The 2014 Printed Electronics Conference featured an entire session on the important topic of Barrier Films and Encapsulation. Effective barrier films and encapsulation are a long-standing challenge for the production of long-lived devices including OLED displays and lighting, flexible displays, as well as printed electronic devices in general. The Barrier Films and Encapsulation session included presentations by 3M, Vitirflex, Schott, Lotus Applied Technology and Vinci Technologies as well as Kateeva’s presentation that I reported on for Display Daily.
Fred McCormick of 3M described the firm’s transparent barrier film (TBF) which 3M developed with OLED displays in mind. However, the firm has applied its TBF technology to 3M’s quantum dot enhancement film (QDEF) product. This internal product application of 3M’s TBF is currently the product’s largest application and is intended for use in notebook PCs and tablets. McCormick described the 3M TBF as a vacuum deposited combination (see illustration) of a polymer/metal oxide/polymer stack (“dyad”).
Barrier films with a single such “dyad” are available now, while multiple dyad products are in development. The firm is currently transitioning roll-to-roll manufacture of its single dyad TBF product from a 14″ web to a 57″ web.
Fred McCormick spent the remainder of his presentation discussing the technical challenges associated with edge ingress of water vapor through the adhesive bondline and the needed 10x to 100x improvement needed for OLED applications.
Vitriflex also presented on its flexible, transparent, ultra-barrier film products. The presenter, Vitriflex CTO and co-founder Ravi Prasad, noted that essentially all devices utilizing OLEDs, transparent conducting oxides (TCOs), quantum dots, nano-materials and graphene, exhibit high sensitivity to moisture and oxygen exposure and require flexible transparent encapsulation films. Prasad envisioned the firm’s transparent barrier films being applied in a wide range of products including solar photovoltaics, displays including flexible OLED displays and quantum dot films, as well as in lighting products including OLED devices and luminaires.
Prasad, speaking in very general terms, described the Vitriflex barrier film as consisting of a “Proprietary mixed-oxide material set” in a “Proprietary thin-film stack based on a “triad” structure (Diffusive layer/Reactive layer/Diffusive layer” combined with a “Proprietary hybrid top seal”. From this description I am not clear on the material science employed but Vitriflex has graduated from a feasibility proof prototype vacuum roll coater to a fully scaled-up manufacturing platform yielding WVTR of 10-6 g/m²-day with roll-to-roll production on a 1.4 meter web (see photo below).
Display Daily Comments
The film uniformity and optical transmission results presented by Vitriflex for its transparent barrier film were very good and the firm’s scale up for manufacturing is impressive. As more firms bring their barrier film expertise to bear, this tough problem appears to be on its way to one or more viable solutions. – Phil Wright
