Solution Processable Barrier Films Using a Filled Polymer to Encapsulate Flexible Printed Electronics

Flexible printed electronics (FPEs) are gaining attention due to their diverse applications, including smart packaging and medical and wearable devices. A key aspect in ensuring the longevity and functionality of FPE devices is their encapsulation, which shields them from adverse environmental factors such as humidity and oxygen. One promising approach to achieve this is solution-processed encapsulation, where fillers are added to a polymer matrix to form barrier films. In this work, glass flakes (GFs), graphene oxide (GO), montmorillonite (MMT), and silica are investigated as possible fillers in poly(vinyl alcohol) (PVA). The barrier films are fabricated by doctor blading. To select the most effective filler type, a water vapor transmission rate (WVTR) test method based on an adapted desiccant method from the ASTM E96/E96M-22 standard is developed. The optimal filler concentration in PVA is also determined. The fabricated barrier films are optically inspected. Moreover, the barrier effect of selected PVA/filler films is validated by resistance measurements of inkjet-printed silver tracks subjected to damp heat and room storage conditions.