Numerical Study of High Spectral Efficiency and High Temperature Energy Harvesting Metamaterial Emitter to Improve Thermophotovoltaic performance

Abstract

iI this work, a broad band and wide angle selective nano-pyramid metamaterial emitter was designed and analyzed. The selective nano-pyramid metamaterial emitter was designed from tungsten and aluminum nitride using COMSOL Multiphysics software. To obtain broadband emission of the emitter, the geometric parameters such as the base length of the pyramid, height of the pyramid, and thickness of dielectric were optimized while the parameters such as width of the unit cell and ground thickness of tungsten were fixed. The numerical simulation showed high emissivity below the cutoff wavelength when the geometric parameters were fixed at w = 395 nm, h3 = 260 nm, h1 = 160 nm, h2 = 80 nm, and b1 = 215 nm. In this study, a high average of emissivity of about 0.964 was achieved below the cutoff wavelength (0.1 µm-2.2 µm), whereas the emissivity was dramatically reduced above the cutoff wavelength. The emissivity below cutoff wavelength was obtained because of the excitation of magnetic polariton and surface plasmon polariton. Furthermore, the designed metamaterial emitter was polarization independent and achieved high emissivity over a wide range of incident angles from 00 to 600 . Moreover, the designed emitter has a higher spectral efficiency than the blackbody for EQE of InGaAs and maximizes the efficiency of the TPV system by 9.3, 5.3, 3.68, and 3 times the blackbody spectral efficiency at 900 K, 1000 K, 1100 K, and 1200 K. Additionally, this emitter had a higher spectral efficiency than Jiang et al. (2019) and black body for EQE of InGaAsSb. Generally, the designed selective nano-pyramid emitter was obtained with 75% and 86.2% spectral efficiency for InGaAs band gap energy (0.55 eV) at 1200 K and 1600 K, which was higher than blackbody and previous scholars