Synthesis and Thermoelectric Properties of Polycarbazole, Polyindolocarbazole, and Polydiindolocarbazole Derivatives
ABSTRACT In a quest for thermoelectric polymeric materials novel polycarbazole and polyindolocarbazole derivatives were synthesized. Alkyl side chains on the carbazole cycle and different side chains (alkyl or benzoyl) on the nitrogen atom of the backbone unit were introduced. Optical, electrochemical, electrical, and thermoelectric properties were investigated on these polymers and on two poly(diindolocarbazole)s. Band structure calculations were used to predict which polymers might be promising as thermoelectric materials. The best combination of Seebeck coefficient and conductivity (power factor) was around 10-7 W m-1 K-2 with copolymers comprising thiophene units alternating with carbazole or indolocarbazole. This family of polymers possesses good Seebeck coefficients, but there is still a need to improve the electrical conductivity, to produce useful thermoelectric materials.
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ABSTRACT: The synthesis, characterization, and field-effect transistor (FET) properties of new indolo[3,2-b]carbazole (IC) based materials are reported. Instead of adding the long alkyl chains on the nitrogen atoms of the IC backbone like many other IC-based molecules, they were added at both ends of the molecule (octylthiophene, p-octylbenzene). Also, the amine groups on the IC backbone were either free or protected by methyl groups. The impact on the organization and thin-film morphology showed that the molecules stand perpendicular to the surface as demonstrated by XRD and AFM. The highest hole mobility obtained by these new p-type organic semiconductors was 0.22 cm2 V−1 s−1 with an on/off ratio of about 105. The best performance was obtained with 3,9-di(p-octylbenzene)-5,11-dihydroxyindolo[3,2-b]carbazole. This performance is one of the best obtained by both IC derivatives and materials containing a secondary amine on the backbone.Journal of Materials Chemistry 01/2009; 19(19). · 5.97 Impact Factor
- Journal of Polymer Science Part A Polymer Chemistry 01/2009; 47(15):3880-3891. · 3.54 Impact Factor
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ABSTRACT: Novel copolymers containing the indolo[3,2-b]carbazole (INC) moiety were synthesized, and the effects of the INC content on their physical properties were investigated. The homopolymer of the INC-containing monomer, 1-octyl-7-(4-vinylbenzyl)indolo[3,2-b]carbazole and copolymers with styrene were prepared by radical polymerization. Four kinds of copolymers with different compositions were obtained. The glass transition temperatures (Tgs) were observed in the range of 101–112 °C, and the decomposition temperatures were nearly 400 °C. The photonic properties of the copolymers were also evaluated in solution in tetrahydrofuran and for spin-coated films on a fused silica substrate. In the ultraviolet-visible absorption spectra, maximum absorption peaks were observed at 340–345 nm in both the solutions and the films. In the case of the solutions, the photoluminescence intensities of the copolymers increased with increasing INC monomer units in the copolymer. On the contrary, the photoluminescence intensities of the copolymer films decreased with increasing INC content in the copolymer, which is likely due to the concentration quenching caused by the condensation of intermolecular interactions derived from INC components. The copolymer with a low content of the INC moiety exhibited high emission and good film-forming ability.Keywords: fluorescence; indolocarbazole; polystyrene; radical copolymerizationPolymer Journal 11/2011; 43(12):959-965. · 1.50 Impact Factor