Color-tunable polymeric light-emitting diodes based on blend of CN-PPV and PVK

Polymeric light-emitting diodes (LEDs) fabricated by sandwiching the blend of cyano-substituted poly(p-phenylene vinylene) (CN-PPV) and poly (N-vinyl carbazole) (PVK) between indium-tin oxide (ITO) and Al are reported. The emission color of the device is tunable. At lower applied voltage, the color is blue, mainly coming from PVK. As the voltage increases, the contribution from CN-PPV gradually increases, and the emission color red-shifts to orange but the electroluminescence intensity of the device decreases. The doping ratio of CNPPV to PVK has an effect on both the turn-on voltage and the ideality factor of the devices.