Light trapping gratings for solar cells: an analytical period optimization approach

Abstract

Solar cells can harvest incident sunlight very efficiently by utilizing grating-based light trapping. As the working principle of such gratings strongly depends on the number as well as the propagation directions of the diffraction orders, the grating period is a key parameter. We present an analytical model for optimizing the grating period, focusing on its impact on light path enhancement and outcoupling probability. Based on the presented model, we formulate guidelines to maximize light trapping in state-of-the-art high-end solar cells. The model increases the understanding of the grating performance in systems like the III-V//Si triple junction solar cell achieving record efficiency.

Nanopatterned Back-Reflector with Engineered Near-Field/Far-Field Light Scattering for Enhanced Light Trapping in Silicon-Based Multijunction Solar Cells

“…The theoretical and numerical analysis presented in ref highlights a slightly higher light path enhancement factor for a hexagonal grating compared to a crossed grating, under the assumptions of unity efficiency in reflection and equal redistribution of power over all the diffraction orders. Moreover, in simulation, we obtained better FOM values for the hexagonal grating compared with the crossed grating.…”

“…When standard texturing of the Si wafer is not compatible with the device design, nanopatterned optical gratings can be used to steer light at angles at which total internal reflection (TIR) is occurring at the top interface . Recent theoretical work , investigates the light-path enhancement induced by the grating period for light trapping in optically thick solar cells. However, a careful design and optimization of the grating at the nanoscale and, at the same time, an assessment of the resulting macroscale far-field light propagation through the entire cell are still missing.…”

Loss Analysis of Fully‐Textured Perovskite Silicon Tandem Solar Cells: Characterization Methods and Simulation toward the Practical Efficiency Potential

“…More details can be found in the study of Messmer et al [46] Besides current matching, reflection and parasitic absorption can further reduce the generated short-circuit current density. While reflection losses are reduced by implementing the fully-textured tandem cell design (reduction in reflection equivalent current from 3.1 to 1.0 mA cm À2 for flat compared to fully-textured tandem design [47] ), we assess the parasitic absorption by performing reflection transmission measurements on the top C 60 /SnO x /ITO contact layers. Out of the three layers, the absorption spectrum of the ETL C 60 is found to be the main source of curtailment of the useful light in the perovskite absorber (Figure S6, Supporting Information).…”

Anti‐Reflective Graded‐Index Metasurface with Correlated Disorder for Light Management in Planar Silicon Solar Cells

“…[7,8] Therefore, planar interfaces are much more preferred, and dedicated light management strategies using metallic grating structures, [9,10] photonic crystals, [11,12] nanospheres, [13,14] and many more were perceived to yield enhanced broadband absorption enhancement. [15,16] Metasurfaces with high refractive index nanostructures have demonstrated exceptional broadband antireflection ef- fect in silicon solar cells when arranged in a periodic lattice configuration. [17][18][19][20] While such periodic arrangements offer outstanding scattering capabilities by utilizing resonant coupling in the system, the complexity of experimentally realizing periodic structures at industrial length scales remains challenging.…”