New Stable Cathode Materials for OLEDs

72603-Many of the cathode materials currently in use in Organic Light Emitting Devices (OLEDs) are metals, such as Mg and Ca, and alloys. In many cases, the migration of these metals to form rough interfaces and hot-spots has lead to reduced lifetimes of the devices. There is a need to develop highly stable cathode materials that have low work function, can be nondestructively coated over large areas as flexible thin films on the organic emitting materials, and possess hermetic sealing properties to promote long device life. This project will develop a new class of cathode materials that have low work function and are highly stable. This class of materials, which can be coated on organic materials as thin films using plasma enhance chemical vapor deposition (PECVD), will allow work function modification, and will be highly dense to resist the penetration of both oxygen and water. During Phase I, the first examples of a new class of stable low work function nanocomposite materials were synthesized. The first small molecule OLED devices incorporating the nanocomposite films as cathodes were made. Areas for optimization of the composition and deposition conditions in Phase II were identified. In Phase II, a specially designed PECVD tool will be constructed for the deposition of nanocomposite cathode films. Deposition conditions will be optimized to provide a low resistivity interface with the organix emitter layer. The deposition tool will be able to coat substrates of up to 6-inch dimensions and will provide cathodes for an OLED pilot manufacturing line. Commercial Applications and Other Benefits as described by awardee: These cathode materials should become an important enabling technology to realize the potential of OLEDs on flexible polymeric substrates. Applications include both illuminated displays and lighting applications.