LUMINESCENCE ENHANCEMENT BY THE INTRODUCTION OF DISORDER INTO POLY(P-PHENYLENE VINYLENE)

A method is described for increasing luminescence in poly(p-phenylene vinylene) (PPV) light-emitting diodes. Cis linkages were engineered in to the PPV chain. These linkages interrupt conjugation and interfere w ith the packing of the polymer chains, which results in the formation of amorphous PPV. Large-area electroluminescent devices were prepared from this polymer, Devices made of an aluminum electrode, PPV as the l uminescent layer, and an electron-transporting layer have internal qua ntum efficiencies of 2 percent, a turn-on voltage of 20 volts, and can carry current densities of 2000 milliamperes per square centimeter. T he current density is at least an order of magnitude higher than previ ously obtained.