Strain engineering of emergent anisotropic responses in WSe 2 monolayer

Abstract Strain engineering offers an effective strategy to break the intrinsic symmetry of two-dimensional (2D) materials, thereby enabling tunable anisotropic responses and broadening their functional versatility. However, achieving novel anisotropic behaviors through strain engineering remains challenging and lacks systematic study. Here, mixed-dimensional 2D/one-dimensional (1D) heterostructures were constructed using monolayer WSe2 and SiO2 nanorods, where the diameter of SiO2 nanorods effectively regulated the strain in monolayer WSe2 to investigate its anisotropic responses. The WSe2 at strained interfaces exhibits tunable photoluminescence enhancement, modulated bandgap, and the emergence of polarized photoluminescence by adjusting the diameter of the nanorods. Interestingly, an unexpected in-plane ferroelectricity was observed in monolayer WSe2 at the heterointerface. Additionally, the heterostructure photodetectors demonstrate outstanding overall performance with a broadband detection range from 375 to 808 nm, a competitive photoswitching ratio of ~ 3200, a high detectivity of 2.4 × 109 Jones, and a fast response speed of ~ 11.3 ms. Another interesting finding is that the photodetectors demonstrate polarization-dependent detection with a tunable dichroic ratio ranging from 1 to 1.51. The heterostructure detectors can reliably capture sequential images of the capital letter “H”. This study provides an effective strategy for tailoring the anisotropic responses of TMDCs and further endowing their diverse functionalities and applications.