Berlin 2015 – scientific programme

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HL: Fachverband Halbleiterphysik

HL 14: Organic photovoltaics and electronics - mostly cell design (with DS)

HL 14.2: Talk

Monday, March 16, 2015, 15:15–15:30, EW 202

Accurate Characterization of Serial Tandem Organic Solar Cells — •Toni Meyer, Ronny Timmreck, Christian Körner, Koen Vandewal, and Karl Leo — Institut für Angewandte Photophysik, TU Dresden, Germany

A well known concept for further improvement of the efficiency of solar cells are tandem solar cells. The most common representative of this concept are the serial tandem solar cells (sTSC) where the subcells are connected electrically in series. Due to Kirchhoff's law this leads to a current limitation of the whole device by the subcell generating less current under a specific spectrum. For scientific comparison and practical application it is inevitable to determine the exact performance of such a device under different illumination conditions. However, the current limitation of a sTSC represents a major challenge for their characterization.

The spectrometric characterization, developed by Meusel et. al, represents a precise method of determining the performance of sTSC for any given illumination spectrum by using a multi-source sun simulator. We apply this method to a state of the art vacuum deposited sTSC with complementary absorbers and compare it to the minimal requirements of the standard ASTM E2236-05 for characterizing multijunction photovoltaic devices. We show that in case of differing fill factors of the subcells of the sTSC it is not sufficient to use only a single source sun simulator, which does usually not yield correct results for the solar cell efficiency in accordance with the standard reporting conditions.