Furan as one of the most important heteroaromatic compounds is widely studied in organic chemistry but less developed as a building block in semiconducting polymers. Its unique properties provide many advantages when furan building blocks are introduced in different positions of polymer chains. Compared with the thiophene units in traditional benzo[1,2-b:4,5-b']dithiophene (BDT) polymers, furan segments display weaker steric hindrance to the adjacent units due to the smaller oxygen atom. Consequently, polymers containing benzo[1,2-b:4,5-b']difuran (BDF) are expected to generate more planar polymer backbone which can further increase conjugation length and optimize p-p stacking. The oxygen atom in furan has higher electronegativity than sulfur. Thus, the furan units as conjugated side chains in the BDT/BDF polymers offer an opportunity to tune the HOMO/LUMO level and the band gap. Semiconducting polymers with adjusted band gaps and improved optoelectronic properties could be envisioned by selectively placing the furan building block in different positions of the monomer structures. As many as four variations of the BDT framework can be synthesized by placing the furan units at different positions. Furthermore, it has been shown that the furan moiety could increase the solubility of polymers. The solvent processability of organic semiconducting materials will thus be enhanced by the furan building block as well.Donor-Acceptor alternative copolymers were synthesized by Stille coupling polymerization of stannylated 4,8-Bis(5-dodecylfuran/thiophene)benzo[1,2-b:4,5,b']difuran/thiophene as electron donors with 1-(4,6-dibromothieno[3,4-b]thiophen-2-yl)octan-1-one as electron acceptor in this work. Perpendicular p-conjugation with furan or thiophene created different electron distributions on the electron donor, leading to a variation in the HOMO/LUMO energy levels of the synthesized polymers. Physical and electrochemical properties of these four semiconducting polymers containing furan building block were investigated. These donor-acceptor polymers were tested in organic thin film transistors and polymer-PCBM bulk heterojunctin solar cells

Synthesis of novel benzodifuran semiconducting polymers and systematic studies on furan building block in optoelectronic applications

247th National Meeting (2014)

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