INFLUENCE OF THE ELIMINATION TEMPERATURE ON LIGHT-EMITTING DEVICES PREPARED FROM POLY(P-PHENYLENE VINYLENE)

We report detailed measurements on the thermal conversion of the tetra hydrothiophene prepolymer to poly( p-phenylene vinylene) (PPV) and sho w the influence of the elimination conditions on the properties of PPV and on light emitting devices (LEDs) prepared in the configuration IT O/PPV/Al. Electroluminescence correlates with a diode behavior in the current-voltage characteristic and can be observed for PPV heated at a minimum temperature of 130 degrees C. Increase of the elimination tem perature results in a red-shift of both the photoluminescence and elec troluminescence spectra by approximate to 10 nm, which enables us to c ontrol the color of our LEDs in a small range. We have observed that r efered to the brightness of the devices the optimum elimination temper ature is 160 degrees C, and we show that a further increase of tempera ture does not improve the properties of PPV-LEDs.