Substituted
pentacene compounds comprise at least one
substituent selected from the group consisting of
electron-donating substituents,
halogen substituents, and combinations thereof; the
substituent(s) each being bonded to a
carbon atom of a terminal ring of
pentacene, and being the only
substituent(s); with the proviso that when the compound has only two substituents, both of which are methyl or alkoxy, and one substituent is bonded to the number 2
carbon atom, the other substituent, if methyl, is bonded to the number 1, 3, 4, 8, or 11
carbon atom and, if alkoxy, is bonded to the number 1, 3, 4, 8, 9, or 11 carbon atom; and with the further proviso that when the compound has only four substituents, all of which are alkoxy, the substituents are bonded to the numbers 2, 3, 9, and 10 carbon atoms.