Symmetry Breaking in Twisted Mixed-Dimensional Heterostructure Interfaces for Multifunctional Polarization-Sensitive Photodetection

Moiré superlattices, created by stacking different van der Waals materials at twist angles, have emerged as a versatile platform for exploring intriguing phenomena such as topological properties, superconductivity, the quantum anomalous Hall effect, and the unconventional Stark effect. Additionally, the formation of moiré superlattice potential can generate spontaneous symmetry breaking, leading to an anisotropic optical response and electronic transport behavior. Herein, we propose a two-step chemical vapor deposition (CVD) strategy for synthesizing WS₂/Sb₂S₃ moiré superlattices. Density functional theory calculations show that the moiré potential and interlayer distance at the WS₂/Sb₂S₃ interface can generate anisotropic electronic states. The atomic-resolution HAADF-STEM image clearly reveals angle-dependent complicated moiré periodicity. The polarization-dependent second harmonic generation, Raman, photoluminescence, and absorption spectroscopy of the WS₂/Sb₂S₃ heterostructure confirm optical anisotropic behavior due to symmetry breaking by the moiré superlattice formation. The WS₂/Sb₂S₃ device exhibits high on/off ratios up to 10⁶, a relatively low leakage current of 10^-13 A, and a broadband optoelectronic response range from 360 to 914 nm. Notably, the broken symmetry by C₂-symmetric Sb₂S₃ nanowires grown on a C₃-symmetric WS₂ nanosheet endows the WS₂/Sb₂S₃ photodetector with strong polarization-dependent photocurrent intensity and high-resolution polarization imaging capability. Our study demonstrates the potential for constructing multifunctional moiré materials by incorporating symmetry-breaking engineering.