Insect eyes inspire new solar cell design from Stanford
Packing tiny solar cells together, like micro-lenses in the compound eye of an insect, could pave the way to a new generation of advanced photovoltaics, say Stanford University scientists.
In a new study, the Stanford team used the insect-inspired design to protect a fragile photovoltaic material called perovskite from deteriorating when exposed to heat, moisture or mechanical stress. The resultsare published in the journal Energy & Environmental Science (E&ES).
“Perovskites are promising, low-cost materials that convert sunlight to electricity as efficiently as conventional solar cells made of silicon,” said Reinhold Dauskardt, a professor of materials science and engineering and senior author of the study. “The problem is that perovskites are extremely unstable and mechanically fragile. They would barely survive the manufacturing process, let alone be durable long-term in the environment.”
Most solar devices, like rooftop panels, use a flat, or planar, design. But that approach doesn’t work well with perovskite solar cells.
“Perovskites are the most fragile materials ever tested in the history of our lab,” said graduate student Nicholas Rolston, a co-lead author of the E&ES study. “This fragility is related to the brittle, salt-like crystal structure of perovskite, which has mechanical properties similar to table salt.”
Eye of the fly
To address the durability challenge, the Stanford team turned to nature.
“We were inspired by the compound eye of the fly, which consists of hundreds of tiny segmented eyes,” Dauskardt explained. “It has a beautiful honeycomb shape with built-in redundancy: If you lose one segment, hundreds of others will operate. Each segment is very fragile, but it’s shielded by a scaffold wall around it.”
Using the compound eye as a model, the researchers created a compound solar cell consisting of a vast honeycomb of perovskite microcells, each encapsulated in a hexagon-shaped scaffold just 0.02 inches (500 microns) wide.
“The scaffold is made of an inexpensive epoxy resin widely used in the microelectronics industry,” Rolston said. “It’s resilient to mechanical stresses and thus far more resistant to fracture.”
Tests conducted during the study revealed that the scaffolding had little effect on the perovskite’s ability to convert light into electricity.
“We got nearly the same power-conversion efficiencies out of each little perovskite cell that we would get from a planar solar cell,” Dauskardt said. “So we achieved a huge increase in fracture resistance with no penalty for efficiency.”
Durability
But could the new device withstand the kind of heat and humidity that conventional rooftop solar panels endure?
To find out, the researchers exposed encapsulated perovskite cells to temperatures of 185 degrees Fahrenheit (85 degrees Celsius) and 85 percent relative humidity for six weeks. Despite these extreme conditions, the cells continued to generate electricity at relatively high rates of efficiency.
Dauskardt and his colleagues have filed a provisional patent for the new technology. To improve efficiency, they are studying new ways to scatter light from the scaffold into the perovskite core of each cell.
“We are very excited about these results,” he said. “It’s a new way of thinking about designing solar cells. These scaffold cells also look really cool, so there are some interesting aesthetic possibilities for real-world applications.”
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It shows you, Bugs know Best. They just need to make it work after sundown like bugs eyes.
turn a porch light on. then it will work………
Is the cost of silicon a major problem of solar generation?
No.
Could, may possibly, perhaps, forecasting, modeling, if, yeah, yeah, yeah, we got it. need more money to save the world.
No. Next!
It seems from the above construction model, the scaffolding reduces the area that can generate electricity, by around 30%, bringing down the planar efficiency to 14%. The image of the actual deposed surface indicates 30% scaffolding may not be met.
“Actually, that’s exactly how fundamental changes take place—through disruptive technologies. ”
Do you mean something like making electricity with steam turbines burning coal? Or were you thinking of converting mass to energy by fission uranium?
Change has already happened. Now some of those freed from the slavery of muscle power worry that the sky is falling because they have no experience providing for there own needs.
The sky is not falling. The power industry is not having a problem producing the finite amount of power that society needs.
Millions of years of “experiments” confirm they work.
Which is not to say they can somehow power civilization, but we are all dreamers.
Here is another problem with this study. Solar cost divides into two parts. The panels (as here) and Balance of System (BOS, mounting brackets, Dc/Ac, cleaning, and such). For utility PV solar, BOS is already more than half. BOS does not scale with panel cost/volume. Is immune to lower cost PV such as speculated here.
Hey, solar haters, get a grip. Technological improvements are awesome. Period. Just because grid-scale photovoltaics doesn’t make much economic sense yet without reliable backup doesn’t mean that will always be the case or that PV power is bad. PV panels are becoming increasingly popular on homes to offset daytime electricity costs, especially when running power-hungry air conditioners. And regardless of how you feel about CO2 emissions, fossil fuels still produce real pollution that can be mitigated by using solar PV. Technology is awesome. Stop being sourpusses.
Residential installations are becoming popular because tax credits and other subsidies make them attractive. No solar installation at any scale can stand on its own economically, though. At best, they just barely break even by the time the panels are in need of replacement (about 20 years).
