Electron injection in magnesium-doped organic light emitting diodes

Abstract

We investigated alkali metal doping mechanism by comparative analysis between an Mg-Alq(3) co-deposition (Mg:Alq(3)) and an Mg deposition on Alq(3) films (Mg/Alq(3)). The operating voltage decreased by 0.4V and the luminance increased by 60 cd/m(2) at 11 mA/cm(2) for devices constructed from the Mg: Alq(3). However, the device characteristics of Mg/Alq(3) samples were degraded. Our experimental results using an in-situ photoemission study showed that alkali metal doping in Alq(3) did not induce band bending, but reduce electron injection barrier by charge transfer from alkali metals to Alq(3) molecules. (C) 2012 American Institute of Physics. [http://dx.doi.org/10.1063/1.4753796]