Strontium (Sr) thin films were prepared by the ionization-assisted deposition (IAD) method for the electron injection layer between tris (8 -hydroxyquinolino)aluminum (Alq(3)) electron transport layer and Al cathode of the organic light emitting diode (LED). The Sr films. around 10 nm in thickness, deposited by IAD were effective in improving the device characteristics such as the luminescence efficiency and, especially, the device lifetime. The best LED characteristics were obtained at the ion acceleration voltage V-a of around 800 V. It was found that the deposition condition influences the morphological and chemical properties of the film. The IAD Sr had smaller interdiffusion into Alq3 compared to the standard evaporated one. The film deposited by IAD at higher V-a was metallic, and had a densely packed uniform microstructure, while the ones deposited at low V(a)or by standard evaporation assumed oxide nature, having considerable amount of voids. It is expected that the IAD can optimize the LED characteristics through the control of Sr film properties. (C) 2003 American Vacuum Society.