Regensburg 2016 – wissenschaftliches Programm

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CPP: Fachverband Chemische Physik und Polymerphysik

CPP 39: Focus: Triplet States in Organic Optoelectronics II

CPP 39.2: Vortrag

Mittwoch, 9. März 2016, 15:30–15:45, H37

Triplet state formation in polymer:fullerene bulk heterojunction blends — •Frédéric Laquai — Solar and Photovoltaics Engineering Research Center (SPERC), King Abdullah University of Science and Technology (KAUST), Thuwal 23955-6900, Kingdom of Saudi Arabia — Max Planck Institute for Polymer Research, Ackermannweg 10, 55128 Mainz, Germany

Triplet state formation is currently being discussed as a potential loss channel in state-of-the-art bulk heterojunction organic solar cells. However, the precise mechanism of triplet state formation, the relation between the material's chemical structure, film morphology and triplet state yield, and its impact on device performance is still unknown. Here, we present recent spectroscopic results obtained by a combination of fs-ms broadband transient absorption spectroscopy and multivariate curve resolution (MCR) data analysis on two prototypic low-bandgap donor-acceptor copolymers, namely PCPDTBT and its silicon-substituted analogue PSBTBT, in blends with fullerene as acceptor indicating that not only the respective energy levels, but also the solid-state morphology and interfacial structure of the blends influence triplet state formation. These studies have very recently been extended to other common donor polymers including DPP-based materials and PBDTTT-C blends, two systems for which we observe very high triplet yields and in the latter case also recreation of charges due to fast triplet-triplet annihilation on the ns-ms timescale.