Dr Otwin BREITENSTEIN

Dr Otwin BREITENSTEIN

Research Group Leader
Max Planck Institute of Microstructure Physics, Halle, Germany

Local Efficiency Analysis of c-Si Solar Cells Based on Luminescence Imaging and Lock-in Thermography

Photoluminescence and electroluminescence imaging and dark lock-in thermography (DLIT) are used for imaging the local series resistance Rs and saturation current density J01, which are essential parameters for local efficiency analysis. The limitation of DLIT is thermal blurring and a higher data acquisition time. However, J01 results for luminescence and DLIT analysis did not agree quantitatively. The reason is the assumption of the model of independent diodes for evaluating the data, whereas in reality Rs is a distributed resistance. This assumption leads to significant errors only for evaluating luminescence images, but not for evaluating DLIT, where the current is measured more directly. Recently two alternative PL evaluation methods were proposed, which are not based on the isolated diode model and lead to high-resolution J01 images comparable to DLIT ones. Together with EL and PL based local voltage analysis this enables a realistic Griddler analysis of inhomogeneous solar cells.

Biography

Dr. Otwin Breitenstein received his Ph.D. in physics from University of Leipzig (Germany) in 1980 with a work on Deep Level Transient Spectroscopy (DLTS). Since 1992 he is with Max Planck Institute of Microstructure Physics, Halle, Germany, where he investigates defects in semiconductors. Since 1999, he has been using lock-in thermography, optical imaging methods, and electron microscopy for characterizing crystalline solar cells. His in mainly interested in detecting internal shunts and generally evaluating the local efficiency of inhomogeneous silicon solar cells. He is Assistant Professor at University of Halle, Germany, giving lectures on the physics of solar cells and on advanced characterization techniques. He is author of several hundred publications in journals and at conferences and author of a book on "Lock-in Thermography" (Springer 2003, second edition 2010).