title: syn-/anti-Anthradithiophene derivative isomer effects on semiconducting properties.
abstract: Isomerically pure syn-/anti-anthradithiophene derivatives have been developed in the past few years. Although anti-isomers showed higher field-effect mobilities than mixture of isomers have been reported, a detailed comparison of syn-isomer and anti-isomer molecules has not been carried out. In this study, we took newly synthesized pure unsubstituted syn-/anti-anthradithiophenes (ADTs) and compared their single crystal structures, physical properties and semiconducting behavior with a previously studied syn-/anti-dimethylanthradithiophenes (DMADTs). Although the both isomers were typical herringbone packing structures with similar parameters, anti-isomers involved less disordered atoms in the crystal packing. The results from thermal analysis, UV-vis spectra, photo luminescence spectra and cyclic voltammograms of syn-/anti-anthradithiophenes were nearly the in the solid state as well as in solution. However, field-effect transistors showed obvious differences with mobilities of 0.12 cm(2) V(-1) s(-1) for anti-anthradithiophene and 0.02 cm(2) V(-1) s(-1) for syn-anthradithiophene. Because the crystallinity of thin-films measured by X-ray diffraction (XRD) and atomic force microscopy (AFM) seems to be better in syn-isomers, the differences in transistor performance are likely attributed to local defects affecting intermolecular interactions, such as disorder in the crystal packing and charge-dipole interactions.
authors.affiliation: Graduate School of Science and Engineering, Yamagata University , Yonezawa, Yamagata 992-8510, Japan.
authors.forename: Masashi
authors.initials: M
authors.lastname: Mamada
authors.forename: Hiroshi
authors.initials: H
authors.lastname: Katagiri
authors.forename: Makoto
authors.initials: M
authors.lastname: Mizukami
authors.forename: Kota
authors.initials: K
authors.lastname: Honda
authors.forename: Tsukuru
authors.initials: T
authors.lastname: Minamiki
authors.forename: Ryo
authors.initials: R
authors.lastname: Teraoka
authors.forename: Taisuke
authors.initials: T
authors.lastname: Uemura
authors.forename: Shizuo
authors.initials: S
authors.lastname: Tokito