Study on interface fatigue failure of flexible OLED display modules based on cyclic cohesive zone model

Abstract

Organic light-emitting diode (OLED) display devices are widely used in the field of electronic display because of their excellent performance, but flexible OLED displays are prone to device damage and peeling failure after multiple bendings. The cohesive zone model (CZM) has great advantages in dealing with interface peeling. In this paper, a cyclic cohesive constitutive model was developed to characterize the peeling phenomenon between the interface of optical clear adhesive (OCA) and cover window under constant cyclic loading in flexible display modules. The model was implemented in ABAQUS by user subroutine to redefine field variables at a material point (USDFLD). Through the bending fatigue peeling experiment and finite element simulation between the cover window and OCA, the cyclic cohesive constitutive parameters were obtained by the parameter inversion method, and the amplification method of fatigue damage variables was optimized. Finally, a flexible OLED simulation model with a multilayer stack structure was established. Compared with the experimental results, the simulation model successfully predicted the peeling failure position, and the relative error between the predicted life value and the experimental value was 16.6%. The applicability of the cyclic cohesive zone model in characterizing the fatigue peeling properties of the interface between the cover window and OCA was validated.