Solution Processible Organic–Inorganic Hybrid Moisture Barrier Film

It is extremely important to provide the substrate of the flexible OLED with transparent and flexible moisture barrier property since the organic functional layers and metal electrodes are highly sensitive to water vapor. Solution processible moisture barrier may be a potential candidate to achieve low cost, high productivity and large area moisture barrier. In this study, we fabricated an organic–inorganic hybrid moisture barrier thin film by the condensation reaction between poly(melamine-co-formaldehyde) (PMF) and tetraethyl orthosilicate (TEOS) using sol–gel method. It was expected that PMF and silicone oxide provided the thin film with mechanical flexibility and moisture barrier property, respectively. It was confirmed that very dense hybrid monolayer and multi-layer films with very smooth surface and high optical transmittance were successfully fabricated using the sol–gel process. Moisture barrier property was determined by water vapor transmission rate (WVTR) measured by Ca-test at 85 °C and 85% RH. WVTR of the bare poly(ethylene naphthalate) (PEN, 150 μm) film was found to be about 17 g/m²/day, while the PEN film coated with the hybrid film showed the lower WVTR value of 4.5 g/m²/day. The WVTR value at 85 °C and 85% RH corresponds to the value in the range of 10^–2–10^–3 g/m²/day under ambient condition, confirming the efficient moisture barrier property of the hybrid layers.