Electrochemistry and electron transport properties of copolymers of electron deficient fluorenes with thiophene

Copolymers of fluoren-9-one and (fluoren-9-ylidene)malononitrile with thiophene have been prepared by the electrochemical polymerization of 2-(2-thienyl)fluoren-9-one, 2,7-di(2-thienyl)fluoren-9-one, and (2,7-di(2-thienyl)fluoren-9-ylidene)malononitrile. 2-(2-Thienyl)fluoren-9-one gave polymer films...

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Bibliographic Details
Published in:Electrochimica acta 2007-04, Vol.52 (14), p.4685-4690
Main Authors: Loganathan, Kavithaa, Pickup, Peter G.
Format: Article
Language:English
Subjects:
Applied sciences
Band gap
Conjugated copolymer
Electrical, magnetic and optical properties
Electron transport
Exact sciences and technology
Fluorene
n-Doping
Organic polymers
Physicochemistry of polymers
Properties and characterization
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Summary:Copolymers of fluoren-9-one and (fluoren-9-ylidene)malononitrile with thiophene have been prepared by the electrochemical polymerization of 2-(2-thienyl)fluoren-9-one, 2,7-di(2-thienyl)fluoren-9-one, and (2,7-di(2-thienyl)fluoren-9-ylidene)malononitrile. 2-(2-Thienyl)fluoren-9-one gave polymer films with low conjugation lengths, indicating poorly defined coupling, while both monomers with two terminal thiophenes gave high quality copolymers. Poly-[2,7-di(2-thienyl)fluoren-9-one] was the most easily p-doped material, and gave the highest p-type conductivity of ca. 0.4 mS cm −1. In contrast poly-[(2,7-di(2-thienyl)fluoren-9-ylidene)malononitrile] was more easily reduced by over 0.5 V (formal potential = −0.60 V versus Ag/AgCl), and exhibited the higher n-type conductivity of ca. 6 μS cm −1. Comparisons between the three copolymers reveal differences in the mechanisms of p-type and n-type conduction, with the former dominated by hole transport along the polymer chains and the latter involving electron hopping between localized sites.
ISSN:0013-4686
1873-3859
DOI:10.1016/j.electacta.2007.01.002