We report the effect of conversion conditions on the device characteristics of poly(p-phenylene vinylene) (PPV) light-emitting diodes. Both electroluminescence and photoluminescence intensities decrease with increasing degree of conversion. Partial conjugation enhances the electroluminescence intensity and gives an efficiency (with Ca as electron-injecting contact) as high as 0.75% photons per electron, about two orders of magnitude more efficient than from similar devices prepared from fully converted PPV. The results of constant current stress measurements suggest that the partially conjugated PPV diode is relatively stable at room temperature.
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