Micro-patterning of a conductive polymer and an insulation polymer using the Parylene lift-off method for electrochromic displays

We have developed a process to pattern the conductive polymer of poly(3,4-ethylenedioxythiophene):poly(styrenesulfonate) (PEDOT:PSS) film and the insulation polymer of the perfluoro polymer (Cytop) with a Parylene lift-off method for the purpose of fabricating a PEDOT:PSS-based electrochromic display device. Because conventional micro-patterning processes decrease the conductivity of organic electronic polymers due to the destructive solutions of photolithography, PEDOT:PSS and Cytop polymers were patterned by using the dry lift-off film of Parylene. Its patterning resolution of PEDOT:PSS was found to be as low as 20 µm. The insulation layer of Cytop was also patterned on the PEDOT:PSS pattern with the same resolution. This process was able to pattern the 300 µm wide wiring and 1 mm square pixels of PEDOT:PSS and the Cytop to cover the entire area except for the pixels constructed to form an electrochromic display. Finally, the fabricated 4 × 4 pixel device displayed a simple shape, a transverse line.