Replacement of Transparent Conductive Oxides by Single-Wall Carbon Nanotubes in Cu(In,Ga)Se2-Based Solar Cells

Thin films of single-wall carbon nanotubes were used as the transparent top electrical contact in Cu(In,Ga)Se ₂-based solar cells. Specifically, we demonstrate that thin layers of carbon nanotubes in combination with insulating polymer layers can effectively replace the metal oxide layers typically used in polycrystalline thin-film solar cells. Replacing the standard n-type ZnO layer with a thin film of carbon nanotubes yielded energy conversion efficiencies up to 13%. The optical and electrical transport properties of the single-wall carbon nanotubes suggest that suitable applications for these materials include multiple-junction solar cells, thermophotovoltaics, and other applications benefiting from a p-type transparent conductor with high near-infrared transmission.