There are a lot of deceptive claims being made out there because the true cost is obscured. The reality is that we all are paying for very expensive solar electricity generation, just so that those on the receiving end can ignorantly crow about the “cheap” energy they are receiving. It’s all an illusion.
Mike, stop hating solar. Technological improvements are awesome. PV panels are used all over the place from solar-powered watches and calculators to satellites, the International Space Station, Mars rovers, and lots of other applications. Most of those applications aren’t subsidized and solar is highly practical for their power-generation needs. They stand on their own economically. Sure subsidies have accelerated the adoption of household PV panels, but it will happen anyway because the costs continue to drop as—guess what?—technology improves. I’m planning eventually to install PV panels with battery backup to reduce reliance on the grid and not need to store gallons and gallons of fuel for a backup generator. I live where the sun shines most days and batteries can handle the rest at night and then some. Stop grousing about solar and be happy. It’s a great technology for a lot of applications.
Stinker, you are the first one who ever suggested – albeit indirectly – that Mars rovers might have been connected to the grid. Solar has its place, but I hate paying a premium to PG&E because of “cheap” solar. How come you don’t have solar yet? Our host Anthony does, and you can read his report – including how subsidies influenced his decision.
Hey, pointing out that solar only exists because of massive subsidies, don’t work, and do nothing to “help” the climate is no reason to hate skeptics.
Solar still produces real pollution.
I have absolutely ZERO objection to those who purchase solar if it competes on an equally footing, unsubsidized.
It’s not PV, but when it comes to solar conversion, it’s hard to beat a leaf.
Solar conversion efficiency of a leaf is about 10%, modern panels are over 20%. But they have to be manufactured and maintained, they don’t grow by themselves.
“Delicate”, “fragile”, “expensive”‘, and “relatively high output “.
Run, don’t walk from this.
Guys, you should learn to read scientific reports:
> But could the new device withstand the kind of heat and humidity that conventional rooftop solar panels endure?
> To find out, the researchers exposed encapsulated perovskite cells to temperatures of 185 degrees Fahrenheit (85 degrees Celsius) and 85 percent relative humidity for six weeks. Despite these extreme conditions, the cells continued to generate electricity at relatively high rates of efficiency.
Have you ever heard that it is the temperature and humidity that degrade the efficiency of PV? Or is it actually UV on the issue of which the report is curiously silent?
miso
‘ I live where the sun shines most days and batteries can handle the rest at night and then some. Stop grousing about solar and be happy. It’s a great technology for a lot of applications.’
Well, who’s a lucky boy then ! For those of us who live in less advantageous situations (the UK for example ) when the green blob has driven conventional energy sources into the ground we face long dark cold winters where PV or wind will never provide the levels of energy required to survive, especially when our idiot politicians fulfil their desire of removing gas as an alternative supply of domestic energy. Still, never mind, you can watch from your nice sunny position and watch us descend into pre-medieval existence.
I kind of hate to be so cynical, but this is a solution in search of a problem, it seems.
Contrast…
• Silicon solar cells: Less than $0.35 a watt “naked”, from China. 18% to 22% efficiency
• Perovskite solar cells: killed by humidity, vibration, still in the labs. 12% to 28% efficiency
LAST I heard, it was (and is) not the efficiency of solar cells that is making their case less-than-economical. Its cost. And anything that’s still “in the labs” and requires nano-patterned crazy-sensitive (but ‘otherwise attractive’) materials, compared to bog-standard, bulk-manufactured, 35¢ a watt silicon, is just kind of crazy.
But remember, all those Solar Research Institutes at every last progressive leaning College or University need to keep applying for grant-money to do underwater basket weaving research, even tho the NAPKIN MATH doesn’t actually work out. Because pure research is a noble endeavor for scientists, even if the results are basically predictable, and the possibilities of a “revolution” rather blindingly slight.
As it is said, “you never know” what might come forth.
And that is true.
The Grad Student(s) researchers will undoubtedly get their PhDs, with plenty of curriculum vitae declaring that the goatskin holder is capable of magnificent achievement in nano-fabrication, solar materials and underwater basket weaving. And he or she will end up working first for a few start-ups that’ll flop, but which will benefit from their PhD laurels in finding gullible venture capital monies. Then around 33 or so, they’ll land a cushioned job at Chevron or ADM or Ford … get paid $150,000+ a year, marry, have kids, live in the Hamptons and speak at Old Man Investor events.
Life.
GoatGuy
If the Great designer is the great designer why does he/she bother with inspiring human design? Why not get on with it and cut out the middle man?
Basically, it is just development of potentially new types of solar cells. I’m fine with that.
Solar cells need to be developed further. Developed to the point where they are as cheap as wallpaper, both to manufacture, and to install and replace. There is a long way to go. This particular line of research is not yet even up to the standard of existing solar cells, but that is to be expected from any genuinely novel technology.
