Fabrication and characterization of an Al2O3/OPSZ/Al2O3 barrier film on a PEN substrate via PEALD and spray-spin coating techniques

Abstract

One of the main drawbacks of the current flexible devices is the lack of a thin-film encapsulation with superior moisture barrier performance, light transmittance and mechanical flexibility. In this study, an inorganic/organic/inorganic composite film was fabricated on a 10 cm × 10 cm polyethylene naphthalate (PEN) substrate, which consisted of two inorganic layers of Al₂O₃ with an organic layer of organic polysilazane (OPSZ) in between. Al₂O₃ was deposited via plasma-enhanced atomic layer deposition (PEALD) with a thickness of about 40 nm. Approximately 200 nm thick OPSZ was prepared using the spray-spin coating method. The multilayer film exhibited outstanding optical transmittance (>90%) and an extremely low water vapor transmission rate (WVTR) (4.6 × 10⁻⁵ g per m² per day, 38 °C, 90% RH), which is two orders of magnitude lower than that of the corresponding single-layer Al₂O₃ film. Moreover, the introduction of an organic layer helped the Al₂O₃/OPSZ/Al₂O₃ film to exhibit good tensile and bending resistance. Thus, the multilayer film may find applications in the encapsulation of flexible devices.