title: A molecular design principle of lyotropic liquid-crystalline conjugated polymers with directed alignment capability for plastic electronics.
abstract: Conjugated polymers with a one-dimensional p-orbital overlap exhibit optoelectronic anisotropy. Their unique anisotropic properties can be fully realized in device applications only when the conjugated chains are aligned. Here, we report a molecular design principle of conjugated polymers to achieve concentration-regulated chain planarization, self-assembly, liquid-crystal-like good mobility and non-interdigitated side chains. As a consequence of these intra- and intermolecular attributes, chain alignment along an applied flow field occurs. This liquid-crystalline conjugated polymer was realized by incorporating intramolecular sulphur-fluorine interactions and bulky side chains linked to a tetrahedral carbon having a large form factor. By optimizing the polymer concentration and the flow field, we could achieve a high dichroic ratio of 16.67 in emission from conducting conjugated polymer films. Two-dimensional grazing-incidence X-ray diffraction was performed to analyse a well-defined conjugated polymer alignment. Thin-film transistors built on highly aligned conjugated polymer films showed more than three orders of magnitude faster carrier mobility along the conjugated polymer alignment direction than the perpendicular direction.
authors.affiliation: Macromolecular Science and Engineering, University of Michigan, Ann Arbor, Michigan 48109, USA.
authors.forename: Bong-Gi
authors.initials: BG
authors.lastname: Kim
authors.forename: Eun Jeong
authors.initials: EJ
authors.lastname: Jeong
authors.forename: Jong Won
authors.initials: JW
authors.lastname: Chung
authors.forename: Sungbaek
authors.initials: S
authors.lastname: Seo
authors.forename: Bonwon
authors.initials: B
authors.lastname: Koo
authors.forename: Jinsang
authors.initials: J
authors.lastname: Kim