Molecular packing and charge transport parameters in crystalline organic semiconductors from first-principles calculations.

The generation of mobile charges and their transport across organic layers are commonly the most critical steps affecting the performance of organic-based electronic devices. Charge-transport properties are often described by quantum-chemical calculations which, however, face a challenge when the nanostructure of the material has to be concomitantly addressed together with electronic aspects. We tackle here this challenging task by applying dispersion-corrected Density Functional Theory methods, which allow us not only to give an insight into the molecular packing but also to accurately extract key molecular parameters governing charge transport. When applied to a set of functionalized (chlorinated) tetracene molecules, our approach yields the expected molecular packing, which has motivated its use to predict the packing of other fluorinated or brominated derivatives which are not yet synthesized. The charge mobilities have been calculated on the basis of the determined packing motifs and exhibit significant differences among the derivatives. This work paves the way towards the development of a computational protocol that could be implemented not only for idealized packing motifs or known crystallographic structures but also for self-organizing materials as well as supramolecular and host-guest interactions.