A new study has found that using nanowires in PV cells, rather than regular metal conductors, could increase PV cell efficiency fifteen-fold.
The study was conducted by scientists from the Nano-Science Center in Denmark and the Ecole Polytechnique Fédérale de Lausanne, Switzerland. The researchers found that nanowires – wires only as wide as a nanometer – can concentrate sunlight up to 15 times more than normal metal conductive wires.
This discovery suggests that using nanowires in PV cells could greatly improve solar cell efficiency, and it’s thanks to years of research into nanowire crystals (a cylindrical structure about 10,000 times thinner than a human hair.
Nanowire crystals used as the solar cells. SEM (Scaning Electron Microscope) image of GaAs nanowire crystal grown on a Silicon substrate. Credit: Niels Bohr Institute
“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,” says Peter Krogstrup, one of the researchers working on the project.
Those resonances allow for a lot more sunlight to be absorbed, thus increasing the amount of sunlight converted to energy. In fact, efficiency using nanowires exceeds the Shockley-Queisser Limit, the previously believed limit for solar cell efficiency.
“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,” says Krogstrup.
“However, it will take some years years before production of solar cells consisting of nanowires becomes a reality.”
The study was published in the journal Nature Photonics.
