Unfortunately, the more layers that are employed, the less flexible is the finished product, so although multilayers are promising candidates for encapsulation based on their excellent barrier performance, they have struggled to meet the needs of flexible, R2R-manufactured OLEDs on plastic substrates.
Today, 3M dominates the market, small though it is. Other firms with multilayer dyad films are Dow, GE, Alcan Packaging, and FujiFilm. An early developer of technology in this area was Vitex Systems, which made a strategic deal in 2010 with Samsung and now appears to have been largely absorbed by Samsung Mobile Displays and Samsung Cheil, which continue to work on barrier systems.
A second, and perhaps even more important, major problem for most dyad films on the market today is cost, which can be as high as $70 to $100 per square meter. Efforts are thus ongoing to reduce the number of layers required to achieve the desired barrier properties. An added benefit from reduction of the number of layers is that it would flexibility could also conceivably be improved.
Multilayer barriers based on ALD: Atomic layer deposition (ALD) strategies for multilayer barrier films have also garnered much interest in recent years. ALD is considered to give better film qualities than CVD or PVD methods; the number of film defects is reduced, so both layer thicknesses and the number of layers can, at least in theory, be reduced.
We note, however, that these advantages are meaningful only if there is a concurrent reduction in the cost of the layers. NanoMarkets believes that there is promise in this area, but remains skeptical about the ability of ALD manufacturing to handle high throughputs or R2R processing – especially for flexible OLEDs. Instead, ALD encapsulation strategies may be practically limited to higher-end and/or batch process OLED lighting markets.
Beneq Oy, an ALD equipment maker and technology developer, is the clear leader in this sub-market of the OLED encapsulation industry, but other firms including SunDew Technologies and ALD NanoSolutions have also entered the fray.
Other kinds of barrier strategies: To meet cost and flexibility goals, the development of a “single layer” barrier has been something of a “holy grail” in the encapsulation industry. To the best of NanoMarkets’ knowledge, this objective has not yet been achieved, but several firms appear to be getting closer:
• Tera Barrier Films is commercializing an innovative barrier film that is purported to solve the defect problem of traditional dyad films by literally plugging the defects in the barrier oxide films using nanoparticles, thereby reducing the number of barrier layers needed in the construction of the barrier film down to just two layers – an oxide and a nanoparticulate sealing layer.
• In addition, Universal Display Corporation, a longtime advocate of Vitex’s Barix, is now also advertising its own “single layer” system, which, if real and cost-effective, could revolutionize the industry.