Perfluoroalkyl-annelated conjugated systems toward n-type organic semiconductors

The syntheses of perfluoroalkyl-annelated conjugated units: hexafluorocyclopenta[c]thiophene, 4,4-difluoro-4H-cyclopenta[2,1-b:3,4-b']dithiophene, and 6,6,12,12-tetrafluoroindeno[3,2-b]fluorine, and these-containing oligomers have been accomplished. The annelation of the perfluoroalkyl groups effectively lowers the lowest unoccupied molecular orbitral (LUMO) energy levels without disrupting the effective conjugation of the backbones, which was unambiguously clarified by spectroscopic and electrochemical measurements as well as X-ray analysis. The perfluoroalkyl-annelated oligothiophenes exhibited n-type semiconducting behavior with field-effect electron mobility up to 0.018 cm(2) V-1 s(-1).