Maskless Patterning of Vapor-Deposited Photosensitive Film and its Application to Organic Light-Emitting Diodes

Photosensitive thin films were prepared by the codeposition of a polymerizable monomer and a photoinitiator, which were patterned by UV irradiation followed by development in an organic solvent. This technique was applied for the preparation of a phosphorescent layer of an organic light emitting diode (OLED) by combining a vinylcarbazole monomer, a dopant of a vinyl derivative of a iridium complex, and a photoinitiator of a benzophenone derivative. An OLED with multiple emitting elements was prepared by repeating this patterning process. It was confirmed that the patterning does not cause harmful damage to the device characteristics. Moreover, the device characteristics can be improved after the photo patterning because the photopolymerization stabilizes the deposited films. This method is advantageous as a new technique for patterning polymer films without using a shadow mask for vapor deposition or a photoresist. (C) 2011 The Japan Society of Applied Physics