Operating stability of light-emitting polymer diodes based on poly(p-phenylene vinylene)

We have developed modified poly(p-phenylene vinylene) (PPV) to improve its performance in organic electroluminescent devices. Encapsulated single-layer devices with this PPV on indium-tin oxide and a calcium cathode have been operated in air for > 7000 h at 20 degrees C and > 1100 h at 80 degrees C without noticeable degradation. Devices fabricated with this PPV, a conducting polymer layer as anode, and a sputtered low work-function alloy as cathode have efficiencies of over 2 lm/W, brightnesses of >600 Cd/m(2) at 4 V, and lifetimes of > 1400 h driven at similar to 100 Cd/m(2) initial brightness. (C) 1997 American Institute of Physics.