Dresden 2006 – scientific programme
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CPP: Chemische Physik und Polymerphysik
CPP 23: POSTER Functional Organic Thin Films
CPP 23.49: Poster
Thursday, March 30, 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.