Regensburg 2022 – wissenschaftliches Programm

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HL: Fachverband Halbleiterphysik

HL 34: Focus Session: Perspectives in Cu(In,Ga)Se 2

HL 34.6: Vortrag

Donnerstag, 8. September 2022, 17:30–17:45, H33

Analysis of the diode factor in CIGSe solar cells — •Valentina Serrano Escalante and Thomas Paul Weiss — University of Luxembourg

In previous work [1] we suggest there is a link between metastable defects and the diode factor. Changes in doping density after light soaking are observed when measuring CV profiles. Those changes are caused by metastable transitions, accounted by the shift of the majority fermi level upon illumination, which in turn increases the diode factor. There are several methods to determine this parameter, namely, from an analysis of the current-voltage curves (JV) [2], using the diode equation or from the slope of the Voc dependence with illumination intensity: Jsc-Voc [3]. Within this work, those methods are tested in a set of CIGSe, Cu poor samples, grown with the three-stage process, with good efficiencies (without any post-deposition treatment) in the range from 15% to 17%. For the analysis of the JV curves under dark, the two-diode model [4] is implemented. Using a 1-diode fit always results in a high value (>1.5), indicating dominant recombination in the space charge region. We use a 2-diode fit to obtain information on the diode factor originating from recombination in the quasi-neutral zone, which is affected by the metastable effects. In the case of JV under illumination, the extraction of the diode factor seems to be hampered by the cross-over between light and dark JV characteristics, which in CIGSe cells might be due to a change in an energetic barrier under light [5]. Therefore, the diode factor under illumination is determined more reliably from Jsc-Voc measurements.