Novel PVD method for thin- polymer-film deposition and applications on organic devices

Thin polymer film was deposited on various substrates by using a novel physical vapour deposition method, the Modified Ionized Cluster Beam (MICB) deposition method. For example, to fabricate polyimide films by the MICB method, PMDA and ODA monomer clusters formed from specially designed sources were deposited to form polyamic-acid (PAA), Then, the PAA films were transformed to polyimide by a low-temperature curing process. The residual gas analyzer (RGA) results show that during the curing process the water molecules were released as a result of the imidization process, The onset temperature and the properties of the film varied with deposition conditions, such as acceleration voltage, ionizer energy and beam current. In this study, PI thin films with various thicknesses and packing densities were used as buffer layers between ITO and MEH-PPV in a, polymer EL device. Precise measurements of the hole-drift velocities in the actual devices with a buffer layer were carried out by using the time-of-flight method and the transient EL method. By controlling the charge-carrier injection ratio and the carrier-drift velocity with the thickness of inserted Pl buffer layers, balanced recombination of charge carriers can be accomplished and, therefore, the quantum efficiency of devices can be increased within a certain range of thickness.