Yoichi Osato

11.3: Novel Electron-Injection Layers for Top-Emission OLEDs

In this paper, we describe the performances of two types of new electron injection layers (EILs) for OLEDs using Cesium Carbonate (Cs2CO3). The first is a thin Cs2CO3, and the other, a co-evaporated layer of a new electron transport material and Cs2CO3. Devices with these EILs exhibited better electrical properties with Al, Ag or Au cathode than the devices using LiF as EIL and Al as cathode. In addition, we have measured the characteristics of the top-emission OLEDs with the EIL using Cs2CO3, and confirmed the EIL effectiveness for the electron injection even from ITO cathode.

Effect of oxygen plasma treatment of indium tin oxide for organic light-emitting devices with iodogallium phthalocyanine layer

We demonstrate the improvement of device lifetime by organic light-emitting devices with an iodogallium phthalocyanine (IGaPc) layer fabricated on indium tin oxide (ITO) treated with positive oxygen ions. The device performance improves markedly as follows: (a) long-term stability (an operational half-lifetime of 100 h at high current density of 100 mA/cm2), and (b) the driving voltage is unchanged. The change in the device characteristics is attributed to changes in IGaPc molecular configurations during the growth process, leading to enhanced hole injection from the ITO to IGaPc layer.