Water vapor and oxygen degradation mechanisms in organic light emitting diodes

The degradation of organic light emitting diodes (OLEDs) due to the growth of dark spots can be: attributed to the synergy of three external causes: d ust particles deposited during the fabrication process, pollution by water vapor, and pollution by oxygen. On the basis of a set of new experiments pe rformed on benchmark devices, we demonstrate that, for a given distribution of dust particles and a given concentration of the polluting agent, water is a thousand times more destructive than oxygen at room temperature. While the thermal diffusion of oxygen causes the oxidation of both the metal at the interface and the dye in the bulk of the device, water acts by an elect rochemical process causing the delamination of the electrode.