Blue emitting fluorophores of phenyleneethynylenes substituted by diphenylethenyl terminal groups for organic light-emitting diodes

Phenyleneethynylene motifs substituted by diphenylethenyl groups at both ends were prepared successfully by use of double elimination protocol of β-substituted sulfones for introducing phenyleneethynylene arrays followed by Wittig-Horner reaction for introducing diphenylethenyl moiety. The hybrid blue fluorophores exhibited strong emission even in the solid-state films (Φ_F ≧ 0.60) while, in CHCl₃ solution, incorporation of substituents on the central phenylene unit significantly enhanced emission efficiency up to Φ_F = 0.57. The OLED devices with use of these blue fluorophores as an emitting material provided maximum external quantum efficiency of η_ext = 2.4%.