Ultra-Large-Period Moiré Lattices in Twisted Trilayer MoS₂ Induced by High-Symmetry Sites.

Abstract

Twisted trilayer (Tt) transition metal dichalcogenides with multiple rotational degrees of freedom offer unprecedented opportunities for constructing large-wavelength moiré superlattices to maximize the effect of correlated behaviors. Precisely stacking trilayer structures to realize ultra-large moiré superlattices remains a significant challenge, hindering investigations of moiré-tuned excitonic properties. Here we fabricate Tt MoS₂ via chemical vapor deposition, in which two commensurate twists of 2.7° and 21.9° are sequentially introduced from the top to middle, and to bottom layers. An unprecedented super-moiré structure with an ultra-large periodicity of around 24 nm is achieved, 30 times larger than that of 21.9°-bilayer MoS₂, hierarchically composed of periodical mirror-symmetric triangular tessellation patterns consisting of five kinds of high-symmetric stacking registrations and the relaxation regions resulting from the interlayer gliding. This robust ultra-large-period superstructure generates a deep moiré potential to effectively suppress intralayer moiré excitons recombination and be against intervalley exchange interaction at the magnetic field up to 9T, associated with the enhanced layer-valley-locked polarization by two-fold larger than that of the trilayer systems with incommensurate angles. Our work presents angle-dependent super-moiré architectures in Tt systems as a versatile platform for designing moiré quantum materials with tailored optoelectronic responses, advancing applications in valleytronic and excitonic devices.