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

We report an efficient electroluminescent device using a binaphthalene-cont aining polymer as the emissive layer and a fluorinated copper phthalocyanin e as the electron injecting/transporting layer. The structural feature of t his polymer is a twisted, nonplanar backbone with two hexyloxy side groups. The energy levels for the highest occupied molecular orbital and the lowes t unoccupied molecular orbital of this polymer were -5.71 and -2.38 eV as d etermined by cyclic voltammetry and ultraviolet-visible measurements. A lig ht-emitting diode with aluminum electrode exhibited high brightness (9400 c d/m(2) at 24.3 mA/cm(2)), excellent luminous efficiency (4.9 lm/W), and a l arge external quantum efficiency (2.0%). (C) 1999 American Institute of Phy sics. [S0003-6951(99)00850-5].