Selective Infiltration in Polymer Hybrid Thin Films as a Gas-Encapsulation Layer for Stretchable Electronics

The infiltration depth and water vapor transmission rate (WVTR) were explored in a variety of Al 2 O 3 –polymer hybrid layers as thin gas barrier films by filling the free volumes of polymers in the subsurface region with Al 2 O 3 using the atomic layer infiltration (ALI) method. Among all, the prepared Al 2 O 3 –polyethylene terephthalate (PET), Al 2 O 3 –polyimide, and Al 2 O 3 –Nylon 6 hybrid thin layers with the infiltration depth in the nanometer ranges showed extremely low WVTR values (<10 –6 g m –2 day –1 ) in a Ca dot corrosion test. Furthermore, we observed selective infiltration among the two polymers [perfluoroalkoxy alkane (PFA) and PET] by a preferential growth of Al 2 O 3 in the PET polymer that might be based on effective functional group anchoring in the ALI process. Then, we demonstrated a novel strategy by employing such a selective infiltration procedure and encapsulating individual segments of 144 Ca dots by Al 2 O 3 –PET hybrid thin films on the PFA polymer substrate rather than wrapping the whole thing together for the stretchable gas-encapsulation film. Regardless of stretching, it showed an extremely low WVTR (<10 –7 g m –2 day –1 ) and is proposed as a highly promising hermetic sealing alternative in stretchable, flexible, and foldable electronic display technologies.