First Optical Rectenna Converts Light to DC Current
Using nanometer-scale components, Georgia Tech researchers have demonstrated the first optical rectenna, a device that combines the functions of antennas and a rectifier diode to convert light directly into DC current. Optical rectennas could provide new technology for photodetectors, energy harvesters that convert waste heat to electricity – and ultimately more efficient solar energy capture. In the new devices, 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.
Transcript
00:00:00 The optical rectenna, you could think of it as like a radio antenna, only for the sun. It's working off of very similar principles, where we instead have very tiny antenna that match the size of the energy coming from the sun or visible light. And when that energy is coupled into the antenna, then another device is used to extract the energy and turn it into electricity.
00:00:27 So making a rectenna is actually a pretty simple process, which was part of the beauty of the discovery. You basically take any type of conductive substrate, and we can grow these carbon nanotubes like a carpet-- vertical off the substrate. We grow our nanotube. We can formally coat them with something that is an electrical insulator, then we deposit another layer of metal on top to create a so-called metal insulator or metal diode
00:00:52 structure. And so that diode structure is important, because it's the fastest diode in the world. And it's the only diode that's fast enough to open and close the gate at the speed of solar energy oscillating in an antenna. What gets me excited today is that we've done it. That we've actually achieved the goal that was six years in the making. But that's enough to get me out of bed every day,
00:01:13 because I think if we achieve that goal, we're going to make solar cells that are twice as efficient of what we have today. And that, to me, is an opportunity to change the world in a very big way.