A facile solution-processed alumina film as an efficient electron-injection layer for inverted organic light-emitting diodes

Abstract

Inverted organic light-emitting diodes (IOLEDs) can effectively improve device stability because they concentrate the air-stable anode and high work function (WF) metal oxide hole-injection layer (HIL) at the top of the devices. In this work, we report a facile solution-processed ultra-thin alumina film used as an electron-injection layer in IOLEDs and present significantly improved device performance. We achieved a high current efficiency of 5.12 cd A⁻¹ at 10 mA cm⁻² and the best current efficiency approaching 5.5 cd A⁻¹ at 40 mA cm⁻² without doping of an emission layer (EML) for a single Alq₃-based green fluorescent IOLED, and a high current efficiency for a green phosphorescent IOLED as well. Furthermore, the extrapolated 50% decay lifetime (t₅₀) shows that our Alq₃-based green fluorescent IOLED is about 5 times more stable than the conventional OLED.