Efficient strain modulation of 2D materials via polymer encapsulation
Zhiwei Li, Yawei Lv, Liwang Ren, Jia Li, Lingan Kong, Yujia Zeng, Quanyang Tao, Ruixia Wu, Huifang Ma, Bei Zhao, Di Wang, Weiqi Dang, Keqiu Chen, Lei Liao, Xidong Duan, Xiangfeng Duan, Yuan Liu
Nat. Commun. 11, 1-8 (2020)
Strain engineering is a promising method to manipulate the electronic and optical properties of two-dimensional (2D) materials. However, with weak van der Waals interaction, severe slippage between 2D material and substrate could dominate the bending or stretching processes, leading to inefficiency strain transfer. To overcome this limitation, we report a simple strain engineering method by encapsulating the monolayer 2D material in the flexible PVA substrate through spin-coating approach. The strong interaction force between spin-coated PVA and 2D material ensures the mechanical strain can be effectively transferred with negligible slippage or decoupling. By applying uniaxial strain to monolayer MoS2, we observe a higher bandgap modulation up to ~300 meV and a highest modulation rate of ~136 meV/%, which is approximate two times improvement compared to previous results achieved. Moreover, this simple strategy could be well extended to other 2D materials such as WS2 or WSe2, leading to enhanced bandgap modulation.