A simple, single nanowire crystal is capable of super-concentrating the intensity of the sunlight that it is exposed to up to a factor of 15, researchers from the Niels Bohr Institute have discovered. The surprising discovery means that the assumed limit to solar cell efficiency, the “Shockley-Queisser Limit,” can likely be increased. The discovery should lead to new types of high-efficiency solar cells, but also will have uses in potential quantum computers and other electronics, the researchers say.
Nanowire crystals are, basically, “a cylindrical structure with a diameter of about 10,000 part of a human hair.” The researchers involved in this discovery had been spending the past couple of years developing them, and working to improve their quality.
During the research, it was discovered 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.”
As a result of this discovery, the theoretical solar cell efficiency limits will very likely have to be increased. While that may not sound important, it should have a significant impact on the development of future solar cell technology. It will probably still be a couple of years until this discovery results in the production of ultra high-efficiency nanowire solar cells though, according to the researchers.