Abstract
Operating conditions of OLEDs are very sensitive to the surface properties of indium tin oxide (ITO). Wettability measurements have been performed to characterize ITO surface properties and their modification upon deposition of a self-assembled monolayer. Contact angle measurements demonstrate that ITO surface is basic. Upon grafting with phosphonic acid, the surface becomes acid. The
I(
V) characteristics of light-emitting diodes (LEDs) based on a soluble PPV derivative: poly(2-octoxy-5-methoxy-1,4-phenylenevinylene) (POMX) by such functionalized ITO show a reduction of the onset voltage and a rectification ratio enhancement. The electrical characteristics follow a space–charge limited conduction (SCLC) behavior. Such modified ITO electrodes lead to main improvements of the diode properties through operating voltage reduction and stability increase.