Computational methods are used recently as reliable tools to uncover the properties of novel conjugated organic materials and understand the physico-chemical mechanism that ultimately controls the overall organic-based device efficiency. Since modelling of charge transport across organic layers needs to address simultaneously single molecule properties together with electronic couplings between neighbouring molecules, which truly depends on the molecular packing, we employ dispersion-corrected Density Functional Theory methods to accurately extract key molecular parameters governing this phenomenon at the nanoscale. It is concluded that controlled functionalization (cyanation and/or halogenation) of state-of-the-art molecules (tetracene) is an efficient way to modulate the charge mobilities. (C) 2010 Elsevier B.V. All rights reserved.