Synthesis and Characterization of Some Donor-Acceptor Type Low Band Gap Polymers Based on Thiophene And Quinoxaline
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Date
2014-10
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Addis Ababa Universty
Abstract
A series of four low band gap, conjugated copolymers containing thiophene and quinoxaline were synthesized via palladium(0)-catalyzed Stille coupling polymerization reaction, with different alkoxy side chains. The synthesis started first by the preparation of the required monomers for the copolymerization reaction. The monomers were characterized by NMR, UV-Vis and IR spectroscopic techniques. The resulting copolymers were a dark purple solid and showed very good solubility in common organic solvents like chlorobenzene, o-dichlorobenzene, chloroform, THF and toluene. The synthesized copolymers were characterized by 1H-NMR, UV-Vis spectroscopy, Square wave voltammetry and cyclic voltammetry.
UV-Vis spectra of the polymers in a solution and in thin films indicated that there are two prominent absorption maxima around 350 and 550 nm in solution and around 367 and 596 nm in film, which are attributable to -* transition and intramolecular charge transfer at the backbone of copolymers, respectively. All the synthesized polymers have low band gaps around 1.74 eV, which were estimated from onset of UV-Vis spectra of thin films of the polymer. The electrochemical band gaps of the polymers were estimated from onset of square wave voltammograms and found to be around 2.0 eV.
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Some Donor-Acceptor Type Low Band Gap Polymers