Optical effects of NiOx interlayer for OLEDs with AZO embedded anodes

Insertion of a nickel oxide (NiOx) in an aluminum zinc oxide (AZO) embedded organic light-emitting diode (OLED) has successfully obtained additional 20% light extraction and led to an enhanced current efficiency up to 42.7%. The introduced NiOx has a high reflective index of ∼2.1 which allows more emitted light to travel through AZO/ITO interfaces. The AZO/ITO interfaces provide deflection and scattering effect to redirect light away from being totally reflected in the reflective-index-mismatched OLED structures and thus are able to enhance external light out-coupling. Results also showed that the coating of NiOx layer increased the electrical resistance of AZO embedded ITO film which limited the current efficiency, and the introduced NiOx showed no benefit on carrier injection as expected.