Stabilization of electrode migration in polymer electroluminescent devices

A thin 3-nm-thick parylene layer is deposited by chemical vapor deposition at room temperature on the indium tin oxide (ITO) coated glass substrate to form a bilayer anode of an organic light emitting diode. The parylene layer forms a conformal film to cover the spikes present in the ITO film. This parylene film presents a smoother surface to the subsequent organic layers. The parylene film not only reduces the occurrence of dark spots, acting as a barrier for oxygen diffusion from either the ITO or from the atmosphere and stabilizing the migration of the electrodes during electrical stress, but also improves the injection of holes from the anode. By inserting another parylene layer in between the organic and cathode layers, the probability of formation of nonemissive areas is further reduced. (C) 2002 American Institute of Physics.