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CPP: Fachverband Chemische Physik und Polymerphysik

CPP 7: Electronic and Optical Properties of Organic Systems II

CPP 7.8: Vortrag

Montag, 22. März 2010, 15:45–16:00, H39

Conjugated Polymers and Fullerenes Under Oxygen Exposure: An Electron Spin Resonance Study — •Hannes Kraus¹, Andreas Sperlich¹, Carsten Deibel¹, and Vladimir Dyakonov^1,2 — ¹Experimental Physics VI, Physical Institute, Julius-Maximilians-University of Würzburg, D-97074 Würzburg — ²ZAE Bayern, Div. Functional Materials for Energy Technology, D-97074 Würzburg

For applications in polymer bulk heterojunction solar cells, the blend of the polythiophene P3HT and the fullerene electron acceptor material PCBM is one of the most promising model systems until now. On the way to industrial scale processing of solar cells from these materials, the stability issue and thus the understanding of degradation mechanisms due to environmental conditions is crucial. We study the light-induced creation of polymer:oxygen-charge transfer complexes in air-exposed P3HT with electron spin resonance, and simultaneously record the evolution of the photoluminescence quenching. We identify two separate photochemical processes leading to these results, and corroborate our findings with triplet-sensitive optically detected magnetic resonance (ODMR) measurements. Furthermore, we propose a protective effect of PCBM on P3HT through triplet quenching in organic solar cells.