Supramolecular Organization in Fluorene/Indenofluorene– Oligothiophene Alternating Conjugated Copolymers

Authors


  • The collaboration between Mons and Mainz is conducted in the framework of the InterUniversity Attraction Pole Program (PAI V/3) of the Belgian Science Policy Office. Research in Mainz is supported by the Deutsche Forschungsgemeinschaft (Schwerpunktprogramm Organische Feldeffekttransistoren SFB 625). Research in Mons is partly supported by the European Commission, the Government of the Region of Wallonia (Phasing Out—Hainaut), and the Belgian National Fund for Scientific Research FNRS/FRFC. M.S. acknowledges F.R.I.A. for a doctoral scholarship. P.L. is a Research Associate of F.N.R.S. (Belgium).

Abstract

A series of conjugated copolymers containing fluorene or indenofluorene units alternating with oligothiophene segments, with potential interest for use as the active layer in field-effect transistors, is investigated. Atomic force microscopy analysis of the morphology of thin deposits shows either the formation of fibrillar structures, which are the signature of long-range π stacking, or the presence of untextured aggregates, resulting from disordered assembly. These morphologies are interpreted in terms of the supramolecular organization of the conjugated chains. Molecular modeling simulations indicate that the commensurability between the lengths of the monomer units and the presence of alkyl side groups are the two key structural factors governing the chain organization into highly ordered assemblies. The most favorable structures are those combining fluorene (indenofluorene) units with unsubstituted bithiophene (terthiophene) segments.

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