1. Laboratory for Photovoltaics; University of Luxembourg; 41, rue du Brill L-4422 Belvaux Luxembourg
2. Department of Engineering and Architecture; University of Parma; Parco Area delle Scienze 181A 43124 Parma Italy
3. Zentrum für Sonnenenergie- und Wasserstoff-Forschung Baden-Württemberg (ZSW); Meitnerstraße 1 70563 Stuttgart Germany
4. Laboratory for Thin Films and Photovoltaics, Empa-Swiss Federal Laboratories for Materials Science & Technology; Überlandstraße 129 8600 Dübendorf Switzerland