LIGHT-EMITTING-DIODES FROM PARTIALLY CONJUGATED POLY(P-PHENYLENE VINYLENE)

We report the effect of conversion conditions on the device characteri stics of poly(p-phenylene vinylene) (PPV) light-emitting diodes. Both electroluminescence and photoluminescence intensities decrease with in creasing degree of conversion. Partial conjugation enhances the electr oluminescence intensity and gives an efficiency (with Ca as electron-i njecting contact) as high as 0.75% photons per electron, about two ord ers of magnitude more efficient than from similar devices prepared fro m fully converted PPV. The results of constant current stress measurem ents suggest that the partially conjugated PPV diode is relatively sta ble at room temperature.