Optical Rectennas -A Review

With the ever-growing geopolitical tensions across borders arising, ultimately from the eternal energy needs, it is the peak time for humanity to put its reliance on a more quasi-perpetuity source of energy, such as the Sun. Even though current photovoltaics are the frontier of solar power harvesting, their efficiencies are reaching a state of stasis sooner or later. The efficiencies of single-junction solar cells are capped by the Shockley-Quiesser limit of 33.7%. Researchers are racing toward a way to beat this limit while keeping the Levelized Cost of Energy (LCE) to its minimum. Amongst all contenders, rectenna (or rectifying antenna), which was invented only a decade after the first practical PV cell by the Bells lab [1], is the most promising technology to take the forefront in quenching the energy needs, not only because of the absence of any such theoretical limit but also a lower cost of production. This report will review three state-of-the-art architectures for optical rectification developed by the leading groups worldwide. The review will compile a concise discussion on Metal-Double-Insulator-Metal diodes, CNT-Insulator-Metal diodes, and Point-contact-Metal-Insulator-Metal diodes, with an elaborative focus on their fabrication methods and results obtained.