Regensburg 2010 – scientific programme

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CPP: Fachverband Chemische Physik und Polymerphysik

CPP 27: Poster: Organic Electronics and Photovoltaics

CPP 27.1: Poster

Wednesday, March 24, 2010, 17:30–19:00, Poster C

Charge carrier pair dissociation in polymer:PCBM blends studied using light induced electron spin resonance. — •Tom J. Savenije^1,2, Andreas Sperlich¹, Hannes Kraus¹, Carsten Deibel¹, and Vladimir Dyakonov^1,3 — ¹Experimental Physics VI, Physical Institute, Julius-Maximilians-University of Würzburg, D-97074 Würzburg — ²Optoelectronic Materials Section, Department of Chemical Engineering, Delft University of Technology, Julianalaan 136, 2628 BL Delft, The Netherlands — ³ZAE Bayern, Div. Functional Materials for Energy Technology, D-97074 Würzburg

Blends of conjugated poly alkylsubstituted-thiophenes or thienothiophenes with a soluble fullerene (PCBM) show promising photophysical properties for application as photoactive layers in photovoltaic devices. On excitation of the polymer, fast electron transfer from the donor to the PCBM occurs leading to a charge carrier pair. For efficient charge collection dissociation of this radical pair is required. However, in view of the low dielectric constant of the blend the mechanism of the dissociation process is still unclear. Using light-induced electron spin resonance measurements we show that the geminate radical pair remains in close proximity at temperatures below ca 40 K. At higher temperatures delocalization of the positive charge on the polymer occurs, leading to an effectively larger radical pair distance.