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Published on October 11th, 2012 | by Zachary Shahan


Black Silicon Solar Cells Get Boost in Efficiency, Efficiency Doubled

October 11th, 2012 by  

While conventional solar cells can absorb a good portion of the Sun’s light, they completely miss the boat on getting anything from the infrared spectrum. But black silicon solar cells are actually designed exactly for this. A group of researchers from the Fraunhofer-Gesellschaft institute in Germany have recently succeeded in doubling solar cell efficiency of black silicon solar cells!

Infrared radiation makes up about 25% of the solar spectrum. Black silicon can absorb almost all of this, and then turn it into electricity. So, there’s quite a bit of potential to improve the efficiency of solar panels by using black silicon.

What the heck is black silicon, you ask? “Black silicon is obtained by irradiating conventional silicon under sulfur atmosphere with a femtosecond laser,” explains Dr. Stefan Kontermann, group manager of the Fraunhofer Project Group Fiber optic sensor systems at the Fraunhofer Institute for Telecommunications, Heinrich-Hertz-Institut.”The surface is roughened, installed individual sulfur atoms in the silicon lattice and the material is black.” (Translations from German courtesy of Google Translate.)

So, how did the researchers boost black silicon solar cell efficiency? (Warning: science speak coming.) “We achieved this by having changed the shape of the laser pulse, with which we irradiate the silicon,” says Kontermann.

Here’s more from the Fraunhofer-Gesellschaft press release: “This allowed the scientists to solve a problem of the black silicon: While the infrared light hitting normal silicon does not have enough energy to raise the electrons in the ‘conduction band’ and thus bring in the current cycle, ie convert it into electricity, the sulfur added to the black silicon creates a sort  of intermediate step here.”

However, this intermediate step also allows electrons to jump the wrong way, resulting in lost electricity. But the researchers’ modification of the laser pulse solves this problem a bit by guiding more electrons in the right direction.

Where to go next?

The researchers’ next step is to evaluate how different shapes of laser pulses affect energy levels of the sulphur. And, eventually, the goal to create a system of algorithms that will be able to automatically identify how the laser pulse should be modified in order to achieve maximum efficiency.

The end goal is, of course, to merge the black silicon solar cells the researchers develop with existing commercial technology in order to bring a leading solar power product to market. According to the researchers, their intention is to add black silicon solar cells to conventional solar cells, creating a tendem solar cell, and thus boosting overall solar cell efficiency by about 1%.

“Furthermore, the scientists are planning a spin-off: In this company they want to market the laser system for manufacturers to expand their existing solar cell lines. They would then be able to produce the black silicon itself and build it into the cells.”

Yeah, this is all a bit over my head, but sounds interesting, and useful. Let’s hope so!

And, apparently, the research is rather highly esteemed, as this project has won an award from the “365 Places in the Land of Ideas” competition. An award ceremony is being held tomorrow (or later today for some of you), October 11, in Goslar.

Reposted from Solar Love! with full permission.

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About the Author

Zach is tryin’ to help society help itself (and other species) with the power of the word. He spends most of his time here on CleanTechnica as its director and chief editor, but he’s also the president of Important Media and the director/founder of EV Obsession and Solar Love. Zach is recognized globally as a solar energy, electric car, and energy storage expert. He has presented about cleantech at conferences in India, the UAE, Ukraine, Poland, Germany, the Netherlands, the USA, and Canada.

Zach has long-term investments in TSLA, FSLR, SPWR, SEDG, & ABB — after years of covering solar and EVs, he simply has a lot of faith in these particular companies and feels like they are good cleantech companies to invest in. But he offers no professional investment advice and would rather not be responsible for you losing money, so don’t jump to conclusions.

  • rkt9

    I think Fraunhofer-Gesellschaft might be a little late to the table with this one. Black Silicon has already been developed by the NREL, and it is licensed to Natcore Technology who is optimizing their commercial machine to coat the silicon now, and a company will be producing panels either here in the US, or Italy or China very soon, and eventually all 3.

    • We just covered NREL’s recent advancements as well. They are actually different advancements/improvements. Perhaps they can/are/will work together to create the best possible technology.

  • Tip of the iceberg! Research goes on! Soon enough Solar Cells that can replace even many oil applications, nuclear applications! Future belongs to the Pan Eurasian Alliance – America for tho corrupt to make any kind of progress in Sciences now – Solendrya a prime example of Coca Cola Corpocracy destroying hope in that country.

  • dcard88

    1% only works if they meant 20% up to 21% efficiency. If they actually meant 20% up to 20.02 % then this is not viable if it adds more than about .01 per watt (2%) to the install cost.
    Maybe the google translator needs an upgrade in efficiency? 🙂

    • Anne

      They usually mean absolute increases in efficiency, so you should interpret it as increasing cell efficiency from 20% –> 21%.

      (And 1% of 20 is 0.2, not 0.02, so your alternative explanation should be from 20% –> 20.2%, not 20.02%)

      • dcard88

        Did you have a point? Because the likelyhood of you schooling me in math is far less than 1%

        • Bob_Wallace

          Because you refuse to learn?

          • dcard88

            Huh? And if I have a doctorate in mathmatics? (despite evidence to the contrary)

        • Telit Likeitis

          Anne did have a point, but you missed it since you were blinded by ARROGANCE… Degrees in math don’t make up for a lack of reading and social skills. Anne was referring to what you actually TYPED in your answer; she was not questioning your math skills (however deficient they look, by your own doing! — read: sloppy writing and lack of proof-reading) FAIL.

          • lol get a life

          • And my point is still good, in spite of a misplaced decimal. And you’re weird no matter what I say

    • i just assumed it meant 20% to 21%. tends to be how they write things in this field.

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