2, Stanford University, Stanford, California, United States
3, Harvard University, Boston, Massachusetts, United States
Graphene, together with other two-dimensional materials, are promising building blocks for both conventional semiconductor technologies and the nascent flexible nanotechnology. However, due to its intrinsic stiffness and strength, it is challenging to utilize them in stretchable electronics. For example, CVD graphene transferred onto a polydimethylsiloxane (PDMS) elastic substrate can only maintain its conductivity up to 6% strain1 and transistor can maintain electrical functional at stretching up to 5%.2 The above stretchability is far less than the minimum required value (~50%) for wearable health monitoring sensors and electronic skin. To address this challenge, graphene kirigami-approach has recently been explored.3 However, this method requires suspended graphene and is extremely complicated in fabrication and operation.
Here, to achieve highly stretchable large-area graphene devices, we developed an all graphene nanostructure that confines graphene scrolls in between stacked graphene layers, namely multi-layer G/G scrolls (MGG). MGG consists of three-dimensional conductive paths, which bridge the fragmented domains to maintain conductivity of the resulting transparent graphene film. Bi- and tri-layer MGG supported on an elastomer exhibited significantly less reduction in conductivity even at the strain up to 100%. An all-carbon transistor fabricated using MGG as electrodes retained 60% of its original performance at 120% strain. This is the first demonstration of highly stretchable and ultra-transparent graphene-based transistors. The concept reported here should be applicable to other 2D materials and thus opens up a new route toward stretchable 2D electronics.
For more information, please refer to: Science Advances, 2017, 3, 9, e1700159.
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2. Nano Letters, 2011, 11, 4642-4646.
3. Nature, 2015, 524, 204-207.