Dielectric Scattering Patterns for Efficient Light Trapping in Thin-Film Solar Cells

• Published in: Nano letters Vol. 15; no. 8; pp. 4846 - 4852
• Main Authors: van Lare, Claire, Lenzmann, Frank, Verschuuren, Marc A, Polman, Albert
• Format: Journal Article
• Language: English
• Published: United States American Chemical Society 12.08.2015
• Subjects: Aluminum - chemistry; Dielectrics; Electric Power Supplies; Light scattering; Lithography; Nanostructure; Nanostructures - chemistry; Nanostructures - ultrastructure; Nanotechnology; Photovoltaic cells; Scattering, Radiation; Semiconductors; Silicon - chemistry; Solar cells; Solar Energy; Sunlight; Thin films; Trapping; Zinc Oxide - chemistry; light trapping; nanophotonics; geometrical resonances; resonant nanostructures; Thin film solar cells
• ISSN: 1530-6984; 1530-6992
• DOI: 10.1021/nl5045583

We demonstrate an effective light trapping geometry for thin-film solar cells that is composed of dielectric light scattering nanocavities at the interface between the metal back contact and the semiconductor absorber layer. The geometry is based on resonant Mie scattering. It avoids the Ohmic losses found in metallic (plasmonic) nanopatterns, and the dielectric scatterers are well compatible with nearly all types of thin-film solar cells, including cells produced using high temperature processes. The external quantum efficiency of thin-film a-Si:H solar cells grown on top of a nanopatterned Al-doped ZnO, made using soft imprint lithography, is strongly enhanced in the 550–800 nm spectral band by the dielectric nanoscatterers. Numerical simulations are in good agreement with experimental data and show that resonant light scattering from both the AZO nanostructures and the embedded Si nanostructures are important. The results are generic and can be applied on nearly all thin-film solar cells.