Since the development of TFT-LCD in 2005, the demand for the water vapor transmission rate (Water Vapor Transmission Rate; WVTR) of the barrier film approach 10-3 g/m2∙day. In recent years, in order to manufacture next generation  flexible displays (such as: E-paper and OLED) and organic solar cells (OPV), the performance requirements of barrier film have been improved to WVTR~10-5 g/m2∙day, so as to avoid the deterioration of organic compound and metals inside the optoelectronic components. The current high-end barrier film products are mainly multi-layer interlaced laminated structures of organic layer/inorganic barrier layer/organic layer.

1. Reduce moisture penetration from materials. 

The steps of water vapor molecule permeation through the substrate include: water vapor adsorption on the surface, diffusion through the substrate, and desorption to the environment. The main rate is the water vapor diffusion through the substrate. According to Fick's Law: F=-D‧ΔC/t, where F is the water vapor diffusion flux, D is the diffusion coefficient, ΔC is the concentration difference on both sides of the barrier film, and t is the thickness of the barrier film . If the diffusion coefficient can be effectively reduced, it will make it difficult for water vapor to diffuse to the other side of the barrier film, or the barrier effect can be improved by increasing the thickness of the barrier film.

2. Reduce pinholes in inorganic coatings. 

When the quality of the inorganic layer is not good, such as the adhesion of particles on the surface of the substrate or the internal stress between the film layers, it may cause pinholes in the film. A uniform inorganic layer is very important.

We use the Roller to Roller Sputtering system to prepare inorganic barrier  film on plastic substrates to overcome the problems of high oxygen and water vapor transmission rates of plastic substrates, which combines the high water resistance of inorganic barrier layers and the flexibility of organic layers. At the same time, through the staggered lamination of multi-layer films, the visible light transmittance of the barrier film more than 80%, the adhesion test is 5B, and the WVTR less than 10^-2 g/m²∙day.