Metal-Dielectric Thin Film Structure Metamaterial for Obtaining High Equilibrium Temperature Under Direct Solar Optical Radiation

Jinnan Chen,Junpeng Guo

doi:10.1109/jphot.2022.3148255

Abstract

Metal-dielectric thin film structure metamaterials can be designed to absorb solar light radiation over a wide spectral band. By using Kirchhoff's law, metal-dielectric thin film metamaterials are investigated for obtaining high equilibrium temperatures under direct solar light radiation at normal incidence. It is found that among all metal-dielectric thin film structures, the dielectric layer on metal (DLM) surface structure is the optimal structure for producing the highest thermal equilibrium temperature under direct solar optical radiation.

Highlights

SOLAR LIGHT absorbers are critical elements for solar thermal energy harvesting systems
It can be seen that the single dielectric film on metal (DFM) structure surface can give over 80% emissivity over a wavelength range from 0.3 μm to 0.6 μm for incident angles below 75 degrees, while a four bilayer structure gives over 90% thermal emissivity in the wavelength range from 0.25 μm to 1.85 μm
Assuming that the thin film metamaterial is thermally isolated from its surroundings, the total absorbed solar power is equal to the total thermal emission power at the equilibrium

Summary

INTRODUCTION

SOLAR LIGHT absorbers are critical elements for solar thermal energy harvesting systems. Equilibrium temperature of multilayer thin film structure metamaterials under direct solar light radiation has not yet been investigated. Equilibrium temperatures of metal-dielectric thin film structures are calculated by using Kirchhoff’s law and law of energy conservation. To find the equilibrium temperature under direct solar illumination, we need to know the thermal emissivity of the thin film structure surface in all radiation directions. Optical absorptance A(θ, λ) of the metal-dielectric multilayer thin-film structure can be calculated by using the transfer matrix method [29]. The optical reflectance R from the thin film structure can be obtained from the elements of the transfer matrix of M in Equation (5), R The transmittance of this structure is zero because the optically thick metal layer prohibits light transmission. A(θ, λ) is the angular and wavelength dependent optical absorptance for unpolarized solar optical radiation in the thin film structure metamaterial

THERMAL EMISSIVITY OF METAL-DIELECTRIC THIN FILM STRUCTURE METAMATERIALS

EQUILIBRIUM TEMPERATURES OF THIN FILM STRUCTURE METAMATERIALS

EQUILIBRIUM TEMPERATURE OF SINGLE DIELECTRIC FILM ON METAL SURFACE STRUCTURE

Findings

CONCLUSION