Berlin 2018 – scientific programme

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HL: Fachverband Halbleiterphysik

HL 45: Organic photovoltaics and electronics

HL 45.1: Talk

Thursday, March 15, 2018, 15:00–15:15, EW 203

Excitons under the Microscope: Optical Observations in Organic Bulk Heterojunctions — •Martin Streiter, Alexander Wagenpfahl, and Carsten Deibel — Institut für Physik, Technische Universität Chemnitz, 09126 Chemnitz, Germany

Most properties of organic bulk heterojunction photovoltaic devices are influenced by energetic disorder in the film. In order to investigate the effects of local morphology and different molecular conformations causing energetic disorder, we investigated organic donor–acceptor films by confocal microscopy with variable excitation photon energies. At higher photon energies we measured photoluminescence lifetimes of neat donor materials accessing the exciton diffusion lengths by varying the acceptor concentration. At lower photon energies, we observed local radiative recombination at the interface of such bulk heterojunctions in order to determine the charge transfer ground state energy by combining photoluminescence and excitation spectroscopy measurements. The combination of optical measurements with different ranges of excitation energies provides insights into bulk heterojunction films at the micron scale.