Refractive indices of layers and optical simulations of Cu(In,Ga)Sesub2/sub solar cells

摘要

Cu(In,Ga)Sesub2/sub based solar cells have reached efficiencies close to 23%. Further knowledge-driven improvements require accurate determination of the material properties. Here, we present refractive indices for all layers in Cu(In,Ga)Sesub2/sub solar cells with high efficiency. The optical bandgap of Cu(In,Ga)Sesub2/sub does not depend on the Cu content in the explored composition range, while the absorption coefficient value is primarily determined by the Cu content. An expression for the absorption spectrum is proposed, with Ga and Cu compositions as parameters. This set of parameters allows accurate device simulations to understand remaining absorption and carrier collection losses and develop strategies to improve performances.