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Observation of Wannier-Rydberg and Charge-Transfer Hybrid Moiré Excitons under Pressure

Jing Song1,*, Yifan Wang2,3,*, Xuan Zhao1,4,*, Yuxuan Song1,4,*, Song Liu5, Chen Hu2,3,†, and Yang Xu1,4,‡

  • *These authors contributed equally to this work.
  • †Contact author: chenhu@cuhk.edu.hk
  • ‡Contact author: yang.xu@iphy.ac.cn
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Phys. Rev. X 16, 041007 – Published 6 October, 2026

DOI: https://doi.org/10.1103/lgl7-ww2r

Abstract

Moiré superlattices in van der Waals heterostructures, arising from lattice mismatch or twist angle, provide a powerful platform for engineering correlated electronic and excitonic states. Moiré excitons form when electrons and holes are individually modulated by the moiré potential yet remain bound by Coulomb interaction, resulting in exciton wave functions with a highly nontrivial and rich real-space structure. However, achieving in situ and dynamic control over the interplay between excitonic Coulomb interaction and the moiré potential remains a central challenge. Here, we demonstrate that hydrostatic pressure provides a continuous and effective means of enhancing the moiré potential and tuning moiré excitons in WSe2/WS2 moiré heterobilayers. As pressure increases, intralayer moiré excitons exhibit systematic redshifts as the moiré potential deepens. Crucially, above ∼3  GPa the system enters a strong-moiré regime, where a new higher-energy intralayer moiré exciton emerges that is not accessible otherwise. Combining dual-gate optical spectroscopy with Bethe-Salpeter equation calculations, we reveal that this emerging moiré exciton state arises from strong pressure-induced hybridization between two distinct exciton series: Wannier-Rydberg and charge-transfer excitons. Enhanced exciton-electron and exciton-exciton interactions observed in doping-dependent photoluminescence further evidence the strengthened moiré potential under pressure. Our work establishes a pioneering paradigm of moiré excitonic wave function engineering, enabling the on-demand creation of tailored excitonic species in moiré superlattices.

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Popular Summary

Achieving in situ and dynamic tuning of moiré exciton states in stacked semiconductor superlattices remains challenging because static twist angles permanently fix the landscape of periodic potentials and Coulombic interactions. We addressed this limitation by combining optical spectroscopy with theoretical calculations to demonstrate that hydrostatic pressure acts as a continuous tuning knob for the moiré potential depth.

We observed that applying pressure drives a transition from a moderate- to a strong-moiré regime, triggering strong quantum hybridization between spatially distinct Wannier-Rydberg excitons and charge-transfer excitons. We found that this pressure-induced mixing gives rise to an emergent, hybrid moiré exciton state whose optical response can be continuously controlled. Our work establishes hydrostatic pressure as an effective mechanism for engineering excitonic states and tailoring quantum excitations on demand in moiré materials.

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Phys. Rev. X 16, 041007– Published 6 October, 2026
  • Received 26 March 2026
  • Revised 20 July 2026
  • Accepted 28 August 2026
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Published by the American Physical Society under the terms of the Creative Commons Attribution 4.0 International license. Further distribution of this work must maintain attribution to the author(s) and the published article’s title, journal citation, and DOI.

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