Synthesis, solid state properties, and semiconductor measurements of 5,6,11,12-tetrachlorotetracene

Tetrachlorotetracene is an organic semiconductor and has possible applications in flexible organic devices. We have synthesized tetrachlorotetracene in multigram quantities in three steps from commercially available substances, with an overall yield of 52%. X-ray crystallographic analysis of tetrachlorotetracene and its precursor dihydroxytetracenedione showed similar packing structures, with better pitch stacking and roll stacking angles observed for tetrachlorotetracene. Single crystals of tetrachlorotetracene are semiconducting with field effect hole mobility values up to 0.2 cm²/V s. The hole mobility has been measured in the temperature range of 230-290 K, and Arrhenius behavior was observed, with an activation energy of nearly 200 meV. Such a large activation energy suggests significant carrier trapping. Air stability studies showed slow degradation of the crystal surface by atomic force microscopy, along with degradation of the semiconducting properties. We hypothesize that the instability of tetrachlorotetracene to air is the result of decomposition to a quinone species, a degradation previously observed in solution phase studies.