Team creates functional ultrathin solar cells

Team creates functional ultrathin solar cells
Solar-powered unmanned airplane. Credit: Michele Sessolo & Henk J. Bolink, Nature Materials (2015) doi:10.1038/nmat4405

(Phys.org)—A team of researchers with Johannes Kepler University Linz in Austria has developed an ultrathin solar cell for use in lightweight and flexible applications. In their paper published in the journal Nature Materials, the group describes how they created their solar cells and then tested them with miniature aircraft.

For engineers working with , two major goals are increasing the amount of electricity that can be harvested from a single cell, and making cells thinner and lighter while still producing the same amount or even more electricity as thicker cells. In this new effort, the research team has found a way to produce a solar cell that is just three micrometers thick, yet is still 12 percent efficient.

To create thinner cells, scientists have turned to new materials, one of which is organolead halide perovskites. They are direct band semiconductors and thus absorb light more efficiently than other materials. Unfortunately, they are also much more sensitive to environmental conditions, deteriorating when exposed to water, and worse as they do so, they tend to cause problems for metal electrodes. To make solar cells out of such materials requires adding protective coatings, which of course cause the end result to be both thicker and heavier.

To make their ultrathin solar cells, the team used a chromium oxide–chromium interlayer to protect the metal contacts against problems with the perovskite, then applied a clear polymer electrode that had been treated with dimethylsulphoxide. The result was an extremely thin one square meter solar cell that weighed just 5.2 grams and was capable of producing 120 watts of power, which the team notes, is a record for power per weight solar cells.

To test their cells, the researchers attached them to a miniature plane and blimp, and report that the cells work as envisioned. The only problem of course, is that the cells have a short lifespan—they are still at the mercy of both water and oxygen because the coatings do not last very long, just a few days, though under optimal conditions they found that cells could survive for up to several months. Still, that may be long enough for some applications, such as weather balloons, drones, etc. especially those that are able to use other means for protecting them.

More information: Flexible high power-per-weight perovskite solar cells with chromium oxide–metal contacts for improved stability in air, Nature Materials (2015) DOI: 10.1038/nmat4388

Abstract
Photovoltaic technology requires light-absorbing materials that are highly efficient, lightweight, low cost and stable during operation. Organolead halide perovskites constitute a highly promising class of materials, but suffer limited stability under ambient conditions without heavy and costly encapsulation. Here, we report ultrathin (3 μm), highly flexible perovskite solar cells with stabilized 12% efficiency and a power-per-weight as high as 23 W g−1. To facilitate air-stable operation, we introduce a chromium oxide–chromium interlayer that effectively protects the metal top contacts from reactions with the perovskite. The use of a transparent polymer electrode treated with dimethylsulphoxide as the bottom layer allows the deposition—from solution at low temperature—of pinhole-free perovskite films at high yield on arbitrary substrates, including thin plastic foils. These ultra-lightweight solar cells are successfully used to power aviation models. Potential future applications include unmanned aerial vehicles—from airplanes to quadcopters and weather balloons—for environmental and industrial monitoring, rescue and emergency response, and tactical security applications.

Journal information: Nature Materials

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Aug 27, 2015
How will thinner cells effect the useful life span of the panels when there are less electrons (from less material) to be knocked loose? Or is the PV process just a skin effect from the top or top few molecular layers?

Aug 27, 2015
We are witnessing an avalanche of technology to replace Filthy Fuels. The next ten years will be exciting in that field.

It is time we saw integrations of these various new technologies produced as units.

Aug 27, 2015
"We are witnessing an avalanche of technology to replace Filthy Fuels. "

While I share your excitementabout renewables it's really pointless (and pretty annoying) that you keep posting content-less stuff like the above sentence (moreso for articles like this one which has absolutely no relevance to replacing fossil fuels because of the degradation issue of these cells)

Aug 27, 2015
Sorry you do not like it. Tough.

What do you want, me to bring up all the possible failure points, like Eikka? We are really glad you have him in Europe, and not here.

A study done a decade or so ago by the Institute for the Future for EDF identified PV building materials as one of the technologies most likely to make a difference in building energy use. We are now starting to achieve it. Shall I pen paragraphs of verbiage for you?

Aug 27, 2015
"""""""Shall I pen paragraphs of verbiage for you?""""""

Non Cher please do not do that. Your bumper sticker slogans are silly enough. Whole paragraphs of it would take up too much spaces from the people who actually understand this kind of stuffs.


Aug 27, 2015
"Your bumper sticker slogans are silly enough."
---------------------------------

I tried complete sentences paragraphs, logic and fact, and you did not like it. You kept taking things out of context and misrepresenting what others said.

I see significant opportunity in these developments. How about you?

