Science

Roses improve modern solar cells energy production

Rose not only incredibly look good, they are also adept to get the most sunlight. Researchers have studied the micro-structures of flowers, which designed an organic solar cell. This simple Bionic trick works for solar cell produces more power. Why?

It is a magnificent sight when the flowers light up the Queen of the garden in all shades of dark red to soft pink in the Sun. Many people enjoy the intense colors of the roses in the summer. While these do not light from an end in itself so beautiful but because strong colour contrasts increase the chances of pollination by insects.

Photovoltaic is similar to photosynthesis

Now have closer to photovoltaics research of the Karlsruhe Institute of technology (KIT) the delicate rose and examines how the garden Queen produces this colour contrasts. The starting point was the idea that photovoltaics is similar to the photosynthesis of plants. Also during photosynthesis, light energy is absorbed and transferred into another form of energy.

It is extremely important as possible to take advantage of the light spectrum of the Sun and to absorb the light from different angle of incidence for the plants. Because the Sun moves from East to West during the day. In their long evolutionary history, plants have learned to take this different light offer optimally.

Rose petals as a role model for solar technology.

It is called the fabric of leaves of higher plants, epidermis, succeeds, perfectly capture the light from all incident angles. The researchers at the KIT in association with other research institutes have found that by they have investigated the epidermal cells of different species on their optical properties and their reflex action.

And in this study, the rose petals were clear favorites. Under the electron microscope showed, is that the epidermis of the leaves of a rose petal from a chaotic field of densely crowded microstructures which is also ribbed placed randomly nano structures.

Polymer based silicon and solar cells

To reproduce this structure, the researchers transferred in a form of Polydimethylsiloxane. They pushed into this negative in an optical adhesive, which they cure under UV light.

“This method is easy and cost-efficient and generates micro-structures of a depth and density, how to do it hardly using artificial techniques”, reported Dr. Guillaume Gomard, head of the group “Nanophotonics” on the light Technology Institute (LTI) of the KIT. The scientists in an organic solar cell integrated so produced transparent replica of the rose petals epidermis.

Twelve percent more effective at vertical incidence of light

Suddenly increased the energy conversion efficiency of vertical light incidence by 12 percent. The efficiency was even greater at shallow incidence angles. Especially the outstanding direction-dependent reflex effect of the reconstructed epidermis is responsible for this increase in efficiency. It is able to keep the surface reflection below five percent, even at extremely flat angle of light incidence by nearly 80 degrees.

Cells act as a micro lens

It is joined by another effect: each of the emulated epidermischen cells acts as a micro lens. Studies with a confocal laser microscope showed that. This micro lens effect, extends the path of light inside the solar cell and increases the chance that particles of light are absorbed.

“Our method can be applied both on plants and other designed,” explains Guillaume Gomard. “Since the surfaces of plants are multi-functional, could it be possible in the future, several of them properties in a step to take.” Now, Research Verbund has published his findings in the journal of advanced optical material.

Roses improve modern solar cells energy production
A snow white rose in the garden of our author Detlef Stoller: The petals of the Rose are so perfectly, that they get sunlight from various directions. Photo: Detlef Stoller

Swedish researchers have seen on the rose. You have installed the major components of electronic circuits in the tiny ducts of the rose. Even to the light, the researchers bring their roses. For what? You want to use the energy of the photosynthesis and once directly to generate electricity in “Energy crops”.