Preparation of light-emitting devices with poly(p-phenylenevinylene): effects of thermal elimination conditions and polymer layer thickness on device performance

The optimum thermal elimination conditions for poly(p-phenylene vinylene) light-emitting diodes were sought. The precursor films should be heated to 230°C and kept at this temperature for 5 min under a N2 flow of 50 ml/min. By the heat treatment the degree of conversion to PPV was about 70%. A method determining the degree of conversion to PPV was proposed with IR measurement. About 8% of the THT resides in the fully converted PPV. A high external quantum efficiency of 0.0078% was achieved for the ITO/partially converted PPV/Al devices. The optimum thickness for the partially converted PPV layer as a electroluminescent was about 150 nm.