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DS: Fachverband Dünne Schichten
DS 6: Thin film photovoltaics: CIGSe + processing
DS 6.3: Talk
Monday, March 26, 2012, 11:45–12:00, H 2032
Investigation of CIGSe Solar Cell Performance Deviations in Nominally Equal Absorbers — •Robin Knecht1, Jürgen Parisi1, Ingo Riedel1, Raymund Schäffler2, and Bernhard Dimmler2 — 1Energy and Semiconductor Research Laboratory, University of Oldenburg, Germany — 2Würth Solar GmbH & Co. KG, Schwäbisch-Hall, Germany
Cu(In,Ga)Se2 (CIGSe) solar cells were fabricated independently by industrial scale co-evaporation in two separate production lines with the same nominal composition and thickness of the absorber film. Although the device properties were believed to be the same we observed substantial deviations of the respective values of the open circuit voltage (△ VOC=40 mV) and of the fill factor (△ FF=4%), whereas the short circuit current was essentially the same. We performed fundamental device analysis, space charge and defect spectroscopy, transient photoluminescence as well as in-depth profiling of the chemical gradients of the absorber films. Using the results from the experiments we set up a simulation baseline which allowed us to conclude that the apparent deviations can be related to the presence of deep recombination centers with different concentration within the CIGSe absorber as well as to variations of the band gap grading.