Spontaneous Periodic Delamination of Thin Films To Form Crack-Free Metal and Silicon Ribbons with High Stretchability

Design of electronic materials with high stretchability is of great importance for realizing soft and conformal electronics. One strategy of realizing stretchable metals and semiconductors is to exploit the buckling of materials bonded to elastomers. However, the level of stretchability is often limited by the cracking and fragmentation of the materials that occurs when constrained buckling occurs while bonded to the substrate. Here, we exploit a failure mechanism, spontaneous buckling-driven periodic delamination, to achieve high stretchability in metal and silicon films that are deposited on prestrained elastomer substrates. We find that both globally periodic buckle-delaminated pattern and ordered cracking patterns over large areas are observed in the spontaneously buckle-delaminated thin films. The geometry of periodic delaminated buckles and cracking periodicity can be predicted by theoretical models. By patterning the films into ribbons with widths smaller than the predicted cracking periodicity, we...