In general, we deal with magnetron sputtering of doped substoichiometric metal-oxide layers (Cu:NiOx, Nb:TiO2-x, Nb:Nb2O5-x, ...), but also with purely metallic and tribological layers. We are also developing new absorber layers for thin-film solar cells. There is currently an intensive dynamic in photovoltaic research in the field of tandem cells. This involves combining two solar cells with customised band gaps. We are developing a hole-selective layer between the solar cells based on Cu:NiO.