A monolithic integration of robust, water-/oil-repellent layer onto multilayer encapsulation films for organic electronic devices

Abstract

A robust, water-/oil-repellent surface layer was integrated monolithically onto a multilayer thin film encapsulation by a sequential deposition of poly(2,4,6,8-tetravinyl-2,4,6,8-tetramethylcyclotetrasiloxane) followed by poly(3,3,4,4,5,5,6,6,7,7,8,8,9,9,10,10,10-heptadecafluorodecyl methacrylate) via a solvent-free initiated chemical vapor deposition method. The fabrication process did not damage the encapsulation performance of the underlying barrier films. Due to the low surface energy coupled with the uniform nano-structure of the poly(3,3,4,4,5,5,6,6,7,7,8,8,9,9,10,10,10-heptadecafluorodecyl methacrylate) layer, the outermost hydrophobic layer on the multilayer thin film encapsulation showed an excellent water-/oil-repellency, with water and hexadecane contact angles of 121.9 ± 4.9° and 75.3 ± 4.7°, respectively. This endowed a substantially improved self-cleaning performance to the multilayer thin film encapsulation. With two dyads of alternating poly(2,4,6,8-tetravinyl-2,4,6,8-tetramethylcyclotetrasiloxane)/Al₂O₃ hybrid multilayer integrated with the self-cleaning layer, the water vapor transmission rate value of 2.3 ± 1.1 × 10⁻³ g m⁻² d⁻¹ was achieved under accelerated condition at 38 °C with the relative humidity of 90%. This value corresponds to 1.1 × 10⁻⁴ g m⁻² d⁻¹ under ambient condition at 25 °C with the relative humidity of 50%. In addition, the film showed the high transmittance of 92.5% in the visible spectrum. The total thickness of the water-/oil-repellent thin film encapsulation layer was only 1.3 μm, which is highly desirable for ultrathin future flexible electronic devices.