Dresden 2011 – scientific programme

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HL: Fachverband Halbleiterphysik

HL 68: Photovoltaics: Chalcopyrites II

HL 68.12: Talk

Thursday, March 17, 2011, 13:15–13:30, FOE Anorg

Comparison of Photovoltaic Parameters of Cu(In,Ga)Se2 Thin Film Solar Cells with Infrared Images Obtained with Lock-In Thermography — •Torben Klinkert¹, Jörg Ohland¹, Robin Knecht¹, Jürgen Parisi¹, Ingo Riedel¹, Raymund Schäffler², and Bernhard Dimmler² — ¹Thin Film Photovoltaics, Energy- and Semiconductor Research Laboratory, University of Oldenburg, D-26111 Oldenburg — ²Würth Solar GmbH & Co. KG, Alfred-Leikam-Straße 25, D-74523 Schwäbisch-Hall

The performance of photovoltaic modules comprised of monolithically series connected solar cells is basically determined by the weakest element in the circuit. In chalcopyrite thin film modules lateral film inhomogeneities and losses due to interconnection are likely to deteriorate the photovoltaic performance of individual cell stripes and, in consequence, to reduce the module efficiency. In this work we correlate microscopic features with the macroscopic device parameters of Cu(In,Ga)Se2 solar cells cut from large-area modules. Imaging of the film imperfections and regions of enhanced joule heating was realized by applying infrared Lock-In Thermography (LIT) with optical (I-LIT) and electrical (D-LIT) excitation of the sample. Via comparison of the infrared LIT images with the photovoltaic cell parameters obtained from STC current voltage profiling and quantum efficiency measurements we try to correlate macroscopic junction failure with microscopic disruptions of the film properties. These problems will also be discussed on the module level by analysis of D-LIT results obtained for individual cell stripes in an integrated series compound of a CIGSe-module.