Klenk, R.; Gerhardt, P.; Lauermann, I.; Steigert, A.; Stober, F.; Hergert, F.; Zweigart, S.; Lux-Steiner, M.: Design, Preparation and Performance of Cu(In,Ga)(S,Se)2/Zn(O,S)/ZnO:Al Solar Cells. In: 39th Photovoltaic Specialists Conference (PVSC), 2013. IEEE , 2013. - ISBN 978-1-4799-3299-3, p. 0853 - 0856
10.1109/PVSC.2013.6744279

Abstract:
Junction formation by chemical bath deposition of CdS is a well established and robust process. To avoid the well known drawbacks of this approach, we propose to omit the CdS buffer layer and to directly sputter a modified window layer where Zn(O,S) is used instead of ZnO to improve the band line-up. This could result in completely dry in-line manufacturing of Cd-free modules using only proven deposition technologies. Key requisites for a new module structure are that the efficiency is not adversely affected and that the process is stable with a wide process window. For a first assessment, tests were carried out using absorbers from industrial production.