OLED with a controlled molecular weight of the PVK (poly(9-vinylcarbazole)) formed by a reactive ink-jet process

Abstract

An ink-jet printing method was proposed to solve several conventional problems of ink jet process. PVK (poly(9-vinylcarbazole)) thin film was synthesized and simultaneousely patterned by the reactive ink-jet process (RIP). Gel permeation chromatography shows a linear relationship between the molecular weight of the PVK and the reaction time. The as-synthesized PVK with a controlled molecular weight was applied to an OLED device. Most of the OLED with the RIP-PVK film performed better compared to the reference OLEDs. The luminance graphs indicated the existence of a proper molecular weight leading to the optimum structural conformity which was matched well to the modified OLED structure, showing a linear relationship with the reaction time in the turn-on threshold. This result implies that one can control the proper molecular weight of a polymer and thus the electrical properties of an OLED device via the RIP method. (C) 2012 Elsevier B.V. All rights reserved.