Energy

Flower power: Transparent rose-petal skin enhances solar cells

Flower power: Transparent rose...
The chaotic organization of a rose petal's epidermis turns out to be a very efficient surface for absorbing light
The chaotic organization of a rose petal's epidermis turns out to be a very efficient surface for absorbing light
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The image at the upper right shows the magnified surface of the rose petal, which was duplicated and applied to a solar cell to boost its effeciency
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The image at the upper right shows the magnified surface of the rose petal, which was duplicated and applied to a solar cell to boost its effeciency
The chaotic organization of a rose petal's epidermis turns out to be a very efficient surface for absorbing light
2/2
The chaotic organization of a rose petal's epidermis turns out to be a very efficient surface for absorbing light

We humans tend to pat ourselves on the back when we make strides in converting the sun's light into energy through solar technology, but plants have been doing much the same thing on Earth for thousands of years. Realizing this, a team of scientists lifted an imprint off rose petals and created a film that significantly boosted the efficiency of solar cells. Their findings have been reported in the journal Advanced Optical Materials.

The researchers from the Karlsruhe Institute of Technology (KIT) and the Center for Solar Energy and Hydrogen Research Baden-Württemberg (ZSW) in Germany began their work by looking at the optical properties of the epidermal cells from a variety of different plants. They were particularly interested in the ability this outer layer had to absorb – rather than reflect – light.

They found that rose petals were particularly good at this skill.

"As the scientists found out under the electron microscope, the epidermis of rose petals consists of a disorganized arrangement of densely packed microstructures, with additional ribs formed by randomly positioned nanostructures," says a KIT report about the research. This not only allows roses to absorb more light, it creates strong colors that assist with drawing insects in for pollination purposes.

The image at the upper right shows the magnified surface of the rose petal, which was duplicated and applied to a solar cell to boost its effeciency
The image at the upper right shows the magnified surface of the rose petal, which was duplicated and applied to a solar cell to boost its effeciency

Once the rose was chosen as a good candidate, the researchers made an imprint of the outer layer of the petals by using a silicon-based polymer. That, in effect, created a mold. They then poured a clear optical glue into the mold and cured it under UV light.

That gave them an exact transparent copy of the structure of the rose petals' epidermis, which they placed atop existing solar cells where they saw a 12 percent boost in efficiency for light that hit the panels vertically. For light that came in at a sharper angle, the efficiency boost was even greater, with an increase of 44 percent at an 80-degree angle of light.

In May, scientists reached a new record in the efficiency of solar cells, logging a 34.5 sunlight-to-electricity conversion rate. Incremental improvements to that number through means such as those demonstrated with the rose petal structure will help to increase solar power's use as a practical energy source.

The researchers are now working to investigate the role of a disorganized surface such as that in a rose petal's epidermis in other photosensitive surfaces and hope to find further improvements in the efficiencies of solar cells.

Source: KIT via Eureka Alert

7 comments
jimbo92107
"...plants have been doing much the same thing on Earth for thousands of years. " Thousands? Don't you mean hundreds?
SaysMe
Scientists have done a similar surface treatment before, though they laser etched the surface to give it a rough pyramidlike and made black, but this is energy and time consuming....
SaysMe
So did they also put the solar glass on top as they do with regular production of panels? Or it was just this silicon molded surface to air?
Bob Vious
Maybe I'm feeling cantankerous today, but a couple of things irritate me about this article. Aren't leaves the part responsible for converting sunlight into energy, and as such, that which should be studied? Also, insects don't see red, from what I've read.
windykites
If a white rose petal absorbed light, it would look dark, which it doesn't. There were solar panels made by Solyndra(out of business) that used hemi-spheric cylindrical lenses to capture more light. It seemed like a good idea at the time.
Island Architect
Engineers will kill for a 3% increase in efficiency. Scientists obviously accomplish much more. These figures of 12 to 44% increases taking the conversion rate to 34.5 bode well for solar power. One would assume that since the angle of incidence is virtually always changing and at extreme angles during the dawning morning and setting sun the collection efficiency must be greatly expanded. So a comparison with wind power comes to mind. Currently the 3 bladed fans are lucky if they hit 20% yet the Retired Suspension Engineer who inspired Sir Alex Moulton hit the 59% efficiency with his 10 bladed fans in a 12 section array, leaving 2 oppositely paired blades out to escape a detrimental axial compression cone, leaves us with huge questions about the cerebral cortex of human beings involved with fans since no one has disproved his findings and no one is willing to replicate his designs. Clearly something is rotten in Denmark. Bill
ljaques
Don't they mean "refract" instead of "absorb"? I liken this to our prismatic refractor lenses on troffer lights, which better spread the light throughout the office. Anything they can do to increase the effectiveness of solar power is a good thing. I just received 1080W worth of panels yesterday and, were they treated with this method, they would be putting out 1231 watts, plus hitting their peak earlier in the day and remaining near peak later in the day. Please keep researching, Mr and Ms Scientist.