Charge Transport in Functionalized Fluorinated Pentacenes

We report on charge transport in fluorinated functionalized pentacenes and discuss the effect of trialkylsilyl and the number of fluorine atoms. We show that modifications in the chemical composition influence the molecular packing, crystal formation and electrical properties, allowing us to measure mobilities from 10$^{-5}$ to 1.7 cm$^{2}$/Vs. The mobilities correlate with the packing, demonstrating that tuning the solid-state order to induce pi-stacking improves electrical properties. By combining Raman measurements with theoretical calculations predicting the vibrational spectrum, we explore the vibrational modes of the crystals, providing information about the intermolecular coupling and electron-phonon interactions governing charge transport. We calculate the intermolecular electronic couplings and band structures by using density functional theory, and study the effect of fluorination and trialkylsilyl substitution on crystal packing and the electronic properties.