Elasto-Plastic Design of Ultrathin Interlayer for Enhancing Strain Tolerance of Flexible Electronics

The ability to tolerate large strains during various degrees of deformation is a core issue in the development of flexible electronics. Commonly used strategies nowadays to enhance the strain tolerance of thin film devices focus on the optimization of the device architecture and the increase of bonding at the materials interface. In this paper, we propose a strategy, namely elasto-plastic design of an ultrathin interlayer, to boost the strain tolerance of flexible electronics. We demonstrate that insertion of an ultrathin, stiff (high Young's modulus) and elastic (high yield strain) interlayer between an upper rigid film/device and a soft substrate, regardless of the substrate thickness or the interfacial bonding, can significantly reduce the actual strain applied on the film/device when the substrate is bent. Being independent of existing strategies, the elasto-plastic design strategy offers an effective method to enhance the device flexibility without redesigning the device structure or altering the material interface.