Reduction of Ambient Light Reflection in Organic Light-Emitting Diodes

The reflectance of ambient light on a light-emitting diode cathode can be reduced to less than 18 %! This is achieved by employing an oxygen-deficient zinc oxide layer between the cathode and the electron-transporting layer. The new structure provides a substantially enhanced contrast under ambient light conditions. The Figure shows devices without (left) and with (right) the zinc oxide layer (see also inside front cover).