Researchers have demonstrated the first optical rectenna, device that combines an antenna with a diode rectifier to convert light directly into electricity. Essentially rectena is a kind of solar cell, but operating in a totally different principle. Instead of using the photoelectric effect, rectenna capture the light as the antennae pick up either wave. Already converts that radiation in direct current sence is name portmanteau of antenna and rectifier.
Made from multi-layer carbon nanotubes and tiny rectifiers, the optical rectenas represent a new technology for highly sensitive light detectors, such as those used in astronomical observations, but eliminating the refrigeration needed today, energy collectors that recycle waste heat into electricity and, finally, a new way to capture solar energy efficiently.
Change the world radically
The carbon nanotubes act as antennas to capture the light from the Sun or other sources, including sources of infrared light, or heat. As light waves reach the antennas they create an oscillating charge that moves towards the built-in rectifier.
The rectifiers and turn off at speeds in the petahertz range, fast enough to cancel the peaks of the waves, creating a continuous current.
“Ultimately, we can build twice as efficient solar cells at a cost that is ten times lower and this for me is a chance to change the world in a radical way,” said Baratunde Cola, the Georgia Institute of Technology, USA.
Perfect capturing moment
Despite the potential impact and the futuristic aspect of technology, first rectennas were developed in the decades of 1960 and 1970, but only work in very short wavelengths. For more than 40 years researchers have been trying to make these devices able to capture the visible radiation.
There were many challenges: how to miniaturize the antennas to capture the small optical wavelengths. To Fabricate diode rectifier small and able to operate fast enough to interact with the oscillations of the waves with wavelengths in the range of nanometers.
The researchers just didn’t give up on all this time because of the high efficiency and low cost that the rectenna.
“Now was the perfect time to try some new things and make a functional device thanks to advances in manufacturing technology” said Cola.
Rectenna Efficiency in laboratory.
Now that the optical rectennas were built, the researchers can devote to increase your efficiency and test emerging concepts, such as the energy cell phone download. The team believes that it can increase energy capture by using optimization techniques, and believe that a rectenna with commercial potential can be available within a year.
“Being robust and high temperature detectors, these rectenna can be a totally disruptive technology if we can get the 1% efficiency. If we can reach even greater efficiencies, we can apply them to energy conversion technologies and capture of solar energy, “said Cola.