Electrical Conduction Behavior of Organic Light-Emitting Diodes Using Inhomogeneous Fluorinated Self-Assembled Monolayer as a Hole-Injection Layer

The modification of a fluorinated self-assembled monolayer (FSAM) on an indium tin-oxide (ITO) anode enhances hole-injection from ITO and prolongs the lifetime of organic light-emitting diodes (OLEDs). The effect of inhoniogeneous modification by shortening the fabrication time can be expressed as the superposition of unmodified and FSAM-modified surface conditions. The FSAM coverage is estimated to be 20-40% by contact angle, work function, atomic force microscopy phase image and current characteristics measurements. The device performance of OLEDs with inhomogeneous FSAMs exhibited intermediate behavior, which suggests that the anode interface condition plays an important role in the conduction and degradation mechanisms of OLEDs. (C) 2011 The Japan Society of Applied Physics