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 giv en to the conditions of the thermal elimination reaction that leads fr om the processable precursor polymer 4 to PPV. We found that a tempera ture of 320-degrees-C is necessary to remove sulphur and chlorine cont aining defect structures which are probably formed by nucleophilic sub stitutions during thermal elimination. PPV prepared by our procedure c ontains 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 fo r one week at ambient conditions and for more than four weeks if opera ted in a glove box at room temperature.