Abstract
Indium tin oxide (ITO) substrates were treated by oxygen plasma for organic light-emitting devices (OLEDs). Using the ITO substrates aged for various times as hole-injecting electrodes, the double-layered OLEDs were fabricated by vacuum evaporation process, and the ageing effect of treated ITO anodes on the performance of OLEDs was studied with respect to the electroluminescence lifetime, efficiency, luminance and driving voltage. Experimental results reveal that the luminescent and electrical characteristics of the OLEDs are strongly dependent on the properties of the ITO anodes used, and the ITO anodes aged for various times result in significant differences in device performance which become worse with the increment of the ageing time. The measurements of X-ray photoelectron spectroscopy (XPS) and contact angle show that the carbon concentration increases, the oxygen concentration decreases and water contact angle raises, and thereby the improved surface properties of ITO tend to decay, as the ageing time increases. It indicates that the change in the electroluminescent performance of the OLEDs is closely related to the changes in the chemical compositions and wettability of the ITO anodes.
Published Version
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