Synthesis And Characterization Of Conjugated Polymer Containing Bifluorenylidene Units

Recently, the low band-gap conjugated polymers receive more attention in the researchof conjugated polymer solar cells, for its high matching degree with the solar spectrum. It isreported in the literature that a novel low band-gap hydrocarbon polymer with high degrees ofpolymerization, which containing bifluorenylidene units exhibits a widely red shifted longestwavelength absorption maximum（λmaxof up to799nm）. Based on this design concept, aseries of conjugated polymers containing bifluorenylidene units are synthesised andcharacterized.The outline of the paper is shown as below:1. A series of novel monomers are designed and synthesised, which have thiol protectionon the9-position of the fluorene unit. With2-bromo-9,9-dioctyl fluorene and2,7-dibromo-9,9-dioctyl fluorene as the starting material, utilized the Suzuki coupling reaction, esterhydrolysis to synthesis the target monomer. Use of existing materials, according to themethod of literature, synthesised of indene and fluorene monomer whose fluorene unit9-position with thiol protection. Utilized the compounds with spiro structure to couple withfluorenone ester using Suzuki coupling reaction, and then fluorene unit9-thiol is synthesisedto obtain the target monomer.2. A series of conjugated polymers containing bifluorenylidene units are synthesized. Inthis paper, used chlorobenzene as the solvent, W(CO)6as the catalyst, synthesized the9-position of the fluorene unit with double bonds linked fluorene structure of polymers,through the coupling reaction of the thiol protected monomer. The polymers are soluable incommon solvents, which makes them processable in application. To determine the specificfunctional groups through testing the infrared spectra. UV absorption spectrum of the newpolymers including the polymer reported in the literature are tested, the maximum absorptionwavelength of freshly polymers up to445nm-495nm, the UV absorption in the film showsredshift when compared to the solution absorption; the thermodynamic properties are alsomeasured, the novel polymers synthesized in this paper have good thermal stability than the polymer reported in the literature. Testing the CV curve，to calculate the value of HOMO、LOMO、Band Gap.