π-Conjugated compounds such as polyphenylenes, polyacetylenes, polythiophenes, and polyacenes have attracted much attention as organic conductive materials. 1 Among them, polyacenes have a very low band gap (0.1-0.5 eV) 2 compared with polyacetylenes (1.4 eV), and polythiophenes (1.71 eV). 1, 2 Therefore, polyacenes have been widely recognized as a promising and useful organic conductive material. 2 In fact, recently, pentacene has ...