Nanowire solar cells come closer to reality
London: Scientists have shown that a single nanowire can concentrate the sunlight up to 15 times of the normal sun light intensity.
These results are surprising and demonstrate the great potential of development of a new type of highly efficient solar cells, said the scientists from the Nano-Science Center at the Niels Bohr Institut, Denmark and the Ecole Polytechnique Federale de Lausanne, Switzerland.
Due to some unique physical light absorption properties of nanowires, the limit of how much energy we can utilize from the sun's rays is higher than previous believed.
The research groups have during recent years studied how to develop and improve the quality of the nanowire crystals, which is a cylindrical structure with a diameter of about 10,000 part of a human hair. The nanowires are predicted to have great potential in the development not only of solar cells, but also of future quantum computers and other electronic products.
It turns out that the nanowires naturally concentrate the sun's rays into a very small area in the crystal by up to a factor 15. Because the diameter of a nanowire crystal is smaller than the wavelength of the light coming from the sun it can cause resonances in the intensity of light in and around nanowires.
Thus, the resonances can give a concentrated sunlight, where the energy is converted, which can be used to give a higher conversion effeciency of the sun's energy, said Peter Krogstrup, who with this discovery contributes to that the research in solar cell technology based on nanowires get a real boost.
The typical efficiency limit - the so-called "Shockley-Queisser Limit" - is a limit, which for many years has been a landmark for solar cells efficiency among researchers, but now it seems that it may be increased.
It's exciting as a researcher to move the theoretical limits, as we know. Although it does not sound like much, that the limit is moved by only a few percent, it will have a major impact on the development of solar cells, exploitation of nanowire solar rays and perhaps the extraction of energy at international level.
However, it will take some years before production of solar cells consisting of nanowires becomes a reality, said Krogstrup who just completed his PhD at the Niels Bohr Institute, University of Copenhagen.
The research is conducted in collaboration with the Laboratory des Materiaux Semiconducteurs, Ecole Polytechnique Federale de Lausanne, the Foundation and the company SunFlake A / S.
The discovery is described in the journal Nature Photonics.