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Suppression of Homocoupling Side Reactions in Direct Arylation Polycondensation for Producing High Performance OPV Materials

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journal contribution
posted on 15.12.2016, 13:50 by Junpei Kuwabara, Yohei Fujie, Keisuke Maruyama, Takeshi Yasuda, Takaki Kanbara
Suppression of side reactions in C–H direct arylation polycondensation is important for developing this method as a reliable synthetic tool for conjugated polymer materials. To find appropriate reaction conditions for avoiding homocoupling side reactions, two types of reaction conditions were investigated: the direct arylation of electron-rich C–H monomers in N,N-dimethyl­acetamide (DMAc system) and the direct arylation of electron-poor C–H monomers in toluene (toluene system). The investigation reveals that homocoupling side reactions are suppressed under the toluene system. Because the combination of electron-poor C–H monomer (acceptor) and electron-rich C–Br monomer (donor) is applicable to the toluene system, a donor–acceptor polymer without a defect structure can be synthesized under the toluene system. The obtained polymer shows almost same power conversion efficiency (PCE) in bulk-heterojunction OPVs as the same polymer prepared by a conventional method and purified by Soxhlet extraction. These results show that the established direct arylation polycondensation affords a high-quality material in terms of both structural integrity and purity. OPV cells with an optimized device structure result in a maximum PCE of 6.8%.