Polyfluorene copolymers containing 2,5-difluoro-1,4-phenylene chains and carbazole conjugates with 1,8-naphthalimides for stable blue OLEDs

Polyfluorene copolymers containing 33 mol% of 2,5-difluoro-1,4-phenylene units and other comonomers comprising chargetransporting triphenylamine, carbazole, and 1,8-naphthalimide groups were synthesized by the Suzuki polycondensation under microwave irradiation. On heating the obtained copolymers to 180°C, their photoluminescence spectra remain stable. The best sample herein obtained provided the OLED brightness of 2830 cd m^–2, current efficiency of 0.5 cd A^–1 and CIE coordinates of x = 0.168 and y = 0.228.