Enhanced electron injection in organic electroluminescence devices using an Al/LiF electrode

TLDR

Band bending at the organic/dielectric interface is believed to drive the observed performance gains. The device uses a bilayer cathode comprising an ultrathin LiF layer adjacent to the electron‑transporting layer, capped with aluminum. The bilayer cathode yields stronger electron injection and higher electroluminescence efficiency than a Mg₀.₉Ag₀.₁ cathode, and similar improvements are seen when LiF is replaced by MgO.

Abstract

A bilayer is used as an electrode for organic electroluminescent devices. The bilayer consists of an ultrathin LiF layer adjacent to an electron-transporting layer and an aluminum outerlayer. Devices with the bilayer electrode showed enhanced electron injection and high electroluminescence efficiency as compared with a Mg0.9Ag0.1 cathode. Similar effects were observed when replacing MgO for LiF. The improvements are attributed to band bending of the organic layer in contact with the dielectrics.