Field of Expertise: Advanced Material Science

Influence of the Bridging Atom in Fluorene Analogue Low-Bandgap Polymers on Photophysical and Morphological Properties of Copper Indium Sulfide/Polymer Nanocomposite Solar Cells
Monika Jäger, Roman Trattnig, Markus Postl, Wernfried Haas, Birgit Kunert, Roland Resel, Ferdinand Hofer, Andreas Klug, Gregor Trimmel, Emil J.W. List
NanoTecCenter Weiz Forschungsgesellschaft mbH, Franz-Pichler-Straße 32, 8160 Weiz Institute of Solid State Physics, Graz University of Technology, Petersgasse 1
15:20 - 17:30 Thursday 24 October 2013 Foyer Alte Technik

This contribution presents the correlation between structural, morphological, and fluorescence properties as well as device performance of nanocomposite solar cells comprising two low-band gap polymers, poly[[9-(1-octylnonyl)29H-carbazole- 2,7-diyl]-2,5-thiophenediyl-2,1,3-benzothiadiazole-4,7-diyl-2,5-thiophenediyl] (PCDTBT) and poly[2,1,3-benzothiadiazole-4, 7-diyl-2,5-thiophenediyl(9,9-dioctyl-9H-9-silafluorene-2,7-diyl)22,5- thiophenediyl] (PSiF-DBT) and copper indium sulfide (CIS). It shows that, in analogy to organic solar cells, the device efficiency is strongly determined by different polymer structures leading to a different packing of the polymer chains and consequently to diverse morphologies. X-ray diffraction investigation indicates increased semicrystallinity in PSiF-DBT compared with the nitrogen analogue PCDTBT. The photoluminescence (PL) quenching of this polymer indicates that the higher photogeneration achieved in PSiF-DBT based films can be correlated to a favorable donor-acceptor phase separation. Transmission electron microscopy studies of PCDTBT:CIS blended films suggest the formation of polymer agglomerates in the layer resulting in a decreased PL quenching efficiency. For the considered polymer:CIS system, the combination of these effects leads to an enhanced overall device efficiency.

J. Polym. Sci. Part B: Polym. Phys. 2013, 51, 1400–141