Berlin 2015 – scientific programme
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HL: Fachverband Halbleiterphysik
HL 10: Photovoltaics: Kesterites and less widely used materials (with DF)
HL 10.3: Talk
Monday, March 16, 2015, 11:45–12:00, ER 164
Reversible band gap changes in Cu2ZnSn(S,Se)4 solar cells induced by post-annealing — •Christoph Krämmer1, Christian Huber1, Christian Zimmermann1, Mario Lang1, Thomas Schnabel2, Tobias Abzieher1,2, Erik Ahlswede2, Heinz Kalt1, and Michael Hetterich1 — 1Institute of Applied Physics, Karlsruhe Institute of Technology (KIT), 76131 Karlsruhe, Germany — 2Zentrum für Sonnenenergie- und Wasserstoff-Forschung Baden-Württemberg, 70565 Stuttgart, Germany
The absence of the environmentally problematic and expensive metals indium and gallium makes the kesterite Cu2ZnSn(S,Se)4 (CZTSSe) material system a promising alternative to the established Cu(In,Ga)Se2. Recent publications demonstrated that the amount of CuZn+ZnCu antisite defect pairs can be influenced by post-annealing experiments. This has a direct impact on the band gap Eg of the material. We demonstrate that this effect can be used to reversibly tune Eg within a range of over 100 meV – even in finished solar cell devices. These reversible band gap shifts are detected using electroreflectance. We demonstrate that the band gap of the material is directly correlated to the amount of Cu–Zn disorder and follows the stochastic Vineyard model.