Berlin 2018 – scientific programme
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HL: Fachverband Halbleiterphysik
HL 6: Photovoltaics I
HL 6.4: Talk
Monday, March 12, 2018, 10:15–10:30, EW 203
Band-gap tuning of Cu2ZnSn(S,Se)4 solar cell absorbers via defined adjustment of the chalcogenide ratio using a post-sulphurization process — •Markus Neuwirth1, Elisabeth Seydel1, Jasmin Seeger1, Alexander Welle2,3, Heinz Kalt1, and Michael Hetterich4 — 1Institute of Applied Physics, Karlsruhe Institute of Technology (KIT), 76131 Karlsruhe, Germany — 2Institute of Functional Interfaces, Karlsruhe Institute of Technology (KIT), 76344 Eggenstein-Leopoldshafen — 3Karlsruhe Nano Micro Facility, Karlsruhe Institute of Technology (KIT), 76344 Eggenstein-Leopoldshafen — 4Light Technology Institute, Karlsruhe Institute of Technology (KIT), 76131 Karlsruhe
Kesterite Cu2ZnSn(S,Se)4 (CZTSSe) thin-film solar cells are promising candidates for the future photovoltaic market. One of their very interesting and useful features is the tunability of their absorber band gap. In our work we achieve this by tuning the chalcogenide ratio x = [S]/([S]+[Se]) from close to 0 up to 1, which corresponds to a band-gap range of about 1.0 eV up to 1.5 eV. Experimentally this is done by post-annealing selenium-rich (x = 0.1) absorbers in a sulphur atmosphere. By varying the temperature and process hold time during this post-sulphurization step, we are able to accurately adjust x. Studies of the elemental composition give insight into the sulphur incorporation process which seems to be strongly correlated with the absorber’s morphology before post-sulphurization. Further morphology studies and current-voltage characteristics of the solar cells show a clear trend for the dependency of the device performance on process parameters.