Synthesis, Characterization of Low Band Gap Quninoxaline-Based Conducting Polymer Containing Different Side Chain and Main Chain Moeities
Date Issued
2009
Date
2009
Author(s)
Hsu, Wei-Chun
Abstract
Two-dimensional donor-acceptor (D-A) structured conducting polymers, PHQT, PFQT, PFQT2, PFQT3, were designed and synthesized by introducing electron-deficient quinoxaline (acceptor) as core with electron-rich alky-fluorene or 4-hexylbenzene as its side chain and thiophene/oligo-thiophene (donor) in the main chain. Benefited from the D-A structures, the polymers possess low bandgaps with energies of 1.79 eV, 1.85 eV, 1.89 eV, and 1.76 eV for PHQT, PFQT, PFQT2, PFQT3, respectively, and show a broad absorption band in the visible region: the shoter wavelength absorption peak at ca. 300 nm~400 nm attributed mainly to the conjugated side chains and the longer wavelength absorption peak (charge transfer CT peak) between 500 nm and 700 nm ascribed to the absorption of the conjugated D-A main chains. The polymers are electrochemically active in oxidation and the corresponding cyclic voltammetry (CV) measurements show that the HOMO level of the polymers is ca. -5.31 eV~ -5.13 eV which is significantly lower than that of the conventional and most studied conducting polymer of poly 3-hexyl thiophene (P3HT). Powder X-ray diffraction analysis confirms that monodispersed PFQT shows a crystalline order plane of (100). The TGA analysis reveals that the temperature at which all polymers degrades was higher than 400 ℃. In summary, these polymers show potential for use as an active material in optoelectronic devices.
Subjects
conducting polymer
donor-acceptor
low band gap
charge transfer
quinoxaline
Type
thesis
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