Anomalously enhanced diffusivity of moiré excitons via manipulating the interplay with correlated electrons

Semiconducting transition metal dichalcogenide (TMDC) moiré superlattices provide an unprecedented platform for manipulating excitons. The in-situ control of moiré excitons could enable novel excitonic devices but remains challenging. Meanwhile, as dipolar composite bosons, interlayer excitons in the type-II aligned TMDC moiré superlattices exhibit strong interactions with fermionic charge carriers. Here, we demonstrate active manipulation of exciton diffusivity by tuning their interplay with correlated carriers in moiré potentials. When electrons form Mott insulators, the interlayer exciton energy is blueshifted due to strong electron-exciton repulsion, leading to the enhancement of diffusivity by as much as two orders of magnitude. In contrast, exciton diffusivity is suppressed at fractional fillings, where carriers form generalized Wigner crystals. In between fractional fillings, electrons populate all moiré traps, resulting in enhanced diffusivity with increasing carrier density, owing to the effectively reduced moiré potential confinement experienced by excitons. Our study inspires further engineering and controlling exotic excitonic states in TMDC moiré superlattices for fascinating quantum phenomena and novel excitonic devices.