Failure mechanisms in flexible electronics

The rapid evolution of flexible electronic devices promises to revolutionize numerous fields by expanding the applications of smart devices. Nevertheless, despite this vast potential, the reliability of these innovative devices currently falls short, especially in light of demanding operation environment and the intrinsic challenges associated with their fabrication techniques. The heterogeneity in these processes and environments gives rise to unique failure modes throughout the devices' lifespan. To significantly enhance the reliability of these devices and assure long-term performance, it is paramount to comprehend the underpinning failure mechanisms thoroughly, thereby enabling optimal design solutions. A myriad of investigative efforts have been dedicated to unravel these failure mechanisms, utilizing a spectrum of tools from analytical models, numerical methods, to advanced characterization methods. This review delves into the root causes of device failure, scrutinizing both the fabrication process and the operation environment. Next, We subsequently address the failure mechanisms across four commonly observed modes: strength failure, fatigue failure, interfacial failure, and electrical failure, followed by an overview of targeted characterization methods associated with each mechanism. Concluding with an outlook, we spotlight ongoing challenges and promising directions for future research in our pursuit of highly resilient flexible electronic devices.