Enhanced Properties of Transparent Conductive Oxide Films Prepared on PEN Substrates with a (SiO2)40(ZnO)60 Gas Barrier Layer

A (SiO2)(40)(ZnO)(60) (SZO) film with a very low water vapor transmission rate (WVTR,) below 10(-3) g/m(2)/day was coated as a gas barrier layer on a poly-ethylene naphthalate (PEN) substrate by rf-magnetron sputtering. This PEN with a SZO gas barrier layer was used as a flexible substrate for various transparent conductive oxide (TCO) films, such as In2O3-SnO2 (ITO), Al-doped ITO (AITO) and In2O3-ZnO (IZO). Their electrical and optical properties were compared to the TCO films deposited on a bare PEN substrate without a gas barrier layer. We found that compared with the TCO films without gas barrier layer, the TCO films with a SZO gas barrier layer showed an enhanced electrical conductivity and electrical stability after bending around a 10-mm-radius cylinder. The enhanced electrical properties were considered to be the result of the SZO film acting as a blocking barrier layer against water vapor permeation or organic-solvent diffusion from the PEN substrate during deposition of the TCO films and as a buffer layer e. sing damage due to bending. Thus, we suggest that the PEN with a SZO barrier layer is sufficiently transparent and has a superior ability to protect against the permeation of water vapor so that it can be applied to TCO films for flexible displays.