A finite element framework on water vapor transmission rates by pinhole damages in inorganic ultrabarriers for flexible electronics

Abstract

This work presents a computational framework to predict possible scenarios of pinhole distributions in hermetic barrier encapsulated organic layers to fill the lack of pinhole damage studies in thin film/organic electronics to a great extent. We describe various scenarios, including multiple pinhole damages of varying sizes and distances on a polymer film. An equation of water vapor transmission rates is proposed for polyimide films encapsulated with ALD ultrabarriers from computational experiments performed with different strategies. The validity of this equation covers pinhole damages ranging from 100 nm to 2.2 mm and any size of surface area of the film can be applied. Since the proposed equation does not include the interaction of wetness gradients with neighboring pinholes, the distance effect is investigated to estimate decreases in WVTR as the distance decreases between pinholes. An interactive, customized graphical user interface was created with ANSYS Parametric Design Language to make computational calculations user-friendly and widely available to researchers. Solution strategies of complete and unit cell runs, including standard and sub-modeling approaches, are proposed with advantages and disadvantages in computational time and accuracy of results.