DC sputtered indium-tin oxide transparent cathode for organic light-emitting diode

The performance of top-emitting organic light-emitting diodes depends not just on the choice of the transparent cathodes but also on their techniques of formation. Compared to the damage induced by radio frequency sputtering of indium-tin oxide cathode, that induced by DC sputtering was verified to be less severe and relatively independent of the sputtering power. Consequently, a high DC sputtering power of 120 W could be employed to achieve a high deposition rate of 0.1 nm/s. Adequate emission efficiency was maintained, even with a relatively thin 7-nm copper (II) phthalocyanine buffer layer.

I. Introduction

Organic light-emitting diodes (OLED) as pixels for flat-panel displays are being actively pursued because of their relatively simple structure, high brightness, and self-emitting nature [1] [2] [3]. A top “through-the-cathode” emitting diode is of considerable interest, particularly for displays fabricated on opaque substrates [4] and high-resolution displays made of vertically stacked full-color pixels [5].