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CPP: Fachverband Chemische Physik und Polymerphysik

CPP 19: Poster Session 1 (joint session with BP)

CPP 19.47: Poster

Dienstag, 1. April 2014, 09:30–13:00, P1

The impact of a varying C₆₀:C₇₀-acceptor mixing ratio on the opto-electronic properties of planar bilayer cells — •Johannes Mahr¹, Michael Brendel¹, and Jens Pflaum^1,2 — ¹Experimental Physics VI, University of Würzburg, 97074 Würzburg — ²ZAE Bayern, 97074 Würzburg

Many small molecule organic photovoltaic cells (OPVCs) are based on the electron acceptor C₆₀. We discuss the effect of employing C₇₀ instead of C₆₀ in prototypical diindenoperylene (DIP) based planar bilayer cells. As a result the short circuit current density (j_sc) is increased by 25 %, whereas the other solar cell parameters such as the fill factor and the open circuit voltage remain almost unaffected. By comparison of complementary optical and electrical measurements, the gain in j_sc is predominantly attributed to an enhanced absorption of the higher order fullerene C₇₀. Both acceptor molecules under investigation, are created simultaneously in common fullerene synthesis procedures. The cost extensive step to obtain pure C₆₀ and C₇₀ is the separation process of the different sizes, rendering pristine mixtures of both materials much cheaper. Therefore the effect of a varying C₆₀:C₇₀-acceptor mixing ratio, realized by co-evaporation of the two fullerenes, on the opto-electronic properties of planar bilayer cells will be elucidated in the course of this study. The occurring changes in the devices performance will be discussed in relation with structural data obtained by AFM and X-Ray diffraction. Financial support by the DFG focus program SPP1355 is gratefully acknowledged.