Based on multi-wall carbon nanotubes and tiny rectifiers fabricated ont 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 and efficient means of capturing 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. When light is incident on the nanotube antennas, it creates an oscillating charge that passes 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 optimisation techniques, and believe that a rectenna with commercial potential may be available within a year. The work is published in the journal, Nature Nanotechnology.