Ying Han1,2,Ke Cao3,Shizhe Feng4,Zhiping Xu4,Yang Lu1,5
City University of Hong Kong1,Pennsilyvinia State University2,Xidian University3,Tsinghua University4,The University of Hong Kong5
Ying Han1,2,Ke Cao3,Shizhe Feng4,Zhiping Xu4,Yang Lu1,5
City University of Hong Kong1,Pennsilyvinia State University2,Xidian University3,Tsinghua University4,The University of Hong Kong5
Due to the outstanding physical and chemical properties, two-dimensional (2D) materials, such as graphene and hexagonal boron nitride (hBN) hold great promise for a variety of mechanical, electrical, optical and many other functional applications. Van der Waals (vdW) heterostructures make 2D flexible electronics device possible with unique properties, especially twisted vdW heterostructures. Furthermore, applying mechanical strain to 2D material could lead to unusual and tunable physical properties for unpreceded strain engineering applications. However, due to the experimental limitation, introducing large uniform strain into 2D materials remains a great challenge. Recently, by developing a protocol for sample transfer, shaping and straining, we report the elastic properties and stretchability of free-standing single-crystalline monolayer graphene grown by chemical vapor deposition [1], with sample-wide elastic strain up to ~6% and Young’s modulus close to theoretical value ~1TPa. Similarly, we demonstrate that large elastic deformation can be also achieved in free-standing h-BN monolayers [2], twisted bilayer graphene[3] and other emerging twisted vdW structures, allowing for unprecedented functional 2D material applications. Our results show that graphene, h-BN, twisted bilayer graphene and other emerging twisted vdW structures have outstanding mechanical properties. The near ideal mechanical strength and resilience of 2D materials and van der Waals heterostructures reported here, as well as our uniform, reversible, dynamic strain controlling mechanism, would facilitate the practical elastic strain engineering (ESE) applications, as well as piezoelectric electronics and flexible electronic.<br/><br/>1. Cao, K., et al., Elastic straining of free-standing monolayer graphene. Nature Communications, 2020. 11(1): p. 284.<br/>2. Han, Y., et al., Large Elastic Deformation and Defect Tolerance of Hexagonal Boron Nitride Monolayers. Cell Reports Physical Science 1.8 (2020): 100172.<br/>3. Han, Y., et al. Deep elastic strain engineering of 2D materials and their twisted bilayers. ACS Applied Materials & Interfaces 14.7 (2022): 8655-8663.