(A) study on protection of brittle layers in rollable display structures

Abstract

For the last decade, flexible OLED (Organic Light-Emitting-Diode) displays have been developed into the rollable display beyond bendable displays in order to achieve high space-usability and design-free forms. In addition, ITO (Indium Tin Oxide) film is used to an anode of the OLED because of excellent electrical properties. However, ITO anode lowers the mechanical reliability of the OLED display due to its brittleness and low elongation. Moreover, rollable displays have different boundary conditions such as the torsion spring for operation of rollable displays from conventional bendable displays. Despite the differences between conventional bendable and rollable displays, designs considering inherent characteristics of rollable displays have not been considered actively. In this study, deformation of the brittle electrode in the rollable OLED display structure is analyzed by finite element analysis. Design guidelines controlling the spring stiffness and modulus of elasticity of adhesive were suggested to protect the brittle electrode from mechanical fracture through this analysis. In addition, test equipment applied boundary conditions of actual rollable display is designed. Finite element analysis modeling for rollable display is also experimentally validated by using various elastic modulus of adhesives and ITO-coated PET films.