A heated tungsten (W) mesh, set between a pentacene source and a substrate in a vacuum chamber, was used to prepare a bulk-phase pentacene film and a pentacene-based organic semiconductor film. Since the pentacene molecules come into contact with the heated W mesh before reaching the substrate, their thermal energy is increased prior to deposition. As the mesh temperature was increased from 23 to 1200 degrees C, the intensity ratio of bulk to thin-film phases increased from 0 to 9.7. Above 1300 degrees C there is a notable decomposition reaction, the products of which were identified as dihydropentacene, p-distrylbenzene, and 2,2'-dimethyl-1,1'-binaphthalene. These decomposed precursors are expected to provide a potential source of large graphene sheets and graphene nanoribbons. (C) 2014 Elsevier B.V. All rights reserved.