Dresden 2011 – scientific programme

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CPP: Fachverband Chemische Physik und Polymerphysik

CPP 12: Organic Semiconductors II: Solar Cells B (jointly with HL, DS)

CPP 12.5: Talk

Tuesday, March 15, 2011, 11:45–12:00, ZEU 222

Influence of Phase Segregation on the Dynamics of Charge Carriers in Organic Solar Cells — •Andreas Baumann¹, Tom J. Savenije³, Dharmapura H. K. Murthy³, Martin J. Heeney⁴, Carsten Deibel¹, and Vladimir Dyakonov^1,2 — ¹Experimental Physics VI, Physical Institute, Julius-Maximilians-University of Würzburg, Am Hubland, D-97074 Würzburg — ²Bavarian Center for Applied Energy Research (ZAE Bayern), Am Hubland, D-97074 Würzburg — ³Optoelectronic Materials Section, Department of Chemical Engineering, Delft University of Technology, 2628 BL Delft, The Netherlands — ⁴Department of Chemistry, Imperial College London, London, SW7 2AZ, United Kingdom

The morphology of a bulk heterojunction solar cell plays an important role in the dynamics of charge carriers, whereas the donor–acceptor ratio have a great impact on the extent of phase segregation. A fine phase intermixing is believed to be beneficial for an efficient photogeneration. However, the charge transport is strongly related to percolated pathways to the electrodes. We studied the influence of phase segregation on the dynamics in the blend system poly(2,5-bis(3-dodecyl thiophen-2-yl) thieno[2,3-b]thiophene) (pBTCT) mixed with [6,6]-phenyl-C61-butyric acid methyl ester. We used the technique of charge extraction by linearly increasing voltage and transient microwave conductivity to study the macroscopic and microscopic transport properties, respectively. We found an enhanced geminate recombination in the 1:1 ratio blends due to fine phase intermixing, whereas extensive phase segregation in the 1:4 ratio led to an efficient polaron pair dissociation.