The Synthesis, Electronical Structure And Photoelectric Properties Of Some Polyfluorene Derivatives

In the development of polymer light-emitting diodes, blue light emission is of particular importance. The polyfluorenes(PFs), as blue emitters, are the most promising materials due to their high photoluminescence (PL) and electroluminescence (EL) efficiency and good thermal stability.In Charpter 2, we had synthesized a series of seven fluorene-based copolymers that contains stable twisted units in polymer mainchains using the Suzuki coupling reaction which exhibited highly efficient ultraviolet photoluminescence (PL). The PDHFSCHD and PDHFDBO both exhibited higher optical bandgaps than PDHF and highly efficient ultraviolet emissions. The spectral properties, fluorescence decay and electrochemistry data indicated that twisted biphenyl compound was an efficient segment to tailor the bandgap of conjugated polymer, which exhibited obvious potential for luminescence-based applications especially for the ultraviolet emitting devices. The structures, ionization potentials (IPs), electron affinities (EAs), and HOMO-LUMO gaps of the oligomers were studied by the density functional theory with B3LYP functional. The outcome showed that the dramatically twisted structure of PDHFDBO in the seven-membered ring results in the decreased conjugation in the...