Synthesis and properties of polyfluorenes containing 1,8-naphthalimide moieties for white electroluminescence

Two polyfluorenes containing 1,8-Naphthalimide units were synthesized by Yamamoto polycondensation reaction. The 1,8-naphthalimide moieties act as both electron and hole trap in the resulting polymers, leading to the EL spectra different from the PL spectra in film. White electroluminescence with a maximum brightness of 11100 cd/m2, an external quantum efficiency of 2.0% and CIE coordinates of (0.26, 0.36) has been realized through partial energy transfer from polyfluorene to 1,8-naphthalimide moieties.