Enhanced stretchability and stability of micro-hole-mesh electrodes <i>via</i> a crack-guiding notch design

The rapid development of flexible devices demands greater stretchability and stability in conductive metal electrodes, which are indispensable components in a wide range of flexible technologies. In this work, we propose and show a novel hole-mesh structure featuring a directional crack-guiding notch (CGN) design, which can help to disperse stretching stress/strain, while effectively confining cracks to pre-notched locations, minimizing harm to the structural continuity and electrical conductivity of the electrode film. As a proof of concept, hole-mesh thin films (Pt/Au) with the CGN design were fabricated and transferred directly onto an elastic polymer substrate (polydimethylsiloxane, PDMS) and tested under repetitive stretching conditions. It was found that the hole-mesh electrodes, with the CGN design, exhibit significantly enhanced stretchability and excellent stability of conductivity, withstanding up to 20% strain for 170 cycles-a remarkable improvement compared to the reference samples without notches, which typically fail at lower strains. Subsequent finite element simulations further reveal that the crack-guiding notches effectively suppress uncontrolled crack propagation through the hole-mesh electrode, releasing accumulated strain only at the predefined notched locations in a well-controlled manner, and thus maintain the overall conductivity of the hole-mesh electrodes. This very convenient but effective CGN design holds great promise for broad applications in stretchable electronics, sensors, and displays.