Spotless hybrid thin-film encapsulation stack for organic light-emitting diodes on organic foils

In order to protect a flexible OLED on plastic foil against water from the ambient atmosphere a top and bottom thin-film encapsulation (TFE) is necessary. A TFE stack SiN-OCP-SiN with getter in OCP results in excellent shelf lifetime. However, the getter particles result in light scattering that is lost upon water ingress in the stack. As a result spots of reduced electroluminescence are observed during exposure to the ambient atmosphere that limit the practical lifetime of the device drastically. For the bottom emitting OLED we reduced the getter content in the bottom barrier to a level that does not exhibit visible light scattering. The reduced getter capacity with respect to the top barrier does not result in a lower performance of the bottom barrier due to the lower pinhole density in SiN-ITO with respect to Al-SiN. The projected shelf lifetime at ambient conditions is 10 years.