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HL: Fachverband Halbleiterphysik

HL 4: Photovoltaics I: mainly CIGS

HL 4.9: Vortrag

Montag, 22. März 2010, 12:30–12:45, H15

Interface properties of Cd-free buffer layers on on CIGSe thin film solar cells — •J.P. Theisen¹, F. Erfurth¹, L. Weinhardt¹, R. Duarte², M. Bär², T. Niesen³, J. Palm³, N. Barreau⁴, F. Couzinié-Devy⁴, J. Kessler⁴, and F. Reinert^1,5 — ¹University of Würzburg, Experimental Physics VII, Würzburg, Germany — ²Helmholtz Institut, Berlin, Germany — ³Avancis GmbH, München, Germany — ⁴Institut des Matériaux , Nantes, France — ⁵Forschungszentrum Karlsruhe GmbH, Gemeinschaftslabor für Nanoanalytik, Karlsruhe, Germany

In order to replace the toxic Cadmium, the substitution of the CdS buffer layer in thin film solar cells based on Cu(In,Ga)(S,Se)₂ (CIGSSe) is of great interest. Alternative buffer layers like (In,Al)₂S₃, In₂S₃, or (Zn_1−x,Mg_x)O deposited by conventional sputter and chemical bath deposition techniques, have shown efficiencies close to or comparable to those of CdS containing solar cells. To understand the chemical and electronic properties of these buffer layers and its influence on the absorber, we studied the buffer-absorber interface using photoelectron spectroscopy (XPS, UPS) and inverse photoelectron spectroscopy (IPES). The combination of these non-destructive techniques provides detailed information about the chemical properties of the studied surface, as well as can be used for a direct determination of the conduction and valence band alignment at the heterojunction. Band-gap values at the surface as derived by UPS and IPES are also verified by electron energy loss spectroscopy (EELS). The results will be discussed in conjunction with the respective cell parameters.