Hmm, looks like both Westinghouse and J. P. Morgan down voted this, OP!

INTRODUCTION

A photovoltaic (PV) rectifier consists of a broadband micro-antenna connected to an ultra-high-frequency diode, as shown in Fig. 1. Such devices, also known as rectennas, have been used for detection and energy harvesting of microwave radiation. Rectennas operating at optical frequencies form a solar cell that does not have the same fundamental limitations as a traditional semiconductor junction solar cell. Rectification of solar electromagnetic-radiation was first proposed in 1972 [1]. Although this concept has the potential to achieve a maximum power conversion efficiency of 93%

Abstract: A solar cell using micro-antennas to convert radiation to alternating current and ultrahigh-speed diodes to rectify the AC can in principle provide extremely high conversion efficiencies. Currently investigated rectennas using metal/insulator/metal (MIM) diodes are limited in their RC response time and have poor impedance matching to the antenna. We have investigated a new rectifier, referred to as a geometric diode, which can overcome these limitations. The geometric diode consists of a conducting thin-film, such as graphene, patterned in a geometry that leads to diode behavior. We have experimentally demonstrated geometric diodes made from graphene and simulated their characteristics using the Drude model for charge transport. Here we compare the characteristics of rectennas using MIM diodes with those based on geometric diodes and show the improved performance of the latter.