Sub-50-nm self-assembled nanotextures for enhanced broadband antireflection in silicon solar cells

Abstract

Materials providing broadband light antireflection have applications as highly transparent window coatings, military camouflage, and coatings for efficiently coupling light into solar cells and out of light-emitting diodes. In this work, densely packed silicon nanotextures with feature sizes smaller than 50 nm enhance the broadband antireflection compared with that predicted by their geometry alone. A significant fraction of the nanotexture volume comprises a surface layer whose optical properties differ substantially from those of the bulk, providing the key to improved performance. The nanotexture reflectivity is quantitatively well-modelled after accounting for both its profile and changes in refractive index at the surface. We employ block copolymer self-assembly for precise and tunable nanotexture design in the range of B10-70 nm across macroscopic solar cell areas. Implementing this efficient antireflection approach in crystalline silicon solar cells significantly betters the performance gain compared with an optimized, planar antireflection coating.

Suppression of reflection peaks caused by moth-eye-type nanostructures for antireflection applications studied by using FDTD simulation

“…The pitch of the array was 450 nm. The last shape was a combination of a cone and a sphere, which was recently realized by polymer self-assembly [13]. The dimensions and pitch of this array were exactly the same as those of the first one (i.e.…”

Black silicon laser-doped selective emitter solar cell with 18.1% efficiency

“…We use black silicon [13,14,11] nanostructuring to achieve low reflectance, which can be modelled in a mean-field approximation as a graded refractive 10 index at the Si-air interface [15]. von Gastrow et al [16] reported excellent passivation of black Si surfaces using atomic layer deposition (ALD) of Al 2 O 3 .…”

“…Compared to the typical front surface reflectance of ∼ 2 and ∼ 8 %, from conventionally textured mono- [8] 5 and multi-crystalline [9] Si solar cells, respectively, nanoscale texturing such as described in [10,11,12] offers a potential of improved power conversion efficiency for Si solar cells due to reduced reflectance loss.…”

Manufacturing of highly ordered porous anodic alumina with conical pore shape and tunable interpore distance in the range of 550 nm to 650 nm

“…However, the nanostructured graded-index AR coatings are the most promising ones with respect to polarization insensitivity, broad-band and omnidirectional antireflectivity properties required for a perfect antireflective performance [9][10][11][12][13][14]. In these materials the optical impedance matching and, therefore, effective suppression of the reflection occurring on the surface, can be implemented via tapered index design, where the ordered array of tapered pillars acts as a layer for the gradually changing refractive indexes.…”