OK, most attempts at improvement will run into the sand, but I can’t object to people trying to actually make something better as long as they don’t lie about what they have achieved or might achieve. By contrast, most global-warming-scientists have never been involved with the difficulties of actually making something useful, or even potentially useful. It is an ‘industry’ that lives off those complaining about the inadequacies of real life industries that actually make the things that keep us alive. Policy makers need to start carefully distinguishing between them when it comes to funding.
I was on the Board of a novel solar cell startup (out of Argonne National lab, failed after 2 years as the 3d nanomaterials science did not work out in the lab the way it did on paper. i was also peripherally involved with Konarko (theynlooked at buying my NanoCarbons invention to save themselves from complete failure). Here are the basic conundrums. 1. The single bandgap Shockley-Queisser quantum efficiency limit is 31%. The best monocrystalline cells are already at 26, and panels made therefrom about 22%. But expensive. All the ‘cheap’ approaches (die sensitized, organic, perovskites) are much lower efficiency and suffer severe lifetime issues. 2. For polysi and CdTe, the BoS costs are more than half and neither scale nor come down learning curves. Lower panel cost does NOT alter that installed cost reality. First Solar CdTe is about $0.47/w for panels, but still ~$1.50/w for utility scale installations. 3. Sun does not shine at night and we have no feasible, economic storage mechanism despite Tesla’s fantasies.
ristvan
What about amorphous Silicon higher voltage cells? (42-48 volts DC) – I understand that amorphous silicon does better (is much more efficient) in diffuse light conditions, and degrades less than single-crystal silicon, but is less efficient that single crystal silicon in pure, clean direct light conditions that are the “standard” against which all cells are judged.
Like climate science in which linear researchers accept a presumed given at the outset that anthropogenic CO2 will kill the planet, solar researchers are stuck by their linear thinking of literally ‘framing’ the problem in squares that sterilize vast tracts of land for low output, when the real problem is arguably this very large land requirement.
Back up a frame. How about researching the bimetal Seebeck effect.
https://en.m.wikipedia.org/wiki/Thermoelectric_effect
I read a technical note in “Chemical Engineering” a couple of years ago about a bimetal product that was manufactured in a ‘fur-like’ format, comprising thousands of bimetal circuits
Oops didn’t finish. This product could be used to recover low grade waste heat from a large variety of sources – stacks, processes, exhausts, possibly waste heat from solar panels or entire bimetal fur solar heat converters, or roof top heat collector converters – the process even refrigerates and could be used on homes for power gen and relieving A/C usage.
It seems real innovation needs to start in the changed thinking of researchers.
I suspect there would be a lot to explore in the ‘nano’ field if applied to thermocouples.
Space probes have used expensive nuclear batteries using thermocouple, but of a more traditional construction.
Nano couples may get us to serious power densities?
Steve see my two posts above yours to add to your thoughts for alternative solar/waste heat electricity.
Space probes generating electricity from radioactive decay heat (usually a slug of plutonium) use solid state thermoelectric generators made from expensive 3-5 semiconductor materials such as (typically) gallium arsenide. No way to get here (commercial, practical) from there (multibillion dollar deep space probes like Cassini). Since I have some nanomaterials inventions/patents and former competitors, as well as Board experience on a nanomaterials solar venture, have a sense as to where nanomaterials are technically interesting and where they might also be practically interesting. The only present possibility I know of in energy is the Fiskers Nanotech Lithium Ion Capacitor (LiC). Wrote that up in a guest post over at Judith Curry’s a few months ago. Fisker has since backed out (at least partly) because the development timeframe exceeds his promised EV launch schedule. First car will have LG Chem LiB, same as Chevy Bolt.
ristvan
Deep space, expensive, hard to build, relatively low power for the high weight (even higher if the radioactive ion generator has to be shielded to allow close approach by humans!) but long-lived. Rule of thumb: Anything closer than Mars-Earth-moon orbits is better served with solar cells, IF they can be rigged on the probe or satellite. (Apollo-Gemini used fuel cells because they could use the water generated, and could not rig that era’s solar cells aerodynamically during launch. The Agena and similar probes could deploy solar cell arrays for earth-moon orbits. )
Now if they could just fab some nano-inverters to keep the majority of cells working when a shadow is cast over the array.
Ah, the wonders of fossil carbon. Never a subsidy, billions in profit, ideal working conditions for coal miners, infinite untapped resources, continuous supply of black aerosol to cool the earth, CO2 and sulfate in rain to nourish crops! What’s not to love?
If it is fossil carbon, then it for sure is not infinite supply.
Evolution doesn’t thank you for supernaturally anthropomorphizing its amazing natural powers.
Evolution of insect eyes, and of arthropod eyes in general, is well understood. No Idiotic Designer required.