The influence of CF4 plasma treatment of indium-tin-oxide (ITO) and polyimide (PI) on the patterning of ink-jet printed polymer is presented. Not much difference between the as-received ITO and PI surface energies was found, but a significant difference in surface energies between ITO and PI after CF4 plasma treatment was noted. It is expected that precise patterning can be achieved by using the difference in surface energies between the inside of the pixel and its surroundings. Also the effects of CF4 plasma treatment of ITO have been studied on the performance of polymer light-emitting diodes (PLEDs). X-ray photoelectron spectroscopy revealed that CF4 plasma treatment led to a decrease in the surface content of carbon contaminants and an increase in the surface content of fluorine, which in turn enhance the performance of PLEDs. (c) 2005 American Vacuum Society.