Berlin 2015 – wissenschaftliches Programm

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HL: Fachverband Halbleiterphysik

HL 10: Photovoltaics: Kesterites and less widely used materials (with DF)

HL 10.3: Vortrag

Montag, 16. März 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 Abzieher^1,2, 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 Cu_Zn+Zn_Cu antisite defect pairs can be influenced by post-annealing experiments. This has a direct impact on the band gap E_g of the material. We demonstrate that this effect can be used to reversibly tune E_g 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.