Alkyl esters, imides and imido-esters of coronene-tri-, -tetra- and -octacarboxylic acids are accessible by a twofold oxidative benzogenic Diels-Alder reaction. Alkyl acrylates add to perylene, and maleic alkyl imides react twice with perylene as well as with perylene-tetracarboxylic tetraesters. Coronenes substituted with a greatly variable number of electron-withdrawing substituents are thus accessible, and di- and tetraimide derivatives are shown to be very pronounced electron-acceptor materials. The tri- and tetraalkyl esters and imidoesters self-assemble into columnar liquid-crystalline phases.

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Columnar liquid crystals are useful for the construction of organic light emitting diodes (OLED) due to their high charge carrier mobility and their ability of developing defect-free superstructures. We investigated the electroluminescent properties of various mesogenic derivatives of triphenylene, pyrene, perylene, benzoperylene and hexa-perihexabenzocoronene (HBC) which combine good charge carrying properties and luminescence. The wavelengths of maximum electroluminescence range from about 400 nm to 720 nm, depending on the core and the substitution of the molecules. Nearly white emission can be obtained in samples containing two or more emitting layers. The perylene core is so efficient that even a single organic layer between an ITO anode and an aluminum cathode can give luminance values up to 100 cd/m 2 . In addition to the electroluminescence, we present results on the photovoltaics in hetero junction structures of the compounds. Samples with two organic layers made of a HBC-and a perylene derivative show an open circuit voltage V oc of about 0.8 V, a short circuit current I sc of a few µA/cm 2 , and a filling factor FF of approximately 31 %.