High‐Resolution Maskless UV Patterning of Vapor Phase Polymerized Conducting Polymer

ABSTRACT Combining UV radiation with vapor phase polymerization (VPP) enables the fabrication of conducting polymer films with tunable electrical, optical, and electrochemical properties. However, traditional mask‐based UV exposure typically requires separation between a photomask and the sample, which limits resolution. This study circumvents this by using a maskless UV exposure system that directly projects high‐resolution patterns onto the substrate. Using poly(3,4‐ethylenedioxythiophene):toluenesulfonate (PEDOT:Tos) as a model material, the resulting minimum feature sizes are approximately 8 µm—nearly half of what has been achieved using mask‐based systems. We find that the obtained resolution is not limited by the optics but is related to material aspects such as molecular diffusion, providing guidelines for further optimizations. Our findings also show that the total delivered dose, rather than exposure time or irradiance, controls the film properties. The resulting PEDOT:Tos patterns exhibit distinct, stable color variations during electrochemical switching, highlighting the potential of maskless UV‐VPP for high‐resolution electrochromic displays.