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SYOP: Symposium Organic Photovoltaics: From Single Molecules to Devices

SYOP 4: Organic Photovoltaics: from Single Molecules to Devices

SYOP 4.50: Poster

Donnerstag, 26. März 2009, 16:30–19:00, P1A

Unsymmetrically substituted n-type perylene bisimides with liquid crystalline properties — André Wicklein and •Mukundan Thelakkat — Universität Bayreuth, Applied Functional Polymers, Universitätsstrasse 30, 95440 Bayreuth (Germany)

Perylene bisimides (PBIs) represent an important class of organic n-type semiconductors exhibiting a relatively high electron affinity among large-band-gap materials. Herein synthesis and characterization of several unsymmetrical N-substituted PBI dyes is presented and the thermotropic behavior, which is strongly affected by the respective N-substituents was investigated. Two different series of highly soluble and fluorescent derivatives have been synthesized: (1) PBIs bearing swallow-tailed alkyl chains, different in size or (2) one swallow-tailed alkyl chain and one branched oligoethylenglycolether. Synthesis of these PBIs is generally feasible by two distinct divergent synthesis approaches. Thermotropic behavior was studied by DSC, POM and XRD measurements. Inherent π-π interactions between cofacially orientated perylene molecules and the elliptic shape of the molecule favor the ordering in columns and self-organized architectures. Among them hexagonal columnar CoIh mesophases, large spherulitic crystals or formation of stable amorphous phases upon rapid cooling from the isotropic phase can be observed. Due to high solubility in organic solvents, film preparation by solution processing is readily feasible. The interesting optical and thermal properties of these compounds allow these organic n-type semiconductors as potential materials for application in organic electronic devices, such as photovoltaics or OFETS.