Aug 27, 2015
Meanwhile, I had a serious question at the beginning of this thread... Thanks,

Aug 27, 2015
""""""""I tried complete sentences paragraphs, logic and fact, and you did not like it."""""""""

No you didn't. From your very first postum it was slogans and snide remarking. You really do not believe that all the postums you ever wrote are still there to be looked at?

""""""""I see significant opportunity in these developments. How about you?"""""""

Yeah, me too. That's how it all works ever since the first Skippy fell out of his tree and learned to start a fire with two sticks.

Aug 27, 2015
Gkam no one in their right mind is against COST/ENERGY effective renewable energy. That being said, poorly thought out or implemented schemes that only benefit the politically connected need to be discouraged. It is great to use taxpayer dollars for renewable research but it is a crime to line the pockets of politically connected corporations advocating unrealistic solutions to our energy needs. Until there is a solution to the intermittent nature of renewables their implementation is not really economically advantageous.

Aug 27, 2015
@SteveL

for many thin film PV technologies, all of the photon adsorption takes place within a few microns. Electrons don't have far to travel, though there are many charge traps and recombination sites along the way, especially when comparing lab made vs. production made modules. Hope that answers your question.

Aug 27, 2015
@SteveL

Please forgive me if I misinterpreted your question. Electrons aren't used up in a PV cell. An analogy might be a roller-coaster. The light releases the electrons (roller-coaster car) and the PN junction pushes them up the first big hill, giving the electrons energy. The circuit is the rest of the ride. At the end of the circuit, the electrons coast back into PV cell with much of the energy used (roller-coaster car enters the station ready to be released and lifted up the hill again).

Aug 27, 2015
Then, when PV panels "wear out" (80-85% capacity after 20 years or so), it's not from electron loss?

Aug 27, 2015
@SteveL

Then, when PV panels "wear out" (80-85% capacity after 20 years or so), it's not from electron loss?


Not quite, more like the material can't generate the same number of useful electrons. It's from various factors such as increased series resistance (degradation of contacts between the top and bottom of the cell), Increased number of defects which increases the number of charge traps and recombination sites, Decreased shunt resistance (the electrical isolation between the top and bottom contacts through the PV material degrades and there are path ways that allow localized shorting). The materials that make up the photo-electric portion of the PV cell often react badly with moisture. Moisture can migrate through the edge seal and especially through plastics. High energy photons (deep-uv, x-ray+) can cause crystal damage (charge traps, recombination sites).

Aug 27, 2015
"What do you want, me to bring up all the possible failure points, like Eikka? We are really glad you have him in Europe, and not here."

What I would want is for people (on all sides) to stick to discussing the articles and not start spouting unrelated propaganda bits every time a word appears that is also mentioned somewhere in their respective agendas (that goes fo 'nuclear' Eikka, as well as the cold-fusion and electric universe guy as well as you).

I know I don't set the policy here (although my wish does reflect the official policy set forth by physorg...which no one seems to care about).

I simply find it vexing that there are people on the 'good side' of issues who feel the need, despite being well supported by facts and evidence, to use methods that are populistic (and scientifically pointless)

Aug 27, 2015
"What do you want, me to bring up all the possible failure points, like Eikka? "


If you have nothing to say, don't say it.

"that goes fo 'nuclear' Eikka"


I usually only reply to nuclear power topics when I find gkam repeating his lies and propaganda, or when disputing your commentary which usually follows along similiar lines of simply repeating age-old myths and FUD.

Aug 27, 2015
-"I simply find it vexing that there are people on the 'good side' of issues who feel the need, despite being well supported by facts and evidence, to use methods that are populistic (and scientifically pointless)"


That is usually because they either don't have the facts and evidence, or the facts and evidence don't actually exist, or their cause isn't as pure as everyone believes.

Being on the "right team" doesn't mean you aren't a self-serving asshole, or someone who's trying to be "more Muslim than Muhammad" for whatever private reasons. Many people pretend to be saints to cover up their sins, or just like to follow the mob because it makes them feel powerful and righteous, or accepted and respected -- they care very little about what it's all about as long as they get a pat on the back for joining the cause and shouting the right things.


Aug 27, 2015
Not quite, more like the material can't generate the same number of useful electrons. It's from various factors such as increased series resistance (degradation of contacts between the top and bottom of the cell), Increased number of defects which increases the number of charge traps and recombination sites, Decreased shunt resistance (the electrical isolation between the top and bottom contacts through the PV material degrades and there are path ways that allow localized shorting). The materials that make up the photo-electric portion of the PV cell often react badly with moisture. Moisture can migrate through the edge seal and especially through plastics. High energy photons (deep-uv, x-ray+) can cause crystal damage (charge traps, recombination sites).

