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

Recently, many research efforts have been dedicated to improving light coupling into solar cells and reducing optical losses. Promising candidates regarding scalability include direct nano-structuring of the absorber layer, anti-reflective (AR) coatings, or combining both, e.g., pyramidal textures with a conformal coating. However, many of these methods are either insufficient or infeasible for application in thin solar cells. Moreover, approaches based on directly texturing the silicon interface simultaneously strongly increase surface recombination, thus degrading the electronic properties of the solar cell. To circumvent these issues, conformal graded-index metasurfaces with a correlated positional disorder for light trapping in solar cells are proposed and experimentally demonstrated in this contribution. When considered as a part of a prototypical solar cell geometry, a broadband reduction in reflection is observed that results in photocurrent enhancement. The combined consideration of disorder and conformal graded-index layers outperforms structures containing only one of these components. The computational guidance toward optimized designs promises to adjust the framework to other settings. The possibility for large-scale fabrication of the samples paves the way toward a future generation of supporting photonic structures in solar cells. This work demonstrates the use of gradient-index metasurface with correlated disorder for light management in solar cells. Such a metasurface is created via self-assembly nanofabrication and atomic layer deposition techniques on macroscopically large wafers. The results unequivocally demonstrate the significant improvement in light trapping and anti-reflective performance for a standard solar cell compared to bare nanostructures and a linear gradient anti-reflection coating. image