This research and that figure 4 plot fundamentally show that conventional barium titanate = BaTiO3 = BTO, produces very little energy from 450 nm light. The researchers fixed this problem with a multilayer cell using strontium titanate, SrTiO3, or STO, then BTO, then calcium titanate, CaTiO3 or CTO, in an STO_2/BTO_2/CTO_2 crystal lattice stack. That's the breakthrough result; they were able to bridge this gap in energy output and take in more wavelengths of visible light.

The actual efficiency of the starting point was about a million times worse than a good silicon cell. There's plenty of room for improvement when you start that low! The end result is still on the order of a thousand times worse than a silicon cell. A production dye-sensitized solar cell today reaches about 10% efficiency, a monocrystaline silicon cell gets about 22%, but the DSSC has potential to be much cheaper to produce, can be flexible, and is not as well understood. This research may help to close that efficiency gap.

MichaelZuo• 5 years ago

A 1000x improvement on a baseline 1000000x worse makes sense. I was wondering for a bit how a PV cell could break conservation of energy. The article has quite a clickbait title.

tomcam• 5 years ago

That explanation was a tour de force. Thank you. You’ve done your good deed for the day!

wiz21c• 5 years ago

I absolutely don't understand all the physics but are "barium titanate" and "strontium titanate" rare stuff ?

tedsanders• 5 years ago

No. Depends on your definition of rare, of course. You can see prices for various formulations and purities if you Google. Strontium titanate is used for jewelry, as it was one of the main diamond simulants back before cubic zirconia. I did my PhD working with crystals of strontium titanate and contributed to two Wikipedia articles on it.

Looking at the elemental abundances you can see that titanium and strontium are fairly high, above both gallium and arsenic, another solar cell pair. Barium is in the ballpark of gallium and arsenic.

https://en.m.wikipedia.org/wiki/Abundance_of_the_chemical_el...

jacquesm• 5 years ago

Any multi junction cells do considerably better than that 22%:

https://en.wikipedia.org/wiki/Multi-junction_solar_cell

Teknoman117• 5 years ago

I wonder what the difference in energy demands for producing them are.

AtlasBarfed• 5 years ago

I do see that a ferroelectric perovskite can do 22%. Maybe this could be the outer protective layer for the perovskite cell. Isn't the main perovskit engineering issue the degradation when exposed to the atmosphere?

Ferroelectric seem to do other interesting thing, like harvest from ultraviolet, and exhibit some "bulk effects" that exceed "theoretical" maximums, but obviously none of that has been found to make a usable commercial cell.

I hope PV research is still being aggressively funded. It seems to me that solar cell costs could be dropped another 50-75% under silicon with the right combination of perovskite and other materials.

The future of our climate hinges on it.

vmception• 5 years ago

Is 1000x from current efficiency good enough?

nick238• 5 years ago

Better title: "Extremely awful solar cell technology improved to be just really bad"

Crystal arrangement results in more power from ferroelectric solar cells

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