Antireflective Huygens’ Metasurface with Correlated Disorder Made from High-Index Disks Implemented into Silicon Heterojunction Solar Cells

Abstract

A large variety of different strategies has been proposed as alternatives to random textures to improve light coupling into solar cells. While the understanding of dedicated nanophotonic systems deepens continuously, only a few of the proposed designs are industrially accepted due to a lack of scalability. In this Article, a tailored disordered arrangement of high-index dielectric submicron-sized titanium dioxide (TiO2) disks is experimentally exploited as an antireflective Huygens’ metasurface for standard heterojunction silicon solar cells. The disordered array is fabricated using a scalable bottom-up technique based on colloidal self-assembly that is applicable virtually irrespective of material or surface morphology of the device. We observe a broadband reduction of reflectance resulting in a relative improvement of a short-circuit current by 5.1% compared to a reference cell with an optimized flat antireflective indium tin oxide (ITO) layer. A theoretical model based on Born’s first approximation is proposed that links the current increase in the arrangement of disks expressed in terms of the structure factor S(q) of the disk array. Additionally, we discuss the optical performance of the metasurface within the framework of helicity preservation, which can be achieved at specific wavelengths for an isolated disk for illumination along the symmetry axis by tuning its dimensions. By comparison to a simulated periodic metasurface, we show that this framework is applicable in the case of the structure factor approaching zero and the disks’ arrangement becoming stealthy hyperuniform.

Over 65% Sunlight Absorption in a 1 μm Si Slab with Hyperuniform Texture

“…By contrast, HUD point patterns naturally arise in many physical systems, which can lead to simple and scalable fabrication of the HUD holes or HUD network patterns. For instance, it has been shown that the structure factor of dispersed colloidal particle (e.g., beads) patterns can be tuned by the ionic strength of the particular solvent − and that the dewetting or phase separation of dielectric layers leads to HUD patterns. , Also, soft-imprint conformal lithography has proven an excellent low-cost alternative to pattern large-areas with a resolution below 10 nm that could actually serve for both HUD holes and HUD network . While a master substrate has to be first made with other lithography methods (such as e-beam lithography), the master can be extensively reused for the creation of multiple-use soft stamps.…”

Toward Hyperuniform Disorder via Self‐Assembly of Bidisperse Colloidal Patterns at an Electrode

“…[ 9,10 ] However, in the crystalline solid phase, aggregates and crystal faults lead to an increase in density fluctuations. We note that even though the obtained structures in the present study do not qualify as effectively hyperuniform, for some applications, e.g., HuD antireflection structures for solar cells, [ 11 ] even a gradual improvement of hyperuniformity is advantageous. Hence, the patterns obtained in the present study may still be of technological use.…”

Light‐Controlled Fabrication of Disordered Hyperuniform Metasurfaces

“…The isotropic nature of DHU structures has enabled the first implementation of isotropic PBGs. [5,6] Moreover, DHU structures have attracted attention in numerous application fields of optics, including light management in solar cells, [7] solid-state lighting, [8] Disordered hyperuniformity (DHU) is one of the most prominent manifestations of the engineered disorder, which aims to circumvent limitations commonly related to order. Considering the k-space, isotropic DHU is characterized by an isotropic suppression of scattering for wavenumbers k approaching zero.…”

“…The isotropic nature of DHU structures has enabled the first implementation of isotropic PBGs. [ 5,6 ] Moreover, DHU structures have attracted attention in numerous application fields of optics, including light management in solar cells, [ 7 ] solid‐state lighting, [ 8 ] waveguide polarizers, [ 9 ] surface‐enhanced Raman spectroscopy (SERS), [ 10 ] and tailored light scatterers. [ 11 ]…”