Abstract
The objective of this study is to design a broadband and wide-angle emitter based on metamaterials with a cut-off wavelength of 2.1 µm to improve the spectral efficiency of thermophotovoltaic emitters. To obtain broadband emission, we conducted the geometric parameter optimization of the number of stacked layers, the inner and outer radii of the nano-rings, and the thickness of the nano-rings. The numerical simulation results showed that the proposed emitter had an average emissivity of 0.97 within the targeted wavelength, which ranged from 0.2 µm to 2.1 µm. In addition, the presented multilayer nano-ring emitter obtained 79.6% spectral efficiency with an InGaAs band gap of 0.6 eV at 1400 K.
Highlights
The conversion of solar and waste heat energies into electricity is a promising energy-harvesting technology due to the abundance, omnipresence, and bio-friendly properties of these energy sources.Thermophotovoltaic (TPV) devices harvest electromagnetic energy and convert it to electrical energy [1]
We extended our study of the optimized multilayer selective emitter with a black body at different temperatures to calculate the spectral efficiency of both the designed selective emitter and the black body
We proposed and numerically analyzed a multilayer optical selective emitter for TPV applications, based on a metamaterial design
Summary
The conversion of solar and waste heat energies into electricity is a promising energy-harvesting technology due to the abundance, omnipresence, and bio-friendly properties of these energy sources.Thermophotovoltaic (TPV) devices harvest electromagnetic energy and convert it to electrical energy [1]. The role of the thermal radiator is to convert solar or waste heat energies into thermal radiation, from which a PV cell generates electricity using the photovoltaic effect [2]. The conversion of electromagnetic energy to electrical power happens only when the photon energy is higher than the energy band gap of the PV cell. To maximize the power of electricity generation and increase the efficiency of TPV systems, the energy of photons should be higher than the band gap of the PV cell. For this reason, the selective emitter should be a perfect broadband and wide-angle emissivity above the band gap energy of the PV cell. If the TPV emitter has high emissivity within the targeted wavelength region and low emissivity above cut-off wavelength, the PV cell can effectively operate to generate electrical power with relatively low thermal loss [3,4,5]
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