With increasing demands and interest in flexible and foldable devices, much effort has been devoted to the development of flexible transparent electrodes. An in-depth understanding of failure mechanisms in nanoscale structure is crucial in developing stable, flexible electronics with long-term durability. The present work investigated the mechanoelectric characteristics of transparent conductive electrodes in the form of dielectric/metal/dielectric (DMD) sandwich structures under bending, including one time and repeated cyclic bending test, and provides an explanation of their failure mechanism. We demonstrate how a thin metallic layer helps to enhance the mechanical robustness of the DMD as compared with that without, tune the mechanical properties of the cohesive layer, and improve the electrode fracture resistance. Abnormal crack propagation and toughening of multilayer DMD structures are analyzed, and its underlying mechanisms are explained. We consider the knowledge of the failure mechanisms of transparent conductive electrodes gained from the present study as a foundation for future design improvements.
Keywords: conducting dielectric−metal−dielectric; crack deflection; crack propagation; fatigue; flexible electronics; fracture mechanics; structural colors; thin films.