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CPP: Chemische Physik und Polymerphysik

CPP 23: POSTER Functional Organic Thin Films

CPP 23.49: Poster

Donnerstag, 30. März 2006, 17:00–19:00, P2

Enhanced intersystem crossing in oligothiophene:fullerene blends — •R. Schüppel¹, T. Müller¹, C. Uhrich¹, A. Petrich¹, M. Pfeiffer¹, K. Leo¹, P. Kilickiran², E. Brier², and P. Bäuerle² — ¹Institut für Angewandte Photophysik, Technische Universität Dresden, Germany, www.iapp.de — ²Abteilung Organische Chemie II, Universität Ulm, Germany, www.uni-ulm.de/oc2

Photoinduced and transient absorption spectroscopy is used to study the excited state properties in thin films of Dicyanovinyl-terthiophene (DCV3T) and blends of DCV3T with fullerene C₆₀. We find an enhanced triplet exciton generation in the blend layer, which is explained as an excitonic “ping-pong”-effect: Singlet energy transfer from DCV3T to C₆₀, evidenced by sensitized emission of C₆₀, followed by immediate intersystem crossing on C₆₀ and triplet exciton back transfer. The rate constants involved into the certain energy transfer mechanisms are discussed in detail. Furthermore, we discuss the triplet exciton densities achieved by the pump laser irradiation including annihilation processes in the precursor singlet state to obtain the triplet diffusion length. Based on long-ranged triplet exciton diffusion in combination with efficient intersystem crossing, a promising new concept of solar cells with an enlarged active layer thickness is introduced.