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HL: Fachverband Halbleiterphysik

HL 4: Photovoltaics I: mainly CIGS

HL 4.7: Vortrag

Montag, 22. März 2010, 12:00–12:15, H15

Current blocking and current collection in CIGSe solar cells depending on sodium content — •Stefan Puttnins^1,2, Felix Daume^1,2, Hendrik Zachmann¹, Andreas Rahm¹, and Marius Grundmann² — ¹Solarion AG, Ostende 5, 04288 Leipzig, Germany — ²Institut für Experimentelle Physik II, Universität Leipzig, Linnéstr. 5, 04103 Leipzig, Germany

IV-curves of thin film solar cells often show non-idealites like voltage dependent carrier collection and current blocking behaviour. Sodium is long known to improve the efficiency of Cu(In,Ga)Se₂ solar cells by increasing V_OC and FF. However, the way in which sodium influences the electrical properties is still under discussion.

We investigated the influence of sodium on voltage dependent carrier collection and current blocking behaviour. Losses caused by incomplete photocurrent collection can be reduced by increased sodium content in the CIGSe layer. Current blocking behaviour like the rollover effect is less pronounced with increased sodium content.

The influences were analyzed both in detailed illumination intensity and temperature dependent IV-measurements as well as by extensive statistical analysis over thousands of produced flexible CIGSe solar cells. Theoretical models for this dependency were simulated with SCAPS-1D and show good agreement with respective measurements.