INFLUENCE OF FABRICATION PROCESS ON THE PERFORMANCE OF LIGHT-EMITTING-DIODES

We have investigated the influence of device fabrication process on th e performance of poly (p-phenylene vinylene) (PPV) and poly (N-vinyl c arbazole) (PVK) blended with triphenylamine (TPA) (PVK:TPA)-based ligh t-emitting diodes by constructing various devices with different struc tures and treated under different conditions. Thermal treatments make modifications to the contacts, affect the electrical properties of the polymer, change the rectification ratio by orders of magnitude, and a ffect the efficiency of the devices. Partially converted PPV improved the efficiency due to short conjugated length, but results in the stab ility of the devices to be compromised. Structure of PVK:TPA/PPV unbal ances the injection of holes and electrons, but lowers the turn-on vol tage.