Stress-matched laminated thin film of SiOxNy/SiO2/ SiOxNy for enhanced encapsulation of organic light-emitting devices

The laminated structure of thin-film encapsulation (TFE) plays an important role for the reliability of organic light-emitting devices (OLEDs). In previous studies of TFE-structures, only the density of the films and the gas-barrier properties were taken into account, while a potential internal stress in the film was largely neglected. Internal stress issues can lead to cracks, warping, and delamination, which affect the performance of the encapsulation layer significantly. Finding ways to eliminate or perhaps utilize potential internal stresses of these films could have substantial benefits for future OLEDs. This study is at the forefront of the stress-related properties of TFE in conjunction with optoelectronic devices. We perform a moisture-barrier test of a fabricated encapsulated laminated structure (Si/50 nm SiO_xN_y/50nmSiO₂/900 nm SiO_xN_y). The 50 nm SiO_xN_y buffer-layer was deposited (via chemical vapor deposition) to prevent the delamination and peeling between the SiO₂ film and the OLEDs because of the high stress acting on the SiO₂ layer. The water-vapor transmission rate of the laminated structure is below 5×10^-5 g/m²·d at 38°C and 100% relative humidity. The concept of a laminated TFE-structure has a great application potential for future flexible and bendable organic optoelectronics.