High efficient bowtie nanoantenna for thermophotovoltaic cells

A novel matching technique and the field enhancement at the terminals of a bowtie nanoantenna are utilized to develop compact, highly efficient, and flexible thermophotovoltaic (TPV) cells. A nano-meter size block of Indium Gallium Arsenide Antimonide (InGaAsSb) with a low bandgap energy of 0.52 eV is mounted at the terminal of the antenna. Such a load presents a frequency dependent impedance with a high resistance and capacitance at the desired frequency (180 THz). For maximum power transfer, a high impedance plasmonic bowtie antenna operating at the anti-resonance mode in conjunction with an inductive stub is realized. At the desired band, the loaded nanoantenna shows an electric field intensity at its terminals which is 23.5 times higher than that of the incident field intensity. The infinite array of the bowtie antennas backed by a metallic reflector is shown to absorb ~ 95% of the incident power which is more than 50% higher than the bulk InGaAsSb TPV cell.