Efficient light-emitting diodes based on a binaphthalene-containing polymer

We report an efficient electroluminescent device using a binaphthalene-containing polymer as the emissive layer and a fluorinated copper phthalocyanine as the electron injecting/transporting layer. The structural feature of this polymer is a twisted, nonplanar backbone with two hexyloxy side groups. The energy levels for the highest occupied molecular orbital and the lowest unoccupied molecular orbital of this polymer were −5.71 and −2.38 eV as determined by cyclic voltammetry and ultraviolet-visible measurements. A light-emitting diode with aluminum electrode exhibited high brightness (9400 cd/m2 at 24.3 mA/cm2), excellent luminous efficiency (4.9 lm/W), and a large external quantum efficiency (2.0%).