Abstract
Over the last decade, plasmonic antireflecting nanostructures have been extensively studied to be utilized in various optical and optoelectronic systems such as lenses, solar cells, photodetectors, and others. The growing interest to all-dielectric photonics as an alternative optical technology along with plasmonics motivates us to compare antireflective properties of plasmonic and all-dielectric nanoparticle coatings based on silver and crystalline silicon respectively. Our simulation results for spherical nanoparticles array on top of amorphous silicon show that both silicon and silver coatings demonstrate strong antireflective properties in the visible spectral range. For the first time, we show that zero reflectance from the structure with silicon coatings originates from the destructive interference of electric- and magnetic-dipole responses of nanoparticle array with the wave reflected from the substrate, and we refer to this reflection suppression as substrate-mediated Kerker effect. We theoretically compare the silicon and silver coating effectiveness for the thin-film photovoltaic applications. Silver nanoparticles can be more efficient, enabling up to 30% increase of the overall absorbance in semiconductor layer. Nevertheless, silicon coatings allow up to 64% absorbance increase in the narrow band spectral range because of the substrate-mediated Kerker effect, and band position can be effectively tuned by varying the nanoparticles sizes.
Highlights
Over the last decade, plasmonic antireflecting nanostructures have been extensively studied to be utilized in various optical and optoelectronic systems such as lenses, solar cells, photodetectors, and others
We show that zero reflectance from the structure with silicon coatings originates from the destructive interference of electric- and magnetic-dipole responses of nanoparticle array with the wave reflected from the substrate, and we refer to this reflection suppression as substrate-mediated Kerker effect
For dipole localized surface plasmon resonance (LSPR) in spherical nanoparticles, which is small in comparison to wavelength, permittivities should satisfy the condition εm + 2εsur = 0, which in case of silver in air occurs in the ultra-violet range[5]
Summary
It is worth noting that in the recent paper[26] narrow-band antireflection properties of silicon spherical particles on a high-index substrate were shown using single nanoparticle microspectroscopy, and here we analyze this effect in more detail In this manuscript, we are aiming on utilizing the controllable scattering directivity of all-dielectric coatings for suppressing light reflection from silicon substrate and comparing their efficiency to plasmonic coatings. We demonstrate that the antireflectance effect of silicon coatings originates from destructive interference of wave reflected from the substrate with the fields reradiated by the electric and magnetic dipoles induced in silicon nanoparticles This effect can be considered as substrate-mediated Kerker effect as an analogue of well-studied Kerker effect for dielectric nanoparticles in air or homogeneous environment (low-index substrates and matched-index covering of nanoparticle array). We numerically calculated the light absorption inside photovoltaic elements in both broad and narrow bands and discuss the efficiency of the coatings comparing to each other and to uncoated structure
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