Tuning layer-hybridized moiré excitons by the quantum-confined Stark effect.

Moiré superlattices offer an unprecedented opportunity for tailoring interactions between quantum particles1-11 and their coupling to electromagnetic fields12-18. Strong superlattice potentials generate moiré minibands of excitons16-18-bound pairs of electrons and holes that reside either in a single layer (intralayer excitons) or in two separate layers (interlayer excitons). Twist-angle-controlled interlayer electronic hybridization can also mix these two types of exciton to combine their strengths13,19,20. Here we report the direct observation of layer-hybridized moiré excitons in angle-aligned WSe2/WS2 and MoSe2/WS2 superlattices by optical reflectance spectroscopy. These excitons manifest a hallmark signature of strong coupling in WSe2/WS2, that is, energy-level anticrossing and oscillator strength redistribution under a vertical electric field. They also exhibit doping-dependent renormalization and hybridization that are sensitive to the electronic correlation effects. Our findings have important implications for emerging many-body states in two-dimensional semiconductors, such as exciton condensates21 and Bose-Hubbard models22, and optoelectronic applications of these materials.