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 (Cn-BDSs)

2,6-Dialkylbenzo[l,2-b:4,5-b']diselenophenes developed as soluble organic semiconductors gave a unique molecular arrangement in bulk single crystals, where π-stacking dimeric pairs and monomeric 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 x 10 -2 cm 2 V -1 s -1 for solution- and 2.3 × 10 -1 cm 2 V -1 s -1 for vapor-processed devices, respectively.