Optical rectenna
schematic
This schematic
shows the components of the optical rectenna developed at the
Georgia Institute
of Technology. (Credit: Thomas Bougher, Georgia Tech)
(September 29, 2015) Using
nanometer-scale components, researchers have demonstrated the first optical
rectenna, a device that combines the functions of an antenna and a rectifier
diode to convert light directly into DC current.
Based on multiwall carbon nanotubes and tiny rectifiers
fabricated onto them, the optical rectennas could provide a new technology for
photodetectors that would operate without the need for cooling, energy
harvesters that would convert waste heat to electricity – and ultimately for a
new way to efficiently capture solar energy.
In the new devices, developed by engineers at the Georgia
Institute of Technology, the carbon nanotubes act as antennas to capture light
from the sun or other sources. As the waves of light hit the nanotube antennas,
they create an oscillating charge that moves through rectifier devices attached
to them. The rectifiers switch on and off at record high petahertz speeds,
creating a small direct current.
Billions of rectennas in an array can produce significant
current, though the efficiency of the devices demonstrated so far remains below
one percent. The researchers hope to boost that output through optimization
techniques, and believe that a rectenna with commercial potential may be
available within a year.
Using
nanometer-scale components, researchers have demonstrated the first optical
rectenna,
a device that
combines the functions of an antenna and a rectifier diode
to convert light
directly into DC current.
“We could ultimately make solar cells that are twice as
efficient at a cost that is ten times lower, and that is to me an opportunity
to change the world in a very big way” said Baratunde Cola, an associate
professor in the George W. Woodruff School of Mechanical Engineering at Georgia
Tech. “As a robust, high-temperature detector, these rectennas could be a
completely disruptive technology if we can get to one percent efficiency. If we
can get to higher efficiencies, we could apply it to energy conversion
technologies and solar energy capture.”
The research, supported by the Defense Advanced Research
Projects Agency (DARPA), the Space and Naval Warfare (SPAWAR) Systems Center
and the Army Research Office (ARO), was reported September 28 in the journal
Nature Nanotechnology.