Improving the structural reliability of multilayered transition metal dichalcogenide electronics via stretching engineering

Transition metal dichalcogenides (TMDs) are promising low-dimensional materials for flexible electronics due to their semiconducting properties alongside their mechanical compliance. The fracture stress/strength of TMDs is among their most influential property when operating as flexible electronic devices. In the present work, we show that their fracture characteristics can be modulated via stretch engineering. By applying successive force loads to suspended multilayered TMDs, we show that we are able to stretch them and increase the internal tension and Young's moduli of WS₂, MoS₂, and Mo_1-xW_xS₂ alloys. This stiffening behavior is accompanied by membrane wrinkle instability, manifested by the creation of permanent deflections and wrinkles. Raman analyses support these findings as we observed Raman modes blueshift and stiffening of in-plane and out-of-plane vibrational modes. Importantly, we found that multilayered TMD alloys show fracture stress that can exceed that of pure materials depending on the composition. Furthermore, we showed that we can tune the fracture stress via successive stretching cycles and increase the fracture stress by ∼400 %. Therefore, we can modulate their fracture properties to endure significantly larger loads before failure occurs. Thus, this work paves the path toward a deeper understanding of the mechanics of multilayered TMDs and improves their structural reliability when integrating into flexible and wearable applications.