Ionization-assisted deposition of SrOx for electron injection layer of organic light emitting diode

Thin SrOx films were prepared as the electron injection layer for organic light emitting diodes. The film deposition process gave a significant influence on the device characteristics, and the ionization-assisted deposition (IAD) gave considerable improvement over the conventional vacuum deposition. X-ray photoelectron spectroscopy and atomic force microscope observation showed that the IAD has the possibility of controlling two factors; the oxidation state and the growth morphology of SrOx film. The IAD-SrOx films had smaller oxygen content than the vacuum-deposited ones. In addition, the IAD gave uniform surface coverage at a smaller thickness, reflecting the initial film growth morphology that consisted of uniformly dispersed small grains instead of coagulated islands by the vacuum deposition