A method of forming a protective barrier in an organic light emitting device is disclosed, wherein the organic light emitting device is formed on a substrate and includes a plurality of layers of materials, the plurality of layers of materials including an organic light emitting layer. The method includes forming an inorganic layer and a semi-crystalline parylene-based polymer layer over an underlying layer, wherein the semi-crystalline parylene-based polymer layer is formed via transport polymerization of a reactive intermediate species. Organic light emitting devices having barriers are also disclosed.