Localization-enhanced moire exciton in twisted transition metal dichalcogenide heterotrilayer superlattices

The stacking of twisted two-dimensional (2D) layered materials has led to the creation of moire superlattices, which have become a new platform for the study of quantum optics. The strong coupling of moire superlattices can result in flat minibands that boost electronic interactions and generate interesting strongly correlated states, including unconventional superconductivity, Mott insulating states, and moire excitons. However, the impact of adjusting and localizing moire excitons in Van der Waals heterostructures has yet to be explored experimentally. Here, we present experimental evidence of the localization-enhanced moire excitons in the twisted WSe2/WS2/WSe2 heterotrilayer with type-II band alignments. At low temperatures, we observed multiple excitons splitting in the twisted WSe2/WS2/WSe2 heterotrilayer, which is manifested as multiple sharp emission lines, in stark contrast to the moire excitonic behavior of the twisted WSe2/WS2 heterobilayer (which has a linewidth 4 times wider). This is due to the enhancement of the two moire potentials in the twisted heterotrilayer, enabling highly localized moire excitons at the interface. The confinement effect of moire potential on moire excitons is further demonstrated by changes in temperature, laser power, and valley polarization. Our findings offer a new approach for localizing moire excitons in twist-angle heterostructures, which has the potential for the development of coherent quantum light emitters.

Automated summary

This study presents experimental evidence of localization-enhanced moire excitons in twisted WSe2/WS2/WSe2 heterotrilayers. The confinement effect of moire potential on moire excitons is demonstrated through changes in temperature, laser power, and valley polarization. The findings have implications for the localization of moire excitons and the development of coherent quantum light emitters.