title: Enhanced photogeneration of triplet excitons in an oligothiophene-fullerene blend.
abstract: Photoinduced and transient absorption spectroscopy is used to study triplet exciton dynamics in thin films of a new thiophene-based oligomer (DCV3T) and blends of DCV3T and fullerene C60. We find enhanced DCV3T triplet exciton generation in the blend layer, which is explained as an excitonic ping-pong effect: singlet energy transfer from DCV3T to C60, followed by immediate intersystem crossing to C60, and triplet exciton back-transfer. Estimations of the rate constants involved show that the ping-pong effect has an overall efficiency close to unity. The singlet-singlet energy transfer from DCV3T to C60 is demonstrated by efficient quenching of DCV3T luminescence in the blend, leading to sensitized emission of C60. We discuss a promising new concept of solar cells with an enlarged active-layer thickness based on potentially long-ranged triplet exciton diffusion in combination with efficient intersystem crossing.
authors.affiliation: Institut für Angewandte Photophysik, Technische Universtität Dresden, Germany. rico.schueppel@iapp.de
authors.forename: R
authors.initials: R
authors.lastname: Schueppel
authors.forename: C
authors.initials: C
authors.lastname: Uhrich
authors.forename: M
authors.initials: M
authors.lastname: Pfeiffer
authors.forename: K
authors.initials: K
authors.lastname: Leo
authors.forename: E
authors.initials: E
authors.lastname: Brier
authors.forename: E
authors.initials: E
authors.lastname: Reinold
authors.forename: P
authors.initials: P
authors.lastname: Baeuerle