Dresden 2009 – wissenschaftliches Programm
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CPP: Fachverband Chemische Physik und Polymerphysik
CPP 43: New Materials
CPP 43.1: Vortrag
Freitag, 27. März 2009, 10:30–10:45, ZEU 114
Electronic Properties of Conjugated Fullerenes using O-, NH-, or CH2-Groups as Bridges — •Markus Reinmöller1,2, Uwe Ritter1, Erich Runge2, and Wichard J. D. Beenken2 — 1Technische Universität Ilmenau, Institut für Physik, FG Chemie, Deutschland — 2Technische Universität Ilmenau, Institut für Physik, FG Theoretische Physik I, Deutschland
We performed quantum-chemical calculations by DFT methods on C60 molecules connected by several conjugated bridges formed by –O– , –NH–, or –CH2– groups. For the optimized structure, we obtain regularly an inter-fullerene-bond (C–C) near the bridging group. Both together form furane-, pyrrole-, or cyclopentane-rings. These molecules were compared with oligo-fullerenes directly connected by two C–C bonds, i.e., where the bridge is cyclobutadien-like. All fullerenes conjugated in the described way exhibit highest occupied molecular orbitals (HOMOs) that are anti-binding regarding the π-system on the bridge. The lowest unoccupied molecular orbital (LUMO) is non-binding in this respect; whereas some unoccupied MOs higher in energy are found to be binding over the bridges and consequently delocalized over the whole chain. These states are of some interest for effective band-like electron transport in conjugated fullerenes. Therefore, we determined the energetics of the localized and delocalized MOs in dependence of the number of conjugated C60 molecules to examine the structure of an evolving conduction-band. Furthermore, we studied the optically excited states by time-dependent DFT in order to get some insights about possible photo-conduction.