Characterization of the molecular parameters determining charge transport in anthradithiophene

The molecular parameters that govern charge transport in anthradithiophene (ADT) are studied by a joint experimental/theoretical approach involving high-resolution gas-phase photoelectron spectroscopy and quantum-mechanical methods. The hole reorganization energy of ADT has been determined by an analysis of the vibrational structure of the lowest ionization band in the gas-phase photoelectron spectrum as well as by density-functional theory calculations. In addition, various dimers and clusters of ADT molecules have been considered in order to understand the effect of molecular packing on the hole and electron intermolecular transfer integrals. The results indicate that the intrinsic electronic structure, the relevant intramolecular vibrational modes, and the intermolecular interactions in ADT are very similar to those in pentacene.