Micro‐cone textures for improved light in‐coupling and retroreflection‐inspired light trapping at the front surface of solar modules

Abstract

Micron-scale textures at the front surface of solar modules have been reported to improve the current generation by both enhancing light in-coupling as well as by reducing light out-coupling via back-reflection, similar to the retroreflective effect.Whereas the general working principle and advantages of these textures have been described previously, here, the interplay of the reflection properties of different substrates with the enhancement effects is analyzed for textures of conical geometry.The study takes into consideration the incident light of arbitrary angle of incidence as well as the overall energy yield. Supported by optical simulations, periodic microcone textures were optimized and prototyped based on direct laser writing and a scalable replication process. Micron-scale textures with cones of various aspect ratios were examined on mono-crystalline silicon (c-Si) solar cells; an optimum aspect ratio of 0.73 was identified. This moderate aspect ratio is suitable for large-scale replication, while showing near-zero surface reflection and excellent light trapping. An increase in energy yield of up to 8% was calculated for the case of micro-cone textures at the front surface of commercial alkaline-etched c-Si solar cells. Moreover, the excellent optical properties of the micro-cone textures were highlighted by improving the power conversion efficiency (PCE) of a Cu(In,Ga)Se 2 (CIGS) thin-film solar cells from 20.2% to 20.9%. A comparable PCE improvement has been achieved by conventional MgF 2 antireflection coatings, but the angular stability and in turn the energy yield of the micro-cone textures is much higher.

Triple-cation low-bandgap perovskite thin-films for high-efficiency four-terminal all-perovskite tandem solar cells

“…The PDMS foils are used to reduce the frontsurface reection losses. [77][78][79][80] The textured PDMS foil we use here signicantly reduces the reectance from the glass ITO substrates (Fig. S13 †).…”

Exploiting the Optical Limits of Thin‐Film Solar Cells: A Review on Light Management Strategies in Cu(In,Ga)Se2

“…[ 120 ] It is these multiple interactions that increase the probability of light incoupling into the solar cell, allowing for a reduced reflection independently of the incident angle. [ 119 ] The MPA may be optimized, such that reflected light from the rear surface impinges the front surface with an angle higher than its critical value, enabling total internal reflection (Figure 5a—ray 4). [ 93 ] Furthermore, the microscale features promote large‐angle light refraction, as opposed to a flat surface, enabling a prolonged optical path length.…”

“…Reproduced with permission. [ 119 ] Copyright 2019, Wiley‐VCH; c) Schematic illustration of the MPA fabrication procedure: A) direct write laser (DWL) master mold fabrication. B) Texture replication on an UV‐curable photoresist through a PDMS stamp.…”

“…[ 124 ] Furthermore, applying texturization schemes to the encapsulation layer leaves the solar cell structure unchanged, avoiding charge dynamic‐related problems. [ 119,124 ] In the case of a periodic approach, the light management performance is very dependent on the array architecture, the height‐to‐length aspect ratio being of critical importance. [ 93,119,125,126 ] Dottermusch et al compared three CIGS solar cell architectures to demonstrate the benefits of an MPA texturization AR approach: [ 119 ] a) bare, a typical CIGS device without any AR strategy; b) MgF 2 , where a single MgF 2 layer on top of the bare device is used; and c) micropyramid, a resist layer patterned with an MPA with a pitch of 25 μm was used as an encapsulation layer on top of the bare device (Figure 5b).…”

Precision Cutting of the Molds of an Optical Functional Texture Film with a Triangular Pyramid Texture

“…Based on geometrical optics analysis, sub-millimeter-scale light functional textured films can effectively reduce the reflection loss of solar cells. Dottermusch [20] et al prepared sub-millimeter-scale tapered textures on monocrystalline silicon solar cells, which can reduce the reflection loss to about 8%. Our previous research [21] also found that by laminating a sub-millimeter-scale optical functional texture film to a smooth surface crystalline silicon cell, as shown in Figure 1, the reflection loss of the cell can be reduced to 13%.…”