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High Charge‐Carrier Mobility in π‐Deficient Discotic Mesogens: Design and Structure–Property Relationship
Author(s) -
Lehmann Matthias,
Kestemont Gaël,
Gómez Aspe Rafael,
BuessHerman Claudine,
Koch Michel H. J.,
Debije Michael G.,
Piris Jorge,
de Haas Matthijs P.,
Warman John M.,
Watson Mark D.,
Lemaur Vincent,
Cornil Jérôme,
Geerts Yves Henri,
Gearba Raluca,
Ivanov Dimitri A.
Publication year - 2005
Publication title -
chemistry – a european journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.687
H-Index - 242
eISSN - 1521-3765
pISSN - 0947-6539
DOI - 10.1002/chem.200400586
Subject(s) - thermotropic crystal , discotic liquid crystal , electron mobility , materials science , crystallography , charge carrier , liquid crystal , orthorhombic crystal system , columnar phase , phase (matter) , differential scanning calorimetry , cyclic voltammetry , side chain , chemistry , crystal structure , organic chemistry , liquid crystalline , electrochemistry , polymer , optoelectronics , electrode , physics , composite material , thermodynamics
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.