Nanowire solar cells raise efficiency limit

March 26, 2013

Nanowire crystals are used as solar cells. Left: GaAs nanowire crystal grown on a Silicon substrate. Middle:a single nanowire. Right: atomic columns. (Credit: Niels Bohr Institute)

A single nanowire can concentrate sunlight up to 15 times the normal intensity, scientists from the Nano-Science Center at the Niels Bohr Institute, Denmark and the Ecole Polytechnique Fédérale de Lausanne have shown.

The nanowires concentrate the Sun’s rays into a very small area by up to a factor of 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 the nanowires.

The nanowire crystal obtained a short circuit current of 180 mA/cm2 at one sun illumination, compared to 42.7 mA/cm2 for crystalline silicon (c-Si), the next-highest-rated technology.