Optical simulation for radiative absorption of plasmonic nanoparticles using metal–insulator–magnetic structure for solar energy applications

Abstract

Recently, solar thermal conversion technology, wherein solar energy is directly converted into thermal energy, has attracted significant attention as it ensures sustainable and modern clean energy generation for a progressive society. A direct-absorption solar collector that uses plasmonic nanofluids is useful for collecting solar energy. Thus, improving the solar absorption performance of plasmonic nanoparticles can further reduce the fabrication cost. We conceptualized multilayer sputtered (metal–insulator–magnetic) plasmonic nanoparticles that exhibit a broadband absorption spectrum and are easy to mass-produce. Particles with a metal–insulator–magnetic structure have not been developed in the past. To clarify the physics of the optical properties of the particles, electromagnetic field analysis was performed using COMSOL Multiphysics. Electromagnetic field analysis of the stacked plasmonic nanoparticles showed that the absorption efficiency depended on particle size and film thickness; the absorption peak increased significantly for an increasing particle size with a long shift, indicating the broadening of the absorption spectrum. In addition, the absorption spectrum could be controlled by changing the number of metal layers and the structure of the plasmonic nanoparticles. To quantitatively evaluate the spectral absorption efficiency, the total sunlight absorption efficiency (TSA) was defined as an evaluation parameter. TSA showed that the solar absorption performance of two-layer plasmonic nanoparticles was approximately 2.4 times that of homogeneous nanoparticles of the same size. Thus, the present study demonstrates the usefulness of bilayer plasmonic nanoparticles.