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DS: Fachverband Dünne Schichten

DS 2: Thin Film Chalcogenide Photovoltaics I (Focused Session -- Organiser: Ronning)

DS 2.1: Topical Talk

Monday, March 14, 2011, 11:00–11:30, GER 37

Cu(In,Ga)Se₂ solar cells: the importance of lateral variations of the absorber quality — •Susanne Siebentritt — University of Luxembourg, Laboratory for Photovoltaics, Belvaux, Luxembourg

Thin film solar cells are considered the second generation of photovoltaic technologies, because of their considerable cost reduction based on the small amounts of material and energy used in production. Among these technologies solar cells based on Cu(In,Ga)Se₂ show the highest efficiencies in the lab as well as in industry. Record efficiencies above 20 % have been reached with these polycrystalline solar cells.

It becomes more and more evident that lateral inhomogeneities, most prominently grain boundaries, limit the efficiency. Electrostatic band bending at grain boundaries appear a major obstacle for higher open circuit voltages. Fluctuations of the band gap and the quasi-Fermi level splitting have been determined by laterally resolved photoluminescence. Some of these variations can be related to lateral changes of the Cu supply during growth - with far reaching consequences for the design of preparation processes.