Brightly fluorescent red organic solids bearing boron-bridged π–conjugated skeletons

Abstract

Two π-conjugated organoboron complexes 1 and 2 with highly efficient red (632 nm) and deep red (670 nm) solid-state fluorescence have been constructed and qualified as potential non-doped red emitters accompanied by excellent electron-transport ability. X-ray crystal analysis demonstrated that the two side phenyl groups coordinated to each boron atom effectively keep the luminescent units apart. As a result, these red fluorophores are brightly fluorescent in the solid state (fluorescence quantum yields: 0.30 for 1 and 0.41 for 2). In addition, these boron complexes possess good thermal stability and high electron-transport ability. Organic light-emitting diodes employing 1 or 2 as non-doped emitters with simple device configuration exhibit bright red and near-infared electroluminescence.