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The investigation of in-plane two-dimensional (2D) anisotropic materials has garnered significant attention due to their exceptional electronic, optical, and mechanical characteristics. The anisotropic optical properties and angle-dependent photodetectors of 2D...

Moiré superlattices in the twisted van der Waals materials have become an excellent platform for exploring new quantum phenomena due to the interaction between atomic structure and electronic correlation. Moiré superlattice can generate periodic moiré potential, which can constrain the recombination of excitons, leading to exotic quantum phenomena, including moiré excitons, flat bands, etc., which have been extensively reported in TMDs structures. However, the effect between the modulating of the moiré potential and the number of twisted layers has not been the subject of experimental research yet. Here we synthesized a twisted trilayer homostructure by a dry-transfer method and the enhancement of the moiré potential by the number of twisted layers is investigated. The moiré potential depths of the twisted bilayer and trilayer homostructure are 111 and 212 meV (increased by 91%), which further demonstrate that the depth of the moiré potential can be controlled by adjusting the number of stacked layers. Enhanced moire potential allows observation of moire excitons at 77 K, which are improved by an order of magnitude bigger than those of other moiré excitons(less than 10 K). Our results provide a new method for controllable preparation of moire potentials and a new avenue for further exploration of highly correlated quantum phenomena.

Moiré superlattice created by the stacking of twisted 2D layered materials have become a new platform for the study of quantum optics. The strong coupling of moiré superlattices can generate flat minibands that enhance electronic interactions and produce a variety of fascinating strongly correlated states such as non-conventional superconductivity, Mott insulating states and moiré excitons. However, the influence between the adjustment and localization of moiré excitons in Van der Waals heterostructures has not been the subject of experimental investigations. Here we report experimental evidence of the localization-enhanced moiré excitons in the twisted WSe2/WS2/WSe2 heterotrilayer with type-II band alignments. At low temperature, we observed multiple excitons splitting phenomena in the twisted WSe2/WS2/WSe2 heterotrilayer, manifesting as multiple sharp emission lines, contrasting strongly with the moiré excitonic behavior of the twisted WSe2/WS2 heterobilayer (the linewidth is 4 times narrower). This is primarily because the enhancement of the two moiré potentials in the twisted heterotrilayer enables the moiré excitons at the highly localized interface. Furthermore, the changes in temperature, laser power and valley polarization further demonstrate the confinement effect of moiré potential on moiré excitons. Our findings provide a new way for the localization of moiré excitons in twist-angle heterostructures, facilitating the development of coherent quantum light emitters.

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