The electronic ground states of transition-metal dichalcogenides are strongly shaped by reduced dimensionality, yet the properties of atomically thin layers remain difficult to probe due to their small size and environmental sensitivity. Here we demonstrate that controlled electrochemical intercalation of organic cations provides a robust bulk platform for accessing monolayer-like physics in NbSe2. Intercalation of tetrapropylammonium and tetrabutylammonium expands the interlayer spacing by nearly a factor of two, electronically decoupling the NbSe2 layers while simultaneously introducing well-defined charge doping. Using a combination of Raman spectroscopy, scanning tunneling microscopy, X-ray diffraction, and photoemission, we uncover a pronounced enhancement of the charge-density-wave transition temperature to ∼130 K together with a strong suppression of superconductivity, reproducing the phase diagram observed in exfoliated monolayers. The enhanced charge-density-wave order and reduced Tc arise from the combined effects of dimensionality reduction and electron injection, and are accompanied by distinct dip-hump anomalies in the tunneling spectra suggestive of collective mode excitations. Our results establish molecular intercalation as a powerful and scalable route for engineering competing orders in layered quantum materials.
@article{arxiv.2601.14902,
title = {Enhanced Charge-Density-Wave Order and Suppressed Superconductivity in Intercalated Bulk $\mathrm{Nb}{\mathrm{Se}}_{2}$},
author = {Huanhuan Shi and Qili Li and Antoine M. T. Baron and Marie-Aude Méasson and Sangjun Kang and Dirk Fuchs and Fabian Henssler and Alexander Haas and Paolo Battistoni and Nour Maraytta and Michael Merz and Amir-Abbas Haghighirad and Wulf Wulfhekel and Christian Kübel and Matthieu Le Tacon},
journal= {arXiv preprint arXiv:2601.14902},
year = {2026}
}