Interplay of charge and excitons in a moiré induced correlated insulator

Moiré heterostructures of MoSe₂/WS₂ provide an ideal platform to explore the interplay between correlated charge order and excitonic phenomena. The moiré potential creates flat minibands where electrons, holes, and excitons can be localized at different spatial sites. While correlated insulating phases have been observed, the nature of the moiré excitons remains relatively less understood. Here, we perform differential reflectance optical spectroscopy to identify two moiré-induced exciton species with differing extended spatial profiles and sensitivity to the localization of the charge filling. While modifying the interlayer band alignment using an out-of-plane electric field, we detect the charge localization between different moiré sites and across the layers using these moiré excitons. The evolution of the exciton spectra with carrier doping and electric field demonstrates strong interplay between charge ordering and the excitonic states in this moiré induced correlated insulator. Our findings highlight the complex excitonic landscape of MoSe₂/WS₂ heterostructures and establish delocalized charge-transfer excitons as a sensitive optical probe of correlated electron phenomena in van der Waals moiré systems.