Regensburg 2016 – scientific programme

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HL: Fachverband Halbleiterphysik

HL 90: Poster III

HL 90.5: Poster

Thursday, March 10, 2016, 16:00–19:00, Poster A

State-Filling Versus Screening of Electrostatic Potential Fluctuations in Cu₂ZnSn(S,Se)₄ thin-film solar cells — Christian Zimmermann¹, Christoph Krämmer¹, Mario Lang¹, •Tobias Renz¹, Tobias Abzieher², Thomas Schnabel², Erik Ahlswede², Michael Powalla^2,3, Christian Huber¹, 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 — ³Light Technology Institute, KIT

Cu₂ZnSn(S,Se)₄ (CZTSSe) is a promising alternative for the well-established absorber material Cu(In,Ga)Se₂ in thin-film solar cells. However, the efficiency of CZTSSe devices is still not competitive and essentially limited by an insufficient open-circuit voltage. Excitation power-dependent photoluminescence (PL) measurements show a “blue-shift“ of the PL maximum by 15–20 meV/decade. This is often explained by a screening of electrostatic potential fluctuations caused by charged defects. In literature, electrostatic potential fluctuations are often held accountable for the low V_OC. In this contribution we investigate excitation-power dependent PL at 10K. We can show by analyzing the whole PL lineshape that the observed “blue-shift“ is rather dominated by filling of defect states than by a screening of electrostatic potential fluctuations.