Observation and Modulation of High-Temperature Moiré-Locale Excitons in van der Waals Heterobilayers.

Abstract

Transition metal dichalcogenide heterobilayers feature strong moiré potentials with multiple local minima, which can spatially trap interlayer excitons at different locations within one moiré unit cell (dubbed moiré locales). However, current studies mainly focus on moiré excitons trapped at a single moiré locale. Exploring interlayer excitons trapped at different moiré locales is highly desirable for building polarized light-emitter arrays and studying multiorbital correlated and topological physics. Here, via enhancing the interlayer coupling and engineering the heterointerface, we report the observation and modulation of high-temperature interlayer excitons trapped at separate moiré locales in WS2/WSe2 heterobilayers. These moiré-locale excitons are identified by two emission peaks with an energy separation of ∼60 meV, exhibiting opposite circular polarizations due to their distinct local stacking registries. With the increase of temperature, two momentum-indirect moiré-locale excitons are observed, which show a distinct strain dependence with the momentum-direct one. The emission of these moiré-locale excitons can be controlled via engineering the heterointerface with different phonon scattering, while their emission energy can be further modulated via strain engineering. Our reported highly tunable interlayer excitons provide important information on understanding moiré excitonic physics, with possible applications in building high-temperature excitonic devices.