Blue and green-blue-variable light-emitting diodes based on the blend of polymer and organic molecules

Organic light-emitting diodes based on the blend of poly (p-phenylene vinylene) (PPV) derivative and naphthyl-imine–gallium complex have been fabricated by spin-coating method. Blue emission and blue-green variation depending on the ratio of the PPV derivative to the complex and the applied voltage have been observed. The investigation on PL (photoluminescence) and EL (electroluminescence) properties demonstrates that the improvement of the luminescent efficiency is related to the injection balance between holes and electrons, and the color variation is attributed to the variation of the recombination zone.