Synthesis and characterization of spiro-linked poly(terfluorene): a blue-emitting polymer with controlled conjugated length

Abstract

The synthesis and characterization of a fluorene-spirobifluorene alternating copolymer, P(OF-SBF), are described. In the case of the spiro-segment, the two fluorene rings are orthogonally arranged and connected through a tetrahedral bonding carbon atom ( the spiro center). As a consequence, the polymer chain periodically zigzags, with an angle of 90degrees at each spiro center. This structural feature not only preserves the rigidity of the polymer chain but also prevents the pi-stacking of the polymer backbone, resulting in an improvement in both thermal and spectroscopic stabilities. Comparing the absorption and emission spectra of P(OF-SBF) and of a terfluorene model compound, it was revealed that P(OF-SBF) possesses a well-defined conjugation length. The polymer can serve as a host matrix to effectively transfer its excitation energy to a derivatized perylene dopant, yielding an efficient blue-light-emitting layer.