Influence of substitution on the optical properties of functionalized pentacene monomers and crystals: Experiment and theory

The influence of solubilizing substitutional groups on the electronic structure of prototypical functionalized pentacene molecules and crystals is studied by a combined experimental and theoretical approach. We experimentally establish characteristic effects of substituents on the electronic structure and relate those to theoretical optical spectra in order to explain the experimental results and provide a comprehensive picture of the substitution effects. Bands associated to C/Si atoms connecting the functional side group to the pentacene in the (6, 13)-positions are the main contributors to the optical transitions. The amplitude of the redshift between the crystals and molecules provides insight in the packing structure.