Use of poly(phenyl quinoxaline) as an electron transport material in polymer light-emitting diodes

We report the use of a poly(phenyl quinoxaline) (PPQ) as an electron transporting conjugated polymer for electroluminescence (EL) applications. Single-layer PPQ devices with ITO anode and aluminium cathode show unipolar electron transport with current densities up to 60 mA/cm(2) but no emission. Two-layer structures combining PPQ as electron transport material with the hole transporting poly(2,5-dialkoxy-p-phenylene vinylene) (PDAOPV) show strong emission from the PDAOPV with brightnesses up to 250 cd/m(2). These two-layer structures have a maximum EL quantum efficiency of 0.35% which is ten-fold enhanced compared with the corresponding single-layer PDAOPV devices. (C) 1996 American Institute of Physics.