Environmental barrier material and methods of making.

A barrier material suitable for use as a barrier stack in encapsulation of, for example, organic light emitting diodes (OLEDs) is described. The barrier stack has improved permeation properties and comprises at least one polymer layer and at least one barrier layer. A high temperature barrier construction is also provided which comprises a high temperature polymer substrate and a barrier stack as described. Methods for making the barrier materials of the invention are also provided.