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Abstract 2D materials can be isolated as monolayer sheets when interlayer interactions involve weak van der Waals forces. These atomically thin structures enable novel topological physics and open chemical questions of how to tune the structure and properties of the sheets while maintaining them as isolated monolayers. Here, this work investigates 2D electroactive sheets that exfoliate in solution into colloidal nanosheets, but aggregate upon oxidation, giving rise to tunable interlayer charge transfer absorption and photoluminescence. This optical behavior resembles interlayer excitons, now intensely studied due to their long‐lived emission, but which remain difficult to tune through synthetic chemistry. Instead, the interlayer excitons of these framework sheets can be modulated through control of solvent, electrolyte, oxidation state, and the composition of the framework building blocks. Compared to other 2D materials, these framework sheets display the largest known interlayer binding strengths, attributable to specific orbital interactions between the sheets, and among the longest interlayer exciton lifetimes. Taken together, this study provides a microscopic basis for manipulating long‐range opto‐electronic behavior in van der Waals materials through molecular synthetic chemistry.
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This content will become publicly available on January 2, 2026
Long-Lived Population Inversion in Resonantly Driven Excitonic Antiferromagnet
Van der Waals magnets are an emerging material family for investigating light-matter interactions and spin-correlated excitations. Here, we report the discovery of a photo-induced state with a lifetime of 17 ps in the van der Waals antiferromagnet NiPS3, which appears exclusively with resonant pumping at 1.476 eV in the antiferromagnetic state. The long-lived state comes with a negative photoconductivity, a characteristic optical response of population inversion. Our findings demonstrate a promising pathway to potentially achieve long-lived lasing at terahertz frequencies in reduced dimensions.
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- Award ID(s):
- 1944957
- PAR ID:
- 10563636
- Publisher / Repository:
- American Physical Society (APS)
- Date Published:
- Journal Name:
- Physical review letters
- Volume:
- 134
- ISSN:
- 1079-7114
- Page Range / eLocation ID:
- 016901
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
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