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Moiré superlattices in van der Waals structures have emerged as a powerful platform for studying the novel quantum properties of two-dimensional materials. The periodic moiré patterns generated by these structures lead to the formation of flat mini-bands, which alter the electronic energy bands of the material. The resulting flat electronic bands can greatly enhance strong correlative interactions between electrons, leading to the emergence of exotic quantum phenomena, including moiré phonons and moiré excitons. While extensive research has been conducted on the exotic quantum phenomena in twisted bilayers of transition metal dichalcogenides (TMDs), and the regulatory effect of stacked layers on moiré excitons remains unexplored. In this study, we report the fabrication of a twisted WSe2/WSe2/WSe2 homotrilayer with two twist angles and investigate the influence of stacked layers on moiré excitons. Our experiments reveal multiple moiré exciton splitting peaks in the twisted trilayer, with moiré potential depths of 78 and 112 meV in the bilayer and trilayer homostructures, respectively. We also observed the splitting of the moiré excitons at 90 K, indicating the presence of a deeper moiré potential in the twisted trilayer. Moreover, we demonstrate that stacked layers can tune the moiré excitons by manipulating temperature, laser power, and magnetic field. Our results provide a new physical model for studying moiré superlattices and their quantum properties, which could potentially pave the way for the development of quantum optoelectronics. [ABSTRACT FROM AUTHOR]

Recently, the discovery of a variety of moiré-related properties in the twisted vertical stacking of two different monolayers has attracted considerable attention. The introduction of small twist angles in transition metal dichalcogenide (TMD) heterostructures leads to the emergence of moiré potentials, which provide a fascinating platform for the study of strong interactions of electrons. While there has been extensive research on moiré excitons in twisted bilayer superlattices, the capture and study of moiré excitons in homostructure superlattices with layer-coupling effects remain elusive. Here, we present the observation of moiré excitons in the twisted 1L-WSe2/1L-WSe2 and 1L-WSe2/2L-WSe2 homostructures with various layer-coupling interactions. The results reveal that the moiré potential increases (~ 260%) as the number of underlying layers decreases, indicating the effect of layer coupling on the modulation of the moiré potential. The effects of the temperature and laser power dependence as well as valley polarization on moiré excitons were further demonstrated, and the crucial spectral features observed were explained. Our findings pave the way for exploring quantum phenomena and related applications of quantum information. [ABSTRACT FROM AUTHOR]

The excitonic effects in two-dimensional transition metal dichalcogenides and their heterostructures have been extensively investigated. Significantly, the moiré excitons, induced by a moiré superlattice in a twisted heterostructure, have triggered tremendous attention, demonstrating the practicability of artificial excitonic crystals. Besides, recent works have shown that the excitonic states in homostructures also exhibit novel properties worthy of further development. Here, we present a tear-and-stack technique for fabricating a regular or a twisted homostructure. Such a strategy was utilized to reassemble a monolayer WSe2 into a twisted homostructure, and various excitons from this structure have been identified in the photoluminescence spectra. Interestingly, the unusual equidistant splitting was first observed in the defect-bound excitons. It is believed that this phenomenon is attributed to the various defect states and the local stacking patterns. This interpretation is supported by theoretical calculations, which show the dependence of the energy band structure on different defect states and local stacking patterns. These unconventional defect-bound excitons are key building blocks in the research of homostructures that highlight the feasibility of artificially manipulating local excitons for practical applications. [ABSTRACT FROM AUTHOR]