The failure mechanism for the thin film encapsulation (TFE) structure in the lateral direction was studied. A series of lateral distances for TFE was achieved by the development of the lowtemperature etching process. Taking the distance and the adhesion force into consideration, a failure model was established.

A series of adhesion strength modified layer (ML) was introduced to develop the new TFE structures. The new encapsulation structures provided the long‐life time performance for the flexible OLED device. No pixel shrinkage or dark spots appeared after storing in an environment of 85% humidity and at 85 °C over 20,000 hours. The adhesion strength of the thin film system improved and the risk of peeling decreased.

We report an ultra-thin film encapsulation structure composited of atomic layer deposition layer and organic layer, which show a 4% improvement in transmittance with tandem TFE film, especially for blue region (94% up to 99%) and a 60% thickness decrease of inorganic layer. The TFE film shows an excellent flexibility performance, there was no crack after 60/90 500 hour static bending for R2. It also shows good reliability, storage for 85/85 500h, which indicates a great potential application in flexible display, especially for bendable display.

This paper studied the characteristics of OLED encapsulation film, the test method of water vapor penetration and improving the ability of water vapor barrier. It was found that the group changes after hygroscopic, transferred to Si‐O bond. Based on this mechanism, the test method of water vapor penetration was studied. The average water vapor penetration rate P of film A and film B was about 0.14nm/h and 34nm/h respectively at 85 °C /85%RH environment by TOF‐SIMS and XPS test. At the same time, the permeability lag phenomenon was found. The enhancement effect of inter‐layer structure on water vapor barrier ability was further studied.