On the interface between kesterite absorber and Mo back contact and its impact on solution-processed thin-film solar cells.pdfVIP

Solar Energy Materials Solar Cells 159 (2017) 290–295 Contents lists available at ScienceDirect Solar Energy Materials Solar Cells journal homepage: /locate/solmat On the interface between kesterite absorber and Mo back contact and its impact on solution-processed thin-?lm solar cells Thomas Schnabel n, Erik Ahlswede Zentrum für Sonnenenergie, und Wasserstoff-Forschung, Industriestra?e 6, 70565 Stuttgart, Germany article info abstract Article history: Received 23 March 2016 Received in revised form 7 September 2016 Accepted 18 September 2016 Available online 24 September 2016 Keywords: Back contact CZTSSe Earth abundant Kesterites Solar cells Solution processing Thin-?lm solar cells with a kesterite-type Cu2ZnSnSxSe4àx absorber have been prepared via a two-step process based on a metal salt solution with subsequent annealing in Se-containing nitrogen-atmosphere. Particular attention is paid to the interface between absorber and molybdenum, where the formation of secondary phases could be proven by a model experiment. To inhibit this formation, different back contact con?gurations of Mo and TiN have been tested. It is shown that TiN is an effective chalcogen barrier and avoids the formation of MoSxSe2àx, but in?uences the crystallinity of the absorber layer in a negative way, thereby also decreasing the open-circuit voltage. An effect on short-circuit current density and series resistance was not observed. The best results were obtained with an additional, thin Mo-layer on top of the TiN. 2016 Elsevier B.V. All rights reserved. 1. Introduction In recent years, the kesterite-type Cu2ZnSnSxSe4àx (CZTSSe) has gained particular interest as absorber for thin-?lm solar cells due to the capacious availability of the constituting elements and its fast progress to power conversion ef?ciencies of 12.6% [1]. It is often compared to the very similar and well-established CuInxGa1àxSySe2ày (CIGSSe) and therefore also the preparation techniques for CIGSSe are widely adapted for