Issue 8, 2019

Approaching the Yablonovitch limit with free-floating arrays of subwavelength trumpet non-imaging light concentrators driven by extraordinary low transmission

Abstract

Metamaterials based on arrays of subwavelength dielectric structures have recently proved to be a viable research tool towards the realization of various photonic devices. In the current study we introduce a new approach towards efficient light trapping and broadband absorption of solar radiation based on silicon surface arrays composed of subwavelength trumpet non-imaging light concentrators (henceforth, trumpet arrays). In geometrical optics, a three-dimensional trumpet non-imaging light concentrator is a hyperboloid of revolution with an ideal light concentration ratio. We use finite-difference time-domain electromagnetic calculations to examine the optical response of an infinite cubic-tiled substrate-less silicon trumpet array under normal illumination. The absorptivity spectra of trumpet arrays are characterized by strong absorption peaks, some of which are just below the Yablonovitch limit. The enhanced light trapping is attributed solely to the efficient occupation of the array Mie modes, and we show absorption enhancement at near infrared that is an order of magnitude higher than that of the optimized nanopillar (NP) arrays. We show superior broadband absorption of solar radiation in trumpet arrays (with unoptimized geometry) compared with that of the optimized NP arrays (∼26% enhancement). The higher optical absorption in the trumpet array is governed by low transmissivity, in contrast to the NP array in which the absorption is governed by low reflectivity. Finally, we show that low reflectivity in trumpet arrays is governed by modal excitation at the upper part of the trumpets (which is also supported by the weak dependency of the reflectivity on the array height), whereas the transmissivity is governed by modal excitation at the lower part of the trumpets.

Graphical abstract: Approaching the Yablonovitch limit with free-floating arrays of subwavelength trumpet non-imaging light concentrators driven by extraordinary low transmission

Supplementary files

Article information

Article type
Paper
Submitted
23 Dec 2018
Accepted
23 Jan 2019
First published
25 Jan 2019

Nanoscale, 2019,11, 3681-3688

Approaching the Yablonovitch limit with free-floating arrays of subwavelength trumpet non-imaging light concentrators driven by extraordinary low transmission

A. Prajapati, A. Chauhan, D. Keizman and G. Shalev, Nanoscale, 2019, 11, 3681 DOI: 10.1039/C8NR10381J

To request permission to reproduce material from this article, please go to the Copyright Clearance Center request page.

If you are an author contributing to an RSC publication, you do not need to request permission provided correct acknowledgement is given.

If you are the author of this article, you do not need to request permission to reproduce figures and diagrams provided correct acknowledgement is given. If you want to reproduce the whole article in a third-party publication (excluding your thesis/dissertation for which permission is not required) please go to the Copyright Clearance Center request page.

Read more about how to correctly acknowledge RSC content.

Social activity

Spotlight

Advertisements