Efficiency limits for solar spectrum rectification

Abstract

Optical rectennas are antennas coupled to high-speed diodes used to convert high-frequency optical radiation to DC. Rectennas have been viewed as alternatives to conventional p-n junction solar cells, with the potential of exceeding the Shockley-Queisser conversion efficiency limit of 33 %. Using the theory of photon-assisted tunneling, we analyze the efficiency limits and show that rectennas can achieve efficiencies up to 100 % under monochromatic illumination. For broadband solar illumination, we find that the diode operating voltage plays the role that bandgap plays in conventional solar cells. We study the effects of poor antenna/diode matching and diode reverse leakage currents showing the importance of careful diode design. We highlight the correspondence between rectification in the classical and quantum limits.