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

Moiré superlattices offer an unprecedented opportunity for tailoring interactions between quantum particles and their coupling to electromagnetic fields. Strong superlattice potentials generate moiré minibands of excitons-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 strengths. Here we report the direct observation of layer-hybridized moiré excitons in angle-aligned WSe/WS and MoSe/WS superlattices by optical reflectance spectroscopy. These excitons manifest a hallmark signature of strong coupling in WSe/WS, 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 condensates and Bose-Hubbard models, and optoelectronic applications of these materials.