Electrostatic-strain control of moiré excitons in suspended WS2/WSe2 heterobilayers

Strain engineering has emerged as a highly effective approach for tailoring moiré potentials in transition metal dichalcogenide (TMD) superlattices, providing a versatile platform for exploring emergent excitonic phenomena. Dynamic, biaxial strain control at cryogenic temperatures is critical for cutting-edge physical studies, yet it remains experimentally challenging. Here, we demonstrate in situ electrostatic strain control of exciton states in suspended WS2/WSe2 heterobilayers. Using this technique, we identify a strain-insensitive, defect-localized interlayer exciton species (IXD)—one that dominates photoluminescence (PL) spectra at zero strain but was overlooked in earlier studies. This method achieves wide-range energy tuning of intrinsic interlayer excitons (IXs) by up to ~237 meV, facilitating the formation of strongly hybridized states with enhanced emission when spin-triplet IXs are redshifted into resonance with IXD. Moreover, this approach enables spectral decoupling of intrinsic IXs from IXD, allowing direct observation of the threshold behavior of dipole-dipole repulsion among moiré-confined excitons. Notably, we observe the emergence of hybridized intra-/interlayer exciton complexes and biexcitons when WSe2 intralayer excitons are strain-tuned into resonance with IXD. These results establish electrostatic strain as a powerful tool for in situ manipulation of moiré excitons, opening avenues for applications in quantum information, electronics, and photonics.