Design, Synthesis, and Photophysical Property of Strongly Fluorescent Benzofuran–Ethynylene Copolymer

A novel alternating benzofuran–ethynylene copolymer is designed and synthesized through a series of palladium‐catalyzed reactions, and extremely strong fluorescence is observed. The electronic levels of frontier orbitals are estimated by electrochemical and photophysical measurements for copolymer and corresponding monomers. The extension of π‐electron conjugation is shown after polymerization reaction, in which the energy of highest occupied molecular orbital (HOMO) is increased and that of the lowest unoccupied molecular orbital (LUMO) is decreased, simultaneously. The fluorescence quantum yield of this copolymer is as high as 75%, and time‐resolved fluorescence measurement confirms this intrinsic property. A preliminary optoelectronic device is fabricated to test the potential application of this copolymer as an emitting layer. In comparison with other known dibenzofuran‐based materials, moderate performance is obtained. The incorporation of a benzofuran group combining acetylene moiety in a polymeric skeleton provides a novel choice of highly fluorescent materials.