@Prok,
That was a "most excellent" explanation of potential PV system degradation...:-)

Aug 27, 2015
-"How will thinner cells effect the useful life span of the panels when there are less electrons (from less material) to be knocked loose? Or is the PV process just a skin effect from the top or top few molecular layers?"


The cell is like a sandwich which usually has a conductive metallic layer underneath, and a conductive glass/polymer layer on top, and the active material in between where the charge separation happens towards the conductive layers. If the current is not carried away through an external circuit, the charges recombine within the cell by dielectric leakage.

Since the cell area and incoming photons don't change with cell thickness, the current density doesn't really increase and there shouldn't be any significant electromigratory wear effects as far as I understand.

Aug 27, 2015
-"Then, when PV panels "wear out" (80-85% capacity after 20 years or so), it's not from electron loss?"


The simple explaination is that the PV cell is a diode. It's two dissimiliar materials that allow electrons to move one way but not the other way. The photon bumps the electron across the diode and it gets stuck there until you let it back to the other side via the external circuit.

Diodes wear out by diffusion, because the two dissimiliar materials slowly mix into one another at the boundary and the difference becomes muddled. The diode becomes less of a diode and more just a conducting piece of material that lets electrons move in either direction.

In solar panels this happens by heat, by radiation (UV), by electrons bumping into atoms and moving them around (electromigration), by chemical reactions (oxidation/corrosion) etc.

Aug 27, 2015
And it creates little heat and no smoke, nor does it use great volumes of cooling water to produce power.

Aug 27, 2015
gkam: http://www.buddha...wise.htm

Should one a man of wisdom meet
who points out faults and gives reproof,
who lays a hidden treasure bare,
with such a sage should one consort.
Consorting so is one enriched
and never in decline.

Let him exhort, let him instruct,
and check one from abasement.
Dear indeed is he to the true,
not dear is he to the false.

Basically, if you only look to the positive and ignore the negative, then you find yourself following false leads and never learning from anything because you always refuse to aknowledge where you were wrong.

People with massive egos can't handle the negative because they take everything so personally; how does this reflect on me, how does this make me look. The prospect of being wrong becomes physically painful because it's experienced through shame, which is why the egoist can't give a toss about the truth.

The false just want to avoid the pain of being found out. The true have no pain.

Aug 27, 2015
Look up the meaning of sophomore.

I understand the negative. We had to overcome it every day, whether in plastic molding, or wire and cable, or power production or casting metal, or making integrated circuits. Or when putting together a new military group with a mission never done before, making it work, deploying it and operating it for a year. When you get out of school and get a job, you'll have to do it, too.

The negatives find you. I didn't have to ask some smart-alec in Europe. And you had better be ready with some positive actions.

Aug 27, 2015
"Look up the meaning of sophomore."


It's a second-year student in a US college. What of it?

-"The negatives find you. And you had better be ready with some positive actions."


Pointing out the negative is a positive action, because it is wiser to find out about problems beforehand rather than blindly bumping into them. "A clever person solves a problem. A wise person avoids it." -Albert Einstein

-"I didn't have to ask some smart-alec in Europe."


Again with the ad-hominems. What do you think you're achieving with personal insults against a person you know nothing of? What do you have against Europeans? What do you even know of Europeans?

Aug 27, 2015
I don't want to waste my time trading insults with you.

Aug 27, 2015
I don't want to waste my time trading insults with you.

Yep, we know you'd rather waste it on your incessant lies.

Aug 28, 2015
"I usually only reply to nuclear power topics when I find gkam repeating his lies and propaganda,"

In the end it doesn't matter. Anyone who pushes an agenda instead of arguing goes on ignore. gkam is just the first one I actually agree with who is added to that list.

Aug 28, 2015
-"I don't want to waste my time trading insults with you."


A glimpse of wisdom at last.

-"Anyone who pushes an agenda instead of arguing goes on ignore."


The ignore function is a bit futile, because it doesn't make the other person actually go away. It's just hiding your own head in the sand.

-"In the end it doesn't matter."


If you don't challenge lies and false authority, other people will start following it and then you're in worse trouble because the cranks and shills multiply.

"The only thing necessary for the triumph of evil is for good men to do nothing." - Edmund Burke

Aug 28, 2015
"The ignore function is a bit futile, because it doesn't make the other person actually go away. "

Arguing (using facts) with someone who pushes an agenda instead of being interested in the articles does not make them go away, either. Why would you think that if they ignore the content of an article they won't ignore the content of a comment posting when it comes to their agenda?

"If you don't challenge lies and false authority, other people will start following it"

There's more ways than one to fight crankery and propaganda.
People who 'follow' anything (be it a false authority OR a true one) are already lost in any case. If you want to promote something - that you can argue is true - then set forth arguments and let people make up ther own minds.

