Electronic properties of organic semiconductors and low-dimensional materials /

Zusammenfassung

Organic semiconductors became very interesting group of materials because of their good charge-transport properties and massive technological applications. Among all of them, rubrene gained grate interest because it is an organic semiconductor with the highest carrier mobility, which can reach 40cm2=V s for holes. Here we give a full firstprinciples description of the electronic properties and electron-phonon coupling (including Holstein and Peierls type of couplings) for the prototypical rubrene crystals. Thereby, a recipe for circumventing the issue of inaccuracies with low-frequency phonons is presented. Low dimensional compounds are known for having anisotropic physical properties and because of their low dimensionality, metallic properties and occurrence of structural modulations, these compounds are often discussed as possible Fermi surface driven CDW materials. However, the real origin of the CDWs in these materials has never been clarified. Thus we have decided to examine if some instability of the Fermi surface is at the origin of structural modulations in these compounds by studying the electronic structure and calculating the Lindhard response function for several low-dimensional materials.