On the scattering directionality of a dielectric particle dimer of High Refractive Index

Ángela I Barreda,Hassan Saleh,Francisco González,Jean-Michel Geffrin,Amélie Litman,Fernando Moreno

doi:10.1038/s41598-018-26359-8

Abstract

Low-losses and directionality effects exhibited by High Refractive Index Dielectric particles make them attractive for applications where radiation direction control is relevant. For instance, isolated metallo-dielectric core-shell particles or aggregates (dimers) of High Refractive Index Dielectric particles have been proposed for building operational switching devices. Also, the possibility of using isolated High Refractive Index Dielectric particles for optimizing solar cells performance has been explored. Here, we present experimental evidence in the microwave range, that a High Refractive Index Dielectric dimer of spherical particles is more efficient for redirecting the incident radiation in the forward direction than the isolated case. In fact, we report two spectral regions in the dipolar spectral range where the incident intensity is mostly scattered in the forward direction. They correspond to the Zero-Backward condition (also observed for isolated particles) and to a new condition, denoted as “near Zero-Backward” condition, which comes from the interaction effects between the particles. The proposed configuration has implications in solar energy harvesting devices and in radiation guiding.

Highlights

Solar energy constitutes one of the most important renewable energy sources
We demonstrate how, by using High Refractive Index Dielectric (HRID) dimers under the dipolar approximation, it is possible to find two spectral regions where the incident radiation is preferentially scattered in the forward direction, i.e. in the direction of a potential photosensitive substrate
Scattering Directionality Conditions (SDCs) have been studied for a homogeneous dimer of HRID spherical particles smaller than the wavelength of the incident radiation

Summary

Introduction

Solar energy constitutes one of the most important renewable energy sources. Its clean and non-polluting energy can be converted into electricity by photovoltaic devices like solar cells, which have become a powerful alternative for solving the problem of climate change. In spite of the good response of metallic particles in infrared (IR) and visible (VIS) spectral regions[12], due to the Joule’s effect and to their inherent ohmic losses, the major part of the incident radiation is converted into heating These photons do not generate electron-hole pairs and, in consequence, do not contribute to increase the electric current. Aggregates of HRID nanoparticles have been analyzed for redirecting the incident radiation into some specific directions eventually different from the forward and backward ones They have shown their utility for building optical switching devices[47,48,49,50,51]

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Conclusion