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HL: Fachverband Halbleiterphysik

HL 30: Photovoltaics: Nanostructured materials

HL 30.1: Vortrag

Dienstag, 17. März 2015, 10:15–10:30, ER 164

Theoretical Study of Frenkel to Wannier-Mott Exciton Transition in a Molecular Dye Aggregate-CdSe Nanocrystal Arrangement — •Thomas Plehn¹, Dirk Ziemann¹, Jörg Megow², and Volkhard May¹ — ¹Institut für Physik, Humboldt-Universität zu Berlin, Newtonstraße 15, D-12489 Berlin, Germany — ²Institut für Chemie, Universität Potsdam, Karl-Liebknecht-Straße 24-25, D-14476 Potsdam, Germany

Transfer processes at hybrid organic-inorganic interfaces have become one of the key research topics. Theoretical studies are presented which give insight into the nature of energy transfer in a realistic molecular-semiconductor hybrid system. Transitions are described from Frenkel excitons in a gigantic tubular cyanin dye aggregate (about 60 nm length and 15 nm diameter) to Wannier-Mott excitons in a nearby placed CdTe nanocrystal (4.5 nm diameter). Despite the size of the system the whole investigation is based on a full atomistic picture. The structure of the tube and the nanocrystal are obtained by molecular dynamics simulations and a tight-binding model, respectively. The Frenkel excitons are described by coupled single molecular excited states and the Wannier-Mott excitons in terms of Coulomb correlated electron-hole pairs. FRET-type rates have been calculated for diverse spatial set-ups. Even brought into contact, the transfer stays incoherent (rates of about 1/k=1 ns). The suggested creation of hybrid excitons does not occur due to only weak coupling across the interface.