The agenda pushers have no coherent arguments as they always run into a conflict between belief and reality.


Aug 28, 2015
-"Arguing (using facts) with someone who pushes an agenda instead of being interested in the articles does not make them go away"


You miss the point. It defuses their propaganda for others.

-"People who 'follow' anything (be it a false authority OR a true one) are already lost in any case."


Indoctrination is exposure and repetition. If you have no-one to contradict the person who is telling lies, then how can the audience believe otherwise?

-"The agenda pushers have no coherent arguments as they always run into a conflict between belief and reality."


They need no arguments when they have nobody to argue with. That's the point of propaganda: you simply make the assertion and skip the debate. If propaganda is not countered with real information with equal intensity, it becomes effective.


Aug 28, 2015
-"There's more ways than one to fight crankery and propaganda."


And all of them should be employed. One simply does what they are reasonably able to.

Yours is a defeatist attitude that hopes the cranks wouldn't do any harm if you just ignore them and don't engange them.

Engaging with cranks also serves a secondary purpose of training yourself in logic and rhetoric against unreasonable and dishonest opponents, so that when you really find the need to shoot down some bullshit in national politics for example, you're already armed with the tools to identify it, expose it and turn it around.


Aug 28, 2015
"You miss the point. It defuses their propaganda for others. "

As I said: if someone falls for propaganda then they are not thinking for themselves. They're already lost (and from the point of view of any kind of fruitful discussion irrelevant). If they can think for themselves they don't need propaganda defused.

"then how can the audience believe otherwise?"

By actually trying to understand instead of regurgitating.

"They need no arguments when they have nobody to argue with. "

That's the point I'm making: You may think you're arguing with them - but they aren't arguing with you. They're just using your posts as a hook to keep replying/repeating their agenda points. You're playing right into their hands. They are trolls - and trolls love to be fed.

Aug 28, 2015
-"If they can think for themselves they don't need propaganda defused."


That's basically blaming the victims of propaganda for believing it. You're making the assumption that everyone is just able to conjure up right information merely by thinking about it.

"By actually trying to understand instead of regurgitating."


We all have to trust some authorities. The point becomes how and which authorities to choose, and which information to trust. It's not reasonable to assume that we are all automatically rational, or even that you yourself are.

-"They're just using your posts as a hook to keep replying/repeating their agenda points."


With no effect, because the points are already defused for all to see so further repetition of the same in the same place is futile and they're only wasting their time.

Aug 28, 2015
-"They are trolls - and trolls love to be fed."


There's a difference between a shill and a troll. The troll does it to get personal attention, while the shill does it for other profit, so the shill moves on when they encounter resistance. The troll is essentially harmless because they eventually make themselves too ridiculous and mostly just get banned for spamming.

-"if someone falls for propaganda then they are not thinking for themselves."


And if someone falls in an open manhole, they weren't looking in front of them. Does that mean we shouldn't at least put up a warning sign next to it?

Aug 28, 2015
-"They're already lost (and from the point of view of any kind of fruitful discussion irrelevant)."


Also, you're making an unsubstantiated claim there: that anyone who believes in propaganda even for a fleeting moment is "lost" and irrelevant. If nobody tells them otherwise, how can they ever change their beliefs?

For example, when gkam goes around telling people that renewable energy costs less than 3 cents, that is in fact true and backed up - but it's not the whole truth. A person seeing it would get a false impression of reality, and they have no reason to correct this false impression because they don't have the external viewpoint of a person who knows that there is more to the truth than that - such as subsidies paid that don't appear in the supply contract price.

In other words, we don't know how much we don't know, and we usually don't bother to check, which is why we fall for propaganda. That however doesn't mean we are stuck with the false notions.


Aug 28, 2015
Prokaryote and Eikka; thank you for your topical explanations and contributions.

I also agree that misinformation must be countered with facts, no matter how unseemly. Facts are rarely pretty and shiny, and often don't make you feel good because truth requires us to grow and change is usually difficult. I just hope that countering misinformation doesn't denigrate to personal insults. And I just wish that countering wouldn't consume +90% of a topic thread. I believe every single one of us has an agenda, whether we wish to recognize that or not, and I believe that is one of the reasons intelligence does not equate to wisdom. Agendas gets in the way.

Aug 28, 2015
Steve, wait until Ira or otto or denglish or 166 get offended by your corrections. They squander almost all of their posts on personal insults.

We can do better. Their insults keep more serious people out of here.

This topic is PV,and how it is changing the very fabric of our generation and distribution systems. When we have broad-based energy harvesting, we will not need concentrated power systems.

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