Inverted top-emitting organic light-emitting diodes using transparent conductive NiO electrode

We report on a top-emitting organic light-emitting device (TE-OLED) using a thermally evaporated and semi-transparent NiO film as a top-electrode. Our TE-OLED was fabricated, basically taking the reverse sequence for the fabrication of a conventional bottom-emitting organic light-emitting device (BE-OLED). Since the resultant sheet resistance of our NiO was high (8 kV/&) and its transmittance was only 50%, the resulting luminance ( 150 cd/m2) and injection current ( 50 mA/cm2) of our TE-OLED were much inferior to those of the BE-OLED device. However, its top-emitting was clearly observable and is thus concluded that our TE-OLED using thermally evaporated NiO, is quite promising if the NiO is controlled to have lower sheet resistance than the present value.