Refractive indices of layers and optical simulations of Cu(In,Ga)Se2 solar cells

• Published in: Science and technology of advanced materials 2018-12, Vol.19 (1), p.396-410
• Main Authors: Carron, Romain, Avancini, Enrico, Feurer, Thomas, Bissig, Benjamin, Losio, Paolo A., Figi, Renato, Schreiner, Claudia, Bürki, Melanie, Bourgeois, Emilie, Remes, Zdenek, Nesladek, Milos, Buecheler, Stephan, Tiwari, Ayodhya N.
• Format: Article
• Language: English
• Subjects: 204 Optics / Optical applications; 209 Solar cell / Photovoltaics; 306 Thin film / Coatings; 50 Energy Materials; absorption losses; Absorption spectra; Absorptivity; carrier collection losses; Composition; Copper; Copper indium gallium selenides; Cu(In,Ga)Se; Cu(In,Ga)Se2; Energy Materials; Material properties; optical losses; optical simulations; Parameters; Performance enhancement; Photovoltaic cells; refractive index; Refractivity; Solar cells; thin films
• ISSN: 1468-6996; 1878-5514
• DOI: 10.1080/14686996.2018.1458579

Cu(In,Ga)Se 2 -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)Se 2 solar cells with high efficiency. The optical bandgap of Cu(In,Ga)Se 2 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.