Transparent conductive electrode deposited by Cs-incorporated RF magnetron sputtering and evaluation of the damage in OLED organic layer

Top-emission organic light emitting devices (TE-OLEDs) and transparent OLEDs (TOLEDs) can be fabricated by employing a transparent cathode with a low work function instead of Mg:Ag or Al:Li films. However, most transparent conductive oxides (TCOs) have a high work function (WF). Therefore, we proposed a new sputtering method for fabricating a novel transparent conductive film. Generally, the sputtering process is a plasma process involving high-energy particles. It cannot avoid bombardment-induced damage to the organic layer. We fabricated ITO:Cs films and evaluated the damage to the organic layers. The turn-on threshold voltages of TOLEDs with such low WF (4.1 eV) ITO:Cs films decreased from 8.5 V to 3.5 V and higher efficiencies were obtained; however, large leak currents were observed.