Sub-Surface Patterning of Polymers with Inorganics by Area-Selective Vapor Phase Infiltration

Abstract

The inherent flexibility and processability of polymers make them indispensable for next-generation flexible electronics, yet their intrinsic electrical properties remain critical bottlenecks. A powerful workaround lies in hybrid materials that challenge this bottleneck by merging organic and inorganic components to unlock unprecedented functionalities through synergies. Beyond composition, area-selective functionalization is equally critical to the practical construction of electronic devices. Here, we demonstrate infiltration of ZnO into a lithographically patterned poly(ethylene terephthalate) (PET) matrix, locally transferring the pattern to the polymer subsurface. Following our approach of area-selective vapor-phase infiltration (AS-VPI), both the region and the depth of infiltration become controllable, even to the micrometer scale. With linear patterns, we demonstrate anisotropic electrical conductivity, showing a difference in resistance of more than 7 orders of magnitude between directions parallel and perpendicular to the infiltrated pattern. The benefit of using VPI to embed ZnO within the polymeric matrix rather than simply coating the surface is demonstrated by the preservation of electrical resistance after bending and deliberate scratching of the sample, as conductive pathways in the subsurface maintain current flow. AS-VPI is therefore demonstrated as an effective strategy for producing electrically functionalized polymers suitable for the design of flexible and wearable electronic devices.