Nearly a decade after the first publications on the topic, it is now well accepted that ALD possesses the unique capability of making the world’s highest performing single layer gas diffusion barriers. Extremely thin ALD barriers have been shown to provide the necessary environmental protection for some of the most sensitive electronics, including CIGS photovoltaics and OLED displays and lighting. However, the low speed and high cost of traditional ALD have prevented its use in these applications. But now, with the demonstrated high speed and low cost of Lotus’ TransFlex and Vortex ALD processes, ALD has become an extremely attractive solution for direct encapsulation of these devices, and for the manufacture of polymer encapsulation films.
The barrier demands of these applications are so extreme that it is incredibly difficult to even measure the low rates of permeation required. At Lotus, we use a combination of internal commercially available testing capabilities, including the state of the art MOCON Aquatran(R) Model 2 to characterize extremely thin ALD layers with water vapor permeation levels in the 10-3 to low 10-4 g/m2/day range. To measure even lower levels of permeation, down into the 10-6 range, we rely on the rigorous calcium testing methods developed at the National Renewable Energy Laboratory (NREL).
Internal and External WVTR Testing
Our newest ALD materials and processes (patents granted and pending) reach the detection limit of the commercial measurement equipment at a thickness of just about 4 nm. With a thickness of just 6-7nm, we begin to approach the detection limits of the calcium test method, with permeation rates in the 10-5 to 10-6 range.
In just a few short years after producing the first ALD films with our methods, we’ve reduced the coating costs for ultra-barrier films on flexible substrates by two orders of magnitude compared with existing organic/inorganic multi-layer methods. With technology we’ve already demonstrated today, a single plant can coat millions of square meters of ultra-barrier film per year, with a projected manufacturing cost under $1 per square meter. Our Vortex rotary ALD technology can provide direct encapsulation of an entire batch of rigid substrates in just a couple of minutes.
And we’re not stopping now. We’re continuing to enhance the technology for further speed increases and cost reduction, recently demonstrating laboratory scale performance necessary to drive down the cost of commercial barrier coatings for high end industrial packaging applications such as military and medical packaging to pennies per square meter, while reducing permeation by two orders of magnitude compared with today’s commercial evaporation processes.