SYNTHESIS, ELECTRICAL-CONDUCTIVITY AND ELECTROLUMINESCENCE OF POLY(P-PHENYLENE VINYLENE) PREPARED BY THE PRECURSOR ROUTE

We present a detailed experimental procedure for the synthesis of poly(p-phenylene vinylene) by the precursor route. Special emphasis is given to the conditions of the thermal elimination reaction that leads from the processable precursor polymer 4 to PPV. We found that a temperature of 320-degrees-C is necessary to remove sulphur and chlorine containing defect structures which are probably formed by nucleophilic substitutions during thermal elimination. PPV prepared by our procedure contains 0.12% of chlorine and 0.15% of sulphur. With this material we are able to prepare large area light emitting diodes (LED) which work at driving voltages as low as 2 Volts in an ITO/PPV/Al configuration. The low threshold results in an improved device performance: So a LED continuously driven with a current density of 20 mA/cm2 emits light for one week at ambient conditions and for more than four weeks if operated in a glove box at room temperature.