Electrochemistry and photoelectrochernistry of two donor-acceptor polythiophene polymers with acceptor moieties in the main chainстатья
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Дата последнего поиска статьи во внешних источниках: 7 ноября 2016 г.
Аннотация:The electrochemical, spectroelectrochemical and photoelectrochemical behavior was studied of two polymers of the polythiophene series containing electron-acceptor groups 1,10-phenanthroline and dimethylazine in the main chain. The polymers were obtained by electropolymerization of corresponding monomers, 3,8-bis(2,2'-bithien-5-yl)-1,10-phenanthroline (BT-phen) and 1,4-dimethyl-1,4-bis(2,2'-bithien-5-yl)-azine (BT-azine). It was shown that both polymers can undergo reversible anodic and cathodic doping in appropriate conditions. This was confirmed by using electrochemical impedance and in situ UV-vis absorption measurements. The optical bandgap values for both poly(BT-phen) and poly(BT-azine) were very close to that of the parent polymer, polybithiophene (PBT), while the electrochemical bandgap for poly(BT-azine) was 0.3-0.4 eV smaller than the electrochemical bandgap values for PBT and poly(BT-phen). A similar trend was derived from DFT calculations of the optimized geometry and electronic structure of corresponding oligomers. This was explained by the flexibility of the poly(BT-azine) backbone as compared to both PBT and poly(BT-phen), which facilitates the structural changes associated with the polymer doping. Both poly(BT-phen) and poly(BT-azine) exhibited cathodic photocurrents when illuminated in solution at negative potentials. The photoefficieney of these two polymers was found to be ca. 25% higher than the efficiency of non-modified polybithiophene, similarly to other donor-acceptor polythiophene polymers studied by us earlier.