fig2

Figure 2. (A) The module stack structure of OLED devices. The rigid or curved phone (left) and foldable phone (right) structures are different. The nomenclatures are generalized for each layer; (B) The bending stiffness of bending structures relates to the thickness and modulus of each layer that constitutes the device as depicted^[15]. Reproduced with permission. Copyright © 2020 The Society for Information Display; (C) The failure mode of display modules occurs when they are bent. The occurrence of failure is related to the modulus of adhesives. If the shear modulus of adhesives is extremely low, the stress throughout the device is dissipated due to the existence of multiple neutral planes; (D) The requirements of environmental reliability according to various applications. OLED: Organic light-emitting diode.