Unique molecular arrangement in semiconducting layer and FET characteristics of thin film transistors based on 2,6-dialkylbenzo[1,2-b:4,5- b′]diselenophenes (C _n-BDSs)

2,6-Dialkylbenzo[1,2-2:4,5-b′]diselenophenes developed as soluble organic semiconductors gave a unique molecular arrangement in bulk single crystals, where π-stacking dimeric pairs and monorneric molecules are arranged in a similar manner to herringbone packing. Such unique structure was preserved in thin films on Si/SiO ₂ substrate, and the thin films fabricated by solution- or vapor-deposition acted as an active channel of field-effect transistors with mobility up to 8.4 × 10 ^-2 cm ^-2 V ^-1 s ^-1 for solution- and 2.3 × 10 ^-1 cm ^-2V ^-1 s ^-1 for vapor-processed devices, respectively.