Efficient and anisotropic strain engineering in few-layer 3R-MoS2 via polymer encapsulation

Efficient strain transfer to few-layer two-dimensional materials remains challenging due to weak interfacial coupling. Here, we apply uniaxial tensile strain up to 4.3% to few-layer 3R-MoS2 using a polymer encapsulation approach on a flexible polyethylene terephthalate substrate. The in-plane lattice vibrations and exciton emissions exhibit pronounced anisotropic modulation efficiency. The response is strongest along the zigzag direction, yielding a maximum phonon mode splitting of 10.81 cm−1 and a bandgap modulation of 175.8 meV, values that surpass those reported for most monolayer and few-layer 2H-MoS2. This work offers a general and effective strain-engineering approach for exploring strain modulation in other few-layer two-dimensional materials.