title: High charge-carrier mobility in pi-deficient discotic mesogens: design and structure-property relationship.
abstract: Hexaazatrinaphthylene (HATNA) derivatives with six alkylsulfanyl chains of different length (hexyl, octyl, decyl and dodecyl) have been designed to obtain new potential electron-carrier materials. The electron-deficient nature of these compounds has been demonstrated by cyclic voltammetry. Their thermotropic behaviour has been studied by means of differential scanning calorimetry and polarised optical microscopy. The supramolecular organisation of these discotic molecules has been explored by temperature-dependent X-ray diffraction on powders and oriented samples. In addition to various liquid crystalline columnar phases (Col(hd), Col(rd)), an anisotropic plastic crystal phase is demonstrated to exist. The charge-carrier mobilities have been measured with the pulse-radiolysis time-resolved microwave-conductivity technique. They are found to be higher in the crystalline than in the liquid crystalline phases, with maximum values of approximately 0.9 and 0.3 cm(2) V(-1) s(-1), respectively, for the decylsulfanyl derivative. Mobilities strongly depend on the nature of the side chains.
authors.affiliation: Laboratoire de Chimie des Polymères, CP 206/1, Université Libre de Bruxelles, Boulevard du Triomphe, 1050 Bruxelles, Belgium. matthias.lehmann@chemie.tu-chemnitz.de
authors.forename: Matthias
authors.initials: M
authors.lastname: Lehmann
authors.forename: Gaël
authors.initials: G
authors.lastname: Kestemont
authors.forename: Rafael
authors.initials: R
authors.lastname: Gómez Aspe
authors.forename: Claudine
authors.initials: C
authors.lastname: Buess-Herman
authors.forename: Michel H J
authors.initials: MH
authors.lastname: Koch
authors.forename: Michael G
authors.initials: MG
authors.lastname: Debije
authors.forename: Jorge
authors.initials: J
authors.lastname: Piris
authors.forename: Matthijs P
authors.initials: MP
authors.lastname: de Haas
authors.forename: John M
authors.initials: JM
authors.lastname: Warman
authors.forename: Mark D
authors.initials: MD
authors.lastname: Watson
authors.forename: Vincent
authors.initials: V
authors.lastname: Lemaur
authors.forename: Jérôme
authors.initials: J
authors.lastname: Cornil
authors.forename: Yves Henri
authors.initials: YH
authors.lastname: Geerts
authors.forename: Raluca
authors.initials: R
authors.lastname: Gearba
authors.forename: Dimitri A
authors.initials: DA
authors.lastname: Ivanov