TECHNOLOGY FOCUS - POLYMERS - Preferred Components: The polyester substrate is biaxially oriented. It is selected from polyethylene terephthalate (PET) or polyethylene 2,6-naphthalate (PEN). The UV absorber is a hydroxyphenyltriazine. The polymeric coating layer is disposed on the substrate using an in-line coating technique. Preferred Parameters: The intrinsic viscosity of the polyester film substrate is at least 0.65. The overall thickness of the composite film is in the range of from about 12 to about 350 mu m. The composite film is transparent and in one embodiment exhibits a haze of no more than 15% and/or where the total luminous transmission for light in the visible region is at least 85%. Preferred Composition: The substrate further comprises a hindered amine light stabilizer (HALS) in the range from about 0.1 to about 10% by weight, relative to the total weight of the layer. The ethylene acrylic acid (EAA) copolymer comprises from about 2 to about 30 wt% acrylic acid co-monomer. Preferred Device: The device is a photovoltaic cell further comprising a photovoltaic-active layer. Photovoltaic cell comprises a photovoltaic-active layer disposed between a supporting substrate and the composite film, where this multilayer assembly is encapsulated within an optically clear encapsulating barrier material. The device is a copper-indium-gallium-(di)selenide (CIGS) photovoltaic cell, where CIGS photovoltaic cell comprises a crystalline layer of photo-active CIGS material disposed between a supporting substrate and the composite film, where the multilayer assembly comprising the supporting substrate and the crystalline layer and the composite film is encapsulated with an optically clear encapsulating barrier material. Encapsulating barrier material is an ionomeric polymer comprising non-polar repeat units and further comprising no more than about 15 wt% of salt-containing units. Encapsulating barrier material is a thermoplastic carboxylate ionomer where the non-polar comonomers are selected from ethylene and styrene, and the salt-containing units are selected from metal salts of methacrylic acid and/or acrylic acid. Encapsulating barrier material is selected from ethylene vinyl acetate copolymer resins, polyvinylbutyral resins and silicone resins. Encapsulated multilayer assembly is disposed between a front-plane and a back-plane, such that the composite film is disposed between the photo-active layer and the front-plane.