"...NovaSolix hopes to use carbon nanotubes to capture a broader portion of the sun’s electromagnetic spectrum, a process they hope will yield a 90% efficient solar cell at a tenth of the cost of modern solar modules..."
This was last years news but somehow I had missed it. I don't ...[text shortened]... f you want to know what "rectennae" are, start here;
You know, there was a short scifi story involving that very concept, WAY before it was thought up for real. The writer actually used the idea of making an antenna small enough to capture light rays just like a wire antenna captures radio waves.
Don't know if they would ever get to 90% or not but even 40% would be near double what we have now.
If you consider a radio wave, and a dipole antenna capturing radio waves, say a one meter wave and the proper antenna, a half wave dipole, and a beam of 1 meter goes by that antenna, I don't think it captures much in terms of what is the total power of the radiated beam. So that means you have to have many such dipoles to capture much of the radiation. So if you had a planar field of such dipoles that intercepted the whole of the beam I suppose you could get a decent amount of % captured so you would have to duplicate a few trillion such antennae of the wavelength of visual light and then you would also have the problem of tuning which would mean some dipole width would capture say green light but not IR so along with those trillion dipoles you would need several sizes tuned to different wavelengths if that association holds up comparing dipole for light waves compared to say 1 meter RF wavelengths. Along with just the dipole you also need to rectify the incoming energy to make for DC which is why they used the term Rectenna, rectifier and antenna in one go. Which also means you need to be able to couple all the different rectifier portions to a matrix of collectors.
It certainly will be a great achievement if they can work it all out.