Simulation Analysis On Folding Process And Factors Affecting Bending Performance Of Flexible OLED

With the rapid development of information technology,people have paid more attention to display products.At present,flexible OLEDs(Organic light-emitting device,OLED)play an important role in display product due to their excellent characteristics such as self-illumination,wide viewing angle,light weight,low energy consumption and flexibility.However,the OLED display module is a composite stacked structure composed of different thin optical film devices,each layer is bonded by optical clear adhesive(OCA).In the bending process of the flexible OLED module,the small bending radius causes the device to be overstressed,meanwhile,the inconsistent deformation between various thin film devices leads to the viscous flow of the OCA,which tends to make the devices peel off and cause permanent damage to the screen.Although mobile phones based on flexible OLEDs have attracted widespread interest,there have been no consumer-grade foldable electronic products.In this paper,the model is based on the structure of flexible OLED screen.The stress and deformation of OCA during the bending process are studied,and the influence of variable factors on the bending performance is explored.The main research contents are shown as follows:Firstly,the mechanical behavior of OCA is studied.The viscoelastic experimental data of the material is obtained by the relaxation experiment.The hyperelastic experimental data of the material is obtained by uniaxial tensile test and simple shear test.Then,the parameters are fitted with the experimental data.Secondly,the simulation model is established based on the flexible OLED screen structure to study the stress of panel and deformation of OCA layer after bending.The maximum stress position and the maximum deformation position of OCA layer are determined.It is also found that the multiple neutral planes are caused by low elastic modulus OCA.Comparing the stress and deformation after bending,it shows that during the static setting process,the stress and the deformation have changed greatly,making the working condition of the device worse.At last,the factors that are easy to control in actual production,such as the thickness and elastic modulus of protect cover and back plate,the thickness of the OCA layer,are studied to explore the impact on the bending performace.In addition,the characteristics of OCA,such as relaxation properties,elastic modulus and Poission's ratio,are also studied to explore the impact on the bending performance from the perspective of theoretical analysis.