High adhesion face-sealing composite film with contactable liquid desiccant for the encapsulation of flexible OLEDs

To address the issues of interfacial adhesion failure in flexible organic light-emitting diodes (FOLEDs) under cyclic bending stress, and performance degradation caused by stress concentration in indium tin oxide (ITO) electrodes and organic layers, we propose a composite encapsulation structure utilizing a submicron liquid hygroscopic agent-modified face-sealing (FS) film and contactable liquid desiccant. By adjusting the neutral plane (NP) position to reduce bending stress in critical functional layers and enhancing barrier performance through the hygroscopic agent, the results demonstrate that when the bending radius of curvature ( r c ) decreases from 12 mm to 6 mm, the interfacial adhesion force between the FS film and polyethylene terephthalate substrate increases from 52 N/m to 76 N/m. The encapsulated FOLED exhibits a maximum current efficiency attenuation rate of only 4.03% after 1000 bending cycles at r c of 12 mm, significantly outperforming unencapsulated devices. This method, leveraging the synergistic effect of the composite encapsulation structure, provides an effective solution for improving the mechanical stability of flexible electronic devices.