Geometry dependent performance limits of stretchable reduced graphene oxide interconnects: The role of wrinkles

Abstract We study the effect of geometrical confinement of reduced graphene oxide (rGO) films on strain-induced wrinkling patterns, which strongly affects their electromechanical response. Quasi-periodic wrinkle patterns are characteristics of uniaxially strained large-area thin films, both free-standing and supported on soft substrates. The universality of their scaling behaviour is known across a wide spectrum of length scales ranging from curtains to atomically thin crystals. Distinct wrinkle patterns oriented orthogonal to those on large-area films are observed in narrow micro-stripes of electrically conducting rGO films on polydimethylsiloxane (PDMS) substrates. Furthermore, as the width is reduced from 100 μm to 5  μm, the onset of the electromechanical response progressively shifts to lower strain, and importantly a breakdown is observed beyond a critical strain of less than 2.5%. Morphology studies suggest this irreversible response to arise as a consequence of local delamination of the strained micro-stripes subsequent to crack propagation. In contrast, large-area films have subdued electromechanical response which is also characterized by reversibility despite cracking. The altered electromechanical response, when going from large-area films to narrow micro-stripes, is reconciled as a consequence of the peculiar wrinkle pattern in the strained films arising from the free edge of the micro-stripes.