Berlin 2012 – scientific programme

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CPP: Fachverband Chemische Physik und Polymerphysik

CPP 6: Poster: Structural Ordering and Electronic Transport (joint focus with HL)

CPP 6.20: Poster

Monday, March 26, 2012, 17:30–19:30, Poster A

Influence of Nongeminate Recombination on the Field-Dependence of the Photocurrent in Organic Solar Cells — •Ian Howard, Ralf Mauer, and Frédéric Laquai — Max Planck Institute for Polymer Research, Mainz

The role of interfacial charge-transfer (CT) states in determining the bias dependence of the photocurrent in Organic Solar Cells is debated. Understanding the bias dependence of the photocurrent is necessary to optimize device fill factors, and therefore resolution of this debate is important. In this contribution we directly determine the field dependence of bimolecular recombination at the charge densities relevant to photovoltaic devices using a novel optical pump electrical probe experiment that enables the ultra fast time resolution of optical spectroscopy to be combined with high signal to noise achievable in current measurements.[1] We relate these results to temperature dependent transient absorption (pump-probe) spectroscopy over the entire relevant timescale from femtoseconds to milliseconds [2] We conclude that in the benchmark polythiophene:methanofullerene system nongeminate recombination plays a dominant role in determining the bias dependence of the photocurrent.

[1] R. Mauer, I.A. Howard, F. Laquai, J. Phys. Chem. Lett. 2011, 2 (14), 1736-1741.

[2] R. Mauer, I.A. Howard, F. Laquai, J. Phys. Chem. Lett. 2010, 1 (24), 3500-3505.