Method for encapsulation of light emitting polymer devices

Abstract

A cost effective manufacturing process encapsulates a light emitting polymer (LEP) device between two flexible sheet materials, where one sheet may act as the substrate for the LEP device and the other sheet may act as a cover for the LEP device, and at least one of the sheets is transparent. Both encapsulating sheets and, as required, an adhesive system binding the sheets together provide sufficient environmental barriers with low moisture vapor transmission rates (MVTR) and oxygen transmission rates (OTR). The encapsulating sheets may, for example, be laminated together, sandwiching the LEP device in a vacuum, or oxygen/moisture free, and inert gas environment. Prior to encapsulation the LEP device may be heated and placed in a vacuum to remove moisture, air and residual solvents. The process may also be designed for roll to roll, sometimes called web based processing, where the LEP device and/or encapsulating sheet material are in a continuous roll format with an adhesive with low air permittivity, such as some UV or thermal curable epoxies, or a melt lamination process used to attach the encapsulating sheets. For LEP devices with short lifetime requirements, the encapsulating material may be in liquid form and applied by spraying, dipping, doctor balding, and the like, or printing, such as screen printing, roller coating or lithographic application in single or multiple layers. Such material may also contain desiccants to further remove water and/or oxygen.