By Volker Sittinger, Senior Scientist, Large Area Coating Department, Fraunhofer IST; Wilma Dewald, Junior Scientist, Magnetron Sputtering Group, Fraunhofer IST; Wolfgang Werner, Engineer, Fraunhofer IST), Braunschweig, Germany; Bernd Szyszka, Head of the Department of Large Area Coatings, Fraunhofer IST; Florian Ruske, Senior Scientist, Helmholtz-Zentrum Berlin für Materialien und Energie GmbH
Highly conductive transparent films are of significant interest in the field of thin-film photovoltaics. The solar cell type defines the necessary properties of the TCO used, as, besides the obvious qualities of transparency and conductivity, stability and morphology are important. The most significant properties of these aspects for front contacts in amorphous/microcrystalline silicon tandem, CIGS and CdTe solar cells are presented in this paper. Commonly used deposition techniques like CVD and sputter technology are described herein, focusing on particular techniques like SnO2:F and ZnO:B (CVD) and ZnO:Al (sputtering). New developments of deposition methods are also discussed.