Electronic Properties of 1,2;8,9-Dibenzopentacene in Solutions, Solid Matrices, and Thin Films

The optical properties of 1,2;8,9-dibenzopentacene molecules in different environments, namely solutions, solid solutions, and thin films, focusing on the shift of the electronic levels as a function of the dielectric properties of the surrounding media are investigated. In all cases, we find that the optical gap of 1,2;8,9-dibenzopentacene is somewhat larger than that of pentacene (by ~0.21 eV in solution) in spite of the larger extent of the π-electron system in the former molecule. This a priori unexpected finding is rationalized on the basis of quantum-mechanical simulations.