Radio waves are a type of electromagnetic energy, so when they’re acquired by traditional metallic antennas, the electrons which are generated could be changed into an electric current. Considering the fact that optical surf is also a kind of electromagnetic energy, a team of scientists from Tel Aviv University wondered if these could also be converted into electricity, with an antenna. It turns out that they are able to – if the antenna is very, very short. These “nanoantennas” could replace the silicon semiconductors in special solar power panels, that could harvest more energy from a wider spectrum of sunlight than happens to be possible.
The nanoantennas are constructed out of small quantities of aluminum and gold, and are each just one micron in length – because light has such a short wavelength (when compared with radio waves), short antennas provide the optimal absorption. After being created, the nanoantennas were then exposed to light, to find out how well they could receive and transmit light energy. According to the initial tests, 95 % of the wattage being absorbed through the antennas was passed along, with only 5 percent being wasted.
Not just would be the nanoantennas efficient, but when their length is varied, the wavelength that they can absorb changes. Therefore, they believe that one panel containing a number of lengths of otherwise-identical nanoantennas could harvest energy from the much broader solar spectrum than is presently allowed by semiconductor technology.
To that particular end, the Tel Aviv team is now in the process of creating experimental plastic solar power panels, nano-imprinted with varying lengths and shapes of nanoantennas. They’re also looking into the electromagnetic-energy-to-electrical-current conversion process, with hopes of improving it.
Although silicon isn’t a particularly expensive material, the scientists think that the superior efficiency of their panels could allow them to be smaller than present solar power systems, and thus more cost-effective.
Similar scientific studies are also under way in the Idaho National Laboratory, where researchers have been developing plastic sheet solar panels stamped with nanoantennas.