Method for deposition of high-performance coatings and encapsulated electronic devices

#This invention pertains to a method for depositing high-performance coatings either as barriers to protect against penetration of oxygen and water vapor, or to provide anti-reflection or optical filtering.

#Thin films that protect an underlying material sensitive to moisture, oxygen and other chemicals are commonly used in many industrial processes. Applications range from food packaging, hard coatings on eyeglass lenses, and window glass, to protection of integrated circuits, display screens, and photovoltaic panels. Such thin films need to be dense, have excellent adhesion to the underlying layer and not crack or peel for the life of the product. In some cases the coating needs to be a hermetic seal, keeping out water vapor and oxygen, and in this case it must not have too many tiny pinhole leaks that would disrupt the function of even tiny areas of the underlying structure or device. Further, for many of the most high value applications such as OLED display screens, lighting panels, or organic photovoltaic panels, where the barrier needs to be tightest, the under-layers must not be exposed during manufacturing to temperatures above a limit that may range from slightly over hundred degrees Celsius in some cases to less than about seventy five degrees for some polymers. In some new products such as flexible circuits and screens, the device that needs to be protected will be built on a flexible substrate material and must be capable of being bent repeatedly without causing the protective function to be compromised.

#Presently, adhesion of deposited coatings is achieved either by first putting down an intermediate layer of highly wettable polymer layers, or by subjecting the surface to an inert plasma. Where the application is very cost sensitive it may be too expensive to use such wettable polymers, and for many inexpensive plastics an inert gas treatment has been found not to be effective in promoting adequate adhesion of the hard coating. Therefore, a more effective and less expensive method of ensuring adequate adhesion of coatings is needed.

#The present invention is further detailed with respect to the following drawings that are intended to show certain aspects of the present invention, but should not be construed as a limit on the practice of the present invention.

#FIG. 1A shows a schematic cross-section representing the general features of an OLED device on a permeable substrate showing where barriers may be needed to protect the photo-active materials;

#FIG. 1B illustrates an OLED device;

#The present invention affords coatings of large substrates, continuous webs, or wafers with flexible, transparent, adherent multi-layer film structures having at least three thin layers that have one or more of the following economically important benefits: Hermetic coatings of materials and devices sensitive to air or moisture that are virtually pinhole and leak-free at highly competitive cost in mass production. Such coatings are more valuable if they are also tolerant of flexure without cracking and tolerant of very hot, moist conditions. Optical coatings of flexible plastic films that tolerate flexure and/or large temperature variations without de-lamination, micro-cracking or discoloration. Hard, protective coatings on moisture sensitive or chemically sensitive devices that can withstand outdoor or highly variable temperature conditions without cracking or peeling.

#An example of an application that benefits from this method is the need for ultra low permeability encapsulation of organic light emitting diode (OLED) displays and lighting. Another example is a coating for CIGS photovoltaic panels that protects from moisture and provides anti-reflection for incident light so that power output of the module is increased.

#Coating processes with one or more of the above qualities may be used for a range of specific applications with rapidly growing, cost-sensitive markets, including but not limited to: Encapsulation of OLED display devices, whether on rigid or flexible substrates. Encapsulation of OLED lighting devices. Encapsulation and/or anti-reflective coating and/or hard coatings for thin film photovoltaic (PV) devices for outdoor energy harvesting. Among those benefiting most are modules or continuous web substrates having Organic PV films or Copper Indium Gallium di-Selenide (CIGS) PV. Hard or protective coatings for plastic (including lowest cost plastics such as acrylic and PET) for windows or other outdoor utilization, where ability to endure large ranges of temperature and humidity without cracking or peeling is required.