Energy

Silver mirror triples efficiency of perovskite solar cells

An artist's impression of a perovskite (cyan) solar cell with a new layer of material underneath (gray), which boosts efficiency by creating reflections of electron-hole pairs (red and blue)
Chloe Zhang
An artist's impression of a perovskite (cyan) solar cell with a new layer of material underneath (gray), which boosts efficiency by creating reflections of electron-hole pairs (red and blue)
Chloe Zhang

Perovskites are one of the most promising new materials for solar cell technology. Now engineers at the University of Rochester have developed a new way to more than triple the material’s efficiency by adding a layer of reflective silver underneath it.

For the better part of a century, silicon has been the go-to material for making solar cells, thanks to its abundance and efficiency in converting light to an electrical current. But in just the last decade, a new contender has rapidly risen through the ranks – perovskite, which is much cheaper and has already caught up to silicon in efficiency.

Now a new study has boosted perovskite’s efficiency by three and a half times, without even tweaking the material itself. Instead, the team found that adding a layer of a different material underneath it changed the interactions of the electrons in the perovskite, reducing an energy-sapping process.

Perovskites and other photovoltaic materials generate electricity by allowing sunlight to excite electrons in the material, causing them to jump out of their atoms, ready to be guided to generate an electrical current. But sometimes, electrons fall back into the “holes” they left behind, reducing the overall current and as such the efficiency of the material. This is what’s known as electron recombination.

The researchers found they were able to drastically reduce electron recombination in perovskite by placing it on a substrate made up of either silver alone, or alternating layers of silver and aluminum oxide. The team says that doing so creates a kind of mirror that produces reversed images of the electron-hole pairs, which lessens the likelihood of electrons recombining with the holes. In tests, the engineers showed that adding these layers boosted the efficiency of light conversion by 3.5 times.

“A piece of metal can do just as much work as complex chemical engineering in a wet lab,” said Chunlei Guo, lead author of the study. “As new perovskites emerge, we can then use our physics-based method to further enhance their performance.”

The research was published in the journal Nature Photonics.

Source: University of Rochester

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19 comments
martinwinlow
"...adding these layers boosted the efficiency of light conversion by 3.5 times."
What does that men in practical terms? That we could have PV modules that have 60%+ efficiency? I thought that was theoretically impossible...
El Greco
Yes, there's some important qualification/clarfication missing here.
Ric
Citing the practical increase in overall efficiency as it compares to silicon (or supplements it if such is the case) would add significantly to the value of this information.
Martin Yale
So the advantage - is cost - and yet we are talking about adding in a layer of silver - which must cost quite a bit and isn't there other concerns. I seem to remember somewhere there was a lot of work in Australia perhaps taking silver out of silicon based solar cells https://www.abc.net.au/news/2021-09-21/australian-start-up-creates-world-s-most-efficient-solar-cell/100476152 - so is there perhaps some additional research to do?
clay
It seems to be 2.5x (250%), not 3.5x.. if you read the actual summary.

While the summary is extremely....light... on details, the concept seems pretty basic (and sound). I am floored no one has previously thought to try this.

If this ~2x holds up, it will go a looooong way to enabling mass production of perovskite base panels simply because current SOTA (State of the Art) formulations could remaining at or above acceptable performance levels for longer periods.. if a perovskite based panel lasts as long as a normal silicon based panel.. and provides comparable output over that period.. then it's lower overall cost and more strategically (geographically/nationally) producibility become compelling.
jzj
"a kind of mirror that produces reversed images of the electron-hole pairs, which lessens the likelihood of electrons recombining with the holes": ???
"boosted the efficiency of light conversion by 3.5 times": ???
These assertions must be explained, or the article is not ready to be published.
Craig
As of about 3 years ago perovskites were achieving 24-25% efficiency. Does this additional discovery boosting it by a factor of 3.5 imply about 85% efficiency??!!
Nizzlund
This is done since long with silicone based cells, its called PERC-technology and raises the efficiency of the cell with about 10% from 20 to about 22% in the best cases. 350% from abt 20 to 70% is unlikely as the theoretical limit is about 35% on a single-junction cell https://www.nature.com/articles/s41598-019-48981-w
peter423
I agree with all the above comments. Let's see a follow-up article.
Adrian Akau
A little more information such as costs would be good.